Cadiovascular Physiology

Question 1

What are the features associated with cardiac muscle fibers?

Answer 1

Striated
Interconnected
Intercalated discs with desmosomes and gap junctions

Question 2

What is the function of the cardiac syncytium?

Answer 2

A collection of cells that operate mechanically and electrically as a single unit to allow for rapid conduction of action potentials directly from 1 cardiac cell to the next.

Question 3

What is unique about SA node depolarization?

Answer 3

Occurs spontaneously and without any external stimulus.

Question 4

What is the difference between systole and diastole?

Answer 4

Systole - heart contraction, pushes blood out of the heart
Diastole - heart relaxation, allows for filling of the heart

Question 5

What are all the heart volume measurements, how do you calculate them, and what do they mean?

Answer 5

End-diastolic volume: ventricles are relatively full (110-120 ml/ventricle)
End-systolic volume: ventricles have just finished contracting and are relatively empty (40-50 ml)
Stroke volume: how much blood was pumped out during systole
EDV-ESV= about 70 ml

Question 6

What factors influence cardiac output?

Answer 6

Stroke volume - 70ml/beat
Heart rate - 72 beats/min
Cardiac output - (70 ml/beat) (72 beats/min) = 5040 ml/min or 5.04 L/min

Question 7

What is the difference in systolic vs diastolic blood pressure?

Answer 7

Systolic - pressure when heart contracts
Diastolic - pressure when heart relaxes

Question 8

What is normal vs abnormal blood pressure?

Answer 8

120/80

Question 9

How can you calculate blood pressure?

Answer 9

Blood pressure = (Cardiac output) (Total peripheral resistance)

Question 10

What ways does the body regulate blood pressure (short-term + long-term)?

Answer 10

Short term control - Baroreceptor reflex, adrenal catecholamines
Long term control - Atrial stretch receptors, hypothalamic osmolarity mechanism, renal blood flow mechanism