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What are the structural components of a neuron and what is their function?
- Dendrites (input of information and integration)
- Soma (cell body)
- Axon (Information transport)
- nerve terminals (Output of information)
What are the types of synaptic interactions between neurons?
What are the two ways of neurotransmission?
electrical and chemical
what is electrical neurotransmission?
direct coupling of electrical activity through gap junctions
What is chemical neurotransmission?
release of transmitters from vesicles at the synapse
4 targets of neurotransmitters after release from the nerve terminal
- 1. receptors on adjacent postsynaptic neurons at a site close to the release site
- 2. extrajunctional site
- 3. on a postsynaptic neuron distant t the release site
- 4. a glial cell distant from the site of release
what is the life cycle of a neurotransmitter?
- re-uptake or degradation(for proteins and peptides)
What are the 4 general types of neurotransmitters?
- amino acids
- biogenic amines
chemical classes of neurotransmitters
- primary amines
- amino acids
- nucleotides and nucleosides
What are the 2 divisions of the peripheral nervous system?
autonomic and somatic
What are the 2 divisions of the autonomic nervous system?
where do the cell bodies reside in the somatic system?
in the CNS
where do the axons in the somatic system extend to?
extend to the skeletal muscles
what are the two motor neurons of the autonomic system?
preganglionic and ganglionic
which is slower? autonomic or somatic
autonomic because it is not myelinated
What does the autonomic system regulate?
regulates the body activities that are generally not under conscious control
what are the receptors in effector organs of the sympathetic system?
what are the receptors in effector organs of the parasympathetic system?
explain 3 different pathways the sympathetic nervous system takes starting from the CNS
- 1. preganglionic neuron (cholinergic)--> ACh-->nicotinic cholinergic receptor--> postganglionic neuron (adrenergic)--> NE--> adrenergic receptor on effector organ
- 2. preganglionic neuron (Cholinergic) -->ACh--> Nicotinic cholinergic receptors on adrenal gland--> Epinephrine --> adrenergic receptor on effector organ
- 3. preganglionic neuron (cholinergic/longer) --> ACh--> nicotinic cholinergic receptor ---> Postganglionic neuron (adrenergic/shorter) --->NE --> adrenergic receptors on effector organ
what is the pathway the parasympathetic system uses starting from the CNS?
preganglionic neuron(cholinergic) -->ACh---> nicotinic cholinergic receptor --> ACh--> mascarinci cholinergic receptor --> cholinergic receptor of effector organ
where is acetylcholine synthesized?
synthesized in presynaptic termia from chopin and acetyl coenzyme A
what is ACh broken down by?
what does AChE break won ACh into?
choline and acetyl CoA
Where does the choline go after it is broken down?
it is reabsorbed by neuron to synthesize more ACh
Where is Norepinephrine synthesized?
in the presynaptic terminal from tyrosine
what kind of receptors does norepinephrine bind to?
- Alpha -2 on the presynaptic neuron
- Alpha 1 or Beta 1 on postsynaptic cell
what breaks down Norepinephrin?
what are the signal transductions from norepinephrine?
- protein kinase activation
- protein phosphorylation
What does catechol - O methyl transferase (COMT) do to norepinephrine and where is it?
it is in the postsynaptic membrane and converts NE to normetanephrine
what does MAO -B do?
What does MAO-A do?
metabolizes NA and serotonin
What is VMA?
vanillylmandelic acid which is the common metabolite
what does acetylcholine induce in heart muscle cells?
decreased rate and force of contraction
what does acetylcholine induce in salivary gland cells?
wat does ACh induce in skeletal muscle cells?
what are the 2 types of ACh receptors?
muscarinic receptors and Nicotinic receptors
what type of receptor is a muscarinic?
What type of receptor is Nicotinic?
General Pathway for muscarinic GPCR receptor
activation--> G𝛼 and Gβ𝛾 dissociates --> Gβ𝛾 opens K+ channels to decrease the amplitude of contraction
which muscarinic receptors are inhibitory?
M2 and M4
Which muscarinic receptors are excitatory?
M1 M3 M5
where are M1 located and what does it do?
secretory glands (salivation, stomach acid, sweating, lacrimation)
where are M2 located?
heart (decreases heart rate = bradycardia)
where are M3 located?
- Smooth muscle (diarrhea,bronchospasm, urination)
- miosis, pupil, and ciliary muscle (increased flow of aqueous humor)
where is Nm located and what does it do?
skeletal muscles end plate (contraction of skeletal muscle)
where is Nn and what does it do?
autonomic ganglia and adrenal medulla (secretion of epinephrine/ controls ANS)
What tissues are 𝛼1 receptors in and what does it do?
- vascular smooth muscle (Contraction)
- pupillary dilator muscle (contraction = dilates pupil)
- pilomotor smooth muscle (errects hair)
- prostate (Contraction)
- heart (force of contraction increased)
What tissues does 𝛼2 receptors in and what does it do?
adrenergic and cholinergic nerve terminals (inhibition of transmitter release)
What tissue is β1 in and what does it do?
heart (force and rate of contraction increased)
What tissue is β2 receptor in and does it do?
- respiratory, uterine and vascular smooth muscle (Promotes smooth muscle relaxation)
- liver (Glycogenolysis increased)
What tissue is β3 receptors in and what does it do?
fat cells (lipolysis increased)
What is the end organ that the somatic nervous system effects?
what is the neurotransmitter for the somatic nervous system?
Activation of Sympathetic Nervous System produces what effects?
- dialates pupils
- stop saliva secretion
- dilate bronchioles
- increase heart rate
- secret epinephrine
- decreases secretion of liver
- decrease motility
- retain contents
- delay emptying bladder
Activation of parasympathetic Nervous System produces what effects?
- constrict pupil
- secrete saliva
- constrict bronchioles
- decrease heart rate
- increase secretion in liver
- increase motility of colon
- empty bladder