lecture 18 - integrated cardiovascular response Flashcards
Where are the 2 key sensors of the arterial Baroreceptor Reflex found?
Aortic sinus, carotid sinus
How will an increase in blood pressure change activity in baroreceptor afferent fibres?
Increase activity - increase parasympathetic activity and decreases sympathetic actvity.
What is the effect of the baroreceptor depressor reflex?
Decrease in blood pressure via bradycardia, reduced peripheral vascular resistance, etc.
What are the 4 key demands on the CVS during exercise?
- Increase lung O2 uptake
- Increase O2 transport around body
- Increase O2 supply specifically to exercising muscle
- Blood pressure stabilisation
How is the demand for increased lung o2 uptake met by the CVS?
Increased RV output to send more blood to the lungs, an increased difference in gas concentration across the blood air barrier
What 2 mechanisms increase venous return?
Skeletal muscle pumps, venoconstriction
What are the consequences if venous return does not increase to match increasing heart rate during exercise?
The shortened filling time and decreased venous return leads to decreased end diastolic volume and a drop in stroke volume
What mechanism is used to increase blood flow to exercising muscle during exercise?
Vasodilation due to local metabolic factors and the release of vasodilators by contracting muscles
What is the rapid/initial CVS response to haemorrhage?
Baroreceptor reflex
What is the intermediate CVS response to haemorrhage?
Fluid reabsorption
What is the long term CVS response to haemorrhage?
Fluid replacement via kidneys, replacement of RBCs
What are the 2 ways blood volume can be restored during haemorrhage?
Transfer of fluid from interstitium to circulation (autotransfusion),
replacement of lost volume via renal system.
What is autotransfusion?
A process whereby circulating volume is maintained by absorbing fluid from the interstitial fluid into the circulation.
What capillary pressure change drives autotransfusion?
A drop in capillary hydrostatic pressure will drive autotransfusion.
What is released in response to reduced renal perfusion during/after haemorrhage?
Renin
