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Biol235 > Chapter 12 > Flashcards

Chapter 12 Flashcards

1
Q

what are Nissl bodies

A

neuronal rough ER

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2
Q

how many spinal nerves are there

A

31

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3
Q

what is lipofuscin

A

product of lysosomes

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4
Q

what is a ganglion

A

cluster of neuronal cell bodies in PNS

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5
Q

what is the trigger zone

A

where nerve impulses arise (axon hillock and initial segment)

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6
Q

what is the axolemma

A

neural cell membrane

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7
Q

what are varicosities

A

contain synaptic vesicles

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8
Q

what is the difference between slow and fast axonal transport

A

fast–200-400mm a day, moves both directions
slow–1-5mm a day, only in anterograde direction, contains axoplasm

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9
Q

where are multipolar neurons found

A

CNS, motor neurons

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10
Q

where are bipolar neurons found

A

eye, ear, olfactory area

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11
Q

where are unipolar (pseudo bipolar) neurons found

A

ganglia of spinal and cranial nerves

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12
Q

what is the difference between protoplasmic astrocytes and fibrous astrocytes

A

protoplasmic in grey matter with short processes, fibrous in white with long branched processes

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13
Q

what is the function of astrocytes

A

strength, secrete chemicals to maintain selective permeability of endothelial cells in BBB, growth and development of embryo, help regulate ion concentration and nerve transmission, help form synapses

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14
Q

what are ependymal cells

A

cuboidal/columnar cells possessing microvilli and cilia, produce and assist in circulation of CSF

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15
Q

what are satellite cells

A

regulate exchange of materials between cells and interstitial fluid

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16
Q

what is a nucleus (vs ganglion)

A

cluster of cell bodies in CNS

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17
Q

nerve vs tract

A

nerve is PNS, tract is CNS

18
Q

what are the 3 factors that lead to resting potential

A
  1. unequal distribution of ions, inability of most anions to leave the cell,Na/K pumps electrogeneicity
19
Q

what is decremental conduction

A

graded potentials diminish as they spread along the membrane through leak channels

20
Q

what is threshold for AP

A

-55mV

21
Q

what is the sequence of events during AP

A
  1. depolarization, VG Na channels open (voltage to 30mV)
  2. Depolarization, Na gates close, K+ channels open, and K+ leaves cell
  3. Hyperpolarization, outflow of K+ causes membrane potential to drop to -90mV
22
Q

What causes the refractory period?

A

Inactivated Na+ channels, smaller diameter axons have longer refractory periods

23
Q

What is saltatory conduction?

A

In myelinated neurons, current “leaps” from node to node due to channels primarily occurring at nodes

24
Q

What are the factors that affect propagation speed?

A

amount of myelin. axon diameter, temperature

25
Q

What are A fibres?

A

large diameter, myelinated, brief refractory period and fast transmission. Occur in somatic sensory neurons and motor neurons

26
Q

What are B fibres

A

medium diameter neurons, myelinated, medium speeds (15m/s), autonomic motor neurons and sensory neurons from viscera to brain

27
Q

What are C fibres

A

smallest diameter (0.5-1.5um), slowest transmission and longest refractory periods, unmyelinated. Pain impulses from viscera, some somatic sensory signals, heart, smooth muscle, glands, and other motor functions for autonomic movement.

28
Q

What are the main advantages of electrical synapses (gap junctions)

A

faster, synchrony

29
Q

What is the synaptic delay?

A

0.5 miliS, for chemical signal to transmit across synapse

30
Q

How are NTs removed from synapse

A
  1. diffusion
  2. enzymes
  3. reuptake
31
Q

What are neurosecretory cells

A

secrete hormones

32
Q

What AA is used to synthesis catecholamines?

A

tyrosine

33
Q

What is the role of NO

A

excitatory, vasodilation

34
Q

what are some examples of neuropeptides?

A

enkephalins, endorphins, dynorphins

35
Q

What is substance P

A

transmit pain signals

36
Q

What is a reverberating circuit

A

neurons further in the cycle stimulate neurons earlier in the cycle (ie breathing, coordination of muscles, arousal, short term memory

37
Q

what is parallel after discharge circuit?

A

single presynaptic cell stimulate a group of nuerons which converges on a single postsynaptic cell. used for precise activities

38
Q

what is epidermal growth factor?

A

stimulates cells in hippocampus

39
Q

What factors affect neurogenesis in brain and spinal cord?

A
  1. oligodendrocytes
  2. absence of growth factors
40
Q

What happens after axonal injury in PNS

A
  1. Chromatolysis (Nissl bodies break up)
  2. Distal part of axon to injury breaks up
  3. Wallerian degeneration (degeneration of distal portion of axon and myelin sheath
  4. proteins and RNA synthesis, Schwann cells divide and form regeneration tube

Prevented by scar tissue or large area

Biol235 (6 decks)

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