Neurology

Question 1

amino acid neurotransmitters

small-molecule NTs

Answer 1

• glutamate (Glu)
• y-amino butyric acid (GABA)
• glycine (Gly)

small molecule NT synthesis uses recycled NTs at axon terminal

Question 2

monoamine neurotransmitters

small-molecule NTs

Answer 2

• serotonin (5-HT)
• dopamine (DA)
• norepinephrine (NE)
• epinephrine (Epi)
• histamine (His)

small molecule NT synthesis uses recycled NTs at axon terminal

NE and Epi are also catecholamine hormones.

Question 3

neuropeptide neurotransmitters

Answer 3

• dynorphin
• enkephalin
• substance P
• neuropeptide Y
• somatostatin

neuropeptide precursors are cleaved to form NTs at axon terminal; large dense core synaptic vesicles in cell body transport precursors + enzymes to terminal

Question 4

other neurotransmitters

Answer 4

• acetylcholine (ACh)
• nitric oxide (NO)
• adenosine
• endocannabinoids

Question 5

hormones

Answer 5

protein/peptide:
- insulin
- glucagon
- adrenocorticotropic hormone (ACTH)

steroids:
- estrogens
- progestins
- glucocorticoids

catecholamines:
- norepinephrine
- epinephrine
- dopamine

Question 6

neuronal cells

Answer 6

CNS:
- astrocytes: support, blood-brain barrier, glial scar
- oligodendrocytes: myelin sheath (1:multiple)
- microglia: immune system, glial scar
- ependymal: secrete cerebrospinal fluid, cilia/microvilli, chroid plexus

PNS:
- satellite cells: insulation from electrical signals
- Schwann cells: myelin sheath (1:1)

Question 7

Na+ and K+ role in

action potential

Answer 7

1. resting: Na+ closed and inactivated, K+ closed
2. reach threshold: Na+ open slightly, K+ closed
3. rising phase: Na+ major influx, K+ open slightly
4. falling phase: Na+ inactivated, K+ major influx
5. hyperpolarization: Na+ closed and inactivated, K+ starting to close

Na+ ion channel has 3 states, K+ ion channel has 2 states

Question 8

somatic vs. autonomic system

Answer 8

somatic:
- 1 neuron
- acetylcholine
- nicotinic (N1) receptor

autonomic:
- 2 neurons: pre-ganglionic fiber –> ganglion –> post-ganglionic fiber –> target organ
- sympathetic and parasympathetic ANS

Question 9

sympathetic vs. parasympathetic ANS

Answer 9

sympathetic:
- short pre- (paravertebral), long post- (prevertebral) ganglionic fibers
- thoracolumbar
- pre-ganglionic neuron releases ACh –> nicotinic (N2) receptor on post-ganglionic neuron –> post-ganglionic neuron releases catecholamines (NE) –> adrenergic (alpha/beta) receptors on target organ cells
- sweat gland post-ganglionic neurons release ACh instead of NE

parasympathetic:
- long pre- (intramural), short post- (terminal) ganglionic fibers
- craniosacral
- pre-ganglionic neuron releases ACh –> nicotinic (N2) receptor on post-ganglionic neuron –> post-ganglionic neuron releases ACh –> muscarininc receptors on target organ cells

Nicotinic and muscarinic receptors are cholinergic (ACh). Alpha/beta receptors are adrenergic (Epi/NE).

Question 9

autonomic receptors

adrenergic (sympathetic)
cholinergic (parasympathetic)

Answer 9

adrenergic:
- a1 = vasoconstriction, smooth muscle contraction, pupil dilation (mydriasis)
- a2 = decreased norepinephrine release
- b1 = increased HR, renin release
- b2 = bronchodilation, vasodilation
- b3 = lipolysis

cholinergic:
- M1 = CNS excitation
- M2 = decreased HR
- M3 = increased GI motility/gland secretion

Question 9

structure of autonomic receptors (G-proteins)

Answer 9

Gq ==> IP3/DAG ==> Ca2+ ==> PKC
- a1
- M1, M3, M5

Gs ==> cAMP ==> PKA
- b1, b2, b3
- M1

Gi = inhibition of adenyl cyclase
- a2
- M1, M2, M4