PRACTICAL 1 NERVOUS SYSTEM

Question 1

1. List and describe the structure and function of the components of the grey matter. (4 marks)

Answer 1

-	containing the 
neuron cell 
bodies(soma),
 glial cells
, axon tracts,
 neuropil (glia, dendrites, and unmyelinated axons),
  blood vessels.

Its function is to interpret the sensory information, as well as the motor information receipt system

Question 2

2. List and describe the structure and function of the components of the white matter. (2 marks)

Answer 2

• containing myelinated axons. this structure connects the brain cells and is distributed in tracts or bundles.

Question 3

FUNCTION of Schwann cells

Answer 3

Schwann cells – protect, nourish, regulate (the extracellular fluid concentration) and insulate the nerve fiber

Question 4

the function of nerve fibre

Answer 4

Nerve fibres enable neurons to connect with one another. They help to send signals to and from the brain

Question 5

axon

Answer 5

electrical conductor

Question 6

3. ## List and describe the structures that make up a peripheral nerve.

Answer 6

Schwann cell which is responsible for the production of myelin sheath
- Astrocytes which acts as a blood barrier, preventing the nerve from entering the nerve

Question 7

4. Where in the body are peripheral nerves found?

-

Answer 7

¬Everywhere besides the brain and spinal cord

Question 8

a = axon –

Answer 8

electrical conductor

Question 9

endoneurial sheath

Answer 9

protects the axon

Question 10

Schwann cell (this should be oligodendrocyte because it is a spine CNS nerve)

Answer 10

it is a glial cell that produces the myelin sheath

Question 11

function of nucleus of Schwann cell

Answer 11

the command center of the cell, where DNA replication occurs

Question 12

the node of Ranvier

Answer 12

space between two consecutive myelin sheaths that increases the speed of conduction of a neuron through saltatory conduction

Question 13

If a person was having difficulty generating words, which area of the brain would you expect to be damaged?

Answer 13

Broca lobe within the frontal left lobe, which is responsible for generation of speech

Question 14

A patient has been in a car accident and has damaged their occipital lobe. What would you expect the patient to have difficulty doing?

Answer 14

Sight( seeing words)

Question 15

1. If a person has difficulty hearing words, what TWO alternative explanations could be given for this patient’s condition?

Answer 15

The midbrain could be impaired or there might be a problem with his ear, particularly the cochlea. But other factors could play a part such a build up of pressure in the ear because the eustachian tube is blocked or the tympanic membrane could be raptured or the ossicles might have fused together and no longer vibrate

Question 16

1. Afferent neuron

Answer 16

The incoming neuron. This is the sensory neuron and transmits the stimuli from the sensory organs to the CNS

Question 17

3. List and describe the structures that make up a peripheral nerve.

Answer 17

• Schwann cell which is responsible for the production of myelin sheath
• Astrocytes which acts as a blood barrier, preventing the nerve from entering the nerve

Question 18

4. Where in the body are peripheral nerves found?

-

Answer 18

¬Everywhere besides the brain and spina cord

Question 19

1. ## Write a short paragraph on the structure and function of the myelin sheath. Include in your paragraph the formation of the myelin sheath and how myelination affects the speed of transmission of neural impulses.

Answer 19

Myelin sheath is a fatty layer that is produces by either the Oligodendrocyte in the CNS or the Schwann cell in the PNS. It being a fatty layer makes it a good insulator and a poor electrical conductor. This ensures that the myelin sheath can adequately insulate the axon. Its role is to protect, insulate and speed up the electrical conduction, regulate the extra cellular fluid

Question 20

1. Multiple sclerosis (MS) is a chronic disease that affects neurons of the brain and spinal cord. MS causes a variety of symptoms, such as changes in sensation in the face and limbs, complete or partial loss of vision (optic neuritis), muscle weakness, unsteadiness when walking, speech difficulties, cognitive impairments and emotional instability. In point form, describe the pathophysiology of MS.

Answer 20

• MS is a condition in which the body’s immune system attacks oligodendrocytes.
• This causes an inflammation of the neuron and leads to degenerated myelin sheath
• The myelin sheath without the oligodendrocytes die and are no longer reproduced
• This causes an exposure of the axons
• The axons are no longer insulated and the conduction of the electrical stimuli either becomes very slow or ceases to exist
• Because it affects the CNS, the conduction to and from the brain and/or spin is thus impaired which explains the numerous symptoms

Question 21

1. What is the advantage of the spinal reflex? (2 marks)

Answer 21

• The signal doesn’t have to travel to the brain to be interpreted, thus saving a lot of conduction time and enabling quick responses to prevent damage to receptors.

This allows for faster reflex actions to occur by activating spinal motor neurons without the delay of routing signals through the brain

Question 22

2. Why do doctors test for the knee-jerk reflex? (2 marks)

Answer 22

• It enables them to check if there are any impairment with the spinal reflexes, thus providing them with a quick and inexpensive technique

Question 23

How are chemical stimuli transduced into electrical impulses and where else in the body are chemical stimuli converted into electrical impulses?

Answer 23

• chemical stimuli is also converted into electrical impulse in the olfactory cell located within the nose
• a flavour enhancer called monosodium glutamate, which occurs naturally in the foods.
• receptors known as the gustation are responsible for converting the chemical stimuli into an electrical impulse which will be perceived in the brain as taste
• there are five different types of receptor cells; Umami (delicious foods), bitter (toxic chemicals), sour (H+), sweet (sugar) and salty (NA+)

Question 24

1. If a person was having difficulty generating words, which area of the brain would you expect to be damaged?

Answer 24

• Broca lobe within the frontal left lobe, which is responsible for generation of speech

Question 25

2. If someone had damage to the area of the brain associated with speaking words, what is the likelihood that the patient would also be suffering from partial facial paralysis?

Answer 25

- Less likely. Speaking of words is associated with the midbrain whilst voluntary control of muscles is associated with the hindbrain, the cerebellum.

Question 26

2. Axon

Answer 26

The electrical conductor of the nervous system

Question 27

3. Axon (nerve) terminal

Answer 27

The end of an axon, composed with dendrites that extends to either postsynaptic neurons or the effector

Question 28

4. Axon hillock

Answer 28

V-shaped structure of the axon where the summation of the graded potential occurs. This serves as the site for which the action potential is generated if the stimuli is equal/exceed the threshold value

Question 29

5. Cell body

Answer 29

The soma of the neuron, where the nucleoplasm and cytoplasm together with their components are suspends

Question 30

6. Central canal (spinal canal)

Answer 30

Hallow opening within the center of the vertebral column which the spinal cords runs through. It serves to protect the spinal cord

Question 31

7. Dendrites

Answer 31

The cytoplasmic extensions of the soma which receives stimuli from the presynaptic neuron. They have a lot of receptor proteins that enables them to receive and convert the chemical stimuli (neurotransmitter) into an electrical stimuli

Question 32

8. Dorsal

Answer 32

The posterior side

Question 33

9. Dorsal (posterior) horn

Answer 33

The posterior extension of the grey matter of the spinal column

Question 34

10. Dorsal fissure

Answer 34

The posterior groove of the vertebral column

Question 35

11. Dorsal root

Answer 35

The incoming root. It transmits the stimuli to the interneuron

Question 36

12. Effector

Answer 36

A gland or muscle that carries out the command of the neural signal

Question 37

13. Efferent neuron

Answer 37

The outgoing neuron. The motor neuron which carries the stimuli to the effector muscle/gland

Question 38

14. Endoneurial sheath | endoneurium

Answer 38

Sheath that is within the inside of the neuron and serves to protect/surround the fibre

Question 39

15. Epineurial sheath (epineurium)

Answer 39

The upper most sheath that serves to protect the fascicle

Question 40

16. Epithelial cells

Answer 40

The upper most cells that line the outer part of an organ

Question 41

17. Grey matter

Answer 41

The site where there is very little to no myelin sheath and a lot of cell bodies

Question 42

18. Interneuron

Answer 42

The interneuron that play a role in the reflex arch in that it connects and allows communication between the afferent neuron and the efferent neuron. It give command to the efferent neuron.

Question 43

19. Muscle

Answer 43

Band of fibrous tissue that can contract and relax either voluntary or involuntary to bring about movement of the body and support the body

Question 44

20. Nerve (neuron)

Answer 44

Neuron is the basic structure of the nerve. The nerve is composed of numerous neurons that allows it to conduct electrical impulses and allows all components of the body to communicate with the command center, CNS.

Question 45

21. Neurilemmal / Schwann cells

Answer 45

Glial cells in the PNS that are responsible for producing the myelin sheath

Question 46

22. Neuroglia / glial cells

Answer 46

Supporting cells of the nervous system. They regulate the extracellular components, protect (microglia), nourish and insulate the nerve

Question 47

23. Neuromuscular junction

Answer 47

The junction/gap between the muscle and neuron which allows for coordinated communication between the two

Question 48

24. Node of Ranvier

Answer 48

A space of no myelin sheath between two consecutive myelin sheaths, which increases the speed pf conduction through saltatory conduction

Question 49

25. Nucleolus

Answer 49

Site of DNA production and the actual command center of the cells, located within the nucleus

Question 50

26. Nucleus

Answer 50

A circular structure which carries the nucleolus and the nucleoplasm. It is surrounded by the nuclear pore

Question 51

27. Receptor

Answer 51

Any cell that receives stimuli and converts it into an electrical impulse to be transmitted to the brain where it will be interpreted

Question 52

28. Sensory neurons

Answer 52

The afferent neuron where sensation is felt. Receptors are located here and send the electrical stimuli throght the sensory neurons

Question 53

29. Spinal cord

Answer 53

An extension of the brain stem that runs through the central canal of the vertebral column. It is part of the CNS and carries out the quick reflexex/ reflex arch

Question 54

30. Taste bud

Answer 54

The circular structure which houses the gustation receptor cells

Question 55

31. Taste pore

Answer 55

The opening of the taste buds

Question 56

32. Transduction

Answer 56

The conduction of the stimuli

Question 57

33. Ventral

Answer 57

The anterior side

Question 58

34. Ventral (anterior) root

Answer 58

Side going out of the interneuron to the effector muscle/gland. This is usually the motor neuron

Question 59

35. Ventral fissure

Answer 59

The anterior groove of the spine

Question 60

36. Ventral horn

Answer 60

The anterior side of the grey matter of the spinal cord

Question 61

37. White matter

Answer 61

The component of the cns which has lots of myelin sheaths which make it appear white