6: Control of arterial blood pressure (2) Flashcards Preview

Cardiovascular Week 1 & 2 2016/17 > 6: Control of arterial blood pressure (2) > Flashcards

Flashcards in 6: Control of arterial blood pressure (2) Deck (42)
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1
Q

Long-term control of blood volume and MAP is achieved by controlling…

A

extracellular fluid volume

2
Q

What two volumes make up the extracellular fluid volume (ECF)?

A

ECF = Plasma Volume (PV) + Interstitial Fluid Volume (IFV)

3
Q

Interstitial fluid bathes ___.

A

cells

4
Q

If plasma volume falls, compensatory mechanisms shift ___ ___ back to the plasma compartment.

A

interstitial fluid

5
Q

Which two factors affect extracellular fluid volume?

A
  1. Water excess or deficit

2. Na+ excess or deficit

6
Q

Extrinsic control of MAP is carried out by…

A

the nervous system and hormones.

7
Q

How do hormones regulate the extracellular fluid volume?

A

They regulate the water and salt balance in our bodies

8
Q

Which three hormone systems regulate extracellular fluid volume?

A
  1. Renin-Angiotensin-Aldosterone System (RASS)
  2. Atrial Natriuretic Peptide (ANP)
  3. Antidiuretic Hormone (Vasopressin) or ADH
9
Q

What two constituents of MAP does the RAAS system regulate?

A

Plasma volume

Total peripheral resistance

10
Q

Where is renin released?

A

The kidneys

11
Q

What molecule does renin act on to produce angiotensin I?

A

Angiotensinogen

12
Q

Where is angiotensinogen produced?

A

The liver

13
Q

Renin stimulates the formation of ___ _ from angiotensinogen.

A

Angiotensin I

14
Q

Which enzyme converts angiotensin I to angiotensin II?

A

Angiotensin converting enzyme (ACE)

15
Q

Where is ACE produced?

A

Pulmonary vascular endothelium

16
Q

ACE converts angiotensin I into ____ _.

A

Angiotensin II

17
Q

What stimulates the release of aldosterone from the adrenal cortex?

A

Angiotensin II

18
Q

What is released from the adrenal cortex when the cortex is stimulated by angiotensin II?

A

Aldosterone

19
Q

Where is aldosterone released after stimulation by angiotensin II?

A

Adrenal cortex

20
Q

Angiotensin II stimulates the release of aldosterone from the adrenal cortex.

Name another effect it has.

A

Causes vasoconstriction, increasing TPR and therefore MAP

Increases thirst and ADH release, increasing plasma volume and therefore MAP

21
Q

Where does aldosterone act?

A

The kidneys

22
Q

What is the effect of aldosterone once it has stimulated the kidneys?

A

Increases Na+ and water retention, increasing plasma volume –> increases MAP

23
Q

What is the rate limiting step for the RAAS system?

A

Renin secretion (from the juxtaglomerular apparatus) from the kidney

24
Q

Name three conditions which stimulate renin secretion from the kidneys.

A

1) Renal artery hypotension (decreased blood pressure)
2) Stimulation of renal sympathetic nerves
3) Decreased [Na+] in renal tubular fluid

25
Q

What does ANP stand for?

A

Atrial natriuretic peptide

26
Q

Where is the hormone ANP stored?

A

Atrial myocytes

27
Q

What is ANP released in response to?

A

Atrial distension / hypervolaemic states in the atrium

28
Q

What are two effects of ANP on the renal system once it has been released following atrial distension?

A

Decreased excretion of Na+ and water from the kidneys, reducing blood volume and therefore MAP

Decreased renin secretion

29
Q

What is an effect of ANP on the vascular system?

A

Vasodilator - decreases MAP

30
Q

Which mechanism does ANP serve as a counter to?

A

Renin-Angiotensin-Aldosterone system

31
Q

What does ADH stand for?

A

Antidiuretic hormone

32
Q

What is ADH also known as?

A

Vasopressin

33
Q

Where in the brain is ADH synthesised?

A

Hypothalamus

34
Q

Where in the brain is ADH stored?

A

Posterior pituitary gland

35
Q

What is the main stimulator of ADH release from the posterior pituitary gland?

A

Increased extracellular fluid osmolarity

Also: reduced extracellular fluid volume

36
Q

What is the normal osmolarity of extracellular fluid?

A

280 milli-osmoles/L

37
Q

Which receptors in the brain monitor plasma osmolarity?

A

Osmoreceptors

38
Q

Where does ADH act?

A

The kidney tubules

39
Q

What effect does ADH have once it has acted on the kidney tubules?

A

Increases reabsoprtion of water, increasing ECF volume and hence cardiac output and MAP

40
Q

What effect does ADH have on blood vessels?

A

Vasoconstriction - increases TPR and therefore MAP

41
Q

What achieves short-term regulation of MAP?

A

Baroreceptor reflex

42
Q

What achieves long-term regulation of MAP?

A

Control of blood volume by hormones