Theme 5 - Nervous System Flashcards
What are the main functions of the autonomic nervous system?
Cause consistency of internal environment (homeostasis)
Includes all involuntary efferent neurons
Controls subconscious effectors
What are the 3 divisions of the autonomic nervous system?
enteric
parasympathetic
sympathetic
What is the difference between sympathetic and parasympathetic nervous system?
Sympathetic - fight or flight
Parasympathetic - rest and digest
What are the neurotransmitters in the sympathetic nervous system?
Adrenergic: noradrenaline
What are the neurotransmitters in the parasympathetic nervous system?
Cholinergic: acetylcholine
What are the receptors involved in cholinergic neurotransmission?
Nicotinic and muscarinic
What are the 2 types of nicotinic receptors and where are they located?
NN - autonomic ganglia
NM - skeletal muscle
What are the 3 types of muscarinic receptors and where are they located?
M1 - gastric parietal (secretes gastric acid)
M2 - heart
M3 - glands/smooth muscle
What are the receptors involved in adrenergic neurotransmission?
Alpha and beta
What are the 2 types of alpha receptors and where are they located?
alpha-1: postsynaptic neurons (esp. smooth muscle)
alpha-2: presynaptic neurons (autoreceptors)
What are the 2 main types of beta receptors and where are they located?
beta-1: intestinal smooth muscle and heart
beta-2: bronchial, uterine, vascular smooth muscle
What is the effect of alpha receptor stimulation
excitatory, except smooth muscle in gut and eye constriction
What is the effect of beta receptor stimulation
inhibitory, except in heart
What is the response of the parasympathetic and sympathetic nervous system on the EYES?
Parasympathetic: constricts pupils
Sympathetic: dilates pupile
What is the response of the parasympathetic and sympathetic nervous system on the HEART?
Parasympathetic: beats slowly
Sympathetic: beats faster and stronger
What is the response of the parasympathetic and sympathetic nervous system on the LUNGS?
Parasympathetic: constricts airways
Sympathetic: relaxes airways, deep breathing
What is the response of the parasympathetic and sympathetic nervous system on the DIGESTION?
Parasympathetic: stimulates
Sympathetic: inhibits
What is the response of the parasympathetic and sympathetic nervous system on the MUSCLES?
Parasympathetic: reduces blood flow to skeletal muscle
Sympathetic: increases blood flow to skeletal muscles
How does glucose and choline enter the neuron?
facilitated transport
With which ion is choline uptake associated with?
Na+
What is glucose converted into in the mitochondria?
Acetyl-CoA
What 2 components combine in the cytoplasm to form acetylcholine and what enzyme is it catalysed by?
Acetyl-CoA and choline
enzyme: choline acetyltransferase
What transports ACh into vesicles for storage?
VAT - vesicle-associated transporter
What activates VAMPS and SNAPS?
influx of Ca2+ into neuron
What do activated VAMPS and SNAPS cause?
exocytosis of ACh, dopamine, noradrenaline into synaptic cleft (vesicle contents)
What happens to ACh in axonal cleft?
binds to receptors and depolarisation occurs
How does the concentration of ACh in synaptic cleft decrease?
Enzyme acetylcholineesterase hydrolyses ACh to choline and acetate
What happens to choline and acetate after it has been hydrolysed?
Choline recycled back to neuron (becomes ACh again)
Acetate used for metabolic purposes
How much ACh reaches circulation
Virtually none, plasmaesterases in blood deactivate ACh immediately
What does tyrosine transform into?
dopa, then dopamine