Nerve Tissue

Question 1

Nervous tissue is an essential part of which system?

Answer 1

Nervous system

Question 2

What are the 2 main subdivisions of nervous tissue?

Answer 2

CNS- Central Nervous System
PNS- Peripheral Nervous System

Question 3

What does the CNS compose of?

Answer 3

brain and spinal cord (and optic nerve)

Question 4

What does the PNS compose of?

Answer 4

all nervous tissue outside CNS

Question 5

What are the 2 divisions of the PNS & their function?

Answer 5

Sensory/afferent division: Information to the CNS.

Motor/efferent division: Information from CNS to the organs (muscles and glands)

Question 6

The Nervous system helps to..?

Answer 6

Maintain homeostasis (along with the endocrine system),

Initiates voluntary movements

Responsible for perception, behaviour and memory

Question 7

The nervous systems activities are grouped under 3 major functions, what are they?

Answer 7

Sensory: Detection of internal and external stimuli and transfer to CNS

Integrative: analysis and storing of information

Motor: stimulation of effectors (e.g. muscle and glands) through PNS i.e.
motor here means “effector”

Question 8

Nervous tissue consists of two types of cells, what are they?

Answer 8

Neurons (nerve cells that can be very large)

Neuroglia (supportive cells – usually small)

Question 9

What is the longest cell in the body that goes from spinal cord to toe- 1m)?

Answer 9

Neurons

Question 10

Are neurons consious or unconsious control?

Answer 10

Both

Question 11

WHat do neurons do?

Answer 11

Have a cell body into which short, branched dendrites convey nerve
impulses (action potentials) and from which a longer, single axon
conducts nerve impulses to another neuron or tissue

Question 12

What are dentites in neurons?

Answer 12

The receiving/input part
of the neuron (looks like branches)

Question 13

What are axons in neurons?

Answer 13

arries the nerve impulse
away from the neuron. It is the
output portion of the neuron.
(looks like tail)

Question 14

Do neurons divide?

Answer 14

No

Question 15

Do neurons have a high metabolic rate?

Answer 15

Yes

Question 16

Will neurons die rapidly without O2?

Answer 16

Yes

Question 17

WHat are the features of a multipolar neuron?

Answer 17

Have 2 or more dendrites
and a single axon.
* Most common neurons in
CNS
* All motor neurons (control
skeletal muscle) are in
this class
* Some of longest (spinal
cord to toe muscles)

(cell body at the top- dentrites branch around)

Question 18

WHat are the features of a Bipolar neuron?

Answer 18

Two distinct processes
– 1 dendritic process (can
branch at tip but not at cell
body)
– And 1 axon
* Has cell body between
axon and dendrite- dentrite at the top
* Rare and small (30μm)
* Special sense organs
(sight, smell, hearing) relay
information from receptor
to neurons

Question 19

What are the features of a Unipolar neuron?

Answer 19

The dendrites and axon
are continuous
* Cell body off to one side
* Whole thing from where
dendrites converge called
axon
* Most sensory nerves are
unipolar
* Very long (1m) like motor
nerves CNS-toe tip

Question 20

Anaxonic neuron features?

Answer 20

Rare and function
poorly understood
* Anatomy cannot
distinguish dendrites
from axons
* Found in brain and
special sense organs

Question 21

Are neuroglia cells found in CNS or PNS

Answer 21

BOTH

Question 22

Neuroglia features?

Answer 22

Make up ~50% the volume of the CNS (“glue”).
* Smaller than neurons but more numerous (5-50x)
* Do not propagate action potentials, but can communicate.
* Can divide within the mature nervous system

Question 23

What are the functions of Neuroglia

Answer 23

Physical structure of nervous tissue
* Repair framework of nervous tissue
* Undertake phagocytosis
* Nutrient supply to Neurons
* Regulate interstitial fluid in neural tissue.

Question 24

What are the 4 types of Neuroglia in the CNS?

Answer 24

Astrocytes
Oligodendrocytes
Microglia
Ependymal cells

Question 25

Astrocytes features

Answer 25

Star-shaped; largest; most
numerous of neuroglia.
Syncytium network.
b. Support (have microfilaments)
and repair (scar).
c. Communicate with neurons via
‘gliotransmitters’ e.g. glutamate
d. Maintain environment around
neuron by e.g. regulating ions.
e. Maintain blood-brain barrier
via endothelium. Wrap around
vessels and influence their
permeability

Question 26

Oligodendrocytes features

Answer 26

Form insulating
multilayered myelin sheath
( protein lipid layer) around
CNS axons.
– Can myelinate more than
one neuron cell’s axon.
Accelerate the action
potential

Question 27

Microglia features

Answer 27

Phagocytic (resident
macrophages) - protection

Inactive microglia= spaced out and smaller

Active microglia = close packed and bigger

Question 28

Ependymal cells features

Answer 28

Produce cerebrospinal fluid (CSF).
* Line the Cerebrospinal Fluid (CSF)-filled
ventricles in the brain and the central
canal of the spinal cord.
* These single layer of predominantly
cuboidal cells have cilia (flow) and
microvilli (sampling).
* Located in ventricles and in other locations
where CSF found.
* CSF mechanical buffer; moves nutrients
and waste

Question 29

Neuroglia in PNS

Answer 29

Sshwaan cells
Satelite cells

Question 30

Schwann cells (“PNS version of CNS oligodendrocyte”) features

Answer 30

form insulating
myelin sheath around axons or can just support and surround several non-
myelinated axons. (Note: One Schwann cell per axon for myelination but
more axons/cell if just support)

Question 31

Satelite cells features (equiv. to astrocytes in CNS)

Answer 31

surround neuron cell bodies. Support and fluid exchange
.