Lecture 4 - Mechanisms of hypertension - Pathophysiology Flashcards
(26 cards)
Define ‘prehypertension’
stage I
stage II
and
Stage III
‘Prehypertension’ - (120-139 / 80-89)
Stage I (140 - 159 / 90-99)
Stage II (160-169 / 100-109)
Stage III (>180 / >110)
what is the mean systemic arterial pressure?
the mean systemic arterial pressure is the product of
a) cardiac output - CO
b) total peripheral vascular resistance TPvR
MAP = CO x TPvR
what is the primary causes of hypertension?
primary cause is 90 -95% of causes and is known as idiopathic - unknown cause
what are the secondary causes of hypertension?
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
what are common causes of secondary hypertension?
intrinsic renal disease
renovascular disease
mineralocorticoid disease
sleep breathing disorder
what are uncommon causes of secondary hypertension?
phaecocytoma
glucocorticoid excess
coarctation of the aorta
hyper/hypothyroidism
what are two causes of renovascular hypertension and. who are the common in?
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
what are risk factors in the development of CVD - hypertension ? x11
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
what are risk factors in the development of hypertension which are central to all cardiovascular diseases ?
atherosclerosis
heart failure
arrhythmias
angina -MI
what are the target organs in hypertension?
CVS (heart and blood vessels)
eyes
kidneys
nervous system
what effects does hypertension have on the CVS?
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
what are the consequences of hypertension on the heart?
heart - left ventricular hypertrophy:
increased workload of left ventricle (increased after load); left ventricle tries to compensate for increased workload
what is left ventricle hypertrophy a major risk for?
left ventricle hypertrophy is a major risk for ischemic heart disease (myocardial infarction, arrhythmias, heart failure and sudden death)
what are the effects of hypertension on the kidneys ?
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
what is the effect of hypertension in the nervous system?
stroke, intracerebral (bleeding in brain tissue), and subarachnoid (bleeding in space surrounding brain) haemorrhage
cerebral atrophy and dementia
what is the effect hypertension on the eyes?
retinopathy, retinal haemorrhages and reduced vision
vitreous haemorrhage and retinal detachment
neuropathy of the verses leading to extra ocular muscle paralysis and dysfunction
what are the determinants in blood pressure?
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
how is long term blood pressure controlled?
by controlling the blood volume
what does the reduction in Renal pressure cause?
intrarenal redistribution of pressure and increased absorption of slat and water
what does decreased pressure in renal arterioles and sympathetic activity cause?
renin and angiotensin II production
what does angiotensin II cause?
direct constriction of renal arterioles
stimulation of aldosterone synthesis - sodium absorption and increase in intravascular blood volume
when can the RAAS system be activated?
reduced blood flow
renal disease
renovascular disease
decrease in kidney blood flow (GFR)
- angiotensin II
- aldosterone
describe heart chronotrophy/ ionotrophy
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
what is the regulation of arterial blood pressure by?
baroreceptor reflex and chemoreceptor reflex
