Cardiovascular System Notes:

The Heart

The human heart creates enough pressure to squirt blood 30 feet.

Interesting Cardiovascular System Facts

NOTES – THE HEART

• Location: • cavity between the lungs, 2/3 left of midsagittal

• roughly the size of a fist

© 2013 Pearson Education, Inc.

Figure 18.2b Location of the heart in the mediastinum.

Mediastinum

HeartLeft lung

Body of T7 vertebra

Posterior

© 2013 Pearson Education, Inc.

Figure 18.2c Location of the heart in the mediastinum.

Superiorvena cava

Pulmonarytrunk

Diaphragm

Aorta

Parietal pleura(cut)

Left lung

Pericardium (cut)

Apex of heart

• Heart Anatomy• PERICARDIUM • outer membrane of the

heart

• 2 layers 1. Parietal pericardium: external (outer) layer

2. Visceral pericardium (epicardium): part of the heart wall

• Functions: • protection – physical barrier• anchors heart to other structures

• provides lubrication to reduce friction – allows the heart to beat easily

1. Epicardium: outer portion (visceral pericardium)

• 3 layers

• THE HEART WALL

EPICARDIUM

2. Myocardium: middle layer consists of twisted cardiac muscle

• THIS IS THE LAYER THAT ACTUALLY CONTRACTS

MYOCARDIUM

3. Endocardium: inner layer made of epithelial tissue

ENDOCARDIUM

© 2013 Pearson Education, Inc.

Figure 18.3 The pericardial layers and layers of the heart wall.

Pericardium

Myocardium

Pulmonarytrunk Fibrous pericardium

Parietal layer of serous pericardium

Pericardial cavity

Epicardium (viscerallayer of serouspericardium)

Myocardium

Endocardium

Heart chamber

Heart wall

© 2013 Pearson Education, Inc.

Homeostatic Imbalance

• Pericarditis– Inflammation of pericardium– Roughens membrane surfaces pericardial

friction rub (creaking sound) heard with stethoscope

– Cardiac tamponade• Excess fluid sometimes compresses heart

limited pumping ability

© 2013 Pearson Education, Inc.

The Pulmonary and Systemic Circuits

• Receiving chambers of heart:– Right atrium

• Receives blood returning from systemic circuit

– Left atrium• Receives blood returning from pulmonary circuit

© 2013 Pearson Education, Inc.

The Pulmonary and Systemic Circuits

• Pumping chambers of heart:– Right ventricle

• Pumps blood through pulmonary circuit

– Left ventricle• Pumps blood through systemic circuit

© 2013 Pearson Education, Inc.

Capillary beds oflungs where gasexchange occurs

Pulmonary CircuitPulmonaryarteries Pulmonary veins

Aorta and branchesVenaecavae

Leftatrium

LeftventricleRight

atrium

Rightventricle

Heart

Systemic Circuit

Oxygen-rich,CO2-poor bloodOxygen-poor,CO2-rich blood

Capillary beds of allbody tissues wheregas exchange occurs

Figure 18.1 The systemic and pulmonary circuits.

© 2013 Pearson Education, Inc.

Figure 18.4 The circular and spiral arrangement of cardiac muscle bundles in the myocardium of the heart.

Cardiacmusclebundles

• HEART CHAMBERS• 4 chambers

• Atrium (left/right atria)

• divided by the INTERATRIAL SEPTUM

• Function of Atria: receives blood from veins

(pig heart)

• RIGHT ATRIA

• receives blood from superior & inferior vena cava

• blood that’s been used• oxygen poor – high in CO2

• receives blood from pulmonary veins

• LEFT ATRIA

• coming from lungs• rich in oxygen

• Ventricles (left/right)

• muscular pumps – divided by INTERVENTRICULAR SEPTUM

(pig heart)

• RIGHT VENTRICLE

• receives blood from the right atria (O2 poor)

• pumps blood to the lungs through the PULMONARY ARTERIES

• LEFT VENTRICLE

• receives blood (O2 rich) from the left atrium

• pumps blood to the body through the AORTA

© 2013 Pearson Education, Inc.

Figure 18.10 Anatomical differences between the right and left ventricles.

Rightventricle

Interventricularseptum

Leftventricle

• Systemic Circulation

• heart – lungs – heart – body – heart

• HEART VALVES (4)

• allow for “one way” circulation

• 2 Atrioventricular Valves (AV valves)

1. Tricuspid Valve: between right atria and right ventricle

2. Bicuspid or Mitral Valve: between left atria and left ventricle

• heavier & stronger of the two

© 2013 Pearson Education, Inc.

Figure 18.6a Heart valves.

Pulmonary valveAortic valve

Area of cutaway

Mitral valveTricuspid valve

Myocardium

Mitral(left atrioventricular)valveTricuspid(right atrioventricular) valveAortic valve

Pulmonary valve

Anterior

Cardiacskeleton

© 2013 Pearson Education, Inc.

Figure 18.6b Heart valves.

Pulmonary valveAortic valve

Area of cutaway

Mitral valveTricuspid valve

Myocardium

Mitral(left atrioventricular)valveTricuspid(right atrioventricular) valveAortic valve

Pulmonary valve

© 2013 Pearson Education, Inc.

Figure 18.6c Heart valves.Pulmonary valve

Aortic valve

Area of cutaway

Mitral valve

Tricuspid valve

Chordae tendineae attached to tricuspid valve flap

Papillary muscle

© 2013 Pearson Education, Inc.

Figure 18.6d Heart valves.

Pulmonary valve

Aortic valve

Area of cutaway

Mitral valve

Tricuspid valve

Opening of inferiorvena cava

Tricuspid valve

Myocardium of right ventricle

Papillary muscles

Mitral valveChordae tendineae

Interventricular septum

Myocardium of left ventricle

• CHORDAE TENDINAE and papillary muscles stop valves from being folded backwards

CHORDAE TENDINAE

3. Pulmonary Semilunar Valve: between the pulmonary artery and right ventricle

4. Aortic Semilunar Valve: between aorta and left ventricle

Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.

Animation

© 2013 Pearson Education, Inc.

Homeostatic Imbalance

• Two conditions severely weaken heart:– Incompetent valve

• Blood backflows so heart repumps same blood over and over

– Valvular stenosis• Stiff flaps – constrict opening heart must exert

more force to pump blood

• Valve replaced with mechanical, animal, or cadaver valve

© 2013 Pearson Education, Inc.

Pathway of Blood Through the Heart

• Pulmonary circuit– Right atrium tricuspid valve right

ventricle– Right ventricle pulmonary semilunar valve

pulmonary trunk pulmonary arteries lungs

– Lungs pulmonary veins left atrium

© 2013 Pearson Education, Inc.

PLAYPLAY Animation: Rotatable heart (sectioned)

Pathway of Blood Through the Heart

• Systemic circuit– Left atrium mitral valve left ventricle– Left ventricle aortic semilunar valve

aorta– Aorta systemic circulation

© 2013 Pearson Education, Inc.

Coronary Circulation

• Functional blood supply to heart muscle itself– Delivered when heart relaxed– Left ventricle receives most blood supply

• Arterial supply varies among individuals

• Contains many anastomoses (junctions)– Provide additional routes for blood delivery– Cannot compensate for coronary artery

occlusion

© 2013 Pearson Education, Inc.

Coronary Circulation: Arteries

• Arteries arise from base of aorta• Left coronary artery branches anterior

interventricular artery and circumflex artery– Supplies interventricular septum, anterior ventricular

walls, left atrium, and posterior wall of left ventricle

• Right coronary artery branches right marginal artery and posterior interventricular artery– Supplies right atrium and most of right ventricle

© 2013 Pearson Education, Inc.

Aorta

Superiorvena cava

Anastomosis(junction ofvessels)

Rightatrium

Rightcoronaryartery

Rightventricle

Rightmarginalartery

Posteriorinterventricularartery

Anterior interventricularartery

Leftventricle

Circumflexartery

Leftcoronaryartery

Left atrium

Pulmonarytrunk

The major coronary arteries

Figure 18.11a Coronary circulation.

© 2013 Pearson Education, Inc.

Homeostatic Imbalances

• Angina pectoris– Thoracic pain caused by fleeting deficiency in

blood delivery to myocardium– Cells weakened

• Myocardial infarction (heart attack)– Prolonged coronary blockage– Areas of cell death repaired with

noncontractile scar tissue

© 2013 Pearson Education, Inc.

Microscopic Anatomy of Cardiac Muscle

• Cardiac muscle cells striated, short, branched, fat, interconnected, 1 (perhaps 2) central nuclei

• Connective tissue matrix (endomysium) connects to cardiac skeleton– Contains numerous capillaries

• T tubules wide, less numerous; SR simpler than in skeletal muscle

• Numerous large mitochondria (25–35% of cell volume)

© 2013 Pearson Education, Inc.

Figure 18.12a Microscopic anatomy of cardiac muscle.

NucleusIntercalated

discsCardiac

muscle cell Gap junctions Desmosomes

© 2013 Pearson Education, Inc.

Microscopic Anatomy of Cardiac Muscle

• Intercalated discs - junctions between cells - anchor cardiac cells – Desmosomes prevent cells from separating

during contraction– Gap junctions allow ions to pass from cell to

cell; electrically couple adjacent cells• Allows heart to be functional syncytium

– Behaves as single coordinated unit