Cardiovascular physiology: BP Flashcards
What causes coronary artery disease?
Atherosclerosis is the underlying cause of CAD. It is an inflammatory disease that hardens the arteries through plaque formation.
Describe the process of atherosclerosis
1) fat deposits on the walls of arteries forming a fatty streak
2)A stable fibrous plaque forms
3) The vulnerable phase occurs when macrophages weaken collagen
Describe the fatty streak phase of atherosclerosis
LDL-cholesterol is trapped between the endothelium and connective tissue of an artery and becomes oxidised. Macrophages ingesting cholesterol and become foam cells. Smooth muscle cells are attracted by the macrophages and begin to take in cholesterol.
describe the stable fibrous plaque phase of atherosclerosis
a fat core builds under the epithelium and fibrous (collagen) scar tissue forms around the lipid core. The smooth muscles in the artery also divide and thicken the artery further.
calcification is deposited in the plaque
Describe the vulnerable plaque phase of atherosclerosis
Macrophages can release enzyme that weaken the collagen that holds the fat core in place. If the plaque bursts and collagen is exposed to the bloodstream, then platelets will initiate a blood clot.
which lifestyle factors can increase the risk of cardiovascular diseases
-smoking
-excessive alcohol
-unhealthy diet
-unhealthy weight
-physical inactivity
-stress
What is pulse pressure
systolic-diastolic
how is MAP calculated
diastolic + 1/3(systolic - diastolic)
What does blood pressure produced by
the driving force of the heart pumping.
how to arteries maintain the driving pressure of the heart?
when ventricular contraction occurs and blood is forced into the arteries, the volume forces the arteries to stretch and compress which helps maintain the driving pressure.
How does sphygmomanometry measure BP
the pressure is first increased until the flow is blocked. The pressure is then slowly released until Korotkoff sounds can be heard. This pressure when the sounds are first heard is the systolic pressure. The sounds are heard because a bolus of blood is forced through by the higher systolic pressure. Then pressure is lowered until no sounds can be heard and this point is the diastolic pressure. the lack of korotkoff sounds indicates that systolic pressure is sufficient to allow the blood to flow at all times.
How can an accurate BP measurement be taken?
-correct cuff size
-device or trained tester
-multiple measurements taken during a period of time
–> this can help mitigate effect of white coat hypertension (stress of seeing a healthcare professional)
what are the critical BP values?
normal: <120/<80
elevated: 120-129/<80
hypertension stage 1: 130-139/80-89
hypertension stage 2: >140/>90
Memory: add ten for systolic and add ten for diastolic in hypertension
How does an increase in blood pressure affect risk of developing cardiovascular diseases?
the risk doubles for every 20/10 mmHg increase in BP
What is essential or primary hypertension?
it is heretical hypertension and is also the most common form of hypertension
-the increase in BP is a result of an increase in resistance and not CO
How should high BP be treated before diagnosis?
3 months of lifestyle modification before meds
which lifestyle modifications are the most impactful for hypertensive individuals?
healthy diet, aerobic exercise
What drugs should be used to treat hypertension and what are their mechanisms?
Calcium channel blockers(fast)
-decreased Ca2+ entry into cardiac and smooth muscle reduces the contractile force of heart and veins. Reduces CO and resistance
Diuretics (slow)
-reduce blood vol
Beta-blockers(fast)
-suppress sympathetic stimulation
ACE Inhibitors(slow) and Angiotensin Receptor Blockers(fast)
-decrease angiotensin vasoconstriction.
How can hypertension change the functioning of baroreceptors?
the constant exposure to high BP will eventually cause the baroreceptors to become used to high BP. This causes less reflex control of BP and can prevent or limit the body’s natural response to high BP.
Explain what MAP= Q x R means
this means that arterial pressure is the result of flow and resistance. can be used to predict result of leftover variable if one is changed.
if blood pressure is increasing what will happen to vagus nerve activity?
It will increase. it carries parasympathetic messages.
Where are alpha 1 receptors found?
majority of sympathetic target tissues
where are beta1 receptors found?
heart, kidney
where are beta2 receptors found
certain blood vessels and organ smooth muscle.
