L37: ANS

Question 1

Nucleus vs Ganglion

Answer 1

Nucleus: cell body in CNS
Ganglion: cell body in PNS

Question 2

Organisation of somatic NS vs autonomic NS

Answer 2

Somatic: upper motor neurone —> lower motor neurone (via somatic motor nuclei)

Autonomic: autonomic motor neurone —> preganglionic neurone (via autonomic nuclei) —> postganglionic neurone (via autonomic ganglion) (比somatic多左ganglion)

Question 3

Sympathetic vs Parasympathetic

Answer 3

1. Function
   SNS: Flight or fight, prepare for emergency
   PNS: Conserves and restores energy
2. Preganglionic fibre
   SNS: short, lateral gray horn T1-L2
   PNS: long, CN3,7,9,10 + S2-S4
   Both: myelinated + ACh as transmitter
3. Ganglia
   SNS:
   - sympathetic chain
   - collateral ganglia —> celiac, superior mesenteric, inferior mesenteric
   - adrenal medulla
   - nicotinic receptor (ligand-gated channel)
   PNS:
   - small ganglia close to viscera
   - nicotinic receptor (ligand-gated channel)
4. Postganglionic fibre
   SNS: Long, non-myelinated (NE most, ACh very few), varicosities at terminal, containing NE vesicles
   PNS: Short, non-myelinated (ACh)
5. Activity
   SNS: Adrenergic receptors (GPCR), widespread + NE/E from adrenal medulla
   PNS: Muscarinic receptor (GPCR), very specific and localised, visceral due to few postganglionic fibre/ do not diverge as extensively
6. Higher control
   Both: hypothalamus

Question 4

Synthesis and release of NE and E

Answer 4

Tyrosine —> L-Dopa —> Dopamine —> NE/E

Question 5

Alpha vs Beta Adrenergic receptor

Answer 5

Affinity: NE»E
Alpha1: activate Gq —> release of intracellular Ca from SER —> excitatory effect
Alpha2: activate Gi —> inhibit adenylyl cyclase

Affinity: NE=E
Beta1-3: activate Gs —> activates adenylyl cyclase to generate cAMP —> activate PKA

Question 6

Nicotinic receptor vs Muscarinic receptor

Answer 6

Nicotinic:

• Gated channels
• Short-lived excitation
• in both sympathetic and parasympathetic NS
• PNS and SNS Ganglion
• NMJ
• Brain
• **- SNS: Sympathetic Vasoconstriction
• **- PNS: same as Muscarinic agonist
• **- NMJ: increase muscle tension / contraction
• **- Brain: CNS stimulation —> tremor, convulsion, stimulate respiratory centre

Muscarinic:

• GPCR
• longer-lasting effect
• excitation/inhibition
• only in parasympathetic NS
• Sweat gland

***- M1: CNS
—> CNS excitation, memory, cognition, locomotor activity, tremor, hypothermia, salivary secretion, gastric acid

***- M2: Heart
—> Decrease rate, force, AV conduction

***- M3: Smooth Muscle + Exocrine gland
—> Smooth muscle contraction except Vasodilation, ocular accommodation (ciliary muscle + constrictor pupillae muscle), glandular secretion