Lecture 9 (4b) - Neurons, Glia, and Nervous Systems Flashcards

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1
Q

Nervous systems can vary in

A

size and complexity
• ganglia larger and fuse in more complex organisms
• ganglia - cluster of neurons

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2
Q

Cnidarians have simple networks of neurons called

A

nerve nets

• there is little or no processing of signals

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3
Q

In more complex animals, neurons are organized into clusters called

A

ganglia

• complex animals must process and integrate larger amounts of information

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4
Q

In bilaterally symmetrical animals

A

the ganglia are often paired

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5
Q

Ganglia may be enlarged and fused at the anterior end to form

A

a brain

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6
Q

Squid

A
signal eye (sensory)   -->
brain (integration )      -->
mantle (motor output to propel)
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7
Q

The human brain contains … neurons

A

10^11 neurons

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8
Q

One given neuron can have … synapses

A

1,000 synapses

10^11 x 10^3 = 10^14 synapses

  • the number of combinations of possible networks is almost infinite
  • the incredible ability of the human brain to process information, learn, solve complex tasks, have emotions…
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9
Q

Neural networks are for

A

information processing

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10
Q

3 stages for information processing

A
  1. sensory input
  2. integragion
  3. motor output
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11
Q

Integration

A

central nervous system of brain and spinal cord

sensory input and motor output

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12
Q
  1. integration
A

vertebrates have a central nervous system including the brain and spinal cord - the sites of most of the information processing, storage, and retrieval

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13
Q
  1. sensory input and 3. motor output are carried in and out of the CNS by
A

the peripheral nervous system

• includes sensory and effector (motor) neurons

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14
Q

Sensor to effector

A
sensory   -->
sensory input (PNS)   -->
integration (CNS)   -->
motor output (PNS)   -->
effectore
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15
Q

Afferent neurons

A

Arrive sensory information to the brain
• carry sensory info to the nervous system
• sensory neurons - internal or external stimuli

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16
Q

Efferent neurons

A

information arrives at the Effectors
(eg motor neurons)
• carry commands to effectors such as muscles, glands
• motor neurons

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17
Q

Information processing is supported by neural networks

A
  • afferent neurons
  • efferent neurons
  • interneurons
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18
Q

Example of a simple neural network - the knee-jerk reflex

A
  • afferent (sensory) axons in a spinal nerve inter the spinal cord through the dorsal rot
  • efferent (motor) axons leave through the ventral root

• cell body in dorsal root
- long axon not in cell body
• dorsal = afferent
• ventral = efferent

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19
Q

Gray matter

A

rich in neural cell bodies

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20
Q

White matter

A

contains myelinated axons

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21
Q

Matter inside/outside

A

gray matter inside, white matter outside

- other way around in the brain

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22
Q

Spinal reflex

A

conversion of afferent to efferent information in the spinal cord without participation of the brain

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23
Q

Limb movements are coordinated by

A

antagonistic sets of muscles - flexors and extensors
• 1 muscle excites and 1 muscle contracts
(bc antagonist muscles opposite)

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24
Q

The coordination of antagonistic muscles is achieved by

A

an interneuron, which makes an inhibitory synapse onto themotor neuron of the antagonistic muscle

  • 1 contracts/flexes
  • 1 extends
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25
Q

Information processing in the spinal cord

A
  • interneuron decides flexor or extensor

* encode, process, store info to regulate physiological/behavioral

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26
Q

What cells are unique to the nervous system?

A
  • CNS includes the forebrain and spinal cord
  • nervous system has 2 types of cells
  • • neurons
  • • glia, or glial cells
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27
Q

Neurons/nerve cells

A

• excitable - they generate and transmit electrical signals called ACTION POTENTIALS

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28
Q

Glia/glial cells

A

modulate neuron activity and provide support

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29
Q

Action potentials are

A

unidirectional

• dendrite –> axon

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30
Q

Action potentials are integrated in

A

the hillock

• integrates action potentials

31
Q

The brain is mostly

A

interneurons

32
Q

The neuron’s structure depends on

A

function

33
Q

Neurons have 4 regions

A
  • cell body
  • dendrites
  • axon
  • axon terminals
34
Q

Cell body

A

contains the nucleus and organelles

35
Q

Dendrites

A

bring information to the cell body

• receive information from other neurons

36
Q

Axon

A

carries information away from the cell body

37
Q

Axon terminal

A

at the tip of the axon

• synapse with a target cell

38
Q

Axons carry informatoin as

A

ationpotentials
away from the originating cell body (presynaptic cell) to the receiving target cell (postsynaptic cell)
UNIDIRECTIONAL

39
Q

The plasma membranes of all neurons can

A

generate and conduct action potentials

40
Q

Action potentials can travel at speeds up to

A

100 m/sec (360 km/hr)

41
Q

The axon terminal comes extremely close to the membrane of

A

the target cell, forming a SYNAPSE

42
Q

Dendrites in the retina are

A

small
• information comes from a local area
• doesn’t need to store information for a long time

43
Q

Some neurons branch over

A

a broad area

44
Q

Axons with fewer dendrites

A

process fewer inputs

45
Q

Bushy dendrites collect information from

A

many other cells

46
Q

Some neurons communicate

A

over long distances via long axons

47
Q

Electrical synapses allow the action potential to pass

A

directly between 2 neurons

48
Q

Synapses can be

A

electrical or chemical

49
Q

In vertebrates, most synapses are

A

chemical

50
Q

The action potential arriving at the terminal causes it to release

A

neurotransmitter chemicals which diffuse to the receptors on the target cells

51
Q

Glial cells outnumber neurons in the human brain by

A

10x

52
Q

In the brain and spinal cord, glial cells are called

A

oligodendrocytes

53
Q

Oligodendrocytes

A

wrap around neuron axons, forming the concentric layers of insulating plasma membrane

54
Q

For the nerves (not CNS), glia is called

A

Schwann cells and wrap the axons

55
Q

Insulating plasma membrane is

A

myelin
• myelin is not continuous = nodes of Ranvier
(jump makes faster)

56
Q

Oligodendrocytes and Schwann cells produce

A

myelin that covers axons

57
Q

Some diseases affect

A

myelin and impair conduction of action potentials

58
Q

Multiple sclerosis

A
  • an autoimmune disesase
  • antibodies to proteins in myelin in the brain and spinal cord are produced (motor impairment)
  • oligodendrocytes myelin
59
Q

Disease that attacks Schwann cells myelin

A

Giullain-Barre syndrome

60
Q

Glia that contribute to the blood-brain barrier

A

astrocytes

61
Q

The blood-brain barrier

A

protects the brain from toxic substances in the blood

62
Q

Astrocytes

A
  • blood-brain barrier
  • take up and release neurotransmitters, and alter the activities of neurons
  • plasticity (memory)
63
Q

Astrocytes store

A

glycogen that can be broken down to supply neurons with fuel
• aid in repair and regeneration of neurons
• make contact with both blood vessels and neurons, and can signal changes in the composition of the blood

64
Q

Projections of 1 astrocyte may make contact with more than

A

100,000 synapses

65
Q

Tripartite synapse

A

the idea that a synapse includes the pre- and postysynaptic neurons as well as connections from astrocytes

66
Q

The blood-brain barrier typically prevents

A

antibodies form entering the brain and spinal cord

67
Q

Microglia act as

A

macrophages and mediators of inflammatory responses, thus providing the nervous system with immune defenses
• microglia = antibodies of the brain

68
Q

The whole nervous system initially comes from

A

the ectoderm

69
Q

The ectoderm gives rise to the

A

epidermis and neural plate

70
Q

The neural plate will give rise to the

A

neural tube and the neural crest cells

71
Q

The neural crest cells

A

lead the development of the connections between the CNS and the rest of the body

72
Q

Nervous system process

A

The whole nervous system initially comes from the ECTODERM
that gives rise tot he EPIDERMIS and the
NEURAL PLATE.
The NEURAL PLATE gives rise to the NEURAL TUBE and the NEURAL CREST cells that lead the development of the connections between the CNS and the rest of the body.

73
Q

Future CNS =

A

forebrain + spinal cord