Nervous System Flashcards

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1
Q

What is the main function of the nervous system?

A

Maintain homeostasis

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2
Q

What is homeostasis?

A

Maintenance of the internal environment (pH, body temp, glucose levels, blood pressure, water levels, etc.)

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3
Q

What are the two main branches of the nervous system?

A
  • Central Nervous System (CNS)

- Peripheral Nervous System (PNS)

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4
Q

What are the two parts of the CNS?

A
  • Brain

- Spinal Cord

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5
Q

What two type of nerves does the PNS branch into?

A
  • Autonomic nerves (involuntary)

- Somatic nerves (voluntary)

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6
Q

What are the 3 kinds of neurons?

A
  • Sensory neurons (afferent)
  • Motor neurons (efferent)
  • Interneurons
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7
Q

What do sensory neurons do?

A

Take impulses from the body receptors to the CNS

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8
Q

What do motor neurons do?

A

Take impulses away from the CNS and to the muscles and glands

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9
Q

What do interneurons do?

A

Are actually in the CNS (brain and spinal cord)

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10
Q

What are neuroglia (glial cells)?

A

Supportive cells that aid the interneurons of the brain (other types of support cells) (nourish neurons, remove waste, protect neurons)

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11
Q

What are the 3 basic parts of the neuron?

A
  • Cell Body
  • Dendrites
  • Axon
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12
Q

What is the cell body?

A

Nucleus and cytoplasm

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13
Q

What are dendrites?

A
  • Finger-like projections of cytoplasm of the cell body

- They receive information

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14
Q

What is the axon?

A
  • Extension of cytoplasm

- Transmits impulse away

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15
Q

What is myelin sheath?

A

White fatty covering that insulates the axon (produced by Schwann cells)

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16
Q

What are Schwann cells?

A
  • A special kind of glial cell that produces a myelin sheath that that wraps around the axons as insulation
  • Also play a minor role in protection
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17
Q

On top of protection, what else does the myelin sheath provide?

A

Faster conduction of impulses and greater power of regeneration

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18
Q

What are the intermitted gaps between the myelin sheath called?

A

Nodes of Ranvier

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19
Q

What do Nodes of Ranvier do?

A

Allow impulses to “jump” from node to node rather than slowly moving through the entire length of the axon (faster impulses)

20
Q

What happens if the myelin sheath is destroyed?

A
  • Slower transmission

- Not death of neuron

21
Q

What is needed to achieve a fast impulse?

A
  • The neuron must have a short axon

- If the axon is long, it must be myelinated (saltatory action)

22
Q

What is saltatory conduction?

A

Generation of action potentials only at nodes of Ranvier in myelinated axons, resulting in rapid transmission of nerve impulses

23
Q

What nerves and neurons are myelinated?

A
  • All nerves of the PNS and all motor and sensory neurons

- Only some of the nerves in the CNS are myelinated

24
Q

What are the Non-Myelinated neurons in the brain called?

A

Grey matter (usually somatic)

25
Q

What are the myelinated nerves in the brain called?

A

White matter (autonomic)

26
Q

What causes multiple sclerosis?

A

Destruction of the myelin sheath that surrounds the nerve axons. The myelinated nerves in the brain and spinal cord are gradually destroyed as the myelin sheath hardens and forms scars, or plaques

27
Q

What does the scar-like tissue prevent?

A

Normal impulse transmission

28
Q

What are symptoms of MS?

A

Double vision, speech difficulty, jerky limb movements, and partial paralysis of voluntary muscles

29
Q

What are nerves?

A

Individual neurons that are organized into tissues

30
Q

What are nerves in the PNS surrounded by?

A

A thin membrane called the neurilemma

31
Q

What does the neurilemma do?

A

Helps regenerate damaged axons

32
Q

Why can’t nerves in the CNS be repaired?

A

Lack neurilemmas

33
Q

What is the reflex arc?

A

Autonomic, quick, involuntary responses to internal or external stimuli (autonomic NS)

34
Q

What part of the CNS do reflex arcs involve?

A
  • Only the spinal cord

- Do not immediately involve the brain

35
Q

What is the main purpose of reflex arcs?

A

Allow quicker reaction times to potentially harmful stimulus

36
Q

Why are reflex arcs extremely fast?

A
  • Every neuron involved is myelinated

- Reflex messages only go to the spinal cord (not the brain)

37
Q

What are the 5 components of a reflex arc?

A
  1. Sensory receptor (senses something)
  2. Sensory neuron (sends signal to CNS)
  3. Interneuron (registers signal)
  4. Motor neuron (sends response back)
  5. Effector (carries out the action)
38
Q

What are sensory receptors?

A

Highly modifies dendrites of a sensory neuron that are activated by an environmental stimulus

39
Q

What are sensory neurons?

A

Neurons that carry impulses to the CNS (also known as afferent neurons)

40
Q

What is an interneuron?

A

A neuron of the CNS that connects with sensory, motor, and other interneurons to integrate sensory input with motor output (also known as association neuron)

41
Q

What are motor neurons?

A

Neurons that carry impulses from the CNS to an effector (efferent neuron)

42
Q

What is an effector?

A

A cell or organ that produces a physiological response when stimulated by a nerve impulse

43
Q

What is a nerve impulse?

A

An action potential

44
Q

What is an action potential?

A

An electrochemical event with a rapid change in polarity (relative electrical potential) down a nerve cell that results in the conduction of a nerve impulse

45
Q

What do the “electro” and “chemical” components of electrochemical represent?

A
  • Electro = What’s happening in the neuron

- Chemical = What’s happening between neurons

46
Q

What causes polarization (resting potential)?

A

Sodium potassium pump causing more sodium to be pumped out than potassium pumped in; resulting in a negative charge inside the axon of the neuron