MEC322: Nervous System Flashcards

1
Q

Which of the 11 body systems play the most important roles in maintaining homeostasis?

A

nervous system and endocrine system

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2
Q

What are the three basic functions of the nervous system?

A
detecting stimuli (sensory function); 
analyzing, integrating, and storing sensory information (integrative function); 
responding to integrative decisions (motor function).
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3
Q

What does CNS stand for?

A

Central nervous system

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4
Q

What does PNS stand for?

A

Peripheral nervous system

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5
Q

What is part of the CNS?

A

Brain

Spinal cord

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6
Q

What is part of the PNS?

A
Cranial nerves
Spinal nerves
Ganglia
Enteric plexuses in small intestine
Sensory receptors in skin
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7
Q

What are the two divisions of the peripheral nervous system?

A

Afferent- brings sensory info to CS

Efferent- carries motor commands from CNS to muscles glands etc

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8
Q

What are the subdivisions in the efferent division?

A

Somatic nervous system SNS

Automatic nervous system ANS

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9
Q

What does the SNS provide?

A

voluntary control over skeletal muscles

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10
Q

What does the ANS provide?

A

involuntary control of cardia and smooth muscle, and glands

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11
Q

What is a neuron cell?

A

cells specialised for nerve impulse conduction and provide most of the unique functions of the nervous system
e.g. sensing, thinking remembering, controlling muscle activity

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12
Q

What is a neuroglia cell?

A

they support, nourish and protect the neurons and maintain homeostasis in the interstitial fluid that bathes neurons

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13
Q

What are the three parts of a neuron?

A

Dendrites
Cell body
Single axon

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14
Q

What is the dendrite in a neuron?

A

main receiving or input region

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15
Q

What is the cell body in a neuron?

A

integration occurs here

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16
Q

What is the axon in a neuron?

A

output part

conducts nerve impulses towards another neuron, muscle fibre or gland cell

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17
Q

Structurally what are the three classifications of neuron?

A

multipolar, –|–o <
bipolar, -|-o– <
unipolar –o-|-

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18
Q

How are neurons classified functionally?

A

Sensory neurons
Motor neurons
Interneurons

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19
Q

What do sensory neurons do?

A

carry sensory info into the CNS

approx 10^6

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20
Q

What do motor neurons do?

A

carry info out of CNS to effectors (muscles and glands)

approx 500000

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21
Q

What do interneurons do?

A

located within the CNS between sensory and motor neurons

approx 20^9

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22
Q

How much of the CNS do the neuroglia make up?

A

half the volume of the CNS

23
Q

What are the neuroglia in the CNS?

A

astrocytes, oligodendrocytes, microglia, and ependymal cells

24
Q

What are the neuroglia in the PNS?

A

Schwann cells and satellite cells

25
Q

What are myelin sheaths?

A

sleeves of fatty tissue that protect your nerve cells

26
Q

Which two types of neuroglia produce myelin sheaths?

A

Oligodendrocytes myelinate axons in the CNS, and Schwann cells myelinate axons in the PNS.

27
Q

What do astrocytes do?

Neuroglia cells in CNS

A
  • Control the chemical environment of the brain
  • Brace neurons and form barrier against capillaries
  • Abundant, star-shaped cells
28
Q

What do microglia do?

Neuroglia cells in CNS

A
  • Spiderlike phagocytes

- Dispose of debris

29
Q

What do ependymal cells do?

Neuroglia cells in CNS

A
  • Line cavities of the brain and spinal cord

- Cilia assist with circulation of cerebrospinal fluid

30
Q

What do oligodendrocytes do?

Neuroglia cells in CNS

A
  • Wrap around nerve fibers in the central nervous system

- Produce myelin sheaths

31
Q

What do Satellite cells do?

Neuroglia cells in PNS

A

Protect neuron cell bodies

32
Q

What do Schwann cells do?

Neuroglia cells in PNS

A

Form myelin sheath in the peripheral nervous system

33
Q

How to neurons communicate with one another?

A

nerve action potential AKA nerve impulses

34
Q

What does generation of action potentials depend on?

A

the existence of a membrane potential and the presence of voltage-gated channels for Na+ and K+.

35
Q

What is the resting membrane potential?

A

RMP= -70mV

inside of the neuron is 70 mV less than the outside

36
Q

What causes the RMP?

A

an unequal distribution of ions on either side of the plasma membrane and a higher membrane permeability to K+ than to Na+. The level of K+ is higher inside and the level of Na+ is higher outside, a situation that is maintained by sodium–potassium pumps.

37
Q

What happens during an action potential?

A
  • voltage-gated Na+ and K+ channels open in sequence
  • results in depolarisation ( the loss and then reversal of membrane polarisation)
  • opening of voltage-gated k+ allows depolarisation and recovery of the membrane potential
38
Q

What is the all-or-none principal?

A

if a stimulus is strong enough to generate an action potential, the impulse generated is of a constant size

39
Q

Can another action potential be generated during the refractory period?

A

NO

40
Q

What is nerve impulse conduction that occurs as a step-by-step process along an unmyelinated axon called?

A

continuous conduction

41
Q

What is saltatory conduction?

A

a nerve impulse “leaps” from one node of Ranvier to the next along a myelinated axon.

42
Q

What conducts impulses faster, large diameter axon or small diameter?

A

large

43
Q

What conducts impulses faster, myelinated axons or unmyelinated axons ?

A

myelinated axons

44
Q

What is a node of Ranvier?

A

a gap in the myelin sheath of a nerve, between adjacent Schwann cells.

45
Q

How do neurons communicate with other neurons and effectors?

A

at synapses in a series of events known as synaptic transmission

46
Q

What are the two types of synapses?

A

electrical and chemical

47
Q

Describe an electrical synapse

A

nerve impulses are conducted between adjacent neurons via gap junctions.
This type of synapse is found in visceral smooth muscle, cardiac muscle and the brain.

48
Q

Describe a chemical synapse

A

the presynaptic neurons release neurotransmitters which will bind to receptors on the plasma membrane of the postsynaptic neuron.
At a chemical synapse, there is only one-way nerve impulse conduction.

49
Q

What does the excitatory neurotransmitter do?

A

depolarizes the postsynaptic neuron’s membrane, brings the membrane potential closer to threshold, and increases the chance that one or more action potentials will arise.

50
Q

What does the inhibitory neurotransmitter do?

A

hyperpolarizes the membrane of the postsynaptic neuron, thereby inhibiting action potential generation.

51
Q

What are the three ways a neurotransmitter can be removed?

A

diffusion, enzymatic destruction, and reuptake by neurons or neuroglia.

52
Q

List some important neurotransmitters

A

acetylcholine, glutamate, aspartate, gamma aminobutyric acid (GABA), glycine, norepinephrine, dopamine, serotonin, neuropeptides, and nitric oxide.

53
Q

What happens when we want to move?

A

, electrical signals cascade from the brain down the spinal cord to instruct our muscle to contract