phsiology of blood pressure and control of BP through RAS Flashcards
what does it mean is the blood vessels is dilated?
low resistance to flow
low peripheral vascular resistance
low blood pressure
what is the long term response of vascular resistance?
Kidneys - regulate loss of Na and water - renin-angiotensin system - important for controlling blood volume
what is resistance proportional to?
fluid viscosity and length of the vessel
what is the flow between two points proportional to?
the pressure difference between. those points
what are factors effecting arterial bp?
- stroke volume
- HR
- peripheral resistance
- elastic vessels
- blood volume
- ventricular ejection
What is systolic pressure?
the maximum arterial pressure reached during ventricular ejection
What is diastolic pressure?
the minimum arterial pressure just before ventricular ejection begins
what is pulse pressure?
the difference between the SP and DP
what is mean arterial pressure ?
the average pressure across the cardiac cycle
what is the pre hypertension values for adults over 18?
120-139/80-89
what is the values for stage one hypertension?
140-159/90-99
what are the values of stage 2 hypertension
160 or above/100 or above
why does endothelial cells release bioactive substances?
prevent inadvertent thrombus formation - release mediators that inhibit platelet activation
cause relaxation/ contraction of underlying smooth muscle
what are examples of endothelium relaxation factors?
Nitric oxide
Prostacylin
Hyper polarising factor
what are examples of endothelium contraction factors?
endothelin
Thromboxane
what is arteriolar constriction produced by?
- sympathetic activity
- circulating noradrenaline
what is vascular smooth muscle innervated primarly by?
sympathetic nervous system through adrenergic receptors ( alpha 1, alpha 2 and beta 2)
how does the baroreceptors act to a change in bp
- Pressure-sensitive receptors on arterial side of the circulation(carotid and aortic arch). Detect amount of stretch in blood vessel and enable short term BP regulation
what are examples of treatment of bp?
ACE inhibitors (act on renin-angiotensin system)
Calcium channel blockers eg. amlodipine
Diruretics - decrease blood volume and total PVR
Adrenoceptor blockers - alpha blockers prevent NA induced effects
what is the effect of blood loss on MAP?
causes a reduction which if left unchecked would result in rapid and irreversible damage to the brain and heart
what are the fundamental roles of the kidneys?
Filtration
Reabaprbtion
Excretion
what is the functional unit of the kidney?
nephron
what is the main driver of filtration in the kidneys?
change in pressure
what does the macula densa sense?
GFR by the amount of sodium in the filtrate
