L2 NTs and ANS

Question 0

Botulinum and Tetanus toxins

Answer 0

Alter synaptic transmission by cleaving SNARE proteins

Botulinum: flaccid paralysis; affecting peripheral cholinergic fibers (Ach)
Tetanus: spastic paralysis; gets taken up by inhibitory neurons in SC

Question 1

How neurotransmission occurs

Answer 1

1. AP travels down the axon
2. AP triggers uptake in Ca via voltage-gated channels
3. Ca uptake causes vesicles with NT inside to fuse with pre-synaptic membrane via SNARE proteins and NT is released.
4. NT receptor on post synaptic cell receives NT and causes either 1) ionotropic FAST event (ion channel) or 2) metabotropic SLOW event (GPCR)
5. Either EPSP or IPSP occurs
6. NT degraded or taken back into pre-synaptic cell

Question 2

EPSP vs. IPSP

Answer 2

EPSPs use Ach/glutamate excitatory NTs, which result in an new inward current that depolarizes the region. Increases probability that AP will occur.
IPSPs use GABA/glycine inhibitory NTs, which stabilizes the cells RMP to that of Chloride by making the cell permeable to Cl. Decreases chance of AP.

Question 3

How does nerve gas work?

Answer 3

Nerve gas, like sarin gas, inhibit the degradation of Ach by AchE therefore cells are excitatory activated indefinitely. Overstimulation, convulsions, paralysis and respiratory failure.

Question 4

Drug cocktails against nerve gas

Answer 4

Diazepam is a sedative to prevent seizures,
Atropine blocks Ach receptors,
Pralidoxime recovers AchE function.

New: Scopolamine enters BBB and raises the lethal dose of sarin 2x

Question 5

Synaptic transmission in ANS vs. CNS

Answer 5

CNS: neuron-neuron – well defined synapse and FAST; ionotropic. NT has a direct effect and causes IPSP/EPSPs

ANS: neuron-viscera – “en passant” synapses are SLOW; metabotropic. NT doesn’t necessarily have a direct effect and causes junction potential (excitatory or inhibitory)

Question 6

Organization of the ANS

Answer 6

Sympathetic and Parasympathetic
2 neuron pathway - pre and post ganglionic
Symp - short pre –> chain ganglia(para-vertebral) or pre-vertebral ganglia –> long post –> target
Parasymp - long pre –> ganglia on target organ –> short post –> target

Most organs have Dual innervation

Question 7

Sympathetic NS (Thoracolumbar)

Answer 7

Pre: -Ach- that goes to Nicotinic/Ionotropic receptors

go to para/prevertebral ganglia (symp trunk)

Post: -NE- that goes to Adrenergic/Metabotropic receptors

Question 8

Parasympathetic NS (Craniosacral)

Answer 8

Pre: -Ach- goes to Nicotinic/Ionotropic receptors

Post: -Ach- goes to Muscarinic/Metabotropic receptors

Question 9

Exceptions: Chromaffin cells from adrenal medulla

Answer 9

Pre-synaptic cells go straight to the target organ without synapsing at paravertebral/prevertebral ganglia

Adrenal glands come from neural crest and don’t go through the neural tube therefore don’t synapse at a ganglion beforehand

Question 10

Autonomic centers in the brain

Answer 10

Pons: respiratory and micturition
Medulla: vasomotor and vasodilator; respiratory, water intake
Hypothalamus: temp regulation, food&water intake, fight and flee, reproduction

Question 11

Excitatory NTs

Answer 11

NE, Ach, CO, NO, ATPs, others