L9- Physiology: parameters of the cardiovascular system Flashcards Preview

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Flashcards in L9- Physiology: parameters of the cardiovascular system Deck (40)
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1
Q

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

A

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).

2
Q

Formula of PP (pulse pressure)

A

PP = SP - DP

3
Q

Mean Arterial Pressure changes when?

A

When you exercise or change posture

4
Q

Heart spends more time in?

A

more time in diastole than systole

5
Q

Formula of MAP (mean arterial pressure)

A

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

6
Q

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

A

MAP = CO x TPR

7
Q

Unit of CO (cardiac output)

A

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

8
Q

TPR is?

A

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

9
Q

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.

A

Sympathetic or parasympathetic neurons

10
Q

Adrenaline (epinephrine) released from?

A

Released from adrenal medulla

11
Q

Adrenaline (epinephrine) stimulates an increase in?

A

Increase in heart rate

12
Q

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

A

Heart rate

13
Q

The force of ventricular contraction is influenced by?

A

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.

14
Q

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

A

Systolic pressure

15
Q

List determinants of systolic pressure

A
  • Force of ventricular contraction
  • Stroke volume
  • Previous diastolic pressure
  • Distensibility of aortic walls
16
Q

Systolic pressure will increase with a decrease in?

A

Decrease in aortic elasticity

17
Q

List determinants of diastolic pressure

A
  • Heart rate
  • Total peripheral resistance
  • Previous systolic pressure
18
Q

An increase in heart rate will increase?

A

Diastolic pressure

19
Q

An increase in TPR will increase?

A

Diastolic pressure

20
Q

An increase in systolic pressure will cause following ?

A

Diastolic pressure to increase

21
Q

Determinants of total peripheral resistance

A
  • Radius of the blood vessel (arterioles mostly)
  • Length of the blood vessels
  • Viscosity of blood
22
Q

Radius of the blood vessels controls?

A

Controls vasoconstriction while local metabolites cause vasodilation

23
Q

What is baroreceptor reflex?

A

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

24
Q

What are baroreceptor afferent nerve fibres?

A

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

25
Q

Where are baroreceptor afferent nerve fibres located?

A

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

26
Q

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

A

Baroreceptor firing rate decreases

27
Q

Decreased baroreceptor firing rate causes an increased?

A

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

28
Q

Increased efferent sympathetic nerves to the heart increases?

A

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

29
Q

Increased post-ganglionic cardiac sympathetic nerves results in?

A

Increased pacemaker activity of SA node

30
Q

Increased pacemaker activity of SA node increases?

A

Increases contractility of ventricular muscle fibres

31
Q

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

A

Results in an increase in heart rate and contractility

32
Q

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

A

Causes vasoconstriction and venoconstriction respectively.

33
Q

Sympathetic activation also causes an increase in?

A

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

34
Q

Net result of baroreceptor reflex

A

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

35
Q

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

A

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

36
Q

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

A

5 to 10 seconds

37
Q

Finapres recording devices allow?

A

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

38
Q

Finapres recording devices monitors?

A

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

39
Q

How does finapres recording device work?

A

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

40
Q

Finapres recording devices measures?

A

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