PRACTICAL 1 NERVOUS SYSTEM Flashcards
- List and describe the structure and function of the components of the grey matter. (4 marks)
- 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
- List and describe the structure and function of the components of the white matter. (2 marks)
- containing myelinated axons. this structure connects the brain cells and is distributed in tracts or bundles.
FUNCTION of Schwann cells
Schwann cells – protect, nourish, regulate (the extracellular fluid concentration) and insulate the nerve fiber
the function of nerve fibre
Nerve fibres enable neurons to connect with one another. They help to send signals to and from the brain
axon
electrical conductor
- ## List and describe the structures that make up a peripheral nerve.
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
- Where in the body are peripheral nerves found?
-
¬Everywhere besides the brain and spinal cord
a = axon –
electrical conductor
endoneurial sheath
protects the axon
Schwann cell (this should be oligodendrocyte because it is a spine CNS nerve)
it is a glial cell that produces the myelin sheath
function of nucleus of Schwann cell
the command center of the cell, where DNA replication occurs
the node of Ranvier
space between two consecutive myelin sheaths that increases the speed of conduction of a neuron through saltatory conduction
If a person was having difficulty generating words, which area of the brain would you expect to be damaged?
Broca lobe within the frontal left lobe, which is responsible for generation of speech
A patient has been in a car accident and has damaged their occipital lobe. What would you expect the patient to have difficulty doing?
Sight( seeing words)
- If a person has difficulty hearing words, what TWO alternative explanations could be given for this patient’s condition?
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
- Afferent neuron
The incoming neuron. This is the sensory neuron and transmits the stimuli from the sensory organs to the CNS
- List and describe the structures that make up a peripheral nerve.
- 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
- Where in the body are peripheral nerves found?
-
¬Everywhere besides the brain and spina cord
- ## 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.
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
- 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.
- 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
- What is the advantage of the spinal reflex? (2 marks)
- 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
- Why do doctors test for the knee-jerk reflex? (2 marks)
- It enables them to check if there are any impairment with the spinal reflexes, thus providing them with a quick and inexpensive technique
How are chemical stimuli transduced into electrical impulses and where else in the body are chemical stimuli converted into electrical impulses?
- 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+)
- If a person was having difficulty generating words, which area of the brain would you expect to be damaged?
- Broca lobe within the frontal left lobe, which is responsible for generation of speech
