Exam 3 - Clinical Applications Flashcards
1
Q
orthostatic (postural) hypotension
A
- lowering of blood pressure upond standing
- causes dizziness, weakness, and syncope
- baroreceptor reflex normally compensates for the drop in blood pressure that occurs when a person stands, which causes about 700 ml of blood to pool in the lower limbs
2
Q
causes of low blood pressure that may result in orthostatic hypotension
A
- dehydration
- medications (i.e. beta-adrenergic receptor blockers)
- postprandial hypotension - when blood pressure falls after eating (in the elderly)
3
Q
- Mark experienced dizziness upon standing after he engaged in prolonged exercise without adequate drinking.
- what caused the dizziness upon standing, and how is it normally prevented?
- what condition did Mark have when he got dizzy, and what caused it?
A
- the dizziness what caused by a lowering of blood pressure
- this is normally prevented the the baroreceptor reflex, which is when a fall in BP evokes an increase in sympathetic nerve activity and a decrease in parasympathetic nerve activity
- Mark had the condition orthostatic (postural) hypotension
- his dehydration caused it
4
Q
valsalva maneuver
A
- a bearing down, as if attempting a forceful exhalation, while preventing air from escaping
- this raises intrathoracic pressure, compressing thoracic veins and reducing venous return to heart
- briefly raises aortic pressure, causing a lowering of the heart via the baroreceptor reflex
- however, the fall in venous return decreases cardiac output, so that the aortic blood pressure falls, stimulating the baroreceptor reflex to increase cardiac rate
- when the person breathes again, the thoracic pressure falls and the aortic pressure breifly falls before the improved venous return raises aortic pressure and slows the cardiac rate
- weightlifters and people straining at stools perform this maneuver, which can be dangerous in those with coronary heart disease
5
Q
- after mark was diagnosed with essential hypertension, his physician advised him not to hold his breath when lifting heavy weights
- what sequence of events occurs when a person lifts a heavy weight while holding their breath?
- how is the baroreceptor reflex involved in these events?
A
- sequence of events:
- intrathoracic pressure rises, which reduces venous return to the heart
- aortic pressure briefly rises, causing a slowing of heart rate (baroreceptor reflex)
- the fall in venous return decreases cardiac output, so the aortic BP falls, stimulating baroreceptor reflex to increase cardiac rate
- he was advised not to perform the Valsalva maneuver when lifting heavy weights, to avoid fluctuations in heart rate and blood pressure that this produces, because hypertension is a risk factor for atherosclerosis and coronary heart disease
6
Q
preeclampsia
what was it formerly called?
incidence?
how does it differ from gestational hypertension?
A
- formerly called toxemia of pregnancy
- occurs in up to 8% of women worldwide who are pregnant beyond their twentieth week
- differs from gestational hypertension by evidence of damage to organs (liver, kidneys)
7
Q
things that can occur during preeclampsia
A
- thrombocytopenia
-
proteinuria
- indicates that plasma proteins are abnormally leaking through the kidneys’ filtering units (glomeruli) into the urine
- this lowers plasma protein concentration and oncotic pressure, producing edema and swelling of the feet, legs, or hands
- if severe, the hypertension can cause seizures and stroke
8
Q
causes of preeclampsia?
cure for preeclampsia?
A
- not well understood, but may stem from dysfunction of the placenta
- obesity increases risk
- the only cure for preeclampsia is delivery of the baby
9
Q
- mark was diagnosed with essential hypertension, for which he was prescribed an ACE inhibitor
- what is essential hypertension, and what are its dangers?
- by what mechanisms does an ACE inhibitor lower BP?
A
- essential hypertension is high blood pressure that is a result of complex and poorly understood processes
- it’s dangers are:
- increased afterload, causing abnormal hypertrophy of ventricles, which increases the risk of arrhythmias and heart failure
- damage to cerebral blood vessels, leading to cerebrovascular accident
- contributes to the development of atherosclerosis, which can lead to heart disease and stroke
- it’s dangers are:
- angiotensin-converting enzyme inhibitors prevent the conversion of angiotensin I to angiotensin II, reducing the ability of angiotensin II to stimulate vasoconstriction
10
Q
statins
A
- drugs that help lower LDL cholesterol concentrations
- inhibitors of HMG-Coenzyme A (the enzyme that catalyzes the rate-limiting step in cholesterol production)
- lowered intracellular cholesterol –> more LDL receptors
- other benefits:
- slightly raises HDL levels
- reduces inflammation
11
Q
two categories of stroke
A
-
ischemic stroke
- caused by blockage of a cerebral artery by a thrombus
- usually a result of atherosclerosis
-
hemorrhagic stroke
- caused by bleeding of cerebral artery, usually cause by aneurism
12
Q
treatment of ischemic stroke
A
- treatments: anticoagulants and thrombolytic drugs
- most effective if delivered soon after stroke because of excitotoxicity
13
Q
excitotoxicity
A
- process where neurons die as a result of ischemia-induced impairment in the removal of glutamate from synaptic clefts
- this results in excessive inflow of Ca through NMDA receptors
- presently no way to prevent
14
Q
platelet aggregation inhibitors
A
- used to prevent clot formation and coronary thrombosis (a major cause of myocardial infarction)
- examples:
- aspirin
- clopidogrel (plavix)
- dipyridamole
- glycoprotein IIb/IIIa drugs
15
Q
aspirin
A
- irreversibly inhibits enzyme cyclooxygenase, which is required for prostaglandin formation
- does so for the life of the platelet, because platelets are not complete cells and cannot generate new enzymes
- inhibits platelets ability to form thromboxane A2 (a prostaglandin)
