Control Of Arterial Blood Pressure 2

Question 1

What is the total body fluid a combination of

Answer 1

Intracellular fluid (2/3)
Extracellular (ecf)
Minus normally 1/3rd of total

Question 2

What sit he ECF volume

Answer 2

Comb of plasma vol and interstitial fluid volume

Question 3

What is the ECF vol

Answer 3

Fluid which bathes cells and acts as a go between the blood and body cells

Question 4

What are two main factors which affect the ECF vol

Answer 4

Water excess of deficit

Sodium excess of deficit

Question 5

What do hormones do to ECF

Answer 5

Act as regulators ( including plasma vol)

By reg water and salt balance in our bodies

Question 6

What are some hormoene that reg ECF vol

Answer 6

R-A-A syst
Atrial natriuretic peptide
ADH

Question 7

What su the role of RAA syst

Answer 7

Role in reg plasma vol and tpr and hence map
Components - renin, angiotensin, aldosterone

Renin - enzyme form kidney Stim form of angiotensin 1 from angiotensinogen (from liver)

Angiontensin1 conv to angiotensin 2 by angiotensin conv enzyme (prod by pulmonary vasc endothelium)

Angiotensin 2 - Stim release aldosterone form adrenal cortex, increase bp, cause systemic vasoconstriction which increases tpr, Stim thirst and ADH release

Aldosterone - steroid hormone acts on kidneys to increase sodium a nd water retention increase plasma vol

Question 8

What is the rate limiting step for RAA syst

Answer 8

Renin sec

Question 9

Where is renin sec

Answer 9

Juxtaglomerular apparatus of nephron in kidney

Question 10

What a re the steps of renin sec

Answer 10

Renal artery hypotension caused by systemic hypotension which Dec bp

Stim of renal symp nerves

Decreased sodium in renal tubular fluid which is sensed by macula dense

Question 11

What is the role of ANP

Answer 11

(28 aa peptide syn and stored by atrial muscle cells)
Released in response to atrial distension - hypovolaemic states
Cause excretion of salt and water in kidneys thereby reducing blood volume and blood pressure
Acts as a vasodilator - decreases bp
Decreases renin sec
Counter regulatory mechanism for RAA syst

Question 12

What is the role of ADH

Answer 12

Peptide hormone derived form prehomrone form hypothalamus and stored in post pit

Sec ADH Stim by reduced extracellular fluid volume or increased extracellular fluid osmolarity

Question 13

What is the normal osmolarity of ECF

Answer 13

280 milli-osmoles/litre

Question 14

What monitors plasma osmolarity

Answer 14

Monitored by osmoreceptors Mainly in brain in close proximity to hypothalamus - increased plamsa osmolarity will stimulate the release of ADH

Question 15

What does ADH do

Answer 15

Act on kidneys tubules to increase water reabs and form conc urine
Increase ECF and plasma vol and increase cardiac output and bp

Question 16

What else does ADH do

Answer 16

Act on blood vessels cause vasoconstriction increasing tpr and bp
Imp in hypovolaemic shock as loss blood vol for any reason (haemorrhage)

Question 17

Summary of map Control

Answer 17

Short term moment to Moment reg of map by baroreceptors reflex

Long term reg of map control blood volume by hormone

ADH reg ECF and plasma vol and osmolarity

RAA syst imp role long term map reg

Aldosterone reg body total sodium and ECF volume in longer term

Question 18

By controlling the extracellular fluid what can be controlled

Answer 18

Blood volume and map