Lecture 14 Part 2 Flashcards
What is pulse pressure?
Systolic pressure - diastolic pressure
What is mean arterial pressure?
Diastolic pressure + (1/3) x pulse pressure
What is incisura?
A diacritic notch, at end of ventricular ejection, due to valve closure
How many components of the arterial pulse are there?
There are normally 2, a forward wave and a reflected wave
Describe the forward wave
Generated when the heart (ventricles) contracts during systole. The wave travels down the large aorta from the heart and gets reflected at the bifurcation
What is the reflected wave?
It is the diastolic phase, after the closure of the aorta valves
What is important with the reflected wave?
The velocity at which the wave returns, the stiffer arteries are the faster it returns
What are pulse pressure waves like in a younger person?
Arterial pulse propagates slowly and there are changes in pulse pressure amplitude and contour
What are pulse pressure waves like in older people?
Arterial pulse propagates more rapidly and wave is relatively unchanged along tree due to less wave reflection
Why in older people to the pressure waves travel faster?
Because the artery walls are stiffer which means the pressure wave travels faster - could be in hypertensive patients
What is the risk of pressure waves traveling fast?
Systolic hypertension, strokes
What does pulse pressure increase with?
Age - pulse pressure can double with age
What is an increase in systolic pressure due to?
Reduced compliance of elastic vessels
What does mean BP increase due to?
Resistance vessel changes (increase TPR)
How does systolic pressure increase more than mean pressure?
Because systolic pressure is affected by the compliance of the large, elastic arteries
What happens to the elastic vessels with ageing?
They have a lower compliance (arteriosclerosis)
What happens to aortic compliance with age?
It is reduced, caused by progressive changes in collagen and elastin content of arterial walls
What is arteriosclerosis?
Reduction in elasticity of elastic arteries
What does fragmentation and loss of elastic lamellae in tunica media =
Weakening of wall and structural dilation
Increase in collagen content =
Vessel walls becomes stiffer
What does remodelling =
Results in increased systolic pressure primarily and increased pulse pressure
What are the physiological adaptions in ageing?
Increased pulse pressure
Reduce compliance - arteriosclerosis
Increased blood pressure - hypertension
Reduced barorecepor sensitivity
Impaired cardiac performance during exercise
What is hypertension?
Increased blood pressure - increases risk of strokes, myocardial infarctions, heart failure, and renal failure
What is an example of increased blood pressure resulting in hypertension?
140/90mmHg in a person below 50 years
Describe essential hypertension (primary hypertension)
No obvious known cause
Benign = symptomless, detected at a check up due to serious consequences like a stroke, heart disease
Malignant = rare, rapid increase in blood pressure leading to cardiac failure, oedema, renal damage
Describe secondary hypertension
Identifiable, pathological cause e.g. primary hyperaldosteronsim, renal artery stenosis
What are some characters of hypertension?
Increase in pulse pressure, increase in mean pressure, increase in systolic wave due to reduced compliance and early return of reflected wave
What is suggested to be altered in certain hypertensive conditions?
Coupling between ca2+ speaks and BKca channels
What happens to baroreceptors in hypertension?
They reset to operate at higher blood pressures
What does an increase in pressure at the baroreceptors result in?
A fall in systemic BP
What are the cardiovascular adaptions in pregnancy?
Increase in cardiac output, stroke volume and heart rate and decrease in peripheral vascular resistance
What happens to eNOS in pregnancy?
Upregulation of eNOS causes reduction in peripheral vascular resistance
What is pre-eclampsia?
Hypertension and proteinuria in pregnancy - impaired NO bioavailability, possible role for increased enothelin production
What can eclampsia cause?
Cerebral oedema (swelling of the brain) and seizures
Describe atherosclerosis
Progressive inflammatory disease of large and medium arteries, accumulation of cholesterol deposits (plaques), stenosis
What is atherosclerosis associated with?
Age, gender, genetics and diet
What does atheroma reduce?
NO levels
What do mutations in key smooth muscle myofilament related proteins increase?
The risk of aortic aneurysms and cerebral vasoconstriction in early adult life
What gene is associated with thoracic aortic aneurysms?
ACTA2
