Nervous Tissue

Question 1

What is the CNS composed of

Answer 1

spinal cord and brain

Question 2

What is the PNS composed of?

Answer 2

cranial nerves and spinal nerves

Question 3

What is the function of nervous tissues

Answer 3

carrying information through electrical impluses throughout the body

Question 4

What does the somatic nervous system regulate?

Answer 4

Somatic nervous system regulates control over skeletal muscle

Question 5

What does the autonomic nervous system regulate?

Answer 5

Autonomic nervous system regulates control over heartrate, breathing, things that are automatic

Question 6

What are the divisions of the ANS and what do they regulate?

Answer 6

The sympathetic division of the ANS is the branch that responds when the body needs sudden or immediate action. Fight or flight response. Increase rate of function in times of need

The parasympathetic division of the ANS regulates less urgent actions. Such as digestion, waste disposal, production of bodily fluids. Regulates basal rate

Question 7

What are the cells of nervous tissue?

Answer 7

neurones, glial

Question 8

What is the role of neurones?

Answer 8

to send signals around the body

Question 9

What are glial cells and what is their role?

Answer 9

support cells and to protect and provide nutrients to neurones

Question 10

What is the basic structure of a neurone?

Answer 10

dendrite, cell body (nucleus), axon, axon terminal (boutons)

Question 11

What is the dendrite?

Answer 11

highly branched cellular process which extends from a large cell body
they form synapses with adjacent neurones

Question 12

What is the axon?

Answer 12

conducts action potentials
rapidly sends signals to the axon terminals
in CNS - mylienated
in PNS - can be mylienated or non mylienated

Question 13

What are the terminal boutons?

Answer 13

neurotransmitter are released here
form synapses with neurones
electrical signal converts to chemical signal

Question 14

What is the fundamental property of a neurone?

Answer 14

excitability

Question 15

Describe how messages are delivered in neurons

Answer 15

Action potential travels through the neuron, reaches the terminal boutons and chemical message is released
and then received by dendrites of the next neuron and then processed to trigger an action potential in that next neurone

Question 16

Identify the neuroglial cells located only within the central nervous system

Answer 16

Ependymal cells, Astrocytes, Microglia, Oligdendrocytes

Question 17

Identify the neuroglia cells located only within the peripheral nervous system

Answer 17

Schwann cells, Satellite cells

Question 18

What are ependymal cells?

Answer 18

Simple ciliated cuboidal epithelium
Lines fluid-filled cavities in brain (ventricles) and spinal canal
No basement membrane

Question 19

What are astrocytes?

Answer 19

Most numerous cell within the CNS.
Mediate the exchange of metabolites between neurones and the vascular system
From blood-brain barrier and have a star-like structure

Question 20

What are microglia?

Answer 20

Microglia are derived from monocytes and microphages
In response to tissue damage, these cells will transform into phagocytic cells. They will remove invading microbes and dead cells from CNS

Question 21

What are oligdendrocytes?

Answer 21

Predominant neuroglia of white matter
Form myelin sheaths around all CNS axons
Provide structural and metabolic support

Question 22

What are Schwann cells?

Answer 22

Form myelin sheaths around PNS axons
Provide structural and metabolic support
Non-myelinated axons are enveloped in cytoplasm of Schwann cell
Myelinated axons are gradually wrapped by the Schwann cell membrane to create a myelin sheath

Question 23

What is an alternative name for nerve fibres?

Answer 23

axons

Question 24

What is each nerve fibre surrounded by in the PNS (around Schwann cells)?

Answer 24

endoneurium

Question 25

What is each fascicle surrounded by?

Answer 25

perineurium

Question 26

What are bundles of fascicles surrounded by?

Answer 26

epineurium

Question 27

What does the perikaryon refer to?

Answer 27

cell body of neuron

Question 28

By looking at the individual fibres at high magnification, you will notice that there are short intervals at which the axon is not covered by a myelin sheath. What is the name of these intervals?

Answer 28

nodes of ranvier

Question 29

What is the function of the nodes of Ranvier?

Answer 29

Allows nutrients and waste to enter and exit the neuron. Enhances conduction speed of axons

Question 30

Local anaesthesia is widely used in dental practice. The local anaesthetic acts by binding to an internal site on the Na+ channels and blocking them. Why are the nodes of Ranvier important in this process?

Answer 30

They allow Na+ to access the sodium channels. Na+ channels are enriched at nodes of Ranvier

Question 31

Do nerve fibres differ in calibra?

Answer 31

yes

Question 32

How can the effectiveness of local anaesthesia be affected by the presence of adipocytes?

Answer 32

The potency of an anaesthetic is associated with its lipid solubility. Greater lipid solubility enhances diffusion through nerve sheaths, as well as the neural membranes of individual axons comprising a nerve trunk.

Question 33

The local anaesthetic bupivacaine is more lipid soluble compared with lidocaine. Which of these anaesthetics is most likely to be prepared at a higher dose to achieve equivalency of action with the other?

Answer 33

lidocaine

Question 34

What organs do the motor neurones at the lumbar level predominantly innervate?

Answer 34

lower limb muscles

Question 35

What organs do the motor neurones at the cervical level predominantly innervate?

Answer 35

upper limb muscles

Question 36

In which direction does information typically travel in the ventral horns?

Answer 36

downwards

Question 37

In which direction does information typically travel in the dorsal horns?

Answer 37

upwards

Question 38

Where are Purkinje nerve cells found?

Answer 38

cerebellum