Physiology - Part 2 Flashcards
which neurotransmitter do sympathetic nerves release?
noradrenaline
where else does adrenaline come from?
adrenal medulla
which receptors do sympathetic nerves act on?
beta 1 receptors on sinoatrial node and myocytes
what effect do sympathetic nerves have on the pacemaker potential?
increases the slope
what effect do sympathetic nerves have on heart rate?
increase
which neurotransmitter do parasympathetic nerves release?
acetylcholine
which receptors do parasympathetic nerves act on?
muscarinic receptors on the sinoatrial node
what effect do parasympathetic nerves have on the pacemaker potential?
hyperpolarises and decreases the slope
what effect do parasympathetic nerves have on heart rate?
decrease
what does starling’s law state in relation to preload?
the energy of contraction is proportional to the initial length of the cardiac muscle fibre
what effect does increased venous return have on the heart?
increased end diastolic volume –> increased stroke volume
what effect does decreased venous return have on the heart?
decreased end diastolic volume –> decreased stroke volume
what is preload?
the end diastolic volume the heart must pump out
what is afterload?
the systolic pressure against which the heart must work to eject blood during systole
what happens to stroke volume if the total peripheral resistance increases?
decreases
is preload affected by the venules/veins (capacitance vessels) or the arterioles (resistance vessels)?
venules/veins (capacitance vessels)
is afterload affected by the venules/veins (capacitance vessels) or the arterioles (resistance vessels)?
arterioles (resistance vessels)
what effect do sympathetic nerves have on stroke volume?
increase contractility
what effect do parasympathetic nerves have on stroke volume?
little to no effect - vagus doesn’t innervate ventricles
what effect does hypercalcemia have on the stroke volume - end diastolic volume curve?
shifts curve up and to the left
what effect does hypocalcemia have on the stroke volume - end diastolic volume curve?
shifts curve down and to the right
what effect does ischaemia have on the stroke volume - end diastolic volume curve?
shifts curve down and to the right
what effect do barbiturates have on the stroke volume - end diastolic volume curve?
shifts curve down and to the right
CO = ? x?
CO = HR x SV
what’s the fancy name for a blood pressure cuff?
sphygmomanometer
does gravity affect the driving pressure from arteries to veins?
no
what is the pressure drop through the arteries?
small - ~95-90 mmHg
what is the pressure drop through the arterioles?
large - ~90-40 mmHg
what is the pressure difference pushing blood back through the veins?
small - ~20-5 mmHg
where might you find a continuous capillary with no clefts or channels?
brain
where might you find a continuous capillary with only clefts?
muscle
where might you find a fenestrated capillary?
intestine
where might you find a discontinuous capillary?
liver
what effect do prostacyclins and nitric oxide have?
inhibit platelet aggregation
what effect does tissue factor pathway inhibitor (TFPI) have?
stops thrombin production
what effect does thrombomodulin have?
binds thrombin and inactivates it
what effect does heparin have?
inactivates thrombin
what effect does tissue plasminogen activator (t-PA) have?
converts plasminogen to plasmin which digests the clot
what is oedema?
accumulation of excess fluid
what can cause oedema?
lymphatic obstruction
raised CVP
hypoproteinemia
increased capillary permeability
