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79 Cards in this Set
- Front
- Back
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what is the single most important compensatory control system for disturbances in arterial blood pressure?
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baroreceptor reflex
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t/f... hormonal mechanisms regulating arterial pressure happen in the short-term
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false, hormonal mechanisms are intermediate
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where are the arterial baroreceptors?
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walls of carotid sinus and aortic arch
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in which cranial nerve do the fibres originating in the carotid sinus run in?
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glossopharyngeal
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which baroreceptor fibres run in the vagus nerve?
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aortic arch baroreceptors
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where do the primary afferent fibres of the baroreceptors terminate?
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nucleus of the solitary tract (NTS) within the medulla oblongata
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over what range of pressure can baroreceptors signal changes?
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50-160mmHg
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how long does it take for baroreceptors to adapt to a change in pressure level?
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1-2 days
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which receptors apart from baroreceptors can reflexly alter the activity of autonomic nerves innervating the CV system?
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chemoreceptors, receptors in the low pressure part of circulation (left and right atria)
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what happens when the arterial chemoreceptors are stimulated?
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reflex vasoconstriction
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what are the arterial chemoreceptors stimulated by?
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decrease in PaO2
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what do receptors in the atria respond to?
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changes in blood volume
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what is the result of signals (of decreased pressure) from the atrial receptors reaching the hypothalamus?
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increase in release of antidiuretic hormone (vasopressin) from the pituitary gland
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t/f... the arterial baroreceptor reflex plays no significant role in setting the long-term level of arterial pressure
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true
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what effect on vessels does the cerebral ischaemic refelx have?
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intense vasoconstriction
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t/f... an increase in the activity of atrial receptors reflexly inhibits the release of vasopressin from the pituitary gland
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true
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t/f... an increase in activiry of atrial receptors results in a reflex vasodilation in the renal vascular bed, which helps to increase urine production
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true
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where in the arterial wall are baroreceptors located?
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adventitia
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what is the pumping efficiency most affected by?
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mean ventricular rate
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what is the emergency treatment for bradycardia with loss of consciousness?
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beta1 adrenergic stimulant e.g. isopropyl noradrenaline
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what is a ventricular bradycardia?
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failure of conduction of the normal electrical impulses from the SA or AV node to the ventricles
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what is ventricular tachycardia due to?
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electrical depolarisations arising within the ventricles
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t/f... left ventricular predisposes to ventricular tachyarrhythmia
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true
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Some ECG changes in VT are...?
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regular QRS complexes at 150-250 per minute, abnormally wide QRS complexes, a delay in the appearance of the maximum negative voltage in the V leads
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what is activated by alterations in renal perfusion?
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renin-angiotensin system
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where is renin released from?
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juxtaglomerular apparatus
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what does renin do?
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converts the plasma protein angiotensinogen to angiotensin
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what form of angiotensin is a biologically active vasoconstrictor?
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angiotensin II
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is atherosclerosis of the renal artery more commonly located at the stem or the orifice of the artery?
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orifice
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give an equation for mean BP
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mean BP=CO x TPR
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Name the 4 first-line agents for drug treatment of hypertension
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calcium antagonists, ACE inhibitors, angiotensin receptor antagonists, diuretics
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which calcium antagonists act exclusively on vascular smooth muscle?
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dihydropyridines
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which calcium antagonists reduce AV nodal conduction and myocardial contractility?
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non-dihydropyridines
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what are the typical side effects of dihydropyridines?
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tachycardia, flushing and headache
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which calcium antagonists are suitable for combination with a beta blocker?
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dihydropyridines
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why are non-dihydropyridines contraindicated in combination with beta blockers?
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risk of profound bradycardia and heart failure
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t/f... most ACE inhibitors are prodrugs
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true
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what is the action of angiotensin receptor antagonists?
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competitively block AT1 subtype of angiotensin II receptors on vascular smooth muscle
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list two contraindications for beta blocker use
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patients with reversible obstructive airways disease, peripheral vascular disease
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what percentage of deaths worldwide are atributable to hypertension?
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14%
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where is renin released from?
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kidney juxtaglomerular cells
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what is the action of angiotensin II on blood vessels?
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vasoconstriction
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what is the effect of angiotensin II on the kidney?
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increase in reabsorption of water and NaCl
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where is aldosterone released from?
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adrenal cortex
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where is ACE found?
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ungs
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does angiotensin II cross the blood brain barrier?
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no
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how does angiotensin II achieve its effects on the brain?
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via the circumventricular organs of the brain (AT1 receptors)
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which two pathways lead to renin release?
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sympathetic stimulation and reduced perfusion of the kidney
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what effect does an increase in salt intake have on the renin-angiotensin system?
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inhibition
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what effect does a change in salt intake have on mean arterial pressure?
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minimal
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how does sympathetic stimulation directly affect the renal function curve?
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via an action on renal vascular resistance - vasoconstriction of renal arterioles
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how much does blood pressure increase during exercise?
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about 20 mmHg
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where does leptin act?
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hypothalamus
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what are the two actions of leptin?
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sympathetic activation and decrease in appetite
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what does the P wave represent?
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atrial depolarisation
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which part of the ECG represents ventricular contraction?
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QRS complex
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what is a first degree heart block?
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all beats conducted but with long conduction time
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which degree of heart block iss associated with no beats at all?
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3rd degree
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which type of heart block occurs with a partial block of the His-purkinje system?
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2nd degree, Mobitz type 2
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what is the definitive treatment of heart block and bradycardia?
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pacemaker
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which drug will prevent loss of consciousness in heart block and bradycardia?
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isoprenaline
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where is renin released from?
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kidney juxtaglomerular cells
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what is the effect of angiotensin II on blood vessels?
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vasoconstriction
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what is the effect of angiotensin II on the kidney?
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increased reabsorption of water and salt
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what is the effect of angiotensin II on the adrenal cortex?
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release aldosterone
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where does aldosterone act?
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kidney
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what is the effect of angiotensin II on the brain?
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release vasopressin, promotes drinking behaviour
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where is vasopressin released from?
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posterior pituitary
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which drugs may cause a hypertensive emergency?
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cocaine, monoamine oxidase inhibitors, oral contraceptives
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what percentage of hypertension is idiopathic?
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95%
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what are the effects of hypertension on the arterioles?
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replacement of SM with hyaline in walls, narrowing of lumen
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what is malignant hypertension?
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rapid rise in BP to 200/120
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name some non-drug ways to control hypertension
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weight loss, exercise, low salt diet, reduced alcohol intake, smoking cessation
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list some factors stimulating renin secretion
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decreased renal perfusion, decreased conc of sodium in distal tubule, reduced glomerular filtration, increased renal sympathetic activity/beta agonists, prostacyclin
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what are the effects of ANP, angiotensin II and beta antagonists on renin secretion?
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inhibit renin secretion
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what are the actions of AT1 receptors?
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vascular growth, vasoconstriction, sodium/water retention
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what is the effect of hypertension on the arteries?
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loss of elastin and smooth muscle in the media with replaceent by fibrous tissue (hypertensive arteriosclerosis)
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what happens to the kidney in hypertension?
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loss of glomeruli and related nephrons, hyperplasia of tubules or surviving nephrons
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t/f... renal function is frequently compromised in hypertension
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false
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