Regulation of Blood Pressure Flashcards
What happens to a tissue if not enough blood is present
undergoes necrosis
What relationship of haemodynamics is inversely proportional
resistance to flow
What does vascular/total peripheral resistance depend on
size of vessel lumen, length of blood vessel, blood viscosity
Describe the effect of blood viscosity on total peripheral resistance
as viscosity increases, blood flow decreases
Describe the effect of blood vessel length of total peripheral resistance
longer the blood vessel - greater the resistance - slower flow
Definition of blood pressure
force or hydrostatic pressure that blood exerts against blood vessel wall
What does blood pressure vary depending on?
system, distance, systole or diastole
what is systole
contraction
what is diastole
relaxation
When is peak systolic arterial BP attained
ventricular systole
When is minimum diastolic pressure attained
ventricular diastole
What is pulse pressure
difference between systolic and diastolic pressure
What is systolic pressure mainly affected by
ejection velocity, stroke volume
What is diastolic pressure mainly affected by
total peripheral resistance, arteriole resistance
What is used to measure arterial BP
sphygmomanometer and stethoscope
What are baroreceptors
free nerve endings
What do baroreceptors detect
changes in stretch within blood vessels
What are some examples of baroreceptors
carotid sinus, aortic arch
What happens to baroreceptors when blood vessels stretch
increased APs - signal to cardio-vascular centres in the medulla
What uses a negative feedback loop
baroreceptors
What is the detector of short term BP regulation
baroreceptors
What is the integrator of short term BP regulation
cardiovascular centre in medulla oblongata
What are the effectors for short term regulation fo arterial BP
cardiac muscle, vascular smooth muscle
What does the vasomotor centre stimulate
sympathetic system
What does activity of the vasomotor centre cause
noradrenaline release, vasoconstriction
What is the function of the acceleratory centre
increase cardiac output, increase cardiac contractility
What system does the acceleratory centre use
sympathetic
What is the function of the cardioinhibitory centre when activated
decreases cardiac output
What system controls the cardioinhibitory centre
parasympathetic
How is blood pressure regulated
altering cardiac output and total peripheral resistance
What does long term decrease in BP cause
release of renin
What is the function of renin
converts angiotensinogen into angiotensin I
What converts angiotensin I into angiotensin II
ACE - angiotensinogen converting enzyme
Where is ACE found
lungs and capillaries
What is the function of angiotensin II
increases thirst, increases blood volume
What brain region does angiotensin II act on
hypothalamus
What does angiotensin II act on directly
blood vessels
What is the effect of angiotensin II on blood vessels
vasoconstriction
What other structure does angiotensin II act on
adrenal cortex
What does angiotensin II cause to be released from the adrenal cortex
aldosterone
What is the effect of aldosterone on the kidney
cells increase salt and water retention
What is long term BP regulation an example of
negative feedback loop
Which drug is an ACE inhibitor
Ramipril
Which drug is an angiotensin receptor blocker
losartan
Which drugs treat high BP
ramipril, losartan, thiazide diuretics, metoprolol, doxazosin, nifedipine
What is the function of thiazide diuretics
reduce blood volume
What drug decreases cardiac output
metoprolol
What is metoprolol
sympathetic beta1 adrenoreceptor antagonist
Which drug decreases total peripheral resistance via vasodilation
doxazosin, nifedipine
What is doxazosin
sympathetic alpha1 adrenoreceptor antagonist
What is nifedipine
calcium channel antagonist
