Cardiovascular system Anatomy and Physiology

Chapter 15 1

Chapter 15 Cardiovascular System 2

Size of Heart Average Size of Heart 14 cm long 9 cm wide 3

Location of Heart posterior to sternum medial to lungs anterior to vertebral column base lies beneath 2nd rib apex at 5th intercostal space lies upon diaphragm 4

Coverings of Heart 5

Wall of the Heart 6

Wall of the Heart 7

Heart Chambers Right Atrium receives blood from Left Atrium inferior vena cava superior vena cava coronary sinus Left Atrium receives blood from pulmonary veins Right Ventricle receives blood from right atrium Left Ventricle receives blood from left atrium 8

Heart Valves 9

Coronal Sections of Heart 10

Heart Valves Tricuspid Valve Pulmonary and Aortic Valve 11

Skeleton of Heart fibrous rings to which the heart valves are attached 12

Path of Blood Through the Heart 13

Path of Blood Through the Heart 14

Blood Supply to Heart 15

Blood Supply to Heart 16

Angiogram of Coronary Arteries 17

Heart Actions Atrial Diastole/Ventricular Systole Atrial Systole/Ventricular Diastole Atrial Diastole/Ventricular Systole 18

Cardiac Cycle Atrial Systole/Ventricular Diastole blood flows passively into ventricles remaining 30% of blood pushed into ventricles A-V valves open/semilunar valves close ventricles relaxed ventricular pressure increases 19

Cardiac Cycle Ventricular Systole/Atrial diastole A-V valves close chordae tendinae prevent cusps of valves from bulging too far into atria atria relaxed blood flows into atria ventricular pressure increases and opens semilunar valves blood flows into pulmonary trunk and aorta 20

Heart Sounds Lubb first heart sound occurs during ventricular systole A-V valves closing Dupp second heart sound occurs during ventricular diastole pulmonary and aortic semilunar valves closing Murmur – abnormal heart sound 21

Heart Sounds 22

Cardiac Muscle Fibers Cardiac muscle fibers form a functional syncytium group of cells that function as a unit atrial syncytium ventricular syncytium 23

Cardiac Conduction System 24

Cardiac Conduction System 25

Muscle Fibers in Ventricular Walls 26

Electrocardiogram recording of electrical changes that occur in the myocardium used to assess heart’s ability to conduct impulses P wave – atrial depolarization QRS wave – ventricular depolarization T wave – ventricular repolarization 27

Electrocardiogram 28

Electrocardiogram A prolonged QRS complex may result from damage to the A-V bundle fibers 29

Clinical Application Arrhythmias Ventricular fibrillation Tachycardia rapid, uncoordinated depolarization of ventricles Tachycardia rapid heartbeat Atrial flutter rapid rate of atrial depolarization 30

Cardiac Cycle 31

Regulation of Cardiac Cycle Autonomic nerve impulses alter the activities of the S-A and A-V nodes 32

Regulation of Cardiac Cycle Additional Factors that Influence HR physical exercise body temperature concentration of various ions potassium calcium parasympathetic impulses decrease heart action sympathetic impulses increase heart action cardiac center regulates autonomic impulses to the heart 33

Blood Vessels arteries carry blood away from ventricles of heart arterioles receive blood from arteries carry blood to capillaries capillaries sites of exchange of substances between blood and body cells venules receive blood from capillaries veins carry blood toward ventricle of heart 34

Arteries and Arterioles Artery thick strong wall endothelial lining middle layer of smooth muscle and elastic tissue outer layer of connective tissue carries blood under relatively high pressure Arterioles thinner wall than artery endothelial lining some smooth muscle tissue small amount of connective tissue helps control blood flow into a capillary 35

Walls of Artery and Vein 36

Arteriole smallest arterioles only have a few smooth muscle fibers capillaries lack muscle fibers 37

Metarteriole connects arteriole directly to venule 38

Capillaries smallest diameter blood vessels extensions of inner lining of arterioles walls are endothelium only semipermeable sinusoids – leaky capillaries 39

Capillary Network 40

Regulation of Capillary Blood Flow Precapillary sphincters may close a capillary respond to needs of the cells low oxygen and nutrients cause sphincter to relax 41

Exchange in the Capillaries water and other substances leave capillaries because of net outward pressure at the capillaries’ arteriolar ends water enters capillaries’ venular ends because of a net inward pressure substances move in and out along the length of the capillaries according to their respective concentration gradients 42

Venules and Veins Venule thinner wall than arteriole less smooth muscle and elastic tissue than arteriole Vein thinner wall than artery three layers to wall but middle layer is poorly developed some have flaplike valves carries blood under relatively low pressure serves as blood reservoir 43

Venous Valves 44

Characteristics of Blood Vessels 45

Blood Volumes in Vessels 46

Arterial Blood Pressure Blood Pressure – force the blood exerts against the inner walls of the blood vessels Arterial Blood Pressure rises when ventricles contract falls when ventricles relax systolic pressure – maximum pressure diastolic pressure – minimum pressure 47

Pulse alternate expanding and recoiling of the arterial wall that can be felt 48

Factors That Influence Arterial Blood Pressure 49

Control of Blood Pressure Controlling cardiac output and peripheral resistance regulates blood pressure 50

Regulation of Cardiac Cycle Autonomic nerve impulses alter the activities of the S-A and A-V nodes 51

Control of Blood Pressure If blood pressure rises, baroreceptors initiate the cardioinhibitory reflex, which lowers the blood pressure 52

Control of Blood Pressure Baroreceptors in the Vena Cava signal cardioaccelerator reflex and sends sympathetic impulses to the heart. Baroreceptors in Vena Cava stretched send signal to cardiac center sends sympathetic impulses to the heart Heart rate increases 53

Control of Blood Pressure Dilating arterioles helps regulate blood pressure (peripheral resistance) 54

Venous Blood Flow not a direct result of heart action dependent on skeletal muscle contraction breathing venoconstriction 55

Central Venous Pressure pressure in the right atrium factors that influence it alter flow of blood into the right atrium affects pressure within the peripheral veins weakly beating heart increases central venous pressure increase in central venous pressure causes blood to back up into peripheral vein 56

Pulmonary Circuit consists of vessels that carry blood from the heart to the lungs and back to the heart 57

Blood Flow Through Alveoli cells of alveolar wall are tightly joined together the high osmotic pressure of the interstitial fluid draws water out of them 58

Systemic Circuit composed of vessels that lead from the heart to all body parts (except the lungs) and back to the heart includes the aorta and its branches includes the system of veins that return blood to the right atrium 59

Major Vessels of Arterial System 60

Major Blood Vessels of the Heart 61

Principal Branches of the Aorta 62

Abdominal Aorta and Its Major Branches 63

Cerebral Arterial Circle Circle of Willis formed by anterior and posterior cerebral arteries, which join the internal carotid arteries 64

Major Vessels of the Venous System 65

Veins That Drain the Abdominal Viscera 66

Veins from the Abdominal Viscera: Hepatic Portal Vein Hepatic portal vein drains one set of capillaries and leads to another set 67

Life-Span Changes cholesterol deposition in blood vessels heart enlargement death of cardiac muscle cells increase in fibrous connective tissue of the heart increase in adipose tissue of the heart increase in blood pressure decrease in resting heart rate 68

Clinical Application Arrhythmias Ventricular fibrillation Tachycardia rapid, uncoordinated depolarization of ventricles Tachycardia rapid heartbeat Atrial flutter rapid rate of atrial depolarization 69