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1

What percentage of the body weight is water?

60%

2

Total body fluid equation?

Intracelullar (2/3) + extracellular fluid - normally 1/3 of the total

3

Extracellular Body fluid volume equation?

ECFV= Plasma volume + Interstitial fluid volume
ECFV= PV + IFV

4

What is ECFV?

The fluid that bathes the cells and acts as the go between for the blood and the body cells

5

What happens if plasma falls?

Compensatory mechanisms shift fluid from interstitial compartment to plasma compartment

6

What else is controlled if ECFV is controlled?

MAP
Blood volume

7

20% of body weight is?

Extracellular fluid

8

40% of body weight is?

Intracellular fluid

9

Components of extracellular fluid?

3/14th plasma
11/14th Interstitial fluid

10

What 2 main factors affect our bodies extracellular fluid volume ECFV?

Water excess or deficit
Na+ excess or deficit

11

How do our bodies control the factors that affect our extracellular fluid volume?

Hormones act as effectors to regulate the ECFV by regulating the water and salt balance in our bodies
Healthy= water input=water output

12

Hormones which regulate the extracellular fluid volume?

The renin-angiotensin - aldosterone system (RAAS)
Natriuretic Peptides (NPs)
Antidiuretic hormone (Arginine Vasopressin) - ADH

13

Role of RAAS?

Important role in plasma volume regulation and SVR - hence the regulation of MAP

14

3 components of RAAS?

Renin
Angiotensin
Aldosterone

15

What is renin?

Renin is released from the kidneys and stimulates formation of angiotensin 1 in the blood from angiotensinogen (produced by liver)

16

Angiotensin 1 conversion?

Converted to angiotensin 2 by angiotensin converting enzyme- ACE

17

Where is angiotensin converting enzyme produced?

Mainly by pulmonary vascular endothelium

18

What does angiotensin 2 do?

-Stimulate the release of aldosterone from the adrenal cortex
- Causes systemic vasoconstriction -which increase SVR
- Also stimulates thirst and ADH release
Contributes to increasing plasma volume mainly by aldosterone

19

What does aldosterone do?

A steroid hormone which acts on kidneys to increase sodium and water retention- increase plasma volume

20

What is the rate limiting step for RAAS?

Renin secretion

21

What is the renin angiotensin aldosterone system regulated by?

Mechanisms which stimulate renin release from the juxtaglomerular apparatus in the kidney.

22

What does the mechanism that regulates RAAS involve?

1)Renal artery hypotension- caused by systemic hypotension (decreases blood pressure)
2)Stimulation of renal sympathetic nerves
3)Decreased [Na+] in renal tubular fluid - sensed by macula densa (specialized cells of kidney tubules)

23

What are natriuretic peptides?

Peptide hormones synthesized by heart (also brain and other organs)

24

When are natriuretic peptides released?

In response to cardiac distension or neurohormonal stimuli

25

What do NPs do?

-They cause excretion of salt and water in the kidneys thereby reducing blood volume and blood pressure.
-Decrease renin release- decrease BP
-Act as vasodilators; decrease SVR and BP
-Provide a counter regulatory system for the RAAS

26

How many types of natriuretic peptides are released by the heart?

2

27

The NPs released by the heart?

1)Atrial natriuretic pepide (ANP)
2)Brian-type natriuretic peptide (BNP)

28

What is ANP and when is it released?

28 amino acid peptide synthesized and stored by atrial
myocytes (Atrial muscle cells)
-Released in response to atrial distension (Hypervolemic states)

29

What is Brian-type natriuretic peptide?

32 amino acid peptide synthesized by heart, ventricles, brain and other organs

30

How is BNP first synthesized?

First synthesized as prepro-BNP (
then cleaved to Pro-BNP (108)
Then finally BNP (32)