Wk 3: Nervous Tissue

Question 1

What is nervous tissue

Answer 1

The main tissue component of the nervous system

Question 2

What is the function of nervous tissue

Answer 2

Neural communication within the body via neurons

Question 3

What is the CNS composed of

Answer 3

• Brain
• Spinal cord

Question 4

Where is the CT in the CNS

Answer 4

• Meninges
• Walls of large blood vessels

Question 5

What is the PNS comprised of

Answer 5

• Branching peripheral cranial & spinal nerves
• Relay centres (ganglia)

Question 6

What can the PNS be subdivided into

Answer 6

• Somatic nervous system
• Autonomic nervous system

Question 7

Function of somatic nervous system

Answer 7

• Controls voluntary functions
• Transmits signals from brain to end organs

Question 8

Function of autonomic nervous system

Answer 8

• Controls involuntary functions - heart rate, blood pressure

Question 9

What do neurons do

Answer 9

Receive & transmit impulses

Question 10

What do neuroglia do

Answer 10

• Support, protect & assisst neurons in neural transmission
• (dont receive or transmit impulses)

Question 11

Where does the impulse in sensory neurons originate

Answer 11

In sensory receptors

Question 12

How are the impulses in sensory neurons conducted

Answer 12

Conducted via sensory (afferent) neurons to the CNS

Question 13

Where do motor neurons originate

Answer 13

In the CNS

Question 14

How are the impulses in the motor neurons conducted

Answer 14

They are conducted via motor (efferent) neurons from CNS to the PNS, muscle tissue or glands

Question 15

Interneurons function

Answer 15

Forms connections between neurons in the CNS

Question 16

What is the axon hillock of the cell body

Answer 16

The region where the axon arises

Question 17

What does the cell body contain

Answer 17

• Nucleus
• Perinuclear cytoplasm

Question 18

What 2 types of processes extend from cell body / soma

Answer 18

1. Single axon
2. One or more dendrites

Question 19

Function of the cell body

Answer 19

Receives signals from other cells & sends them towards the axon

Question 20

What does the branching of dendrites result in

Answer 20

Synaptic terminals

Question 21

What do dendrites function as

Answer 21

The major sites of information input into the neuron

Question 22

What is the portion of axon that stretches from the origin at the axon hillock to the beginning of the mtelin sheath

Answer 22

Initial segment

Question 23

What are the swellings on the ends of the axon branches called. What do these form??

Answer 23

• Terminal boutons
• These form synapses

Question 24

What does an axon being myelinated mean

Answer 24

It has a myelin sheath

Question 25

What does the grey matter of the CNS & PNS contain (2)

Answer 25

1. Cell bodies 2. Dendrites

Question 26

What does the white matter of the CNS & PNS contain

Answer 26

Axons

Question 27

Structure of bipolar neurons

Answer 27

* Single dendrite * Single axon

Question 28

Structure of unipolar neurons

Answer 28

One process which branches into central & peripheral branch

Question 29

Structure of multipolar neurons

Answer 29

* Multiple dendrites * Single axon

Question 30

How does a chemical synapse work

Answer 30

* Presynaptic membrane releases neurotransmitters into synaptic cleft * Neurotransmitter diffuses across synaptic cleft to gated ion channel receptors (located on postsynaptic membrane) * Binding results in ion channels opening, allowing passage of ions - reverses membrane potential

Question 31

What is the synaptic cleft

Answer 31

A gap separating the presynaptic & postsynaptic membranes

Question 32

What are neurotransmitters decomposed by in the synaptic cleft

Answer 32

Enzymes

Question 33

4 functions of neuroglia

Answer 33

1. Monitoring synapses 2. Regulating flow of CSF 3. Scavenging neurotransmitters 4. Releasing gliotransmitter - such as glutamate

Question 34

Which 4 neuroglia are of the CNS

Answer 34

1. Astrocytes 2. Oligodendrocytes 3. Microglia 4. Ependymal cells

Question 35

What neuroglia is of the PNS

Answer 35

Schwann cells

Question 36

Function of astrocytes

Answer 36

Provide structural & metabolic support ot neurons

Question 37

Function of fibrous astrocytes

Answer 37

Maintains blood brain barrier

Question 38

2 functions of oligodendrocytes

Answer 38

1. Electrical insulation 2. Myelin production in the CNS

Question 39

Where are oligodendrocytes located

Answer 39

Grey & white matter of CNS

Question 40

Function of interfascicular oligodendrocytes

Answer 40

Manufacture & maintain myelin on axons of CNS

Question 41

Function of microglial cells

Answer 41

Function as phagocytes: clear debris in CNS, protect nervous systme from viruses, m/os & tumour formation.

Question 42

What happens when microglial cells are activated

Answer 42

* When activated by pathogens, they secrete interferon gamma which causes other microglia to be activated. * Release signalling molecules to recruit T lymphocytes

Question 43

Function of ependymal cells

Answer 43

Facilitates movement of CSF

Question 44

What kind of epithelial cells are ependymal cells

Answer 44

Low columnar epithelial cells

Question 45

Where are ependymal cells found

Answer 45

Lining the ventricles of the brain & central canal of the spinal cord

Question 46

Function of schwann cells

Answer 46

Form both myelinated & unmyelinated coverings over axons in PNS

Question 47

what are peripheral nerves

Answer 47

Bundles of nerve fibres (fascicles) Located outside the CNS

Question 48

What are the 3 layers of peripheral nerves

Answer 48

1. Epineurium - outermost layer 2. Perineurium 3. Endoneurium - innermost layer