![Page 1: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/1.jpg)
CardiovascularSystem
![Page 2: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/2.jpg)
Human heart
![Page 3: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/3.jpg)
Heart Functions
a. Generates the pressure that propels blood thru blood vessels.
b. Separates oxygenated and deoxygenated blood.
c. Helps regulate the body’s blood supply.
![Page 4: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/4.jpg)
Position of the Heart
a. Within the mediastinum, the medial cavity of the thorax.
b. Apex rests on the superior diaphragmatic surface and points toward the left hip.
c. Base points towards the right shoulder.
d. Medial to the lungs, anterior to the esophagus and vertebrae, and posterior to the sternum.
![Page 5: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/5.jpg)
Position of the Heart
Mediastinum
Pericardium
Epicardium
Myocardium
Endocardium
![Page 6: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/6.jpg)
Pericardium
a. Encloses the heart. b. Outermost layer is the fibrous pericardium – a collagenous
structure that protects and anchors the heart and prevents it from distending.
c. Deeper is the serous pericardium, a 2 layered serous membrane. d. Parietal serous pericardium is the outer of the 2 and abuts the
fibrous pericardium. e. Visceral serous pericardium is the inner of the 2 and is the external
covering of the heart and is a.k.a. the epicardium. f. Parietal and visceral layers are continuous with one another where
the great vessels leave the heart. g. Pericardial cavity is the space between the parietal and visceral
layers and contains serous fluid, which reduces friction.
![Page 7: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/7.jpg)
Heart wall
Divided into 3 layers. A. Epicardium
i. Most superficial and is a.k.a. visceral serous pericardium. ii. Composed of simple squamous epithelium overlaying thin loose CT.
B. Myocardium i. Middle layer. ii. Primarily cardiac muscle, but also contains blood vessels, nerves, and
CT. iii. Myocardial CT forms a dense network known as the fibrous skeleton,
which supports the heart valves, acts as origin/insertion for the cardiac muscle cells, and helps direct the spread of electrical activity within the heart along defined pathways.
C. Endocardiumi. Inner layer ii. Consists of endothelium (simple squamous epithelium) resting on a layer of thin CT. iii. Lines the heart chambers and its folds create the heart valves.
![Page 8: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/8.jpg)
Heart Surface
![Page 9: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/9.jpg)
Heart Posterior
![Page 10: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/10.jpg)
Heart Chambers
a. 2 superior atria and 2 inferior ventricles.
b. Thin interatrial (IA) septum divides the 2 atria
c. Thick interventricular (IV) septum divides the 2 ventricles.
![Page 11: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/11.jpg)
Heart Interior
![Page 12: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/12.jpg)
Human Heart Interior
![Page 13: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/13.jpg)
Heart consists of 2 pumps connected in series.
a. Each pump sends blood to a different circuit.
b. Pulmonary circuit runs btwn the heart and the lungs.
c. Systemic circuit runs btwn the heart and the rest of the body tissues.
d. Right side of the heart receives deO2 blood from the systemic circuit and pumps it thru the pulmonary circuit.
e. Left side of the heart receives O2 blood from the pulmonary circuit and pumps it thru the systemic circuit.
![Page 14: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/14.jpg)
Circulation
![Page 15: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/15.jpg)
Atria
a. Heart’s receiving chambers.
b. Small and thinly muscled. Large muscle mass is unnecessary, since atrial contraction propels only a small amount of blood to the ventricles.
![Page 16: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/16.jpg)
Right atrium
A. Receives deO2 blood from the systemic circuit via 3 vessels:
i. Superior vena cava carries blood from arms, head, and upper torso
ii. Inferior vena cava carries blood from the legs, abdomen, and pelvis
iii. Coronary sinus carries blood from the coronary circulation – which nourishes the heart wall.
B. Sends blood to right ventricle thru tricuspid orifice, via the tricuspid valve.
![Page 17: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/17.jpg)
Heart Surface
![Page 18: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/18.jpg)
Heart Posterior
![Page 19: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/19.jpg)
Heart Interior
![Page 20: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/20.jpg)
Left atrium
a. Receives O2 blood from the pulmonary circuit via the 4 pulmonary veins.
b. Sends blood to left ventricle thru mitral (bicuspid) orifice, via the mitral (bicuspid)
valve.
![Page 21: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/21.jpg)
Heart Surface
![Page 22: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/22.jpg)
Heart Posterior
![Page 23: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/23.jpg)
Heart Interior
![Page 24: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/24.jpg)
Left and right auricles
a. Muscular pouches connected to the left and right atria.
b. Function as reservoirs for blood.
![Page 25: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/25.jpg)
Heart Surface
![Page 26: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/26.jpg)
Fossa ovalis
a. Remnant of the foramen ovale, a hole in the fetal atrial septum.
i. Fetal blood flowed through the hole from RA to LA thus bypassing the pulmonary circuit (since the fetal lungs are neither developed nor oxygenated).
![Page 27: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/27.jpg)
Heart Interior
![Page 28: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/28.jpg)
Ventricles
a. Large, muscular chambers.
b. Thick musculature is necessary because they are the actual pumps.
c. Contain muscular ridges known as trabeculae carneae as well as muscular bulges known as papillary muscles.
![Page 29: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/29.jpg)
Right ventricle
a. Discharges blood into the pulmonary trunk, the first vessel of the pulmonary circuit.
b. Separated from the pulmonary trunk by the pulmonary semilunar valve
![Page 30: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/30.jpg)
Left ventricle
a. Discharges blood into the aorta, the first vessel of the systemic circuit.
b. Separated from the aorta by the aortic semilunar valve.
c. More muscular than the RV.
i. Necessary because the LV pumps blood a farther distance and against greater pressure (note – RV and LV pump the same volume of blood per beat).
![Page 31: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/31.jpg)
Systemic and Pulmonary circuits
Systemic circuit:
LV—Aorta—Systemic arteries—Syst capillaries—Syst veins—Vena Cava—RA
Pulmonary circuit:
RV—Pulmonary Trunk—Pulm Arteries—Pulm capillaries—Pulm veins--LA
![Page 32: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/32.jpg)
If we combine the 2 circuits, note that we have 2 pumps in series:
LA—LV—Syst Blood Vessels—RA—RV—Pulm Blood Vessels
The circuit then begins again.
Systemic and Pulmonary circuits
![Page 33: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/33.jpg)
Circulation
![Page 34: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/34.jpg)
Ways in which the systemic circuit differs from
the pulmonary circuit
a. Longer
b. Much larger blood volume.
c. Its blood is under far greater pressure.
d. Resistance to blood movement is also far greater.
e. Systemic arteries are O2 rich & CO2 poor. Pulmonary arteries are O2 poor & CO2 rich.
Systemic veins are O2 poor and CO2 rich. Pulmonary veins are O2 rich and CO2 poor.
![Page 35: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/35.jpg)
Hepatic Portal Circulation:
a. The hepatic portal circulation collects blood from the veins of the pancreas, spleen, stomach, intestines, and gallbladder and directs it into the hepatic portal vein of the liver.
b. This circulation enables the liver to utilize nutrients and detoxify harmful substances in the blood.
![Page 36: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/36.jpg)
Fetal Circulation:
a. The fetal circulation involves the exchange of materials between fetus and mother.
b. The fetus derives its oxygen and nutrients and eliminates its carbon dioxide and wastes through the maternal blood supply by means of a structure called the placenta.
c. At birth, when lung, digestive, and liver functions are established, the special structures of fetal circulation are no longer needed.
![Page 37: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/37.jpg)
Coronary circuit
a. Network of blood vessels supplying/draining the 3 heart layers.
b. Needed b/c the heart requires a prodigious amount of O2 and nutrients, and little O2 or nutrients can diffuse thru the thick myocardium.
![Page 38: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/38.jpg)
Basic pathway of blood in the coronary circuit is:
LV—Aorta—Coronary arteries—Cor. Capillaries—Cor. Veins—Cor. Sinus--RA
Coronary circuit
![Page 39: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/39.jpg)
Coronary Arteries
![Page 40: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/40.jpg)
Coronary Veins
![Page 41: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/41.jpg)
Human Heart
![Page 42: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/42.jpg)
4 Heart valves
a. Ensure 1-way flow within the heart.
b. 2 atrioventricular valves separating the atria from the ventricles
c. 2 semilunar valves separating the ventricles from their great vessels.
![Page 43: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/43.jpg)
AV valves
a. Consist of a flap of endothelium with a core of connective tissue.
b. Tricuspid valve has 3 flaps and prevents backflow of blood from the RV to the RA.
c. Mitral (bicuspid) valve prevents backflow from the LV to the LA
d. AV valve flaps are attached to strings of collagen called chordae tendineae.
e. Chordae tendineae attach to papillary muscles in the ventricle wall.
f. Blood goes thru an AV valve from atria to the ventricle when atrial BP > ventricular BP. i. At this time the chordae tendineae are slack, and papillary muscles are relaxed.
![Page 44: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/44.jpg)
AV valves
g. When the ventricle contracts: i. Ventricular BP > atrial BP. ii. Blood will attempt to flow down its pressure gradient
back into the atria. This pushes the valve flaps towards the atria (closing them). iii. Chordae tendineae tighten as papillary muscles contract thus preventing the valve flaps from flipping up (prolapsing) into the atrium.
h. Note that the chordae tendinae and papillary muscles do NOT close the AV valves themselves. Blood’s attempt to backflow is what pushes the valves shut.
![Page 45: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/45.jpg)
Heart Valve Locations
![Page 46: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/46.jpg)
Surface of Valves
![Page 47: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/47.jpg)
Valves
![Page 48: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/48.jpg)
Mitral Valve Prolapse
![Page 49: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/49.jpg)
Cardiac muscle
a. Comprises the bulk of the heart wall. b. Involuntary c. 2 types of cardiac muscle cells – contractile cells and
autorhythmic cells. d. Contractile cells
i. 99% ii. Generate the force involved in pumping. iii. Striated, short, and branched.
e. Autorhythmic cells i. 1% ii. Spontaneously depolarize to set the rate of contraction.
![Page 50: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/50.jpg)
Intercalated discs
a. Link cardiac muscle cells together mechanically and electrically. b. Contain 2 separate structures: gap junctions and desmosomes. c. Gap junctions
i. Protein channels that allow ions to flow btwn adjacent cells. ii. Create an electrical connection btwn cardiac muscle cells. iii. Allow the depolarization wave initiated by autorhythmic cells to
spread through the cardiac musculature. Electrical excitation of cardiac muscle cells causes an increase in intracellular Ca2+ levels. Calcium binds w/ troponin to produce contraction via the familiar sliding filament mechanism. iv. Allows the heart to function as a single coordinated unit (functional syncytium), which helps maximize its efficiency.
d. Desmosomes i. Protein filaments that physically connect adjacent cardiac muscle cells and prevent them from separating during contraction.
![Page 51: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/51.jpg)
Heart Tissue
![Page 52: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/52.jpg)
Fibrous skeleton of the heart
a. Dense irregular CT w/i the heart.
b. Provides origins and insertion points for cardiac contractile cells.
c. Supports heart valves
d. Separates the atria from the ventricles both physically and electrically
![Page 53: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/53.jpg)
Intrinsic control of heart rate
a. Performed by the autorhythmic cells
b. 5 main groups of autorhythmic cells:
i. Sinoatrial node (SA node)– group of autorhythmic cells near opening of the SVC.
ii. Atrioventricular node (AV node)– group of ACs in inferior IA septum near tricuspid orifice.
iii. Atrioventricular bundle – group of ACs in the superior IV septum.
iv. Right and left bundle branches – group of ACs in middle & inferior IV septum.
v. Purkinje fibers – separate autorhythmic cells that wind through the ventricles.
![Page 54: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/54.jpg)
Conduction System
![Page 55: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/55.jpg)
Intrinsic control of heart rate
c. The above list also gives the path of the electrical conduction system within the heart.
d. All autorhythmic cells have the ability to rhythmically and spontaneously depolarize.
e. SA node cells have the fastest rate of depolarization
i. They set the pace for other autorhythmic cells as well as the rest of the heart. \
ii. SA node is known as the pacemaker of the heart.
![Page 56: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/56.jpg)
Intrinsic control of heart rate
f. Spread of depolarization:
Depolarization wave travels to atrial contractile cells.
SA node cells depolarize
Atrial contractile cells contract. Note that the right atrium begins to contract before the left.
Depolarization wave travels to AV node. Depolarization wave is briefly delayed, allowing atria to complete contracting before the ventricles begin.
Depolarization wave travels down AV bundle & bundle branches. (Fibrous skeleton prevents it from traveling directly from atria to ventricles)
Depolarization wave travels thru the ventricles via Purkinje fibers.
Ventricular contractile cells depolarize and then contract.
![Page 57: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/57.jpg)
Intrinsic control of heart rate
g. W/o any input (neural or hormonal), the inherent rate of SA node depolarization determines heart rate.
i. Normal uninfluenced rate is roughly 100 depolarizations per minute.
h. Fibrous skeleton of the heart electrically isolates the atria and the ventricles. The AV bundle is the only electrical connection btwn them.
i.Ventricular depolarization and contraction begin at the apex of the heart and proceed upward.
This allows blood to be propelled up out of the ventricles into the great vessels.
![Page 58: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/58.jpg)
P= wave from SA node through atria
QRS = ventricular depolarization
T wave = ventricular repolarization
P-Q interval = time from atria contraction to beginning of ventricular contraction.
Q-T interval = ventricular depolarization to repolarization.
![Page 59: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/59.jpg)
![Page 60: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/60.jpg)
![Page 61: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/61.jpg)
Note:Systole& Diastole
![Page 62: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/62.jpg)
The Echo Image
![Page 63: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/63.jpg)
Echo Images
![Page 64: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/64.jpg)
Echo - Doppler
![Page 65: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/65.jpg)
Electrocardiogram:
a. The record of electrical changes during each cardiac cycle is referred to as an electrocardiogram (ECG).
b. A normal ECG consists of a P wave (spread of impulse from SA node over atria), QRS wave (spread of impulse through ventricles), and T wave (ventricular repolarization). The P-R interval represents the conduction time from the beginning of atrial excitation to the beginning of ventricular excitation. The S-T segment represents the time between the end of the spread of the impulse through the ventricles and repolarization of the ventricles.
![Page 66: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/66.jpg)
Electrocardiogram:
c. The ECG is invaluable in diagnosing abnormal cardiac rhythms and conduction patterns, detecting the presence of fetal life, determining the presence of several fetuses, and following the course of recovery from a heart attack.
d. An artificial pacemaker may be used to restore an abnormal cardiac rhythm.
![Page 67: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/67.jpg)
Pacemakers
Located in the right chest wall, a catheter is threaded through the subclavian vein, into the brachiocephalic vein, into the superior vena cava , then into the right atrium.
The pacemaker overrides the impulse from the SA node.
![Page 68: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/68.jpg)
Action Potentials
![Page 69: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/69.jpg)
Action Potential – Ventricle
![Page 70: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/70.jpg)
Extrinsic control of heart rate
a. Refers to factors originating outside of cardiac tissue that affect heart rate.
b. Most extrinsic control is nervous or endocrine in nature.
![Page 71: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/71.jpg)
Extrinsic control of heart rate
Medulla oblongata contains 2 cardiac centers that can alter the heart’s activity.
a. Cardioacceleratory center
i. Projects via the cardiac sympathetic nerves to the SA node, AV
node, and the ventricular myocardium.
ii. These neurons release NE, which increases contraction rate
and force.
![Page 72: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/72.jpg)
Extrinsic control of heart rate
b. Cardioinhibitory center
i. Contains parasympathetic neurons that project (via the vagus nerve, CN X) to the SA node and
AV nodes. T
ii. These neurons release ACh, which causes a decrease in heart rate but no change in the heart’s contractile strength.
c. At rest, both parasympathetic and sympathetic neurons are releasing neurotransmitters onto the heart, but the parasympathetic branch is dominant.
d. During stress, exercise, and excessive heat the sympathetic influence is dominant.
![Page 73: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/73.jpg)
Heart sounds
2 associated with each heart beat.
a. 1st heart sound
i. LUB
ii. Caused by the shutting of the atrioventricular valves
iii. Occurs at the onset of ventricular contraction.
b. 2nd heart sound
i. DUP
ii. Caused by the shutting of the semilunar valves
iii. Occurs at the end of ventricular contraction.
![Page 74: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/74.jpg)
Cardiac cycle
a. Refers to all events associated with blood flow thru the heart during one heartbeat.
b. Includes the contraction (systole) and relaxation (diastole) of all 4 chambers.
c. Divided into 4 parts: ventricular filling, isovolumetric contraction, ventricular ejection, and isovolumetric relaxation.
d. We’ll discuss the cardiac cycle in terms of the left side of the heart, but analogous events are occurring on the right side.
![Page 75: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/75.jpg)
Ventricular filling
a. LA BP is lower than the BP of the pulmonary vasculature, so blood enters the left atrium.
b. LA BP is greater than LV BP, so blood enters the LV.
c. B/c LA BP is greater than LV BP, the mitral valve is pushed open.
d. LV BP is less than aortic BP. As a result, blood tries to back flow from the aorta into the LV and this forces the aortic semilunar valve closed.
e. Neither atrial nor ventricular muscle is contracting. Both are in diastole.
![Page 76: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/76.jpg)
Ventricular filling
f. About 80% of the ultimate ventricular volume will enter in this passive manner.
g. At the end of ventricular filling, while the LV is still relaxing, the LA depolarizes and contracts.
i. This pushes roughly the final 20% of blood into the LV.
ii. LV now has the maximum volume it will contain during this particular cycle.
1. This is the end diastolic volume (EDV). (Typically = 130mL).
h. For the rest of the cycle, the LA will be in diastole.
![Page 77: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/77.jpg)
Isovolumetric contraction
a. LV depolarizes, contracts, and LV BP rises quickly almost immediately exceeds LA BP.
b. Blood is pushed upward shutting the mitral valve– creating the 1st heart sound (LUB).
c. However, the opening of the aortic semilunar valve requires much more pressure than
was necessary to close the mitral valve.
![Page 78: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/78.jpg)
Isovolumetric contraction
d. So after the mitral valve is shut, the LV continues to contract and its BP rises, but until LV BP exceeds aortic BP, the aortic semilunar valve remains shut.
e. Thus, during this period, the AV and semilunar valves are shut and the volume within the LV is not changing. Hence this phase is known as “iso” “volumetric” contraction.
![Page 79: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/79.jpg)
Ventricular ejection
a. LV BP now exceeds aortic BP (80mmHg), the semilunar valve is forced open, and blood is ejected from the LV into the ascending aorta.
b. Not all of the blood in the LV is ejected. The amount remaining after ventricular contraction is known as the end systolic volume (ESV). A typical value is 70mL. i. This gives a reserve amount of blood that could also be ejected if necessary (e.g., during exercise).
c. Amount of blood ejected during this phase is known as the stroke volume. i. Stroke volume is the difference btwn end diastolic
and end systolic volumes: SV=EDV-ESV. ii. A more vigorous contraction will result in a decreased ESV and an increased SV.
![Page 80: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/80.jpg)
Isovolumetric relaxation
a. Once the LV has completed contracting, its BP falls and quickly becomes less than aortic BP and blood tries to back flow, which shuts the semilunar valve– creating the 2nd heart sound (DUP).
b. However, it takes a bit longer for the LV BP to drop below the LA BP – and cause the mitral valve to open.
![Page 81: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/81.jpg)
Isovolumetric relaxation
c. During this time, as LV BP is falling, the AV and semilunar valves are shut and LV volume is not changing.
d. Once LV BP falls below LA BP (which is rising
as blood returns to the heart), the mitral valve will open and the cycle will begin anew with another round of ventricular filling.
e. With an average heartbeat of 75/min, a complete cardiac cycle requires 0.8 sec.
f. A peculiar sound is called a murmur.
![Page 82: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/82.jpg)
![Page 83: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/83.jpg)
LV vs. RV
a. Note that the events on the left side of the heart during a normal cardiac cycle are mirrored by the events on the right side of the heart.
b. Both the right and the left side of the heart contract at the same rate.
c. They have identical stroke volumes on average.
![Page 84: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/84.jpg)
LV vs. RV
d. The only difference is the pressure involved. The LV must contract harder to open its semilunar valve. This is because the systemic circuit is under a much higher pressure than the pulmonary circuit. The left and right ventricle must have identical stroke volumes. If LV SV > RV SV, then blood would back up in the systemic circuit. If LV SV < RV SV, then blood would
back up in the pulmonary circuit.
![Page 85: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/85.jpg)
Cardiac output
a. Cardiac output (CO) is the amount of blood ejected by the left ventricle into the aorta per minute. It is calculated as follows: CO = stroke volume x beats per minute.
b. Stroke volume (SV) is the amount of blood ejected by a ventricle during each systole.
c. Stroke volume (SV) depends on how much blood enters a ventricle during diastole (end-diastolic volume) and how much blood is left in a ventricle following its systole (end systolic volume).
d. The maximum percentage that cardiac output can be increased above normal is cardiac reserve.
![Page 86: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/86.jpg)
Cardiac output
e. Heart rate and strength of contraction may be increased by sympathetic stimulation from the cardioacceleratory center in the medulla and decreased by parasympathetic stimulation from the cardioinhibitory center in the medulla.
f. Pressoreceptors are nerve cells that respond to changes in blood pressure. They act on the cardiac centers in the medulla through three reflex pathways: carotid sinus reflex, aortic reflex, and right heart (atrial) reflex.
g. Other influences on heart rate include chemicals (epinephrine, sodium, potassium), temperature, emotion, sex (gender and physical activity), and age.
![Page 87: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/87.jpg)
Cardiac Output
CO = SV x HR
SV = ml/beatHR = Heart Rate
![Page 88: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/88.jpg)
![Page 89: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/89.jpg)
![Page 90: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/90.jpg)
Nervous system regulation of heart rate.
a. Increases in heart rate achieved by:
i. Increase in cardioacceleratory center activity. This increases sympathetic nerve activity and increases NE release on the heart. ii. Decrease in cardioinhibitory center activity.
This decreases parasympathetic nerve activity and decreases ACh release on the heart.
![Page 91: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/91.jpg)
Nervous system regulation of heart rate.
b. Decreases in heart rate are achieved by:
i. Decrease in cardioacceleratory center activity. This decreases sympathetic nerve activity and decreases NE release on the heart.
ii. Increase in cardioinhibitory center activity. This increases parasympathetic
nerve activity and increases vagus nerve activity (a.k.a. vagal tone), and increases ACH release on the heart.
![Page 92: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/92.jpg)
Nervous System Control
![Page 93: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/93.jpg)
Relationship between heart rate and stroke volume
Note that if heart rate changes without a change in contractility (the strength of the contraction), stroke volume will change also.
This is because changing the heart rate alters the filling time (i.e., the time btwn beats during which the heart fills up with blood).
![Page 94: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/94.jpg)
Hormonal influences on heart rate
a. Epinephrine, released by the adrenal medulla (an endocrine organ found atop the kidneys), increases HR.
b. Thyroxine, released by the thyroid gland (located in the anterior neck), increases HR.
![Page 95: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/95.jpg)
Other factors that raise heart rate
Increased body temperature
Chemicals: caffeine, nicotine, and ephedrine
![Page 96: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/96.jpg)
Other factors that decrease heart rate
Decreased body temperature
Drugs such as beta blocker
![Page 97: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/97.jpg)
Regulation of stroke volume
Depends on 3 main variables:
1. Preload a. Refers to the degree of ventricular stretch during filling.
b. An increase in heart muscle is stretched (up to a point), causes increased contractile force
c. Increased in stretch causes more optimum cross-bridge formation btwn actin and myosin and a stronger contraction, thus ejecting a larger volume.
d. Frank-Starling law states: “What returns to the heart will get pumped out of the heart.”
![Page 98: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/98.jpg)
Regulation of stroke volume
Preload cont….e. As venous return (the volume of blood
returning to the heart per minute) increases, EDV increases, and stroke volume increases.
f. A decrease in HR will increase the filling time and thus increase EDV (and preload).
g. An increase in venous pressure will also increase EDV (and preload).
h. The stroke volume is greatly influenced by changes in preload.
![Page 99: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/99.jpg)
Regulation of stroke volume
2. Contractility a. Strength of the heart’s contraction
independent of its degree of stretch.
b. Increase in contractility will result in an increase in stroke volume and a decrease in end systolic volume.
c. Factors that increase contractility include: increased cardioacceleratory activity; and hormones such as epinephrine and thyroxine.
![Page 100: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/100.jpg)
Regulation of stroke volume
3. Afterload a. Pressure that must be overcome to open the semilunar
valve and eject blood.
b. Equivalent to arterial blood pressure.
c. Increase in arterial BP will increase afterload. This makes the heart expend more time/energy on opening the semilunar valve and less on ejecting blood.
d. Thus, an increase in afterload will cause stroke volume to decrease and end systolic volume to increase.
e. However, it takes a significant increase in afterload before the pumping output of the heart is hampered.
![Page 101: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/101.jpg)
Cardiac Output Affected By
Frank-Starling Law / Marey’s Law Cardiac Reserve (Max CO – CO at rest) Contractility (hormones, drugs, sympathetic
reactions, etc. Afterload (remaining blood in ventricles) Congestive heart failure
![Page 102: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/102.jpg)
Risk Factors for CAD
High blood cholesterol High blood pressure Smoking Obesity Diabetes mellitus Type “A” personality Sedentary lifestyle
![Page 103: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/103.jpg)
Arteries:
a. Arteries carry blood away from the heart. Their wall consists of a tunica interna, tunica media (which maintains elasticity and contractility), and tunica externa.
b. Large arteries are referred to as elastic (conducting) arteries and medium-sized arteries are called muscular (distributing) arteries.
c. Many arteries anastomose-the distal ends of two or more vessels unite. An alternate blood route from an anastomosis is called collateral circulation. Arteries that do not anastomose are called end art.ener
![Page 104: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/104.jpg)
Arteries:
![Page 105: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/105.jpg)
Arterioles:
a. Arterioles are small arteries that deliver blood to capillaries.
b. Through constriction and dilation they assume a key role in regulating blood flow from arteries into capillaries.
![Page 106: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/106.jpg)
Arterioles
![Page 107: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/107.jpg)
Capillaries:
a. Capillaries are microscopic blood vessels through which materials are exchanged between blood and tissue cells; some capillaries are continuous, others are fenestrated.
b. Capillaries branch to form an extensive capillary network throughout the tissue. This network increases the surface area, allowing a rapid exchange of large quantities of materials.
c. Precapillary sphincters regulate blood flow through capillaries.
d. Microscopic blood vessels in the liver are called sinusoids.
![Page 108: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/108.jpg)
Capillaries
![Page 109: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/109.jpg)
Venules:
a. Venules are small vessels that continue from capillaries and merge to form veins.
b. They drain blood from capillaries into veins.
![Page 110: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/110.jpg)
Venules
![Page 111: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/111.jpg)
Veins:
a. Veins consist of the same three tunics as arteries, but have less elastic tissue and smooth muscle.
b. They contain valves to prevent back flow of blood.
c. Weak valves can lead to varicose veins or hemorrhoids.
d. Vascular (venous) sinuses are veins with very thin walls.
![Page 112: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/112.jpg)
Veins
![Page 113: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/113.jpg)
Blood Flow and Blood Pressure:
a. Blood flows from regions of higher to lower pressure. The established pressure gradient is from aorta (100 mm Hg) to arteries (100-40 mm Hg) to arterioles 40-25 mm Hg) to capillaries (25-12 mm Hg) to venules (12-8 mm Hg) to veins (10-5 mm Hg) to venae cavae (2 mm Hg) to right atrium (0 mm Hg).
b. Any factor that increases cardiac output increases blood pressure.
c. As blood volume increases, blood pressure increases.
![Page 114: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/114.jpg)
Blood Flow and Blood Pressure:
d. Peripheral resistance is determined by blood viscosity and blood vessel diameter. Increased viscosity and vasoconstriction increase peripheral resistance and thus increase blood pressure.
e. Factors that determine heart rate and force of contraction, and therefore blood pressure, are the autonomic nervous system through the cardiac center. chemicals, temperature, emotions, sex, and age.
f. Factors that regulate blood pressure by acting on blood vessels include the vasomotor center in the medulla together with pressoreceptors, chemoreceptors, and higher brain centers; chemicals; and autoregulation.
![Page 115: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/115.jpg)
Blood Flow and Blood Pressure:
g. The movement of water and dissolved substances (except proteins) through capillaries by diffusion is dependent on hydrostatic and osmotic pressures.
h. The near equilibrium at the arterial and venous ends of a capillary by which fluids exit and enter is called Starling's law of the capillaries.
i. Blood return to the heart is maintained by several factors including increasing velocity of blood in veins, skeletal muscular contractions, valves in veins (especially in the extremities), and breathing.
![Page 116: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/116.jpg)
Blood Reservoirs:
a. Systemic veins are collectively called blood reservoirs.
b. They store blood which through vasoconstriction can move to other parts of the body if the need arises.
c. The principal reservoirs are the veins of the abdominal organs (liver and spleen) and skin.
![Page 117: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/117.jpg)
Checking Circulation – Pulse:
a. Pulse is the alternate expansion and elastic recoil of an artery with each heartbeat. It may be felt in any artery that lies near the surface or over a hard tissue.
b. A normal rate is between 70 and 80 beats per minute.
![Page 118: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/118.jpg)
Measurement of Blood Pressure:
a. Blood pressure is the pressure exerted by blood on the wall of an artery when the left ventricle undergoes systole and then diastole. It is measured by the use of a sphygmomanometer.
b. Systolic blood pressure is the force of blood recorded during ventricular contraction. Diastolic blood pressure is the force of blood recorded during ventricular relaxation. The average blood pressure is 120/80 mm Hg.
c. Pulse pressure is the difference between systolic and diastolic pressure. It averages 40 mm Hg and provides information about the condition of arteries.
![Page 119: Cardiovascular System. Human heart Heart Functions a. Generates the pressure that propels blood thru blood vessels. b. Separates oxygenated and deoxygenated](https://reader035.vdocuments.us/reader035/viewer/2022070323/56649e195503460f94b056b8/html5/thumbnails/119.jpg)
Disorders - Homeostatic Imbalances: a. An aneurysm is a sac formed by an outpocketing of a
portion of an arterial or venous wall. b. Coronary artery disease (CAD) refers to an
inadequate blood supply to the heart muscle. Two principal causes are atherosclerosis and coronary artery spasm.
c. Atherosclerosis is a process in which fatty substances are deposited in the walls of arteries.
d. Coronary artery spasm is caused by a sudden contraction of the smooth muscle in an arterial wall that produces vasoconstriction.
e. Hypertension is high blood pressure and may damage the heart, brain, and kidneys.