Blood Pressure Control

Question 1

What does the short term response to BP change (CO x TPR) use

Answer 1

Baroreceptors at carotid artery and aorta

Question 2

What do baroreceptors respond to

Answer 2

Stretch of the artery due to BP change

Question 3

What does the stretch in high BP allow

Answer 3

Higher freq of ap from baroreceptors to the medulla control centre

Question 4

What would happen if there was a decrease in BP

Answer 4

Less AP fired to the medulla which causes increased sympathetic stimulation

Question 5

When SNS is stimulated to increase BP, what happens

Answer 5

To increase BP the cardiac output needs to be increased via increased HR and SV (via SNS and contractility eg phospholamban)

TPR is also increased to increase BP

Question 6

How is TPR increased to increase BP

Answer 6

Sympathetic vasoconstriction via adrenaline/nadr and A1 receptors

= vasoconstriction

Question 7

What is it called when TPR increases in veins

Answer 7

Central venous pressure

Question 8

If there was an increase in BP, what would happen

Answer 8

Less stretching
Less AP sent to medulla

PNS would be stimulated to decrease HR via ach and cause vasodilation via ach producing NO

This would decrease CO and also TPR (or central venous pressure)

Question 9

How does lying down decrease BP

Answer 9

Blood flows to the veins which decreases VR

VR decrease will decrease SV (less stretch)

This causes decrease in CO and therefore BP

Question 10

What 3 things happen when baroreceptors detect low BP eg when standing from lying down

Answer 10

Tachycardia (increase HR) 
Ionotropic effect (increase contractility via SNS) 
Vasoconstriction via A1 binding to increase TPR

Increased CO and TPR = increased BP

Question 11

Other than CO and TPR what else causes BP change

Answer 11

Blood volume

Question 12

How is change in blood volume detected

Answer 12

Either by stretch of atria (high volume)

Or via volume receptors at atria + baroreceptors (decreases volume)

Question 13

How would the CVS regulate blood volume

Answer 13

To increase BV
= increase vasoconstriction (TPR)
And increase CO (via HR and contractility)

To decrease BV

= increase vasodilation
And lower CO

Question 14

Which organ is also involved in blood volume regulation

Answer 14

Kidney

Question 15

Which hormone is released from atrial volume receptors detecting high BV

Answer 15

ANS - it causes water and Na excretion

Question 16

Which 2 hormones would decrease in production if there was high BV

Answer 16

ADH ( causes water uptake)

Renin - causes release of aldosterone = na and water uptake

Question 17

How does thirst increase BV and BP

Answer 17

Causes increased uptake into ECF and ICF which increases BV

Question 18

When can blood volume increase

Answer 18

Excess salt intake would cause water reabsorption via ADH/aldosterone

Too much aldosterone production

Genetic diseases

Question 19

When would blood volume decreases

Answer 19

Haemorrhage - loss of blood

Diarrhoea - loss of water

Diabetes - excess urine

Question 20

What is the cortico hypothalamic influence on BP

Answer 20

Adaptive responses by the hypothalamus to pain, stress or fear

Question 21

How does stress in the cortico hypothalamic system cause lower BP

Answer 21

Increases the SNS ach release (vasodilator) this will cause vasodilation via No and therefore lower TPR

Also increases the PNS response which decreases HR decreasing CO and therefore BP