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

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Flashcards in Lecture 9 (4b) - Neurons, Glia, and Nervous Systems Deck (73)
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1

Nervous systems can vary in

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

2

Cnidarians have simple networks of neurons called

nerve nets
• there is little or no processing of signals

3

In more complex animals, neurons are organized into clusters called

ganglia
• complex animals must process and integrate larger amounts of information

4

In bilaterally symmetrical animals

the ganglia are often paired

5

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

a brain

6

Squid

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

7

The human brain contains ... neurons

10^11 neurons

8

One given neuron can have ... synapses

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...

9

Neural networks are for

information processing

10

3 stages for information processing

1. sensory input
2. integragion
3. motor output

11

Integration

central nervous system of brain and spinal cord
sensory input and motor output

12

2. integration

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

13

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

the peripheral nervous system
• includes sensory and effector (motor) neurons

14

Sensor to effector

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

15

Afferent neurons

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

16

Efferent neurons

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

17

Information processing is supported by neural networks

• afferent neurons
• efferent neurons
• interneurons

18

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

• 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

19

Gray matter

rich in neural cell bodies

20

White matter

contains myelinated axons

21

Matter inside/outside

gray matter inside, white matter outside
- other way around in the brain

22

Spinal reflex

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

23

Limb movements are coordinated by

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

24

The coordination of antagonistic muscles is achieved by

an interneuron, which makes an inhibitory synapse onto themotor neuron of the antagonistic muscle
-1 contracts/flexes
-1 extends

25

Information processing in the spinal cord

• interneuron decides flexor or extensor
• encode, process, store info to regulate physiological/behavioral

26

What cells are unique to the nervous system?

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

27

Neurons/nerve cells

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

28

Glia/glial cells

modulate neuron activity and provide support

29

Action potentials are

unidirectional
• dendrite --> axon

30

Action potentials are integrated in

the hillock
• integrates action potentials