PNS and Synapses

Question 1

synapse

Answer 1

connection between neuron and target cell
pre–>post synaptic component

Question 2

electrical synapse vs chemical synapse

Answer 2

electrical: passing of electrical signals (gap junctions in cardiac)

chemical: the rest of our body; uses neurotransmitters

Question 3

structures involved in typical chemical synapse

Answer 3

axon terminal (presynaptic)
synaptic cleft (gap between neurons)
neurotransmitter receptors

Question 4

events of synaptic transmission in chronological order

Answer 4

1. action potential reaches axon terminal
2. opens voltage gated calcium channels
3. presynaptic vesicles perform exocytosis
4. neurotransmitter cross cleft and binds to post synaptic receptors
5. ligand gated channels open (graded potential)
6. termination through degradation

Question 5

what is excitatory postsynaptic potential (EPSP)

Answer 5

graded potentials thats purpose is to generate action potential (cholinergic and adrenergic)
–> depolarization

Question 6

what in inhibitory post synaptic potential (IPSP)

Answer 6

graded potentials thats purpose is to avoid action potentials (GABA-ergic)
–>hyperpolarization

Question 7

how can a single neurotransmitter elicit different responses at different postsynaptic cells

Answer 7

by binding to different receptors at different synapses

Question 8

most common excitatory and inhibitory neurotransmitters

Answer 8

excitatory: glutamate, epinephrine

inhibitory: GABA, serotonin

Question 9

reuptake mechanism

Answer 9

the whole neurotransmitter molecule is taken back into the axon terminal that released it

Question 10

enzymatic breakdown

Answer 10

enzyme binds to neurotransmitter and breaks it apart so that the neurotransmitter can no longer fit into a receptor of receiving cell

Question 11

diffusion mechanism

Answer 11

the neurotransmitter drifts away and can no longer act on receptor

Question 12

formation structure and branches of spinal nerve

Answer 12

dorsal ramus, spinal nerve, dorsal root ganglion, dorsal root, ventral root, gray ramus, white ramus, and ventral ramus

Question 13

number of spinal nerve pairs emerging from each spinal cord

Answer 13

8 C
12 T
5 L
5 S
1 C

Question 14

spinal nerve plexus

Answer 14

group of nerves that merge from different spinal nerves to connect to certain parts of body

Question 15

cervical nerve plexus

Answer 15

C1-C4 head and neck
nerves: C1-C4

Question 16

brachial nerve plexus

Answer 16

C5-T1 upper extremities
nerves: musculocutaneous, median, ulnar (pinky) , axillary, and radial (thumb)

Question 17

lumbar nerve plexus

Answer 17

L1-L4 (abdomen, thighs, and genitalia)
nerves: fermoral (quads) and obturator (medial side of leg)

Question 18

sacral nerve plexus

Answer 18

L4-S5 (pelvis and below knee)
nerves: sciatic, tibial (back of leg), deep fibular (front of leg), superficial fibular (lateral of leg)

Question 19

reflex

Answer 19

quick involuntary stereotyped reactions of glands or muscles to stimuli (any muscle types)
–> generated at spinal level

Question 20

describe reflex responses in terms of the major structural and functional components of a reflex arc

Answer 20

1. receptor detects stimulus
2. it sends afferent signal to posterior horn
3. reaches integrating center where there is synaptic contact
4. efferent signal from anterior horn
5. carriers motor impulse to muscles or effectors

Question 21

describe functions and locations of first, second, third, order neurons

Answer 21

first order: sensory neurons that produce action potentials ; enter through dorsal root and synapse with second

second order (interneuron): dorsal gray horn of spinal cord and decussates to ascend spinal cord

third order: integrated in primary somatosensory cortex

Question 22

locations of lower and upper neurons

Answer 22

these are motor neurons

upper motor: in primary motor cortex and propagates its AP to lower motor neurons

lower motor: in brain stem where signal exits via ventral root and enters spinal nerve

Question 23

decussation and its implication

Answer 23

occurs in the medulla and allows for coordinated control of movement and sensation between both sides of the brain