cardiovascular system- heart intro

7/31/2019 Cardiovascular System- Heart Intro

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CARDIOVASCULAR SYSTEM: Heart

Pericardium-a sac that covers and protects

the heart

-confines the heart to itsposition in the mediastinum

while allowing sufficient

freedom of movement for

contraction

-reduces friction between heart

and surrounding organs

-TWO main parts:

Fibrous pericardium-Outer membrane

-tough, inelastic, dense irregular connective tissue that resembles a bag that rests on & attaches to the

diaphragm-prevents overstretching of the heart, provides protection, and anchors the heart in the mediastinum

Serous pericardium-Inner membrane; thinner and more delicate

-Forms a double layer: outer parietal layer & inner visceral layer (epicardium)

-contains the pericardial fluid (thin film of lubricating serous fluid that reduces friction between layers of

the serous pericardium as the heart moves

Heart Wall EPICARDIUMvisceral layer of the serous membrane; outermost, thin transparent layer

-composed of mesothelium and delicate connective tissue that imparts a smooth, slippery, texture to theoutermost surface of the heart

MYOCARDIUM middle layer; bundles of cardiac muscles; makes up about 95% of the heart-responsible for the pumping action;

Size: 12 cm (5 in.) long, 9 cm (3.5 in.) wide at broadest point, 6 cm (2.5 in.) thick Shape: pear-shaped Weight:

Males: 300-350gFemales: 250-300g

Location: rests on the diaphragm to the midline of the thoracic cavityLies in the mediastinum, an anatomical region that extends from:

the sternum to the vertebral columnthe first rib to the diaphragmand between the lun s

2/3 of its mass lies the left side of the body Apex: formed by the tip of the left ventricle and rests on the diaphragm;

directed anteriorly, inferiorly and to the left

Base: the posterior surface; formed by the atria of the heart, mostly left atrium Surfaces and Borders: anterior surface- deep to the sternum and ribs inferior surface- part of the heart between the apex and right border; rest mostly on the diaphragm right border-faces the right lung and extends from the inferior surface of the base left border- pulmonary border; faces the left lung and extends from the base to the apex


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PERICARDITIS: inflammation of the

pericardium

-Types:

acute pericarditis- chest pain on left

shoulder to left arm, pericardial

friction; last one week with anti-

inflammatory drugs

chronic pericarditis- build up ofpericardial fluid compresses

heartcardiac tamponadethat

results to ventricular filling decrease,

CO reduced, venous return to heart

decrease, BP falls, breathing difficulty

Pericardiocentesis: procedure that

uses needle to remove fluid from the

pericardial sac, the tissue that

surrounds the heart.

ENDOCARDIUM innermost layer of endothelium overlying athin connective tissue; provides smooth lining for the chambers

of the heart, covers the valves of the heart; continuous with

endothelial lining of large blood vessels attached to the heart

-minimizes surface friction as blood passes through the heat

and blood vessels

Chambers of the Heart-Function of the Chambers:RV pumps blood at a fairly low pressure to the lungsLV pumps blood at a higher pressure to all parts of the body

-Anatomy of the Chambers:

LV wall 2-4 times THICKER than RV Atria- superior receiving chambers; entry hallsRight atrium

-receives blood from 3 veins: superior vena cava, inferior

vena cava, coronary sinus [Veins always return blood to the

heart]

interatrial septum: partition between left and rightatrium

fossa ovalis: prominent feature of the septum;depression or opening of in the interarterial septum of

fetal heart that closes upon birth

-remnant of foramen ovale pectinate muscles- muscular ridges ridges present in the posterior wall of the RA that causes it to be

rough

(anterior wall of RA smooth, but posterior is rough)

Triscupid valve/ right atrioventricular valve- valve between right atrium to right ventricle

-composed of dense connective tissue covered by endocardium

Left atrium-forms most of the base of the heart

-receives blood from the lungs through the four pulmonary veins

-both anterior and posterior surfaces of LA are smooth

Biscuspid (mitral valve)/ left atrioventricular valce: left atrium left ventricle Ventricles- inferior pumping chambersRight ventricle

-forms most of the anterior surface of the heart

Trabeculae carneae-raised bundles of cardiac muscle


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Chordae tendinae- where the cusps of the tricuspid valve are connected; also connected to cone-shaped trabeculae carnae, papillary muscles

Interventricular septum- a partition that separates the right ventricle from the left ventricle Pulmonary valve/ pulmonary semilunar valve- right ventricle pulmonary trunk, arteries lungs

[ARTERIES always take the blood away from the heart]

Left ventricle-thickest chamber of the heart

-forms the apex of the heart

-Also contains trabeculae carnea and chordae tendinae

Aortic valve: left ventricle ascending aorta-some blood in aorta flows to coronary ateries ascending aorta

-remainder blood passes into the arch of the aorta and descending aorta (thoracic and abdominal)

throughout the body

Auricle-wrinkled pouch-like structure on anterior surface of each atrium; increases the capacity of an atriumso it can hold a great blood volumes

Sulci- series of grooves on the surface of the heart that contains the coronary blood vessels and variableamount of fat

-marks the external boundary between the superior atria and inferior ventricles-coronary sulcus: deep; encircles most if the heart and marks the external boundary between thee superior

aorta and inferior ventricles

-anterior and posterior interventricular sulcus: shallow groove on the anterior surface of the heart that

marks the external boundary between right and left ventricles

Heart Anatomy

Heart Valves-Thin leaflets of tissue which open and close at the proper time during each heart beat cycle -dense connective tissue covered by endocardium

-open and close in response to pressure changes

-ensures the one way flow of blood by opening to let blood through and then closing to prevent its backflow

ATRIOVENTRICULAR (AV) VALVES situated between an atrium and a ventricle1. when it opens, the rounded ends of the cusps project into the ventricles

2. when the ventricles are relaxed, papillary muscles relax, chordae tendineae slack, blood moves from the

higher pressure in the atria to the lower pressure in the ventricles


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STENOSIS: narrowing of the heart

valve that restricts blood flow

INSUFFICIENCY/INCOMPETENCE:

failure of a valve to close completely

mitral stenosis- scar formation or a

congenital defect causes narrowing of

mitral valve

mitral insufficiency- caused by mitral

valve prolapsed

-there is a backflow of blood from

the left ventricle into the left

atrium)

-one or both cusps of MV

protrudes into the left atrium

during ventricular contraction

Aortic stenosis- aortic valve isnarrowed

Aortic insufficiency- backflow of

blood from the aorta to LV

3. at same time, papillary muscle contract to pull and tighten

chordae tendinae (prevents the valves to open into the atria

due to high ventricular pressure)

Tricuspid valve: right AV valve; RA RV Bicuspid or mitral valve: left AV valve; LA LV

SEMILUNAR (SL) VALVES- made up of three crescent moon-shaped cusps-allow ejection of blood from the heart into arteries but

prevent backflow of blood into the ventricles

1. Free border of the cusps project into the lumen of the artery

2. When ventricles contract, pressure builds up within the

chambers

3. SL valves opens when pressure in the ventricles exceeds the

pressure in the arteries

4. Blood ejected from ventricles into the pulmonary trunk and

aorta

5. When ventricles relaxes, blood will flow back to the heart

6. Backward flow of blood will fill the valve cusps that causes

SL valves to close tightly

Pulmonary SL valve: RV pulmonary trunk Aortic SL valve: LV aorta

Systemic &PulmonaryCirculations-arranged in series

1. RIGHT side: pumpfor pulmonary

circulation

Right atrium receives deoxygenated

blood from systemic circulation

2. Right ventricle ejects blood into

pulmonary trunk

3. From pulmonary trunk, it divides into

pulmonary arteries that carry blood to

lungs-pulmonary capillaries, unload of CO2

and pick up O2 oxygenated blood

4. LEFT side: pumpfor systemic

circulation


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RHEUMATIC FEVER

-infectious disease that damage or

destroy the heart valves

-acute systemic inflammatory disease

that usually occurs after a

streptococcal infection (group B -

hemolytic streptococcus) such as

strep throat or scarlet fever

-the bacteria trigger an immune

response in which the antibodies

produced to destroy the bacteria

instead attack and inflame the

connective tissues in joints, heart

valves, and other organs

-may weaken the entire hear wall,

most often damages the bicuspid and

aortic valves

Left atrium receives

oxygenated blood from lungs

5. Left ventricleejects the

blood into aorta

6. From aorta, blood divides

into separate streams,

entering progressively smaller

systemic arteries (throughout

the body expect lungs)

-arteries arterioles

systemic capillaries

-loss of O2, and picks up

CO2

-Systemic venules carry

deoxygenated blood away

from tissue systemic

veins right atrium

Coronary Circulation: Blood Supply of the

Heart-network of blood vessels of cells s that are to help diffuse nutrients

quickly from blood in the chambers of the heart to supply all the

layers of cells that make up the heart wall

Coronary arteries-branch from the ascending aorta and encircle the heart

left coronary artery

anterior interventricular branch / left anterior descendingartery

-is in the anterior interventricular sulcus and supplies

oxygenated blood to the walls of both ventricles

circumflex branch-lies in the coronary sulcus

-distributes oxygenated blood to the walls of left ventricle

and left atrium

right coronary artery- supplies small branches (atrialbranches) to the right atrium and continues inferior to the

right auricle

posterior interventricular branch-follows the posterior interventricular sulcus and supplies

the walls of the two ventricles with oxygenated blood

marginal branches-transports oxygenated blood to the myocardium of the right ventricle

*anastomoses- connections between branches of more than one artery that supply blood to the same region

*collateral circuits- alternated routes provided by anastomoses for blood to reach a particular organ or tissue

Coronary veins-Blood from the arteries capillaries, where it delivers oxygen and nutrients and collects CO2 and wastes

veins (Coronary Veins)

-the main veins that carry blood into the coronary sinus: Great cardiac vein- drains the areas of the heart supplied by the left coronary artery Middle cardiac vein-drains the areas supplied by the posterior interventricular branch of the right

coronary artery ( left and right ventricles)

Small cardiac vein- drains the right atrium and right ventricle


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CORONARY ARTERY DISEASE (CAD)

-results from the effects of the accumulation of atherosclerotic plaques in coronary arteries

-leads to a reduction in blood flow to the myocardium

-inadequate blood flow to coronary arteries hypoxia

-RISK FACTORS: smoking, high BP, diabetes, high cholesterol levels, obesity, type A personality, sedentart lifestyle,

family history of CAD

-TYPES: Partial obstruction Complete obstruction

-TREATMENT:

Drugs: antihypertensive, nitroglycerine, beta blockers, cholesterol lowering drugs, clot-dissolving agents Coronary artery bypass grafting (CABG)

-surgical procedure in which a blood vessel from another part of the body is attached grafted to a

coronary artery to bypass an area of blockade

Percutaneous Transluminal Coronary Angioplasty (PTCA)-non-surgical procedure, in which a balloon catheter with un-inflated balloon is threaded to obstructed

area in artery

Stent in an artery-a stent is a stainless steel device, resembling a spring coil

-to correct the renarrowing from PTCA

Anterior cardiac vein- drains the right ventricle and open directly into the right atrium*reperfusion- deprivation of oxygen to the heart muscle due to the blockage of a coronary artery

-during reestablishment of blood flow, may cause more tissue damage due to the formation offree radicals

from the reintroduced oxygen

Coronary sinus-where deoxygenated blood from myocardium drains into

-on posterior surface of the heart RA

-large vascular sinus

*vascular sinus- thin-walled vein that has no smooth muscle to alter its diameter

cardiovascular system- heart intro

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