Synapses & NT PPT-Biancardi

Question 1

ESPSs are associated with the _________ of the postsynaptic membrane

Answer 1

Depolarization

Question 2

IPSPs are associated with the ___________ of the postsynaptic membrane

Answer 2

Hyperpolarization

Question 3

List the 4 major differences between electrical and chemical synapses

Answer 3

1) chemical synapses have a greater distance between pre and post synaptic membranes

2) electrical synapses have gap-junction channels while chemical has active zones, vesicles, and postsynaptic receptors

3) electrical synapses don’t have a delay, but chemical synapses have 1-5ms long delays

4) electrical is bidirectional and chemical is unidirectional

Question 4

Neurotransmitters are considered_________ chemicals

Answer 4

Endogenous

Question 5

After calcium enters the presynaptic terminal, what 4 steps occur?

Answer 5

1) translocation of synaptic vesicle to the presynaptic membrane via docking proteins

2) fusion w/ membrane

3) exocytosis of NT

4) Recycling of synaptic vesicle

Question 6

Desccribe auto-inhibition of NT release (negative feedback)

Answer 6

Autoreceptors on pre-synaptic terminal bind with the released NT and inhibit further synth. or release of NT

Question 7

Examples of auto-inhibiting drugs

Answer 7

Clonidine, xylazine

Question 8

Axo-axonic synapses can _______ or ______ transmitter release by the presynaptic cell

Answer 8

Inhibit; facilitate

Question 9

Examples of presynaptic inhibition via axo-axonic synapses

Answer 9

1) GABA and Glycine

2) Endogenous opioids

Question 10

Why does hypocalcemia increase neuronal excitability?

Answer 10

Since Ca2+ binds to Na+ channels and block it from entering the cell, a low Ca2+ concentration increases the possibility of Na+ entering the cell

Question 11

Why does hypercalcemia decrease neuronal excitability?

Answer 11

Low concentration of Ca2+ decreases the possibility of Na+ entering the cell

Question 12

What is the pathophysiology of hypocalcemia in small animals?

Answer 12

Lower neuronal threshold (easily excitable neuron)

Question 13

Clinical signs of hypocalcemia in small animals?

Answer 13

Face rubbing, seizures, behavior change, muscle tremors, uncoordinated/stiff gait

Question 14

What causes hypocalcemia in ruminant livestock?

Answer 14

Secretion of calcium into the colostrum and milk which causes a decline in the cow’s extracellular calcium in the body

Question 15

Early stage cow hypocalcemia/milk fever signs

Answer 15

CNS hyperexcitability, hyperesthesia, restlessness, tremors, ear twitching, tetany

Question 16

Late stage cow hypocalcemia/milk fever signs

Answer 16

Flaccid paralysis due to depletion of neurotransmitter

Question 17

Beef cattle, sheep, and goat signs of hypocalcemia

Answer 17

Hyperesthesia and tetany

Question 18

Describe the 5 steps in the GPCR mechanism

Answer 18

1) NT binds to receptor

2) G protein activated

3) G protein subunits or intracellular messengers modulate ion channels

4) ion channels open

5) ions flow across membrane

Question 19

List the 3 steps in the removal of NT from synaptic region

Answer 19

1) specific enzyme degradation

2) reuptake into presynaptic terminals or glial cells

3) diffusion away from synapse