W14 Physiological systems Flashcards
what are 4 main receptors
enzymes
transporters
ion channels
receptors
What does pns stand for
peripheral nervous system
what does the PNS represent
output of the CNS and acting independently to regulate the body’s internal environment
what are the 2 parts of the PNS
autonomic nervous system
Somatic (motor) nervous system
what do efferent nerves control
movement by innervating skeletal muscle
what do afferent nerves respon to
external stimuli e.g. pain sensing fibres
what are the 3 parts of the autonomic nervous system
Parasympathetic nervous system
Sympathetic nervous system
Enteric nervous system
what is the parasympathetic nervous system
cranial sacral output
synapse at ganglia close to innervated tissue.
what is sympathetic nervous system
thoracic lumbar output synapse at ganglia either side of vertebral column
ganglia distal to innervated tissue
what is enteric nervous system
neurones with cell bodies in the wall of the intestine that innervates GI tract, pancreas and gall bladder.
what are the main processes that the ANS regulate
heart beat
smooth muscle contraction and relaxation
all exocrine function
some endocrine secretions
some steps in intermediate metabolism
in general what does the sympathetic system do
evokes a flight and fight response whilst the parasympathetic system mediates a rest and digest state.
what is cholinergic transmission
all motor nerves releases acetyl choline which act on nicotinic acetylcholine receptors
all postganglionic parasympathetic nerves release acetyl choline which act on muscarinic acetylcholine receptors
What is acetyl choline regulated by
inhibitory presynaptic m2 muscarinic acetylcholine receptors
where are the m1 receptors located
Ganglia
CNS
where are the m2 receptors located
Cardiac
CNS
where are the m3 receptors located
Glands
Smooth Muscle
Blood Vessels
where are the m4 receptors located
CNS
where are the m5 receptors located
CNS
why is it important to know about different receptor types
selectivity
what are the parasympathetic effects
Bradycardia Vasodilation Increases secretion Bronchoconstriction Increased gut motility Reduction of itraocular pressure
what actions of atropine
block secretion Tachycardia Pupillary dilation and cillary muscle paralysis inhibits gut motility paralysis of bladder smooth muscle relaxation CNS effects: excitatory
what are the three types of ACh receptors
muscle
ganglion
cns
What are depolarizing blockers
Agonists which cause a depolarizing block of the muscle fibre endplate = depolarizing blockers.
what are some uses of competitive blockers
Widely used as muscle relaxants as an adjunct to anaethesia
what are some uses of depolarizing blockers
continually stimulation of the NMJ by agonists causes muscle paralysis muscle contracts due to maintained depolarization but cannot repolarize causing loss of excitability.
what do the vast majority of postganglionic sympathetic fibres release
noradrenaline to act either on alpha or beta adrenoreceptors
what is adrenergic transmission
working on adrenaline or noradrenaline (or on their receptors).
When not further qualified, it is usually used in the sense of enhancing or mimicking the effects of epinephrine and norepinephrine in the body.
what is nor adrenaline release in presynaptic receptors regulated by
inhibitory presynaptic alpha adrenoceptors
what is noradrenaline released by
post ganglionic sympathetic nerves
what is adrenaline secreted by
adrenal gland
what is dopamine
it is a central nervous system transmitter and precursor of noradrenaline and adrenaline
what is isoproterenol
synthetic catecholamine
what is the mechanism by which tyrosine is converted to adrenaline (4 Steps)
TDNA
tyrosine + tyrosine hydroxylase = DOPA
DOPA + Dopa decarboxylase = Dopamine
Dopamine + Dopamine B hydroxylase = Noradrenaline
Noradrenaline + phenylethanolamine N Methyltransferase = adrenaline
What does adrenaline do the arterial pressure
causes systolic + mean to rise (low)
diastolic drops (low)
what does adrenaline do to heart rate
increases moderatly
what does adrenal do to peripheral resistance
decrease low
what does nor adrenaline do to arterial pressure
overall increase in systolic mean and diastolic
what does noradrenaline do to heart rate
decreases low
what does noradrenaline do to peripheral resistance
high increase
what does isoprenaline do to arterial pressure
systolic increases low
diastolic decreases high
overall drop
what does isoprenaline have on heart rate
moderate increase
what does isoprenaline do to peripheral resistance
decreases
how does sodium cause an overall increase in blood pressure
causes vasoconstriction which causes reflex bradycardia due to baroreceptor response due to acetyl choline action at vagal nerve causing higher bp
what is an example of indirect sympathomimetics
systemic pseudophedrine is used as a nasal decongestant acts as substrate uptake system leading to noradrenaline and thus vasoconstriction of the mucosal blood vessels which in turn reduces oedema of the nasal mucosa
