C&T; Nervous Tissue

Question 1

what are the two main subdivisions of the nervous system?

Answer 1

central nervous system ; brain, spinal cord, optic nerve
and peripheral nervous system ; all nervous tissue outside cns

Question 2

what are the two subdivisions of PNS?

Answer 2

sensory afferent division; information to the cns
motor efferent division; information from cns to organs.

Question 3

what does the nervous system help to do?

Answer 3

maintain homeostasis
initiates voluntary movements
responsible for perception, behaviour and memory

Question 4

three major functions of the nervous system

Answer 4

sensory; detection of environmental stimuli + transfers to CNS
integrative; analysis and storing of information
motor; stimulation of effectors through pns

Question 5

what are the two types of cells that nervous tissue is composed of?

Answer 5

neurons and neuroglia

Question 6

what are the features of neurons?

Answer 6

unconscious and conscious control
have a cell body, dendrites, axons
they do not divide, and have a high metabolic rate

Question 7

dendrites

Answer 7

receiving/input part of the neuron
short and branched
convey nerve impulses (action potentials)

Question 8

axon

Answer 8

carries nerve impulse away from the neuron
long and single

Question 9

types of neurons

Answer 9

multipolar, bipolar, unipolar, anaxonic

Question 10

multipolar neurons

Answer 10

have 2< dendrites cell body is in the middle w single axon
most common neurons in cns
motor neurons (skeletal muscle)
longest

Question 11

bipolar neurons

Answer 11

1 dendritic process -> cell body -> 1 axon
rare and small
special sense organs (sight, smell, hearing) relay information from receptor to neurons

Question 12

unipolar neurons

Answer 12

dendrites + axon are continuous, cell body is off to the side
most sensory nerves
very long

Question 13

anaxonic neuron

Answer 13

rare and function poorly understood
cannot distinguish dendrites from axons
found in brain and special sense organs

Question 14

what are the features of neuroglia?

Answer 14

found in both the cns and pns
make up 50% the volume of cns “glue)
smaller than neurons but more numerous
do not propagate action potentials, but can communicate
can divide within the mature nervous system

Question 15

what are the functions of neuroglia?

Answer 15

physical structure of nervous tissue
repair framework of nervous tissue
undertake phagocytosis
nutrient supply to neurons
regulate interstitial fluid in neural tissue

Question 16

types of neuroglia

Answer 16

astrocytes, oligodendrocytes, microglia ependymal
schwann, satellites

Question 17

astrocytes

Answer 17

starshaped, largest, most numerous, synctium network

support (microfilaments) and repair (scar)

communicate w neurons via gliotransmitters

maintains environment around neuron by regulating ions

maintain blood brain barrier via endothelium. wraps around and influences their permeability

Question 18

oligodendrocytes

Answer 18

forms insulating multilayered myelin sheath (protein lipid layer) around cns axons

can myelinate more than one neurons cells axon; accelerates action potential

Question 19

microglia

Answer 19

phagocytic (resident macrophages) for protection

Question 20

ependymal cells

Answer 20

produces CSF (mechanical buffer that moves nutrients and waste)

lines the CSF filled ventricles in the brain + central canal of the spinal cord

have cilia and microvilli

Question 21

schwann cells

Answer 21

like oligodendrocyte;
- insulating myelin sheath around axons (just one)
can support + surround several non myelinated axons. (multiple)

Question 22

satellite cells

Answer 22

surround neuron cell bodies; support and fluid exchange
- like astrocytes in cns.