Blood Pressure Control Flashcards
What does the short term response to BP change (CO x TPR) use
Baroreceptors at carotid artery and aorta
What do baroreceptors respond to
Stretch of the artery due to BP change
What does the stretch in high BP allow
Higher freq of ap from baroreceptors to the medulla control centre
What would happen if there was a decrease in BP
Less AP fired to the medulla which causes increased sympathetic stimulation
When SNS is stimulated to increase BP, what happens
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
How is TPR increased to increase BP
Sympathetic vasoconstriction via adrenaline/nadr and A1 receptors
= vasoconstriction
What is it called when TPR increases in veins
Central venous pressure
If there was an increase in BP, what would happen
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)
How does lying down decrease BP
Blood flows to the veins which decreases VR
VR decrease will decrease SV (less stretch)
This causes decrease in CO and therefore BP
What 3 things happen when baroreceptors detect low BP eg when standing from lying down
Tachycardia (increase HR) Ionotropic effect (increase contractility via SNS) Vasoconstriction via A1 binding to increase TPR
Increased CO and TPR = increased BP
Other than CO and TPR what else causes BP change
Blood volume
How is change in blood volume detected
Either by stretch of atria (high volume)
Or via volume receptors at atria + baroreceptors (decreases volume)
How would the CVS regulate blood volume
To increase BV
= increase vasoconstriction (TPR)
And increase CO (via HR and contractility)
To decrease BV
= increase vasodilation
And lower CO
Which organ is also involved in blood volume regulation
Kidney
Which hormone is released from atrial volume receptors detecting high BV
ANS - it causes water and Na excretion
Which 2 hormones would decrease in production if there was high BV
ADH ( causes water uptake)
Renin - causes release of aldosterone = na and water uptake
How does thirst increase BV and BP
Causes increased uptake into ECF and ICF which increases BV
When can blood volume increase
Excess salt intake would cause water reabsorption via ADH/aldosterone
Too much aldosterone production
Genetic diseases
When would blood volume decreases
Haemorrhage - loss of blood
Diarrhoea - loss of water
Diabetes - excess urine
What is the cortico hypothalamic influence on BP
Adaptive responses by the hypothalamus to pain, stress or fear
How does stress in the cortico hypothalamic system cause lower BP
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
