Control of arterial BP part 2

Question 1

What percentage of the body weight is water?

Answer 1

60%

Question 2

Total body fluid equation?

Answer 2

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

Question 3

Extracellular Body fluid volume equation?

Answer 3

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

Question 4

What is ECFV?

Answer 4

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

Question 5

What happens if plasma falls?

Answer 5

Compensatory mechanisms shift fluid from interstitial compartment to plasma compartment

Question 6

What else is controlled if ECFV is controlled?

Answer 6

MAP

Blood volume

Question 7

20% of body weight is?

Answer 7

Extracellular fluid

Question 8

40% of body weight is?

Answer 8

Intracellular fluid

Question 9

Components of extracellular fluid?

Answer 9

3/14th plasma

11/14th Interstitial fluid

Question 10

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

Answer 10

Water excess or deficit

Na+ excess or deficit

Question 11

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

Answer 11

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

Question 12

Hormones which regulate the extracellular fluid volume?

Answer 12

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

Question 13

Role of RAAS?

Answer 13

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

Question 14

3 components of RAAS?

Answer 14

Renin
Angiotensin
Aldosterone

Question 15

What is renin?

Answer 15

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

Question 16

Angiotensin 1 conversion?

Answer 16

Converted to angiotensin 2 by angiotensin converting enzyme- ACE

Question 17

Where is angiotensin converting enzyme produced?

Answer 17

Mainly by pulmonary vascular endothelium

Question 18

What does angiotensin 2 do?

Answer 18

-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

Question 19

What does aldosterone do?

Answer 19

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

Question 20

What is the rate limiting step for RAAS?

Answer 20

Renin secretion

Question 21

What is the renin angiotensin aldosterone system regulated by?

Answer 21

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

Question 22

What does the mechanism that regulates RAAS involve?

Answer 22

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)

Question 23

What are natriuretic peptides?

Answer 23

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

Question 24

When are natriuretic peptides released?

Answer 24

In response to cardiac distension or neurohormonal stimuli

Question 25

What do NPs do?

Answer 25

- 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

Question 26

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

Answer 26

2

Question 27

The NPs released by the heart?

Answer 27

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

Question 28

What is ANP and when is it released?

Answer 28

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

Question 29

What is Brian-type natriuretic peptide?

Answer 29

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

Question 30

How is BNP first synthesized?

Answer 30

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

Question 31

What can be measured in patients with suspected heart failure?

Answer 31

Serum BNP | N-terminal piece of pro-BNP (NT- proBnp)

Question 32

Where is ADH synthesized and stored?

Answer 32

Hypothalamus and stored in posterior pituitary

Question 33

What is secretion stimulated by?

Answer 33

1) Reduced extracellular fluid volume | 2) Increased ECF osmolality (main)

Question 34

What does plasma osmolality indicate?

Answer 34

Relative solute-water balance

Question 35

What is osmolality monitored by?

Answer 35

Osmoreceptors in brain in close proximity to the hypothalamus

Question 36

What is ADH release stimulated by?

Answer 36

Increased plasma osmolality?

Question 37

What does ADH do?

Answer 37

Acts in the kidney tubules to increase water reabsorption(conserves water) antidiuresis (concentrating urine

Question 38

What does antidiuresis cause?

Answer 38

increased ECFV and plasma volume hence cardiac output and BP

Question 39

How does ADH act on blood vessels?

Answer 39

Causes vasoconstriction which increases SVR and blood pressure- this effect is small in normal people but for people in hypovolaemic shock it becomes important (haemmorhaging people)

Question 40

How is short term moment to moment control of MAP carried out?

Answer 40

Baroreceptor reflex (rapid)

Question 41

Long term regulation of MAP is achieved by?

Answer 41

Control of Blood volume by hormones

Question 42

Summary of what ADH does?

Answer 42

Regulates ECF including plasma volume and osmolality to deal with fluid loads/deficits

Question 43

Role of Renin angiotensin aldosterone system?

Answer 43

Important role in long term regulation of MAP

Question 44

Role of natriuretic peptides?

Answer 44

Act as counter-regulatory to RAAS