L22 Pharmacology Flashcards
what type of communication occurs between nerves and target cells?
chemical (neurotransmitters)
what type of communciation occurs between nerve cells?
electrical (action potential) and chemical (neurotransmission)
how are neurotransmitters released from pre-synaptic terminal across synaptic cleft?
excotyosis
how do they enter neighbouring neuron?
they don’t. they bind to receptors in post-synaptic cleft to cause a stimulated response in the neuron (action potential)
do action potential amplitudes differ?
no they all have the same amplitude no matter the stimulus
do action potentials have different frequencies?
yes
what does an increas of action potential frequency mean?
more neurotransmitters are being released - more of an effect on target cell
what is the common pathway by which CNS controls skeletal activity?
Efferent nervous system -> motor nervous system
what neurotransmitter is present at a neuro-muscular junction?
acetylcholine, ACh
what type of receptor does ACh bind to on muscle cells? what does this mean?
nicotinic, they also bind nicotine neurotransmitters
what happens when ACh binds to nicotinic receptors?
it triggers a response - influx of Ca2+ ions which allow muscle depolarisation and contraction
what causes the muscle to contract?
end plate potential from
how does the signal stop/ muscle contraction stop?
acetylcholinesterase enzyme inactivates acetylcholine, end plate potential stops - contraction stops
what substance can cause excessive muscle contraction?
venom from black widow spider - causes explosive release of acetylcholine and organophosphates like sarin gas
what effect does high concentration of acetylcholine have on muscle cells?
pro-longed depolarisation can lead to fatigued muscle and respiratory failure
what substance can cause lack of acetylcholine?
botulinum blocks release of acetylcholine and curare blocks binding of ACh with nicotinic receptors
what effect does low concentrations of acetylcholine have?
inactivated muscles, can cause paralysis
what medical purpose does botulinum have?
botox and prevents rigid contraction in skeletal muscle after strokes
what is the autonomic nervous system composed of?
parasympathetic and sympathetic systems
what knowledge allows development of target drugs?
types of neurotransmitters and receptors involved and pattern of receptor dispersion
what system is the adrenal medulla part of?
endocrine and sympathetic nervous system
what are adrenal glands?
modified ganglia
how do parasympathetic and sympathetic systems work opposingly in relation to the eye?
P - contricts pupil/ S - dilates pupil
how do parasympathetic and sympathetic systems work opposingly in relation to the salivary gland?
P - stimulates secretion/ S - Inhibits secretion
how do parasympathetic and sympathetic systems work opposingly in relation to the lungs?
P- constricts bronchi/ S- relaxes bronchi
how do parasympathetic and sympathetic systems work opposingly in relation to the heart?
P- slows heart/ S- accelerates heart
How are adrenal glands stimulated to produce hormones/ neurotransmitters?
sympathetic nerves stimulate pre-ganglionic fibres of adrenal gland and cause secretion
what hormones does adrenal gland release?
80% adrenalin, 20% noradrenalin
how does the autonomic system regulate physiology of the body?
via parasympathetic system and sympathetic system working opposingly AND acetylcholine and noradrenaline
what nerves emerge from CNS always?
pre-ganglionic nerves
pre-ganglionic nerves (efferent) always emerge from CNS, what neurotransmitter do they ALWAYS release?
acetylcholine
what is the sympathetic pathway beginning from CNS?
1) ACh is secreted from pre-ganglionic neuron
2) Noradrenalin is secreted from post-ganglionic neuron
OR
2) Epinephrine/ Adrenalin is released from adrenal gland
what is the parasympathetic system beginning from CNS?
ACh is released from pre-ganglionic neuron and post-ganglionic neuron
what does noradrenalin/ adrenalin from sympathetic pathway bind with?
effector cells with adrenergic receptors
what does ACh from parasympathetic pathway bind with?
effector cells with muscarinic/ nicotinic cholinergic receptors
what neurotransmitters do pre-ganglionic nerves always secrete?
ACh
what neurotransmitters do post-ganglionic nerves secrete?
in sympathetic pathway: noradrenalin
in parasympathetic pathway: ACh
what ACh and NA/Ad receptors do tissues have that are innervated by autonomic nervous system?
nicotinic cholingeric receptors and muscarinic cholinergic receptors (ACh)
alpha and beta adrenergic receptors (NA/Ad)
what do receptor agonists do?
bind to same receptor as neurotransmitter and cause an effect similar to neurotransmitter
what do receptor antagonists do?
bind to receptor and block neurotransmitter response
what is salbutamol?
a pharmalogical angonist that mimics effect of NA and Ad
what causes widening/dialtion of bronchioles?
pre-ganglionic sympathetic nerves in lungs secrete adrenalin and bind to Beta adrenergic receptors on bronchioles causing dialtion (agonist - salbutamol)
sympathetic nervous system accelerates heart rate and force of contraction, how do you stop this pharmalogically?
beta blockers lower heart rate and blood pressure
what is the blood-brain barrier?
arrangement of blood vessels and glial cells along with neurons
what does prozac do?
blocks serotonin uptake
what is L-dopa?
a precursor of dopamine, can get passed blood brain barrier and allieviate symptoms of Parkinson’s
Common Neurotransmitters
acetylcholine, dopamine, noradrenaline, serotonin, histamine, glycine, glutamate, aspartate, GABA
