Physiological regulation of blood pressure Flashcards

1
Q

What is blood pressure

A

the hydrostatic pressure exerted by blood on the walls of the blood vessels

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2
Q

How will the blood pressure differ in the arteriole and venous system

A

Arteriole= high
Venous= low
Blood flows from arteriole to venous system

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3
Q

What is systolic pressure

A

the maximum pressure achieved during ventricular contraction

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4
Q

What is diastolic pressure

A

The lowest level of arterial pressure

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5
Q

What is the mean arterial pressure (MAP)

A

Pressure that propels blood to tissue

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6
Q

How is MAP calculated

A

(2x diastolic)+ systolic / 3

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7
Q

What is the usual MAP range for dogs

A

70-110mmHg

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8
Q

What MAP is necessary to perfuse coronary arteries, brain, kidneys

A

60mmHg

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9
Q

What is MAP dependent on

A
  • Cardiac output
  • Total peripheral resistance
  • volume of blood
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10
Q

What affects cardiac output

A

heart rate and stroke volume

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11
Q

How do the flexible walls of the arterial system affect the flow of blood

A

Flexible walls absorb pressure energy, reducing the amplitude. The wall returns the energy after the wave, maintaining the pressure

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12
Q

What is the starling effect with regards to blood pressure

A

Leads to increased stretching of heart muscle, leading to increased contraction

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13
Q

How does the sympathetic nervous system affect blood pressure

A

increases HR and force of contraction (increasing BP)

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14
Q

How does the parasympathetic nervous system affect blood pressure

A

Decreases HR and contraction force (decreasing BP)

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15
Q

What is total peripheral resistance

A

The overall resistance of the entire systemic circulatory system

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16
Q

What factors can affect the total peripheral resistance

A
  1. Blood volume and viscosity

2. Vascular elasticity

17
Q

What impact would exercise have on MAP

A

Exercise would increase heart rate, stroke volume and MAP. More proportion of the cycle will become systole

18
Q

What techniques can be used to measure MAP

A
  • Sphygmomanometer

- Invaise methods (direct) using fluid filled catheter

19
Q

What factors could affect the BP measure

A
  • Stress
  • Position
  • Temperature
  • Position of the cuff
  • Full bladder
20
Q

What is pulse pressure

A

is the difference between systolic and diastolic pressure

pulse pressure= systolic- diastolic

21
Q

What is autoregulation of blood flow

A

how blood flow to an organ remains constant over a wide range of perfusion pressures

22
Q

What are baroreceptors

A

Baroreceptors sense changes in BP from vasoconstriction and vasodilation

23
Q

What are chemoreceptors

A

A receptor that responds to a change in the chemical composition (PaCO2 and pH) of the fluid around it

24
Q

How can haemorrhage affect cardiac function?

A
  • Decreased preload, due to loss of venous return
  • Decrease stroke volume
  • Decrease in MAP
  • Decrease in tissue oxygen delivery
25
Q

What will recognise the reduce blood pressure after haemorrhage?

A

Baroreceptors due to loss of stretch

26
Q

What are the autonomic affects from the heart

A
  • Noradrenaline released from nerve endings to act of B1 adrenoreceptos
  • Parasympathetic vagal tone decreased
  • HR increases
  • Increased force of contraction
27
Q

What is the result of these changes from the autonomic affects of the heart

A
  • Increased stroke volume and Cardiac output

- This increases MAP back toward normal

28
Q

What happens to blood vessels during haemorrhage?

A

Vasoconstriction, increased systemic vascular resistance

29
Q

What is the role of angiotensin II during haemorrhage?

A

Increases blood vessel tone (vasoconstriction)

30
Q

What is the effect of increased perfusion pressure on the kidney

A
  • Reduced Na+ and thus water resorption in proximal tube
  • Increased Na+ and water excretion
  • ECF volume decreases and thus BP increase diminished
31
Q

What is hypovolemia

A

decreased blood volume, loss from the vasculature itself

leads to inadequate oxygen delivery to tissues

32
Q

How is dehydration different to hypovolemia

A
Dehydration= loss of fluids from ECF and ICF
Hypovolemia= a decreased volume of circulating blood in the body- is loss from vasculature
33
Q

What are some signs of hypotension

A
  • prolonged CRT
  • tachypnoea
  • pale mucous membranes
  • poor pulse pressure
  • tachycardia
  • weakness
  • thirst
34
Q

What are the signs that distinguish dehydration from hypotension

A
  • Skin/ fur tenting

- altered packed cell volume