Heart Physiology 1

Question 1

Cardiac Output of Heart per minute

Answer 1

5 L/min

Question 2

Drug that increases the strength of heart contraction - mechanism involves pump, exchangers, contractile protein control

Answer 2

DIGITALIS

Question 3

Drug that increases heart contraction and heart rate; is agonist for sympathetic receptors in heart (G-protein coupled receptors); modulate ionic channels through cAMP

Answer 3

Sympathomimetic amines (dopamine and dobutamine)

Question 4

Drug that increases heart contraction and heart rate; Inhibits break-down of cAMP

Answer 4

Phosphodiesterase Inhibitors

Question 5

Drug to treat angina, hypertension, arrythmias; partially blocks ionic channels important to heart and smooth muscle function

Answer 5

Calcium-channel Blocker

Question 6

Drug that decreases heart rate and contraction; blocks sympathetic nervous system action on heart

Answer 6

Beta-blocker (adrenergic antagonist)

Question 7

Drug that treats arrhytmias; work at changing ionic channels and autonomic receptors in cardiac cell membrane

Answer 7

Anti-arrhytmic drugs

Question 8

What are approximate rates of death due to cardiovascular disease in different age groups?

Answer 8

Around 45 = 40%

Around 65 = 50%

Over 74 = 64%

Question 9

Label this external heart

Answer 9

Question 10

Label this internal heart

Answer 10

Question 11

Label the heart valves

Answer 11

Question 12

When do tricuspid and mitral valves open?

Answer 12

During ventricular diastole; When pressure in atrium is greater than pressure in ventricle

Question 13

When do tricuspid and mitral valves close?

Answer 13

During ventricular systole; When pressure in ventricle greater than pressure in atrium because of ventricular contraction

Question 14

What structure prevents valve eversion during ventricular systole (ventricular pressure is high)?

Answer 14

Chordae Tendineae attached to Papillary muscles

Question 15

When are the semilunar valves closed?

Answer 15

During ventricular diastole (when pressure in aorta and pulmonary artery is greater than pressure in ventricles)

Question 16

When are the semilunar valves open?

Answer 16

During ventricular systole (pressure in ventricles greater than pressure in aorta and pulmonary artery)

Question 17

What is the name for the heart condition where blood flows abnormally between aorta and pulmonary artery (ductus arteriosus blood vessel from fetus stays open instead of closing)?

Answer 17

Patent Ductus Arteriosis

Question 18

Narrowing of valve that often causes heart to pump much harder; has decreased cardiac reserve for exercise (because already contracting close to max); leads to left ventricular hypertrophy

Answer 18

Valve Stenosis

Question 19

This disease often causes mitral or tricuspid valve stenosis

Answer 19

Rheumatic fever

Question 20

Name for leaky valve that allows regurgitation; mitral regurgitation often leads to elevated atrial pressure, left ventricular dilation, reduced cardiac reserve, increased workload on heart

Answer 20

Valve Insufficiency

Question 21

Define timeline of left ventricular systole

Answer 21

Starts with left ventricular contraction, continues with ejection of blood from left ventricle into aorta, ends with closing of aortic semilunar valve

Question 22

Define timeline of left ventricular diastole

Answer 22

Starts with closing of aortic semilunar valve; continues with filling of ventricle; ends with ventricular contraction

Question 23

Mitral regurgitation results from what? (simple answer)

Answer 23

Mitral valve insufficiency

Question 24

How does the systolic pressure of the right heart (pulmonary circulation) compare to the systolic pressure of the left heart (systemic circulation)?

Answer 24

Right ventricular systolic pressure only reaches about 25mmHg (1/5 of normal systolic 120 BP in systemic circulation)

Question 25

Define Cardiac Output

Answer 25

Amount of blood leaving each ventricle per minute

Question 26

Define the formula for cardiac output

Answer 26

CO = HR x SV

Question 27

Provide the range for Heart Rate

Answer 27

Ranges 60-180; ~70 (resting)

Question 28

Provide rangel for Stroke Volume

Answer 28

70-120 mL; resting ~ 70-75mL

Question 29

What variables influence stroke volume?

Answer 29

1) Heart Contractility (inotropic state)

2) Filling of heart (preload)

3) Pressure against heart must work (afterload)

Question 30

Cellularly, what determines contractility of the heart?

Answer 30

1) Amount of Calcium that enters the myoplasm during each heartbeat

2) Number of functional myocytes

3) Coronary blood supply

Question 31

What determines heart preload?

Answer 31

Central Venous Pressure

Question 32

Label this diagram

Answer 32

Question 33

Label this diagram

Answer 33

Question 34

Define tidal volume (Vt)

Answer 34

Amount of (fresh) air inspired per breath

Question 35

Define functional residual capacity (FRC)

Answer 35

Resting volume of the lung; point at which the force of chest wall expansion balances the force of lung collapse

Question 36

Define minute ventilation

Answer 36

Amount of air that enters the lung per minute

Question 37

Provide the formula for minute ventilation

Answer 37

Minute ventilation = frequency of breaths x tidal volume (increase minute ventilation by either taking bigger breaths or more breaths)

Question 38

Where are chemoreceptors located that sense arterial blood oxygen and carbon dioxide to regulate ventilation?

Answer 38

Bifurcation of carotid artery in neck and aortic arch have receptors to sense oxygen; brainstem has receptors to sense CO2

Question 39

What is the formula for caculating partial pressure?

Answer 39

Partial Pressure = total pressure x fraction of gas component

Question 40

What is the partial pressure of oxygen entering the lungs at sea level? in alveoli?

Answer 40

160 mmHg; 102 mmHg

Question 41

How is partial pressure of oxygen decreased in the body so that oxygen travels from atmosphere into bloodstream?

Answer 41

**1) Air is humidified **

2) Oxygen is being removed into bloodstream

Question 42

What is the partial pressure of CO2 entering the lungs at sea level? at alveoli?

Answer 42

Almost 0mmHg; 40mmHg in circulation and alveoli

Question 43

Provide bicarbonate buffering system equation.

Answer 43

CO2 + H20 = H2C03 = H+ + HC03-

**(carbon dioxide combines with water to form carbonic acid, which in turn rapidly dissociates to form hydrogen ions (H+) and bicarbonate) **

**All catalyzed by carbonic anhydrase **

Question 44

Explain the resultant pathologies of mitral valve insufficiency (regurgitation).

Answer 44

When left ventricle contracts, some blood goes the wrong direction up into the left atrium

Atrial pressure is thus increased, backing up to cause pulmonary hypertension and pulmonary congestion; the left atrium adapts by enlarging

The left ventricle will hypertrophy to compensate for increased preload

Cardiac reserve is decreased because ventricle is already working harder than normal

Eventually, left ventricle begins to fail; ventricle dilates and weakens; ejection fraction decreases dramatically and patient experiences chronic heart failure

Question 45

Explain resultant pathologies of aortic valve stenosis.

Answer 45

Heart must pump much harder and create more pressure at ventricle to maintain normal downstream areterial flow and pressure

**Cardiac reserve for exercise greatly decreases because the heart is already contracting close to max **

**The heart adapts by hypertrophy of the left ventricular **

In later stages, the left ventricle dilates and thins: muscle dissapears and systolic function deteriorates leading to chronic heart failure