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Biology161 > Nervous > Flashcards

Nervous Flashcards

1
Q

When do Action Potentials occur?

A

only when membrane potential at axon hillock reaches threshold

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2
Q

Explain the 3 phases of Action potentials

A
  1. Depolarization (Na+ channels open first)
  2. Repolarization (K+ channels open more slowly)
  3. Hyperpolarization (Na+ channels close; K+ channels close slowly)
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3
Q

What is Absolute Refractory Period?

A

cell incapable of generating a new AP

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4
Q

What is Relative Refractory Period? How is it caused in APs?

A

more difficult to generate new AP

caused by open K+ channels

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5
Q

What is Myelin? What’s its function?

A

insulating layer of lipid-rich Schwann cells wrapped around axon
reduce “leakage” of charge across membrane

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6
Q

What are Schwann Cells?

A

a type of Glial cell (Cells other than neurons that support neuron function)

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7
Q

What are Nodes of Ranvier?

A

areas of exposed axonal membrane between Schwann cells

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8
Q

What are Internodes?

A

the myelinated region of axon

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9
Q

Describe Saltatory conduction

A

Rapid conduction
APs leap from node to node
APs occur at nodes of Ranvier, and electrotonic current spread through internodes

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10
Q

How do Action Potentials go in one direction?

A

APs start at axon hillock and travel towards axon terminal
Up-stream Na+ channels are in the absolute refractory period which prevents backward (retrograde) transmission and summation of APs
Relative refractory period also contributes by requiring a very strong stimulus to cause another AP

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11
Q

What does Action Potential Frequency carry? How does it increase? How does magnitude respond?

A

AP frequency carries information
AP frequency increases w/ stronger stimuli
Magnitude of each AP does not change

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12
Q

What is Maximum frequency limited by?

A

by the absolute refractory period

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13
Q

What is a Synapse?

A

a specialized site of contact of a neuron w/ another neuron or w/ an effector

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14
Q

What is a Synaptic Cleft?

A

20-30nm space that typically separates neurons at a synapse

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15
Q

Presynaptic ____ cell

A

transmits

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16
Q

Postsynaptic ____ cell

A

receives

17
Q

How are spinal nerves arranged and numbered?

A

sequentially arranged and numbered according to region of the vertebral column (Cervical (C-1), Thoracic (T-1), Lumbar (L-1), Sacral (S-1))

18
Q

Afferent fibers enter spinal cord via the ….?

A

dorsal root

19
Q

Efferent fibers leave via the ….?

A

ventral root

20
Q

What is Gray matter?

A

contains neuronal cell bodies

21
Q

What is a Ganglion?

A

a mass of nerve cell bodies

22
Q

What is the Autonomic Nervous System part of and involved in?

A

Part of Peripheral Nervous System (PNS)
Involved in homeostatic regulation of most physiological functions (ex heart rate, blood pressure, breathing)
[Not under voluntary control]

23
Q

Describe the 3 components of the Autonomic Nervous System

A
  1. Sympathetic (active during stress or physical activity)
  2. Parasympathetic (resting and digesting – opposes sympathetic)
  3. Enteric (only digestion – separate from other 2)
24
Q

Compare the components of the Sympathetic and Parasympathetic ANS

A

Sympathetic: preganglionic neuron short; Neurotransmitter of preganglionic neuron is ACh; Neurotransmitter of postganglionic neuron is NE or E
Parasympathetic: preganglionic neuron is long; Neurotransmitter of preganglionic neuron is ACh; Neurotransmitter of postganglionic neuron is ACh

25
Q

Describe the Visceral reflex

A

4 neurons involved
neurons leaving ventral root are preganglionic and can synapse w/ sympathetic ganglion, collateral ganglion, or at the visceral organ

26
Q

Describe Somatic motor pathways

A

2-3 neurons in circuit
Only a single neuron in the efferent motor outflow (to effector via spinal nerve)
Skeletal muscle only
Utilizes Acetylcholine

27
Q

Describe the pathway of Acetylcholine and motor neurons

A
  1. acetyl CoA synthesized in mitochondria
  2. Choline acetyl transferase catalyzes the conversion of choline and acetyl CoA to ACh
  3. The ACh is packaged into synaptic vesicles
  4. ACh is released into the synapse
  5. ACh binds to its receptor on postsynaptic cell
  6. AChE breaks down ACh into choline and acetate, terminating signal in postsynaptic cell
  7. Presynaptic cell takes up and recycles choline; acetate diffuses out of the synapse
28
Q

Where are Nicotinic ACh receptors found? What do they cause?

A

on skeletal muscle cells
binds to nicotine; ligand-gated ion channels open; Na+ rapidly enters muscle cell causing excitatory postsynaptic potential

29
Q

Describe Myasthenia gravis

A

decreased # of ACh receptors on the muscle membrane

characterized by fatigue that increases throughout the day

30
Q

The number of spinal nerves varies with …

A

the number of segments in the trunk or tail

31
Q

What is White Matter?

A

surrounds gray matter and is composed of nerve fibers linking levels of the spinal cord and between SC and brain
[often myelinated, giving white appearance]

32
Q

What is a CPG?

A

Central Pattern Generator
Rhythmic activity arising from the spinal cord that has no feedback
Neural network
System must repeatedly return to starting condition

33
Q

What are some examples of CPGs?

A

Swallowing, walking, hiccups, other rhythmic behaviors

34
Q

What is Autotomy?

A

the act whereby an animal severs one or more of its own appendages
ex. rats (tail skin), geckos, lizards

35
Q

Describe what happens during tail autotomy in lizards

A

muscular contractions break vertebrae at autotomy plane

tail regenerates following autotomy

36
Q

Describe the motor patterns during the autotomy in lizards. What two theories may be the cause of these complex motor patterns?

A

Rhythmic swings and Complex flips and jumps.

  1. Sensory feedback from the environment [probably not since experiments on a clear arena]
  2. Multiple central pattern generators [more likely]
37
Q

Why is it crucial for brain development in birds to have one eye exposed to light?

A

so brain’s 2 hemispheres can properly integrate information

Biology161 (6 decks)

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