Lecture 4 - Mechanisms of hypertension - Pathophysiology

Question 1

Define ‘prehypertension’
stage I
stage II
and
Stage III

Answer 1

‘Prehypertension’ - (120-139 / 80-89)

Stage I (140 - 159 / 90-99)

Stage II (160-169 / 100-109)

Stage III (>180 / >110)

Question 2

what is the mean systemic arterial pressure?

Answer 2

the mean systemic arterial pressure is the product of
a) cardiac output - CO
b) total peripheral vascular resistance TPvR

MAP = CO x TPvR

Question 3

what is the primary causes of hypertension?

Answer 3

primary cause is 90 -95% of causes and is known as idiopathic - unknown cause

Question 4

what are the secondary causes of hypertension?

Answer 4

renal or renovascular disease
endocrine disease
- phaecocytoma (abnormal secretion of adrenaline or noradrenaline) - renal
- cushings syndrome - renal
- acromegaly(excess growth hormone) and hypothyroidism - pituitary

coarctation of the aorta
iatrogenic
- hormonal/ contraceptive
- NSAIDs

Question 5

what are common causes of secondary hypertension?

Answer 5

intrinsic renal disease

renovascular disease

mineralocorticoid disease

sleep breathing disorder

Question 6

what are uncommon causes of secondary hypertension?

Answer 6

phaecocytoma

glucocorticoid excess

coarctation of the aorta

hyper/hypothyroidism

Question 7

what are two causes of renovascular hypertension and. who are the common in?

Answer 7

atheroscelerosis 75-90% more common in older patients

fibromuscular dysplasia 10-25% (narrowing and widening of regular arteries in the body) more common in young patients

Question 8

what are risk factors in the development of CVD - hypertension ? x11

Answer 8

family history - ethnicity
smoking
diabetes
Hypercholesterolaemia (excess cholesterol in bloodstream)
physically inactivity
stress
poor diet
infection
hypertension
Microalbuminuria or estimated GFR <60 mL/min
Age (older than 55 for men, 65 for women

Question 9

what are risk factors in the development of hypertension which are central to all cardiovascular diseases ?

Answer 9

atherosclerosis

heart failure

arrhythmias

angina -MI

Question 10

what are the target organs in hypertension?

Answer 10

CVS (heart and blood vessels)

eyes

kidneys

nervous system

Question 11

what effects does hypertension have on the CVS?

Answer 11

ventricular hypertrophy (thickening of the wall of the hearts main pumping chamber), dysfunction and failure

arrhythmias (abnormal heart rhythm)

coronary artery disease, acute MI (heart attack)

arterial aneurysm, dissection, rupture

Question 12

what are the consequences of hypertension on the heart?

Answer 12

heart - left ventricular hypertrophy:
increased workload of left ventricle (increased after load); left ventricle tries to compensate for increased workload

Question 13

what is left ventricle hypertrophy a major risk for?

Answer 13

left ventricle hypertrophy is a major risk for ischemic heart disease (myocardial infarction, arrhythmias, heart failure and sudden death)

Question 14

what are the effects of hypertension on the kidneys ?

Answer 14

glomerular sclerosis (scarring of the filtering part of the kidneys glomerulus) leading to impaired kidney function and finally end stage kidney disease

a reduction in the GFR

ischemic kidney disease especially when renal artery sclerosis is the cause of hypertension (secondary)

cause and effect cyclical

Question 15

what is the effect of hypertension in the nervous system?

Answer 15

stroke, intracerebral (bleeding in brain tissue), and subarachnoid (bleeding in space surrounding brain) haemorrhage

cerebral atrophy and dementia

Question 16

what is the effect hypertension on the eyes?

Answer 16

retinopathy, retinal haemorrhages and reduced vision

vitreous haemorrhage and retinal detachment

neuropathy of the verses leading to extra ocular muscle paralysis and dysfunction

Question 17

what are the determinants in blood pressure?

Answer 17

blood volume: this is the volume of blood available in the system

overall compliance: the elastic characteristics of the vessels contribute to the overall pressure …(age related, minor)

cardiac output: CO is related two other factors: heart rate and stroke value

total peripheral vascular resistance

Question 18

how is long term blood pressure controlled?

Answer 18

by controlling the blood volume

Question 19

what does the reduction in Renal pressure cause?

Answer 19

intrarenal redistribution of pressure and increased absorption of slat and water

Question 20

what does decreased pressure in renal arterioles and sympathetic activity cause?

Answer 20

renin and angiotensin II production

Question 21

what does angiotensin II cause?

Answer 21

direct constriction of renal arterioles

stimulation of aldosterone synthesis - sodium absorption and increase in intravascular blood volume

Question 22

when can the RAAS system be activated?

Answer 22

reduced blood flow
renal disease
renovascular disease
decrease in kidney blood flow (GFR)
- angiotensin II
- aldosterone

Question 23

describe heart chronotrophy/ ionotrophy

Answer 23

Cardiac output
Nodal tissues (normally)
CNS
—–Sympathetic vs. parasympathetic influences
At rest parasympathetic predominate

Sympathetic fibres-noradrenaline -β1receptors, increasing the permeability of the nodal cell plasma membrane to Na+and Ca2+

Parasympathetic- acetylcholine -M2 receptors, increasing the permeability to K+and decreasing the Na+and Ca2+permeability

Question 24

what is the regulation of arterial blood pressure by?

Answer 24

baroreceptor reflex and chemoreceptor reflex

Question 25

what is neuronal control vs hormonal control?

Answer 25

neuronal control is sympathetic imediate

hormonal control is parasympathetic - long term

Question 26

what does hormonal control, control?

Answer 26

Vasopressin (antidiuretic hormone)
Angiotensin II
Aldosterone
Atrial natriuretic peptide (ANP)