Blood Pressure Regulation Flashcards
What is blood pressure dependent on?
Blood pressure (P) = Blood flow (Q) x Resistance (R)
Describe excitatory and inhibitory chronotropic affects that influence HR>
Excitatory: Sympathetic beta-ADRs cause calcium channels to open, bringing cell closer to threshold (increase HR)
Inhibitory: Parasympathetic muscarinic receptors cause potassium channels to open, making the cell more negative and slowing HR.
What is mean arterial pressure determined by?
- Blood volume
- Cardiac output
- Peripheral resistance
- Distribution of blood between arterial and venous vessels
- Age
- Gender (M>F)
What is systemic vascular resistance determined by?
- Size of lumen
- Blood viscosity
- Blood vessel length
What are the short term and long term ways of controlling blood pressure?
Short term - baroreceptor reflex.
Long term - hormonal regulation (kidney)
Describe the baroreceptor reflex.
Regulated by pressure sensitive receptors in carotid arteries and other larger arteries in neck/chest:
Carotid sinus regulates BP for brain.
Aortic baroreceptors regulates systemic BP.
When blood pressure falls, baroreceptors are stretched less.
- Decrease parasympathetic stimulation
- Increase sympathetic stimulation
Vice versa for when blood pressure is too high.
Describe the hormonal regulation of BP (3 types: RAAS, ANP, ADH)
Renin-angiotensin aldosterone system.
Raises BP by vasoconstriction and release of aldosterone (reabsorb more Na+, increase blood volume)
Atrial natriuretic peptide (ANP) is released by cells in atria upon stretch (high BP). Results in vasodilation and increased loss of Na+, decreasing blood volume.
Antidiuretic hormone (ADH) / Vasopressin produced by hpoythalamus in response to decreased BP. Causes vasoconstriction and increased water retention.
Descibe how venous pressure changes if cardiac output changes.
Venous pressure decreases is CO increases, as more blood is pumped into atrial system and out of venous system.
