Part 9 Flashcards
Where would you find nicotinic and muscarinic synapses
Nicotinic - on neurons and skeletal muscle
muscarinic – body tissues and CNS neurons
Acetyl choline stimulates two types of cholinergic receptors discerned by different agonists
nicotine and muscarine
Catecholamines comprise norepinephrine, epinephrine and dopamine, what type of receptors are stimulated?
- Norepinephrine, epinephrine stimulate adrenergic receptors
* Dopamine has its own dopamine receptor
explain the metabolism of Acetyl choline ACH?
Metabolism: AcetylCoA + Choline > Choline + acetate
• Synthesis by Choline Acetyltransferase
• Breakdown by Acetylcholine Esterase (AChE)
How do nicotinic receptors work?
- Ionotropic : opens Na /K channels, short term synaptic effects
- Located in autonomic ganglion (postganglionic) neurons and skeletal muscle
- Acetylcholinesterase blockade increases ACh levels and produces extreme ANS responses
How do muscarinic receptors work?
- Metabotropic: uses G proteins for its actions, more prolonged synaptic effect
- Many functions including heart deceleration
- Located throughout CNS and in tissues innervated by postganglionic parasympathetic and some sympathetic neurons (sweat glands).
- Stimulated by Muscarine
how is norepinepherine and epinephrine synthesized and removed?
- Synthesis: Tyrosine > L-DOPA >Dopamine > Norepinephrine > Epinephrine
- Removal: Reuptake or destruction by monoamine oxidase (MAO) or catechol-O-methyl transferase (COMT)
Explain how adrenergic (alpha and beta) receptors work
- Alpha (α1)receptors (IP3 and DAG) regulate Ca++ & K+ channels.
- Beta receptors (cAMP) regulate smooth muscles, metabolism, heart .
- Beta 1 (β1) and Beta 2 (β2) receptors respond to NE & are affected by drugs.
Explain the many interesting aspects of neuropeptides.
- Responsible for long term changes in ion channel permeability, number of receptors, gene transcription of proteins, etc
- Synthesis & packaging into vesicles occurs in the cell body.
- Slow destruction by enzymes extends the transmitter effect
- Co-release with other transmitters
- Neuropeptide receptors are mostly metabotropic in that they utilize second messengers
Axonal transport carries pre-peptides and enzymes to the axonal terminal. what modifications may happen along this route?
pre-peptides are modified by enzymes into neuropeptides
Peripherial nervous system is made up of the ?
somatic motor system
autonomic nervous system (ANS)
explain the somatic motor system?
α-Motor neuron cell bodies are located in the ventral horn of spinal cord and project axons to skeletal muscle
Explain the autonomic nervous system.
Sympathetic and Parasympathetic nervous systems consist of two neurons (preganglionic and postganglionic) in sequence:
• Preganglionic neurons synapse onto postganglionic neurons within Autonomic Ganglia.
• Postganglionic neurons project to smooth muscle, cardiac muscle, & glands
further explain the sympathetic nervous system of the ANS (which is also part of the PNS)
- fight, fright or flight
- Preganglionics in T1-L2
- Postganglionic cell bodies in ganglia or adrenal medulla
- Postganglionic axons project to organs and extremities (blood vessels, sweat glands, etc)
- Increases HR and BP, bronchodilates, etc.
further explain the parasympathetic nervous system of the ANS (which is also part of the PNS)
• rest and digest
• Preganglionic cells
– Cranial cells in brain stem project to head, thorax and
abdomen
– Sacral cells in the S2,3,4 region project to pelvic viscera
• Postganglionic cells form ganglia near or within the target structures
• Postganglionic project short axons into organs
• Lowers HR , promote GI peristalsis, etc
