control of blood pressure Flashcards
(22 cards)
define blood pressure
pressure exerted by blood upon walls of vessel
why is blood pressure important
to maintain flow of blood in vessels
what is the equation for blood pressure
bp= cardiac output x systemic vascular resistance
what is systemic resistance
resistance in the circulatory system that is used to create blood pressure, the flow of blood
whats the equation for cardiac output
cardiac output = heart rate x stroke volume
what do you use to measure blood pressures
sphygomomanometer
(band wrapped around arm with meter attached, pump at the end and pump applies pressure to band. depending on the sounds hear the meter tilts towards diastolic or systolic side)
whats the typical stroke volume
70 mls
typical heart rate
70bpm
what is a pulse
rhythmic expansion and contraction of artery made by waves of pressure caused by ejection of blood from left ventricle of heart as it contract
where are the 4 places pulse can be measured
carotid
radial
femoral
dorsalis pedis
what are the 3 things that control you blood pressure/ keep it stable
baroreflex
adrenaline
RAAS renin-angiotensin-aldosterone system
how does the bare reflex control bp
- stretch receptors in aorta carotid since send signals to brainstem
-this stimulate or depress the sympathetic nervous system
- when stimulated local noradrenaline released
- this increase stroke volume by increasing cardiac contractions or
- increase heart rate via actions on SA/AV node or
- contract blood vessels
OR
signals are sent to stimulate/depress parasympathetic nervous system where it acts upon heart rate by releasing acetyl choline
how does adrenaline control BP
the adrenal medulla increases the AD concentration in sympathetic nerve endings
what is postural hypotension
a drop in blood pressure when you stand up after lying or sitting down. This can make you feel dizzy and can even cause you to faint. You might: feel lightheaded or dizzy when you stand.
how does RAAN control bp
It regulates your blood pressure by increasing sodium (salt) reabsorption, water reabsorption (retention) and vascular tone (the degree to which your blood vessels constrict, or narrow).
Aldosterone also causes water to be reabsorbed along with sodium; this increases blood volume and therefore blood pressure.
what does ANP AND BNP stand for
atrial naturetic peptide
brain naturetic peptide
secreted by atria and ventricles respectively
how does ANP and bnp lower bp
- they’re released in response to atrial and ventricular distension
- both stimulate the excretion of sodium (naturesis) and therefore water
- this lowers blood volume and hence blood pressure
HIGH levels of BNP in blood can be used as part of diagnostic workup for heart failure
what negative affect can adrenaline and noradrenaline induce
can induce venocontriction which has the effect of squeezing blood in the venous circulation back to the heart
liberating some of the blood that is effectively ‘stored’ in the venous circulation
what does LVEDV stand for
left ventricular end diastolic volume
what is the frank-starling curve and what does it show
the normal relationship between the length and tension of the myocardium.
The greater the stretch on the myocardium before systole (preload), the stronger the ventricular contraction.
what are the difference in structure of artery and veins
artery:
- thick muscular walls
- narrow lumen
- not readily collapsible (withstands high pressure)
- dont have valves
veins:
- thin muscular walls
- wide lumen
- easily collapsible
- have valves
