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Anatomy and Physiology > Lecture 13- Blood Pressure Regulation > Flashcards

Lecture 13- Blood Pressure Regulation Flashcards

1
Q

blood pressure

A

the force exerted upon vessel walls as blood flows through

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2
Q

what is required to exchange substances/ fluids across capillary networks

A

a minimum pressure (capillary hydrostatic pressure)

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3
Q

formula for blood pressure

A

cardiac output x total peripheral resistance

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4
Q

what total peripheral resistance dependant on

A

dependant upon arteriolar radius

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5
Q

autoregulation of local flow is also known as

A

intrinsic control of blood flow

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6
Q

what system is responsible for short term regulation

A

neural/ nervous system

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7
Q

what system is responsible for long term regulation

A

endocrine system

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8
Q

outline intrinsic control when local blood flow in a tissue is too low

A
  1. homeostasis disturbed from physical stress (trauma, high temp etc), chemical changes (lower oxygen, lower pH, increased carbon dioxide or increased vasodilatory metabolites) or increased tissue activity (lactate)
  2. inadequate local blood pressure and blood flow
  3. autoregulation: precapillary sphincters relax and vasodilatory metabolites (nitrogen, potassium ions, hydrogen ions, carbon dioxide and lactate) enter arterioles allowing capillary regulation
    4.local decrease in resistance and increase in blood flow
  4. homeostasis returns
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9
Q

what occurs if blood pressure is still too low to meet demands even after autoregulation

A

central mechanisms are activated to increase systemic blood pressure

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10
Q

which branch of the autonomic nervous system is activated to restore blood pressure if intrinsic control can’t bring the body back to homeostasis

A

sympathetic nervous system

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11
Q

how does the SNS help regulate blood pressure

A

increases heart rate and stroke volume
enhances vasoconstriction

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12
Q

what centres in the CNS are activated by baroceptors

A

cardiovascular centres

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13
Q

baroreceptors

A

sensitive to changes in pressure and found in aorta and carotid sinus (blood flow to brain/ cerebral blood flow)

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14
Q

what effect does a fall in blood pressure have on baroreceptors

A

inhibition (less activation/ firing of the baroreceptors)

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15
Q

when baroreceptors are inhibited what centres are activated

A

cardio acceleratory centre activation and vasomotor centre activation (region in medulla)

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16
Q

what centre is inhibited when baroreceptors are inhibited

A

cardioinhibitory centre

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17
Q

what effect does a rise in blood pressure have on baroreceptors

A

baroreceptor stimulation

18
Q

when baroreceptors are stimulated, what centres are inhibited

A

cardio acceleratory centre and vasomotor centre

19
Q

when baroreceptors are stimulated, what centres are activated

A

cardioinhibitory centre

20
Q

what occurs when blood pressure is too high

A

less sympathetic activity and more parasympathetic activity
reduced peripheral resistance

21
Q

where are peripheral chemoreceptors found

A

body/ blood

22
Q

why is there a fall in pH with increased CO2

A

co2 dissolves in the blood and forms hydrogen ions lowering the pH

23
Q

what is activated by an increased respiratory rate

A

respiratory centre activation

24
Q

what does respiratory centre activation lead to

A

a rise in CO2

25
Q

effect of a rise in co2 on cerebral vessels

A

vasodilation of cerebral vessels leading to increased blood flow to the brain (must be a preserved blood flow to the brain at all times)

26
Q

what receptors are found in the medulla which are sensitive to co2

A

central chemoreceptors

27
Q

central chemoreceptors

A

activate the respiratory centre

28
Q

why is the respiratory centre activated when there is a rise in co2

A

there is not enough o2 and too much co2 so there is no point increasing more blood as it won’t be able to pick up enough oxygen as not breathing fast enough so respiratory centre is activated meaning more oxygen in the lungs so the increased blood can pick up more oxygen

29
Q

what centres are activated and inhibited when chemoreceptors are activated

A

cardio acceleratory centre activation
cardioinhibitory centre inhibition
vasomotor centre activation

30
Q

what does activation of the vasomotor centre lead to

A

peripheral vasoconstriction

31
Q

what are the three endocrine responses to a low blood pressure even after autoregulation

A

ADH/ vasopressin
Erythropoietin
Renin-Angiotensin-Aldosterone System (RAAS)

32
Q

how does ADH regulate a low blood pressure

A

pituitary gland secretes ADH
ADH is a vasoconstrictor and increases fluid retention (increases thirst)
increase permeability of the csm of the collecting duct

33
Q

how does erythropoietin help regulate a low blood pressure

A

fall in blood oxygen stimulates erythropoietin (main hormone in the formation of rbcs)
is a vasoconstrictor
more rbcs increases the blood volume
more minor compared to the others

34
Q

how does Renin-Angiotensin Aldosterone System (RAAS) help regulate a low blood pressure

A

kidney cells have their own baroreceptors which stimulate the enzyme renin which converts angiotensinogen to angiotensin 1

angiotensin 1 is inactive but the angiotensin converting enzyme converts t into angiotensin 2 which is an active and potent vasoconstrictor (causes a greater increase in vasoconstriction and peripheral resistance)

angiotensin 2 stimulates aldosterone (increases the activity of sodium potassium ATPase pump so more sodium ions are absorbed in the distal convoluted tubule and collecting duct therefore more water is reabsorbed which increases the volume of the blood within the vascular system )

35
Q

role of sensors in muscle cells of atria and ventricles

A

able to detect when they are being stretched too much

36
Q

what is secreted when there is increased stretching of atria and ventricles when blood pressure is too high

A

secretion of natriuretic peptides from muscle cells

37
Q

what natriuretic peptides do the atria and ventricles secrete

A

atria: atrial natriuretic peptides
ventricles: brain natriuretic peptides

38
Q

renal effect of natriuretic peptides

A

act on the kidney
increased sodium loss in the urine ( inhibits sodium potassium pump therefore less sodium is reabsorbed in the kidney and more water lost in the urine)
reduced thirst (inhibit secretion of ADH)
reduce blood volume

39
Q

vascular effects of natriuretic peptides

A

inhibition of ADH, aldosterone, NA and adrenaline release
peripheral vasodilation
reduce blood pressure

40
Q

what are the 5 consequences of blood loss (severe haemorrhage)

A

decreased atrial pressure
altered blood gases
RAS activation
catecholamine release
vasopressin release

41
Q

role of chemo and baroreceptor reflex in severe blood loss

A

cardiac stimulation
systemic vasoconstriction
fluid and volume redistribution

42
Q

role of RAAS and ADH secretion in sever blood loss

A

restore blood volume, inhibit secretion of water at kidneys, recall fluid from the tissues, less ADP sceretion as want more retention of water

Anatomy and Physiology (14 decks)

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