Regulation of Cardiovascular function

Question 1

what are the responses to blood loss

Answer 1

• decrease in blood volume
• cardiac receptors will sense the decrease in volume, will cause an increase in SNS and decrease in vagal stimulation
• will increase HR, inotropic state to increase CO
• also will get increase catecholaimes released from adrenal medulla
• get renin and angiotensin 2 released
• also get restriction of resistance vessles in skeletal muscles, renal, splanchnic, and cutanous circulations which maintains MAP when there is a reduced CO, do get oxygen going to essentail organs such as heart and brain
• also get venoconstriction to get more venous return

Question 2

what is mechanism to shift fluid from interstitial space to plasma?

Answer 2

• get precapillary vessels to vasoconstrict

- this allows more fluid absorption from tissues

Question 3

Restoration of ECF

Answer 3

osmoreceptors sense increase in osmolality after water has left ecf, and then get adh secreted

• this will cause an increase in water absorpiton in collecting duct and increase thirst
• renin is also released - get angiotensein 2 and aldoesterone
• aldoesterone will also be made and takes longer, however will also help with sodium and water absorpiton

Question 4

blood cell loss

Answer 4

hepatic syntehsis of proteins into blood
-=also get eryhtropotein generated by kidney due to low oxygen to get an increase in red blood cell production - takes a while for this to get back to normal

Question 5

Non-hypotensive haemorrhage

Answer 5

• MAP is normal
• pulse rate increases
• pulse pressure declines
• cardiovascular homeostasis is maintained
• no change in firing of arterial baroreceptors because no change in MAP
• decrease in firing of cardiac recetpors
• adh and aldoesterone increase
• increase in HR and inotropic state

Question 6

Hypotensive haemorrhage

Answer 6

• greater decrease in mean arterial pressure
• arterial baroreceptors declne, and cardiac recetoprs
• adh and aldoesteron elevesl increase
• increase in HR
• more intesne restriction of resistance and capacitance evssles
• in extreme blood loss some blood flow to places is lost
• get haemorhagic shock

Question 7

What happens when you stand up?

Answer 7

• same as non-hypotensive haemorhage
• get increased hydrostatic pressure on blood vessels in legs and get a blood volume shifting downwards
• this causes a redcued blood volume, and decrease cardiac filing
• get increase HR, inotropic stat to minismise fal in CO
• also get restriction of resistance vessles - skeletal muscle and total peripher resitance
• can prevent this if you had somethign that increases pressure aroudn the legs

Question 8

systemic arterial baroreceptors

Answer 8

• get acute changes
• however if prolonged increase in pressure, then can reset these receptors and cause new normal level
• this shifts the curve to the right if there is hypertension
• the receptors reset

Question 9

experimental evidence to show effect of baroreceptors

Answer 9

if these are both remvoed, get sustained hypertension with wide fluctiatons in perssure
-long term regulation of arterial pressure may be influenced by the interaction of cardiac and arterial baroreceoprs

Question 10

kidney

Answer 10

-increases in renal sns , causes constriction of renal arteriols
-decrease in GFR
-increase tubular reabsorption of salt and water
-stimulates renin release and activates aldosterone
-ADH- icnreases water absorption
-JG cells - are sensitivt to cahnges in arterial pressure
=when this falls, renin productin is increased activation RAAS

Question 11

structural remodelling and arterial pressure

Answer 11

read notes ! pg 9 smail