blood pressure control (short/long term)

Question 1

importance of regulating mean arterial pressure

Answer 1

allows evaluation of how well blood flows through your body and whether it’s reaching all major organs

regulated by changes in CO and systemic vascular resistance

Question 2

components and function of arterial baroreceptor reflex

Answer 2

homeostatic mechanism - helps maintain blood pressure at nearly constant levels - responsible for short term control of arterial blood pressure
baroreceptors located in the carotid sinus and the aorta detect changes in blood pressure and relate info back to cardio centres in the brain

provides rapid negative feedback loop

Question 3

identify other inputs to medullary cardiovascular centres

Answer 3

cardiopulmonary receptors - sensing central blood volume
central chemoreceptors - sensing arterial pCO2 and pO2
chemoreceptors in muscle - sensing metabolite conc.
joint receptors - sensing joint movement
higher centres - hypothalamus and cerebral cortex

Question 4

explain relationship between CO, TPR, and MAP

Answer 4

MAP = CO x TPR

Question 5

importance of coordinated control of CVS system using response to exercise as eg

Question 6

describe effects of changes in posture on CVS system

Answer 6

transition from supine to standing tends to cause a drop in blood pressure of at least 20mmHg systolic and 10mmHg diastolic

Question 7

postural hypotension

Answer 7

person’s blood pressure abnormally drops as they go from sitting or lying down to standing position

Question 8

postural hypotension

Question 9

describe effect of Valsalva manoeuvre on CVS system

Answer 9

increased thoracic pressure is transmitted through aorta
increased thoracic pressure reduces filling pressure from veins, which therefore decreases VR, EDV, SV, CO, MAP
reduced MAP detected by baroreceptors which initiates reflex increase in CO and TPR
at end of manoeuvre, decrease in thoracic pressure is transmitted through to aorta - hence drop
VR is restored so SV increases
eventually, back to normal…

Question 10

cardiopulmonary (arterial) baroreceptors

Answer 10

located in atria, ventricles and pulmonary vessels

stretch receptors stimulated by change of arterial wall when pressure changes

Question 11

medullary cardiovascular centres

Question 12

baroreceptors

Answer 12

mechanoreceptors located in blood vessels near heart that provide brain with info pertaining to blood volume and pressure, by detecting level of stretch on vascular walls
as blood volume increases, vessels stretched and firing rate of baroreceptors increase

Question 13

recognise role of kidneys in regulating plasma volume and therefore BP

Answer 13

renal counter-current system creates very high osmolarity outside collecting duct
control over Na+ transport determines how big that osmotic gradient is
control over permeability of collecting duct to water determines if water follows that osmotic gradient or not
hence, can control amount of water lost in urine, and how much retained

Question 14

identify receptors involved in sensing plasma volume

Answer 14

osmoreceptors baroreceptors

Question 15

renin-angiotensin-aldosterone hormone system mechanism – long term control of BP

Answer 15

angiotensin ii stimulates release of aldosterone from adrenal cortex, which increases Na+ reabsorption in loop of Henle, therefore, reducing diuresis and increasing plasma volume
also increases release of ADH from pituitary which increases water permeability of collecting duct, therefore reducing and increases plasma volume and sense of thirst

Question 16

angiotensin

Answer 16

peptide hormone causes vasoconstriction and an increase in BP
also stimulates release of aldosterone from adrenal cortex to promote Na+ retention by kidneys

Question 17

renin

Answer 17

produced from juxtaglomerular

converts angiotensinogen to angiotensin i - which is then converted by ACE to angiotensin ii

Question 18

angiotensin converting enzyme (ACE)

Answer 18

catalyses conversion of angiotensin i to angiotensin ii

Question 19

aldosterone

Answer 19

steroid hormone released by adrenal glands - adrenal cortex
controls balance of water and salts in kidney by keeping Na+ in and releasing K+ from body

too much can cause high BP and build-up of fluid in body tissues

Question 20

angiogenesis

Answer 20

formation of new blood vessels

involves migration, growth and differentiation of endothelial cells , which line inside wall of blood vessels

controlled by chemical signals in body

Question 21

atrial and brain natriuretic peptide

Answer 21

small peptide secreted by heart, myocardial cells in atria and ventricles respectively, upon atrial stretch and high systemic BP

tends to decrease MAP
increases excretion of Na+ (natriuresis)
inhibits release of renin
acts on medullary CV centres to reduce MAP

Question 22

antidiuretic hormone

Answer 22

produced in brain, causes kidney to release less water, decreasing amount of urine produced

Question 23

juxtaglomerular cells

Answer 23

granular cells - in the kidney that synthesise, store and secrete enzyme renin
specialised smooth cells mainly in walls of afferent arterioles (some in efferent) that deliver blood to glomerulus

Question 24

vasoconstrictor on TPR

Answer 24

increases TPR