Hypertension

Question 1

What is the calculation for mean arterial BP?

Answer 1

SV x HR x TPR

Question 2

Explain how blood pressure is controlled in the longer term

Answer 2

neurohumoral responses =

1. Renin-angiotensin-aldosterone system
2. Sympathetic nervous system
3. Antidiuretic hormone (ADH)
4. Atrial natriuretic peptide (ANP)

Question 3

explain how blood pressure is controlled in the short term

Answer 3

baroreceptors reflex =

1. adjust sympathetic and parasympathetic inputs to heart to alter CO,
2. adjust sympathetic input to peripheral resistance vessels to alter TPR

Question 4

Where are the baroreceptors found?

Answer 4

Aortic arch and carotid sinus = sensitive to stretch

Question 5

Outline the baroreceptor reflex for high and low BP

Answer 5

Stretching = baroreceptors recognise higher BP = afferent signal to medulla centre = raise vagus stim + lower sympathetic stim = efferent signal to SA node to slow heart rate and vasodilation.

Low BP = less stretching = lower frequency afferent signals to medulla centre = lower vagus stim + raise sympathetic stim = efferent signal to SA = speed up HR, vasoconstriction

Question 6

Why are baroreceptors not able to control longer term changes in BP?

Answer 6

Reflex resets normal to a higher BP - and maintains this new normal higher BP

Question 7

Define the stages of hypertension

Answer 7

Stage 1 = >140/90mmHg.

Stage 2 = >160/100mmHG

Severe = >180/>110mmHg

Question 8

Explain the impact of hypertension on organs and tissues in the body

Answer 8

Heart - L ventricle = hypertrophy. 
Kidney – nephrosclerosis and renal failure. 
Eyes - damaged vessels - retinopathy. 
Aneurysm
cerebrovascular disease = Stroke

Question 9

What cells is renin released from?

Answer 9

granular cells of juxtaglomerular apparatus (JGA) in kidney

Question 10

What factors stim renin release?

Answer 10

a) Reduced NaCl delivery to distal tubule
b) Reduced perfusion pressure in the kidney causes the release of renin (baroreceptors in afferent arteriole)
c) Sympathetic stimulation to JGA increases release of renin

Question 11

What effect does angiotensin II have on the body?

Answer 11

Arterioles = vasoconstriction,

kidney = Na reabsorb,

sympathetic NS = release of NA,

adrenal cortex = release aldosterone,

hypothalamus = thirst

Question 12

What effect does ACE have on bradykinin?

Answer 12

ACE is a kinase enzyme = breaks down bradykinin (vasodilator) = no vasodilation

Question 13

What occurs after taking an ACE inhibitor?

Answer 13

Stops angiotensin I converting to angiotensin II = no effect on raising BP.

ACE can no longer break down bradykinin = vasodilation occurs = lowers BP

Question 14

How does the sympathetic nervous system control BP?

Answer 14

Vasoconstriction in kidneys, decrease GFR = decrease Na excretion, stim renin prod = increased BP

Direct = baroreceptor reflex

Question 15

How does atrial natriuretic peptide work?

Answer 15

Released from atria due to stretch = vasodilation + promotes Na excretion = water follows = lower circulating blood vol = lower BP

Question 16

What is prostaglandin and its clinical effect?

Answer 16

Lipid compound =

1) enhance glomerular filtration and reduce Na+ reabsorption
2) inhibit platelets aggregation
3) buffer to excessive vasoconstriction by SNS and RAAS = vasodilation

Question 17

What are the causes of hypertension?

Answer 17

Primary = unknown cause.

Secondary = cause defined renovascular disease (occlusion = renal artery stenosis, decreased perfusion), chronic renal, hyperaldosteronism, cushings (excess glucocorticoid cortisol)

Question 18

Why is it important to treat hypertension?

Answer 18

Although hypertension may be asymptomatic, it can have unseen damaging effects on, heart and vasculature, can = heart failure, MI, stroke, renal failure and retinopathy

Question 19

How is hypertension treated?

Answer 19

Always recommend lifestyle changes

Primary = work out possible targets using: BP = SV x HR x TPR

Secondary = treat the primary cause

Question 20

How is hypertensions treated targeting the RAAS?

Answer 20

ACE inhibitors

Ang II antagonists

Question 21

How is hypertension treated via vasodilation?

Answer 21

L-type Ca channel blockers

alpha-1 receptor blocker

Question 22

How is hypertension treated using diuretics?

Answer 22

Thiazide diuretics = reduce circulating vol

Question 23

How is hypertension treated with beta blockers?

Answer 23

Blocking beta-1 receptors = reduce effect of sympathetic output = reduce ionotrophy and chronotropy

Question 24

What is bradykinin?

Answer 24

Peptide =

1) vasodilation = fall in BP