CVS Physio Pt 1/2

Question 1

Role of the circulatory system?

Answer 1

to meet metabolic req of body via fluid exchange at capillaries.

Additional qns: What is the goal of fluid exchange at the capillaries?

Question 2

Explain Starling’s forces enabling fluid exchange at the capillaries (= the whole point of the circulatory system)

Hint: 2 in, 3 out

Question 3

Which vessel of the body has the greatest volume of blood, and why?

Which vessel of the body has the lowest pressure of blood and way?

(thus pulse can’t be palpated, but can be seen)

Question 4

Formula for arterial blood pressure?

Answer 4

B.P. = CO x TPR (BCT)

Question 5

What causes the ‘systolic p.a.’ and ‘diastolic p.a.’?

Question 6

Define cardiac output.

What is the CO formula?

Answer 6

(CSH)

Question 7

Name 3 factors affecting CO.

Define each factor.

Answer 7

1. Preload
2. Afterload
3. (heart factors)
   - contractility
   - HR

Question 8

1. Use Starling’s Law to explain the relationship between (preload and thus stretching of cardiac muscle) and SV.

(note –> is the adaptation of the heart to cope with differing venous return vol.s)

2. Draw a graph to show Starling’s Law at normal, exercise and HF.

Question 9

What is the normal Stroke Volume (per heart beat)?

Formula for Stroke volume?

Question 10

Define Ejection fraction.

Formula for ejection fraction?

Normal EF values?

What EF value considers significant ventricular fxn impairment?

Question 11

What regulates/ controls basal HR (in a normal person)?

Answer 11

basal HR due to rhythmic discharge of electrical signals through conduction system (usually SA node) (p.symp has greater control)!

Question 12

What are the factors affecting rate of (SA node rhythmic) discharge of electrical signals (to stimulate HR)?

Answer 12

Hint:

direct: TTC

via VMC –> symp. NS: PBPC

Question 13

Outline the components of the conduction system of the heart.

What is their main purpose?

(note: ECG measures this electrical activity of heart)

Answer 13

Main purpose: conduct electrical signals to activate the depolarisation of cardiac muscles (recall: cardiac muscle action potential graph) to trigger cardiac fibres to contract when depolarised.

Question 14

Explain what is sinus arrhythmia.

Answer 14

Inspiration causes impulses from the respiratory centre to overflow into the VMC –> increase in HR every time one inspires air in

(note: sinus __ - eg. sinus tachy/ sinus brady/ sinus arrhythmia = ‘normal occurrence of (sth)’)

Question 15

What is the hierarchy of conduction system of heart in terms of:

(i) generation of signals
(ii) conduction of signals?

Question 16

Draw a graph and explain the action potential that happens during the depolarisation of a cardiac muscle cell.

Question 17

Importance of coronary blood flow?

Question 18

What is the blood pressure of coronary blood flow?

Question 19

What are the 3 mechanisms regulating coronary circulation? (MNM)

Answer 19

pls don’t confuse these stretch receptors on BV walls with the atrial/ventricular stretch receptors (and ANP-BNP)!!