Cardiac Physiology

Question 0

Primary regulation of heart rate and blood pressure are controlled where?

Answer 0

Medulla

Question 1

What effect do the following have on calcium?
Volatile anesthetics
Nitrous oxide
Local anesthetics
Acidosis
Digitalis

Answer 1

Volatile anesthetics = decrease
Nitrous oxide = decrease
Local anesthetics = decrease
Acidosis = decrease
Digitalis = increase

Question 2

Parasympathetic fibers primarily innervate what?

Answer 2

Atria and conducting tissues

Question 3

Where do the cardiac Excelerator fibers originate?

Answer 3

Thoracic spinal cord T1 to T4

Question 4

Merrill receptors in the lungs have what effect on the heart rate during inspiration?

Answer 4

Increase the heart rate

Question 5

What are baroreceptors And where they located?

Answer 5

Pressure receptors in the wall of the carotid sinuses and aorta detect changes in atrial pressure in the circulation

Question 6

What is usually the most important determinant of myocardial bloodflow?

Answer 6

Myocardial oxygen demand

Question 7

The myocardium usually extracts what percentage of the oxygen in arterial blood compared with what percentage in most other tissues?

Answer 7

65% myocardium

25% other tissues

Question 8

At what stage is the heart perfused?

Answer 8

Diastole

Question 9

An increase in heart rate will do what to the time in diastole?

Answer 9

It will diminish it

Question 10

How is coronary perfusion pressure measured?

Answer 10

CPP = Arterial diastolic pressure - LVEDP

Question 11

What factor has the largest effect on oxygen supply in the CaO2 equation?

Answer 11

Hemoglobin concentration

Question 12

What effect will aortic stenosis and regurgitation have on myocardial oxygen supply and why?

Answer 12

Both will decrease supply by worsening blood flow into the coronary arteries

Question 13

Ventricular ____ function involves ventricular ejection whereas _____ function is related to ventricular filling

Answer 13

Systolic

diastolic

Question 14

What is a normal cardiac index and how is it calculated?

Answer 14

Normal C.I. = 2.5 - 4.2 L/min/m2

C.I. = CO/BSA

Question 15

What is a normal mixed venous O2 saturation?

Answer 15

65 to 73%

Question 16

Wedge pressure is equivalent to ?

Answer 16

LA pressure

Question 17

Cardiac output is generally directly proportional to what?

Answer 17

HR

Question 18

Stroke volume is regulated primarily by what three factors?

Answer 18

Preload
Afterload
Contractility

Question 19

What is preload and what is it equivalent to?

Answer 19

Pressure generated in the left ventricle at the end of diastole

CVP

Question 20

What is afterload and what is equivalent to?

Answer 20

Resistance or impedance to ejection of blood from the ventricle

SVR

Question 21

Atrial arrhythmias can reduce ventricular filling due to a loss of the atrial kick. why?

Answer 21

15 to 20% of the volume in the right ventricle comes from the atrial kick

Question 22

What is a normal CVP?

Answer 22

2-8 mmHg

Question 23

What effect do respiration and cardiac output have on CVP?

Answer 23

Respiration = increases CVP

Cardiac output = decreases CVP

Question 24

What normally has the most important effect on contractility?

Answer 24

Sympathetic nervous system activity

Question 25

What are some causes of myocardial contractility depression?

Answer 25

Anoxia
Acidosis
Depletion of catecholamine
Loss of functioning muscle mass

Question 26

Stenosis of an AV valve reduces stroke volume by what mechanism?

Answer 26

By decreasing ventricular preload

Question 27

Stenosis of a semilunar valve reduces stroke volume by what mechanism?

Answer 27

By increasing ventricular afterload

Question 28

How is ejection fraction calculated and what is a normal value?

Answer 28

EF = (EDV-ESV) / EDV