Part 9

Question 0

Where would you find nicotinic and muscarinic synapses

Answer 0

Nicotinic - on neurons and skeletal muscle

muscarinic – body tissues and CNS neurons

Question 1

Acetyl choline stimulates two types of cholinergic receptors discerned by different agonists

Answer 1

nicotine and muscarine

Question 2

Catecholamines comprise norepinephrine, epinephrine and dopamine, what type of receptors are stimulated?

Answer 2

• Norepinephrine, epinephrine stimulate adrenergic receptors

* Dopamine has its own dopamine receptor

Question 3

explain the metabolism of Acetyl choline ACH?

Answer 3

Metabolism: AcetylCoA + Choline > Choline + acetate
• Synthesis by Choline Acetyltransferase
• Breakdown by Acetylcholine Esterase (AChE)

Question 4

How do nicotinic receptors work?

Answer 4

• 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

Question 5

How do muscarinic receptors work?

Answer 5

• 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

Question 6

how is norepinepherine and epinephrine synthesized and removed?

Answer 6

• Synthesis: Tyrosine > L-DOPA >Dopamine > Norepinephrine > Epinephrine
• Removal: Reuptake or destruction by monoamine oxidase (MAO) or catechol-O-methyl transferase (COMT)

Question 7

Explain how adrenergic (alpha and beta) receptors work

Answer 7

• 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.

Question 8

Explain the many interesting aspects of neuropeptides.

Answer 8

• 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

Question 9

Axonal transport carries pre-peptides and enzymes to the axonal terminal. what modifications may happen along this route?

Answer 9

pre-peptides are modified by enzymes into neuropeptides

Question 10

Peripherial nervous system is made up of the ?

Answer 10

somatic motor system

autonomic nervous system (ANS)

Question 11

explain the somatic motor system?

Answer 11

α-Motor neuron cell bodies are located in the ventral horn of spinal cord and project axons to skeletal muscle

Question 12

Explain the autonomic nervous system.

Answer 12

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

Question 13

further explain the sympathetic nervous system of the ANS (which is also part of the PNS)

Answer 13

• 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.

Question 14

further explain the parasympathetic nervous system of the ANS (which is also part of the PNS)

Answer 14

• 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

Question 15

what part of the brain controls the ANS?

Answer 15

Hypothalamus at base of brain controls the ANS through brain stem structures
• Hypothalamic and brain stem control of the ANS is governed primarily by the limbic system which includes areas such as the hippocampus, cingulate gyrus

Question 16

Explain the 2 types of tissue innervation by the PNS

Answer 16

• Somatic Motor: axon branches of motor neurons innervate single muscle fibers
• Autonomic: postganglionic axon has several varicosities that synapse on different tissue cells. Less specific than somatic motor.