Cardiac Physiology Flashcards Preview

AP: Cumulative > Cardiac Physiology > Flashcards

Flashcards in Cardiac Physiology Deck (29):
0

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

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

1

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

Medulla

2

Parasympathetic fibers primarily innervate what?

Atria and conducting tissues

3

Where do the cardiac Excelerator fibers originate?

Thoracic spinal cord T1 to T4

4

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

Increase the heart rate

5

What are baroreceptors And where they located?

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

6

What is usually the most important determinant of myocardial bloodflow?

Myocardial oxygen demand

7

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

65% myocardium
25% other tissues

8

At what stage is the heart perfused?

Diastole

9

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

It will diminish it

10

How is coronary perfusion pressure measured?

CPP = Arterial diastolic pressure - LVEDP

11

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

Hemoglobin concentration

12

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

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

13

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

Systolic
diastolic

14

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

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

15

What is a normal mixed venous O2 saturation?

65 to 73%

16

Wedge pressure is equivalent to ?

LA pressure

17

Cardiac output is generally directly proportional to what?

HR

18

Stroke volume is regulated primarily by what three factors?

Preload
Afterload
Contractility

19

What is preload and what is it equivalent to?

Pressure generated in the left ventricle at the end of diastole

CVP

20

What is afterload and what is equivalent to?

Resistance or impedance to ejection of blood from the ventricle

SVR

21

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

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

22

What is a normal CVP?

2-8 mmHg

23

What effect do respiration and cardiac output have on CVP?

Respiration = increases CVP
Cardiac output = decreases CVP

24

What normally has the most important effect on contractility?

Sympathetic nervous system activity

25

What are some causes of myocardial contractility depression?

Anoxia
Acidosis
Depletion of catecholamine
Loss of functioning muscle mass

26

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

By decreasing ventricular preload

27

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

By increasing ventricular afterload

28

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

EF = (EDV-ESV) / EDV