Hypertension

Question 1

What is hypertension and what is the normal adult BP range

Answer 1

Sustained increase in blood pressure

Between 90/60 and 120/80mmHg

Question 2

What are the three classifications of hypertension and what are the BPs associated with them

Answer 2

Stage 1 = >140/90

Stage 2 = >160/100

Severe = >180 systolic or >110 diastolic

Question 3

How are the causes of hypertension classified

Answer 3

Primary - cause is unkown

Secondary - cause can be defined

Question 4

Name some diseaes attributable to hypertension

Answer 4

Heart failure

Stroke

Cerebral haemorrhage

Chronic kidney failure

Coronary heart disease

Myocardial infarction

Left ventricular hypertrophy

Aortic aneurysm

Peripheral vascular disease

Myocardial ischaemia

Question 5

What controls an acute change in BP

Answer 5

The baroreceptor reflex

Question 6

How is BP controlled in the medium and long term

Answer 6

Through interaction of neurohumoral responses directed at controlling sodium balance and extracellular fluid volume

Question 7

What are the four neurohumoral pathways that control circulating volume and BP

Answer 7

Renin-angiotensin-aldosterone system

Sympathetic nervous system

Antidiuretic hormone (ADH)

Atrial natriuretic peptide (ANP)

Question 8

What causes renin release

Answer 8

Reduced NaCl delivery to distal tube

Reduced perfusion pressure in kidney

Sympathetic stimulation to JGA

Question 9

Where is renin released from

Answer 9

Granular cells of juxtaglomerular apparatus

Question 10

How does the renin-angiotensin-aldosterone system work

Answer 10

Angiotensinogen found in blood is converted to angiotensin I by renin

Angiotensin converting enzyme in lungs converts Ang I into Ang II

Ang II acts at AT1 receptor causing vasoconstriction, stimulates Na⁺ reabsorption in kidney, stimulates aldosterone, causes increased release of NA, increases thirst sensation (ADH release)

Question 11

What are the actions of aldosterone

Answer 11

Acts on principal cells of collecting ducts

Stimulates Na⁺ and water reabsorption

Activates apical Na⁺ channel [epithelial Na channels (ENaC)] and apical K⁺ channel

Question 12

What is one of the side effects of using an ACE inhibitor and why

Answer 12

Causes a dry cough

Inhibiting ACE means bradykinin is not broked down by ACE into peptide fragments, so its levels rise causing the dry cough

Question 13

How does the SNS control BP

Answer 13

High levels of SNS stimulation reduces renal blood flow by vasoconstriction of arterioles and decreased GFR, both of which raise BP

Actives apical Na/H-exchanger and basolateral Na/K-ATPase in PCT

Stimulates renin release

Question 14

How is ADH involved in control of BP

Answer 14

Involved in formation of concentrated urine by retaining water to control plasma osmolarity - increases water reabsorption in distal nephron

Stimulates Na⁺ reabsorption - thick ascending limb, stimulates apical Na/K/H co-transporter

Causes vasoconstriction

Question 15

How is ADH release stimulated

Answer 15

Increased plasma osmolarity

Severe hypovolaemia

Question 16

How do natriuretic peptides control BP

Answer 16

ANP promotes Na⁺ secretion reducing the circulating volume

They are released by atria cells in response to strech with more released at higher BP

Question 17

What are the actions of ANP

Answer 17

Vasodilation of afferent arteriole of kidney

Increased blood flow increaes GFR

Inhibits Na⁺ reabsorption

Question 18

What are prostaglandins and what are their functions

Answer 18

Are vasodilators - buffer to excessive vasoconstriction

Enhance glomerular filtration

Reduce Na⁺ reabsorption

Question 19

Where is dopamine produced and what are its affects

Answer 19

Formed in kidney from L-DOPA

Receptors are present on renal BV and cells of PCT and TAL

Cause vasodilation and increase renal flow

Reduce reabsorption of NaCl by inhibiting NHX and N-K-ATPase

Question 20

Name some diseases/syndromes which cause hypertension

Answer 20

Renovascular disease

Renal parenchymal disease

Conn’s syndrome

Cushing’s syndrome

Tumour of adrenal medulla

Question 21

What happens in renovascular disease to cause hypertension

Answer 21

There is renal artery stenosis causing a fall in perfusion pressure to that kidney

This causes an increased renin production - activation of renin-angiotensin-aldosterone system

Results in vasoconstriction and Na⁺ retention at other kidney

Question 22

How does renal parenchymal disease cause hypertension

Answer 22

Na⁺ and water retention dje to inadequate glomerular filtration

Question 23

What are some non-pharmacological approaches to treating hypertension

Answer 23

Exercise

Diet

Reduced Na⁺ intake

Reduced alcohol

Question 24

What can you use to target the RAA system

Answer 24

ACE inhibitors

Ang II receptor antagonists

Question 25

Name some vasodilators

Answer 25

L-type Ca²⁺ channel blockers - reduce Ca²⁺ entry to vascular SM causing relaxtion of them

Alpha-1 receptor blockers - reduce sympathetic tone

Question 26

Name some diuretics

Answer 26

Thiazide diuretics - reduce circulating volume, inhibit Na/Cl transporter on apical membrane of cells in DT

Aldosterone antagonists

Question 27

What do beta blockers do

Answer 27

Block B1 receptors in heart to reduce effects of sympathetic output - reduce rate and contractility