CARDIO- blood pressure and regulation Flashcards
what is bp
CO x TPR
more accurately
HR x SV x TPR
what is systolic blood pressure
blood pressure in the brachial artery during ejection of the left ventricle
what is diastolic blood pressure
blood pressure in the brachial artery during relaxation and filling of the left ventricle, non - ejection phase of the heart
what are the risks of high blood pressure
cardiovascular disease - MI, HF - heart has to work against high pressure
what are the risks of hypotension
poor oxygen transport
poor pressure gradient generation to drive oxygen and nutrients to tissues
cannot remove waste - carbon dioxide leading to ischemia
how does HR control blood pressure
increase in HR = increase in CO (HRxSV)
therefore increased force of contraction = increased blood pressure
how does stroke volume control blood volume
reduced SV (such as during haemorrhage and hypovolaemia)
= decrease CO (HR x SV)
= decreased bp
how does TPR control blood pressure
more constricted vessel system = more resistance = increased blood pressure
outline the effects of the sympathetic nervous system on bp
drop in blood pressure - sensed by baroreceptors = signals to SNS to increase bp
releases noradrenaline
releases adrenaline from adrenal glands
affects beta-1-receprotrs on blood vessels causing vasoconstriction
outline the effects of the RAAS on bp
a drop in blood pressure - stimulates SNS
stimulates kidney to release renin which causes angiotensin to be converted to angiotensin I
enters the blood stream and circulates to the lung
angiotensin I is then converted to angiotensin II by ACE
angiotensin II acts at AT1 receptors on blood vessels causing vasoconstriction - increasing TPR and BP
also acts on adrenal glands to release aldosterone which increases NA and H20 absorption
outline the effects of ADH/ vasopressin on BP
hormone produced in the hypothalamus - taken to pituitary gland - posterior pituitary secretes into blood stream
stimulated by a decrease in BV - less blood volume return to the heart = trigger
vasopressin increases BV and BP via causing vasoconstriction
also inserts aquaporin channels into kidney which increases water reabsorption
outline the effect of Cardiac natriuretic peptides on BP
ANP and BNP release from cardiac cells in the atria of the heart - sense increase in cardiac filling due to increased blood volume / increased blood pressure
act on the kidney - increases excretion of Na and water
acts of blood vessels causing vasodilation
what are increased levels of plasma ANP / BNP indicative of
heart failure
