Lecture 1

Question 1

Stroke volume

Answer 1

volume of blood ejected by the left ventricle after one contraction. SV=EDV-ESV

Question 2

Pericardium

Answer 2

composed of two layers, the fibrous pericardium and the serous pericardium.

Question 3

fibrous pericardium

Answer 3

dense, irregular connective tissue that protects and anchors the heart which prevents overstretching.

Question 4

serous pericardium

Answer 4

thin, delicate membrane that consists of the parietal layer (outer layer), pericardial cavity that’s filled with pericardial fluid and the visceral layer.
Other functions include prevention of displacement, providing physical barrier against infection and inflammation, and having pain and mechanoreceptors to elicit changes.

Question 5

EDV

Answer 5

volume of blood in the right and/or left ventricle at end load or filling in diastole

Question 6

Ejection fraction

Answer 6

measurement of the percentage of blood leaving your heart each time it contracts, which is usually 55 to 75%.
EF=SV/EDV

Question 7

Cardiac index

Answer 7

better indicator of cardiac function.

CI= CO L/min /body surface area

Question 8

Cardiac output

Answer 8

normally 3.5 to 8 L per min, maximum is 20 to 30 L per min.

CO = HR X SV

Question 9

Frank Starling’s law

Answer 9

increase in EDV increases stretching (Preload) which increases stroke volume.

Question 10

Factors that affect stroke volume

Answer 10

preload, contractility, and afterload

Question 11

Myocardial contractility

Answer 11

increase in strength of contraction that increases stroke volume. Epinephrine and calcium ions increase contractility.

Question 12

Preload

Answer 12

dependent on EDV and 2 facts effect EDV. First, venous return or venous pressure and second, the duration of diastole.

Question 13

Afterload

Answer 13

ventricular wall tension

Question 14

La Place formula

Answer 14

Wall Tension = (Intraventricular pressure x Radius)/ Ventricular wall thickness

Question 15

How does arterial pressure affect afterload?

Answer 15

Increase in arterial pressure increases resistance to ventricular ejection

Question 16

relationship between ventricular function curve and contractility

Answer 16

Curves can shift upward when cardiac performance is enhanced or shift downward when cardiac performance is depressed.

Question 17

enhanced cardiac performance

Answer 17

increased inotropy, increased heart rate, and reduced afterload ie sympathetic stimulation, epinephrine, digitalis, caffeine

Question 18

depressed cardiac performance

Answer 18

decreased inotropy, decreased heart rate, and by increased afterload ie hypoxia, acidosis, hypercapnia, CHF, barbiturates

Question 19

mechanism of action of digitalis

Answer 19

digoxin inhibits the Na/K pump
Na builds up in the cell
low gradient for Na to run Na/Ca transporter.
calcium ions increase in cell and therefore force of contraction will increase.

Question 20

parasympathetic ns

Answer 20

connected the vagus nerves
slows down heart rate, parasympathetic tone is 40 bpm
under resting conditions parasympathetic NS predominates.

Question 21

Sympathetic activity and epinephrine

Answer 21

fight or flight response
speeds up heart rate and stroke volume
Sympathetic tone can increase heart rate up to 180-200 bpm
increase force of contraction
reduce systole period
people with heart disease sym. NS predominates.