Control of blood pressure

what is ANP

atrial natriuretic peptide

where are carotid bodies

in the carotid sinus of the carotid artery

function of aortic bodies

detect change in blood pressure to the body

what happens to mechanoreceptors when increased stretch

They increase firing, so decrease firing in less stretch so the frequency of the impulse increases and decreases

function of unmyelinated mechanoreceptors

free nerve endings measuring heart distension

atrial - inspiration

ventricular - systole

2 reasons why rodent HR is high

high basal metabolic rate

higher peripheral resistance due to small diameter of blood vessels

3 actions of symapthetic due to change in blood pressure

vasoconstriction or vasodilation due to contraction or relaxation of vascular smooth msucle to increase or decrease peripheral resistance (TPR)

change stimulation of SA node to B1 adrenoceptors to change HR and therefore CO

change stimulation of ventricular myocardium to change the force (not frequency) of contraction

2 actions of parasympahtetic system due to a change in BP

change stimulation of M2 Muscarinic receptors in the SA node to change HR

change stimulation of atria myocardium to change force (not frequency) of contraction

NT of symapthetic regarding the heart

noradrenaline

NT of parasymapthetic always - including the heart

ACH

what is the point of blood pressure regulation

daily activities change the blood pressure, so it is homeostasis to keep levels within the normal limits - pathology is a failure of homeostasis

function of coronary artery baroreceptors

more sensitive to change in BP

3 things detected by chemoreceptors

low arterial oxygen

high arterial CO2

low arterial pH

2 medications taken to reduce BP

ACE inhibitors

Angiotensin receptor inhibitors

3 things produced due to the stimulation of mineralocorticoid nuclear receptors

Na+ ion channels

K+ ion channels

Na+/K+ ion channels

why do Ca2+ ions move in (2 places)

macula densa - NaCl in leading to non-selective cation channels opening so Ca2+ ions move in

Cells of the zona glomerulosa - increased blood K+ opens Ca2+ ion channels leading to the secretion of aldosterone (remember ACTH is also required but doesn’t regulate levels)

where are juxtaglomerular (granular) cells located and composition

in the interstitium of the afferent arteriole

modified smooth muscle cells containing renin vesicles

actions of angiotensin II

release of ADH from the neurohypophysis

removal of C22-27 cholesterol side chain as the first step in the production of aldosterone in the zona glomerulosa

vasoconstriction of the afferent and efferent renal arterioles to reduce GFR

(mentioned in the diagram - increase in sympathetic action)

action of ANP

inhibit Na+ ion reabsorption so more excretion

vasodilation of afferent arteriole to increase GFR

inhibit ADH

inhibit renin and aldosterone

why does a hot shower reduce MAP

standing up - blood pools due to gravity

standing up - longer distance to the heart

hot water - thermoregulation in place to reduce body temperature so peripheral vasodilation so blood pooling in the extremities

therefore lower TPR so lower CO less blood to the brain so fainting