L9- Physiology: parameters of the cardiovascular system

Question 1

With each ventricular ejection of blood by the heart, what happens to BP, SP and DP?

Answer 1

BP blood pressure in the aorta and other arteries sharply rises to a maximum (systolic pressure) and then falls to a minimum as ventricles relax (diastolic pressure). Difference between these extremes is defined as pulse pressure (PP).

Question 2

Formula of PP (pulse pressure)

Answer 2

PP = SP - DP

Question 3

Mean Arterial Pressure changes when?

Answer 3

When you exercise or change posture

Question 4

Heart spends more time in?

Answer 4

more time in diastole than systole

Question 5

Formula of MAP (mean arterial pressure)

Answer 5

MAP = DP + 1/3 (SP - DP) = DP + 1/3 PP

Question 6

Formula of MAP in relation to cardiac output and total peripheral resistance

Answer 6

MAP = CO x TPR

Question 7

Unit of CO (cardiac output)

Answer 7

Volume of blood ejected by the heart per minute (L/min )

Question 8

TPR is?

Answer 8

Total resistance of peripheral vasculature in the systemic circulation and has the units of mm Hg (L/min)

Question 9

An increase in firing rate of the autonomic _____ or _____ neurons, which innervate the pacemaker, the sino-atrial node, will increase or decrease heart rate respectively.

Answer 9

Sympathetic or parasympathetic neurons

Question 10

Adrenaline (epinephrine) released from?

Answer 10

Released from adrenal medulla

Question 11

Adrenaline (epinephrine) stimulates an increase in?

Answer 11

Increase in heart rate

Question 12

An increase in the volume of blood returning to the heart (venous return) can indirectly increase?

Answer 12

Heart rate

Question 13

The force of ventricular contraction is influenced by?

Answer 13

sympathetic neuronal output and an increased volume of blood returning to the heart will induce a greater force of contraction (Starling’s LAw of the Heart) respectively.

Question 14

The previous DP (if DP increases then the following ____ increases)

Answer 14

Systolic pressure

Question 15

List determinants of systolic pressure

Answer 15

• Force of ventricular contraction
• Stroke volume
• Previous diastolic pressure
• Distensibility of aortic walls

Question 16

Systolic pressure will increase with a decrease in?

Answer 16

Decrease in aortic elasticity

Question 17

List determinants of diastolic pressure

Answer 17

• Heart rate
• Total peripheral resistance
• Previous systolic pressure

Question 18

An increase in heart rate will increase?

Answer 18

Diastolic pressure

Question 19

An increase in TPR will increase?

Answer 19

Diastolic pressure

Question 20

An increase in systolic pressure will cause following ?

Answer 20

Diastolic pressure to increase

Question 21

Determinants of total peripheral resistance

Answer 21

• Radius of the blood vessel (arterioles mostly)
• Length of the blood vessels
• Viscosity of blood

Question 22

Radius of the blood vessels controls?

Answer 22

Controls vasoconstriction while local metabolites cause vasodilation

Question 23

What is baroreceptor reflex?

Answer 23

It regulates homeostatic control of blood pressure automatically restoring any changes in blood pressure back to normal after a posture change.

Question 24

What are baroreceptor afferent nerve fibres?

Answer 24

Cranial nerves IX (sympathetic) and X (parasympathetic) fibres

Question 25

Where are baroreceptor afferent nerve fibres located?

Answer 25

Located in the blood vessel walls of the carotid sinuses and aortic arch.

Question 26

When MAP falls when changing from a sitting to standing position, firing rate of baroreceptor?

Answer 26

Baroreceptor firing rate decreases

Question 27

Decreased baroreceptor firing rate causes an increased?

Answer 27

Increased firing of efferent sympathetic nerves to the heart and a decreased firing of efferent parasympathetic nerves via interneurons in the brainstem.

Question 28

Increased efferent sympathetic nerves to the heart increases?

Answer 28

Increased activity of post-ganglionic cardiac sympathetic nerves, resulting in increased pacemaker activity of the sino-atrial node (SA node)

Question 29

Increased post-ganglionic cardiac sympathetic nerves results in?

Answer 29

Increased pacemaker activity of SA node

Question 30

Increased pacemaker activity of SA node increases?

Answer 30

Increases contractility of ventricular muscle fibres

Question 31

Increased contractility of ventricular muscle fibres with decreased cardiac vagal activity results in an?

Answer 31

Results in an increase in heart rate and contractility

Question 32

Increased activity in sympathetic vasomotor nerves to arterioles and veins causes?

Answer 32

Causes vasoconstriction and venoconstriction respectively.

Question 33

Sympathetic activation also causes an increase in?

Answer 33

Increase in adrenal medullary hormone secretion, principally adrenalin (epinephrine) which also affects blood vessels and the heart.

Question 34

Net result of baroreceptor reflex

Answer 34

Rise in CO and TPR, and hence MAP, thereby restoring it to normal.

Question 35

Change in posture from lying to standing will _____ the pressure in the vessels below the heart and result in?

Answer 35

Increased pressure in the vessels, and results in immediate changes in SP, DP, MAP and HR.

Question 36

How long till body baroreceptor reflex kicks in to restore MAP after postural change?

Answer 36

5 to 10 seconds

Question 37

Finapres recording devices allow?

Answer 37

Allow continuous measurement of BP and visualization of the immediate effects of postural change

Question 38

Finapres recording devices monitors?

Answer 38

Monitors intra-arterial blood pressure changes using a finger cuff.

Question 39

How does finapres recording device work?

Answer 39

Waves of increasing and decreasing volumes of blood flowing through finger with each cardiac cycle evaluated as pressure changes in the cuff.

Question 40

Finapres recording devices measures?

Answer 40

Measures the highest and lowest pressures representing the systolic pressure and diastolic pressures respectively, while MAP and CO are derived from the software.