CH. 13 Cardiovascular System: Cardiac Function

Question 1

What path is taken throughout the blood vessels?

Answer 1

heart - arteries - arterioles - capillaries - venules - veins

Question 2

Function of erythrocytes?

Answer 2

transport oxygen and carbon dioxide

Question 3

Function of leukocytes?

Answer 3

white blood cells that defend the body against pathogens

Question 4

What is the path of the pulmonary circuit?

Answer 4

• supplied by right heart

- blood vessels from heart to lungs, and from lungs to heart

Question 5

What is the path of the systemic circuit?

Answer 5

• supplied by left heart

- blood vessels from heart to systemic tissues, and from tissues to heart

Question 6

Where does oxygenation of blood occur?

Answer 6

capillaries

Question 7

What can occur from parallel blood flow within the systemic or pulmonary circuit?

Answer 7

independent regulation of blood flow to organs

Question 8

What supplies the heart capillaries?

Answer 8

coronary arteries that arise from the aorta

Question 9

What is the pericardium?

Answer 9

membranous sac surrounding the heart that lubricates the heart and decreases friction

Question 10

What are the three layers of the heart wall?

Answer 10

1. epicardium (outer)
2. myocardium (middle)
3. endothelium (inner)

Question 11

What is the difference in muscle thickness of the left and right ventricle?

Answer 11

left ventricle is much thicker than the right

Question 12

What do the heart valves allow for and how do they function?

Answer 12

they prevent the back flow of blood and open passively based on pressure gradient

Question 13

What is meant by autorhythmicity?

Answer 13

the ability to generate its own rhythm

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Question 14

How do autorhythmic cells function in the heart?

Answer 14

they provide a pathway for spreading excitation through the heart

Question 15

How is the conduction system of the heart broken down?

Answer 15

pacemaker cells and conduction fibers

Question 16

How do pacemaker cells and conduction fibers work together to coordinate and provide rhythm to the heartbeat?

Answer 16

pacemaker cells produce spontaneously depolarizing membrane potentials that generate action potentials that are then rapidly conducted to the myocardium by conduction fibers

Question 17

Where are pacemaker cells of the myocardium found?

Answer 17

• sinoatrial node (pacemaker of the heart)

- atrioventricular node

Question 18

Where are conduction fibers of the myocardium found?

Answer 18

• internodal pathways
• bundle of his
• purkinje fibers

Question 19

What is the firing rate of the SA node at rest?

Answer 19

70-80 AP/min

Question 20

What allows for the coordination of the conduction system of the heart?

Answer 20

presence of gap junctions and conduction pathways

Question 21

What are intercalated disks?

Answer 21

junctions between adjacent myocardial cells

Question 22

What causes spontaneous depolarizations of the heart autorhythmic cells?

Answer 22

closing of potassium channels

Question 23

What occurs in the electrical activity in a pacemaker cell?

Answer 23

1. pacemaker potential goes to threshold
2. rapid depolarization
3. repolarization brings down to -70mV
4. process repeats

Question 24

What are the 5 phases of electrical activity in cardiac contractile cells?

Answer 24

Phase 0: increased permeability to sodium
Phase 1: decreased permeability to sodium
Phase 2: increased permeability to calcium, decreased permeability to potassium
Phase 3: increased permeability to potassium, decreased permeability to calcium
Phase 4: resting membrane potential

Question 25

How is calcium removed from the cytosol of cardiac muscle?

Answer 25

1. Calcium/ATPase in sarcoplasmic reticulum 2. Calcium/ATPase in plasma membrane 3. Sodium/Calcium exchange in plasma membrane

Question 26

What is an electrocardiogram?

Answer 26

external measure of electrical activity of the heart

Question 27

What are the factors that distance and amplitude of spread of an electrocardiogram dependent on?

Answer 27

1. size of potentials | 2. synchronicity of potentials from other cells

Question 28

What is ECG arrhythmias?

Answer 28

abnormal heart rates

Question 29

What is a sinus rhythm? - Tachycardia - Bradycardia

Answer 29

- pace generated by SA node | - tachycardia is fast rhythm and bradycardia is slow rhythm

Question 30

What comes as a result of an extra contraction on an electrocardiogram?

Answer 30

- results in an extra systole | - premature atrial contraction followed by an extra ventricular contraction

Question 31

What comes as a result of a ventricular fibrillation on an electrocardiogram?

Answer 31

- loss of coordination of electrical activity of heart | - death can ensue within minutes unless corrected

Question 32

What are the two main periods of the cardiac cycle?

Answer 32

1. systole: ventricle contraction | 2. diastole: ventricle relaxation

Question 33

When do AV valves open and when do semilunar valves open?

Answer 33

- AV valves: when atrial pressure is greater than ventricular pressure - Semilunar valves open when ventricular pressure is greater than arterial pressure

Question 34

What are the 4 phases of the cardiac cycle?

Answer 34

1. ventricular filling (diastole) 2. isovolumetric ventricular contraction (systole) 3. ventricular ejection (systole) 4. isovolumetric ventricular relaxation (diastole)

Question 35

How does the elasticity of the aorta and large arteries aid in maintaining blood flow through the entire cardiac cycle?

Answer 35

1. acts as a pressure reservoir 2. stores energy during systole as walls expand 3. releases energy during diastole as walls recoil inward

Question 36

What is the equation for stroke volume?

Answer 36

SV = end-diastolic volume - end-systolic volume

Question 37

What causes the sound of a heart beat?

Answer 37

1st sound: AV valves close simultaneously | 2nd sound: semilunar valves close simultaneously

Question 38

What is cardiac output and what is the equation used to find this?

Answer 38

volume of blood pumped by each ventricle per minute - cardiac output = SV x HR

Question 39

What are the extrinsic and intrinsic regulation of cardiac output?

Answer 39

- extrinsic: neural and hormonal (autonomic) | - intrinsic: autoregulation

Question 40

What occurs when the SA node is under control of the ANS and hormones and is at rest?

Answer 40

parasympathetic system dominates

Question 41

What occurs when the SA node is under control of ANS and hormones and is excited?

Answer 41

sympathetic system takes over and heart rate increases

Question 42

What two hormones help to control heart rate?

Answer 42

1. epinephrine: interacts with beta one receptors - increases AP frequency at SA node - increases velocity of AP conduction in muscle fibers 2. glucagon: increases heart rate

Question 43

What are the primary factors affecting stroke volume?

Answer 43

1. ventricular contractility: how well ventricles contract 2. end-diastolic volume 3. afterload: how much blood is in arteries all together

Question 44

What hormones can increase force of contraction?

Answer 44

thyroid hormones, insulin, and glucagon

Question 45

What two factors affect end-diastolic volume?

Answer 45

1. end-diastolic pressure: preload - filling time - atrial pressure - central venous pressure 2. afterload: pressure in aorta during ejection

Question 46

Describe what occurs at the different stages (A-H) of the left ventricular pressure-volume curve.

Answer 46

``` A: Phase 1 - ventricular volume increase B: Atrial contraction C: Phase 2 - Volume remains constant; pressure increases dramatically D: Semilunar valves blow open E: Phase 3 - volume decreases to 60 mL, pressure rises, then falls precipitously F: Semilunar valves shut G: Phase 4 - pressure continues to fall H: AV valves blow open ```