L58: CVS 4 Flashcards
What is average BP at rest?
120/80 mmHg
What are the four main control systems of the cardiovascular system?
- BP;
- C.O.;
- Local circulation (hyperaemia etc.);
- Blood and extracellular volumes.
Where are baroreceptors located?
- Aortic arch (heart);
- Carotid sinus (brain).
How do baroreceptors detect change in BP?
By stretch of the blood vessels
Where is BP processed by in the brain?
Nucleus tractus solitari (NTS)
How is low blood pressure detected by the brain and how is it restored?
- BR input to NTS;
- Stimulates β1 receptor;
- Activates bulbar circulatory centres (BBC);
- NA increased;
- Force and rate of HR increased;
- Inhibits vagal nucleus (VN);
- ACh decreased.
> Increased C.O.
Increased PR
How is high blood pressure detected by the brain and how is it restored?
- BR input to NTS;
- Stimulates α2 receptor;
- Activates vagal nucleus (VN);
- ACh increased.
- Force and rate of HR decreased;
- Inhibits bulbar circulatory centres (BBC);
- NA decreased.
> Decreased C.O.
Decreased PR
What effect does ACh have on BP and why?
Decreases HR by vasodilation which reduces resistance
What effect does NA have on BP and why?
Increases HR by vasoconstriction which increases resistance
What stimulates local control (through vessel diameter) of BP?
- Independent of nerves and hormones;
- Dependent on blood gases and endothelium-derived factors.
Provide an example of local control.
Adenosine, by-product of metabolising tissue (breakdown of ATP), DILATES vessels
What is hypertension (high BP)?
When BP exceeds a specified threshold (e.g. 90mmHg DIASTOLIC)
What happens if BP is chronically raised?
BR adjust to a higher level e.g. 140/90 mmHg, ‘normal’
Why is it necessary to monitor BP in 50+?
Hypertension is often unknown until it is critically high due to few symptoms
What can untreated hypertension lead to?
- Thickening of arteries;
- Left ventricular hypertrophy;
- Stroke;
- CKD;
- Heart failure;
- Angina.
