Long Term Control of Blood Pressure Flashcards

1
Q

What does long term control of blood pressure revolve around?

A

Control of plasma volume by the kidneys

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2
Q

What are the 3 main hormonal systems involved in long term control of blood pressure?

A

Renin-angiotensin-aldosterone system

Antidiuretic factor (ADH, vasopressin)

Atrial natriuretic peptide

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3
Q

What is antidiuretic factor also known as?

A

ADH or vasopressin

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4
Q

What are some examples of the functions of the kidneys?

A

Excretion of waste products

Maintenance of ion balance

Regulation of pH

Regulation of osmolarity

Regulation of plasma volume

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5
Q

What is controlled to regulate mean arterial pressure in the long term?

A

Plasma volume

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6
Q

How do the kidneys regulate plasma volume?

A

1) Renal counter-current system creates a very high osmolarity outside the collecting duct
2) Control over Na+ transport determines how big that osmotic gradient is
3) Control over the permeability of the collecting duct to water determines if water follows that osmotic gradient or not
4) Hence you can control how much water is lost in the urine, and how much is retained

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7
Q

What determines how big the osmotic gradient between the collecting duct and outside it is?

A

Control over Na+ transport

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8
Q

What determines whether water follows the osmotic gradient of the collecting duct or not?

A

Control over the permeability of the collecting duct

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9
Q

What are the 2 things the collecting duct can be made to be?

A

Very permeable to water

Very impermeable to water

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10
Q

What does the kidney duct being very permeable to water result in?

A

Lots of water reabsorption, little urine and conserve plasma volume

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11
Q

What does the kidney’s collecting duct being very impermeable to water result in?

A

Little reabsorption, lots of urine and a reduction in plasma volume

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12
Q

What is diuresis?

A

Increased or excessive production of urine

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13
Q

What is increased or excessive production of urine called?

A

Diuresis

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14
Q

What are the 3 distinct hormonal processes that regulate the permeability of the collecting ducts, and in turn plasma colume?

A

Renin-angiotensin-aldosterone system

Antidiuretic factor

Atrial natriuretic peptide

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15
Q

What is renin produced by?

A

Juxtaglomerular (granule cells) of the kidneys

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16
Q

What is production of renin triggered by?

A

Activation of sympathetic nerves to juxtaglomerular apparatus

Decreased distension of afferent arterioles (known as the renal baroreflex)

Decreased delivery of Na+/Cl- through the tubule

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17
Q

What does renin do?

A

Converts inactive angiotensinogen to angiotensin I, which in turn is converted by angiotensin converting enzyme to angiotensin II

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18
Q

What catalyses the reaction of angiotensinogen to angiotensin I?

A

Renin

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19
Q

What catalyses the reaction of angiotensin I to angiotensis II?

A

Angiotensis converting enzyme

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20
Q

What are all of the things that production of renin is triggered by a sign of?

A

Low arteriolar pressure

21
Q

What does angiotensin II do?

A

Stimulates release of aldosterone from the adrenal cortex

Increases release of vasopressin from the pituitary

Acts as a vasocontrictor

22
Q

Where is aldosterone released from?

A

Adrenal cortex

23
Q

Where is vasopressin released from?

A

Pituitary

24
Q

What does aldosterone do?

A

Increases Na+ reabsorption in the loop of Henle

Therefore reduces diuresis and increases plasma volume

25
Q

What does vasopressin do?

A

Increases water permeability of the collecting duct

Therefore reduces diuresis and increases plasma volume

Increases sense of thirst

26
Q

What does aldosterone being a vasocontrictor allow it to do?

A

Increase total peripheral resistance

27
Q

What do all of the things that angiontensin II does cause?

A

Increase in mean arteriolar pressure

28
Q

What kind of system is the renin-angiotensin-aldosterone system?

A

Negative feedback

29
Q

Why is the renin-angiotensin-aldosterone system a negative feedback system?

A

1) Multiple mechanisms detect any decrease in mean arteriolar pressure
2) Stimulates release of renin
3) Evokes multiple mechanisms to increase mean arteriolar pressure

30
Q

What is antidiuretic hormone produced and released from?

A

Produced from hypothalamus

Released from posterior pituitary

31
Q

What triggers the release of antidiuretic hormone?

A

Decrease in blood volume

Increase in osmolarity of interstitial fluid

Circulating angiotensin II

32
Q

What is a decrease in blood volume detected by?

A

Cardiopulmonary baroreceptors

33
Q

What is an increase in interstitial fluid osmolarity detected by?

A

Osmoreceptors in the hypothalamus

34
Q

What are all of the things that trigger the release of antidiuretic hormone a sign of?

A

Low plasma volume and/or low mean arteriolar pressure

35
Q

What does antidiuretic hormone do?

A

Increases permeability of collecting duct to water, therefore reducing diuresis and increases plasma volume

Causes vasocontriction (increases mean arteriolar pressure)

36
Q

What kind of system is the release of antidiuretic hormone?

A

Negative feedback

37
Q

How is the release of antidiuretic hormone a negative feedback system?

A

1) Multiple mechanisms detect any increase in mean arteriolar pressure
2) Stimulates release of vasopressin
3) Evokes multiple mechanisms that increase mean arteriolar pressure

38
Q

What does ANP stand for?

A

Atrial natriuretic peptide

39
Q

Where is atrial natriuretic peptide produced?

A

Produced in and released from myocardial cells in the atria

40
Q

What triggers the release of atrial natriuretic peptide?

A

Increase distension of atrium, which is a sign of increased mean arteriolar pressure

41
Q

What does the atrial natriuretic peptide do?

A

Increases excretion of Na+ (natriuresis)

Inhibits release of renin

Acts on medullary cardiovascular centres to reduced mean arteriolar pressure

42
Q

What kind of system is the release of atrial natriuretic peptide?

A

Negative feedback system

43
Q

How is the release of atrial natriuretic peptide a negative feedback system?

A

1) A mechanism that detects any increase in mean arteriolar pressure
2) Stimulates release of atrial natiuretic peptide (ANP)
3) Evokes multiple mechanisms which reduce mean arteriolar pressure

44
Q

What is hypertension?

A

Persistant elevation of blood pressure

45
Q

What is persistant elevation of blood pressure called?

A

Hypertension

46
Q

What percentage of hypertension is classed as secondary?

A

5-10%

47
Q

What is secondary hypertension?

A

Due to a known cause

48
Q

What is primary hypertension?

A

Due to an unknown cause

49
Q

What are examples of drugs used to treat hypertension?

A

Ca2+ channel antagonists

B-adrenoceptor antagonist

Thiazide diuretics

Angiontensin converting enzyme inhibitors