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
- 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?
- Less likely. Speaking of words is associated with the midbrain whilst voluntary control of muscles is associated with the hindbrain, the cerebellum.
- Axon
The electrical conductor of the nervous system
- Axon (nerve) terminal
The end of an axon, composed with dendrites that extends to either postsynaptic neurons or the effector
- Axon hillock
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
- Cell body
The soma of the neuron, where the nucleoplasm and cytoplasm together with their components are suspends
- Central canal (spinal canal)
Hallow opening within the center of the vertebral column which the spinal cords runs through. It serves to protect the spinal cord
- Dendrites
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
- Dorsal
The posterior side
- Dorsal (posterior) horn
The posterior extension of the grey matter of the spinal column
- Dorsal fissure
The posterior groove of the vertebral column
- Dorsal root
The incoming root. It transmits the stimuli to the interneuron
- Effector
A gland or muscle that carries out the command of the neural signal
- Efferent neuron
The outgoing neuron. The motor neuron which carries the stimuli to the effector muscle/gland
- Endoneurial sheath
endoneurium
Sheath that is within the inside of the neuron and serves to protect/surround the fibre
- Epineurial sheath (epineurium)
The upper most sheath that serves to protect the fascicle
- Epithelial cells
The upper most cells that line the outer part of an organ
- Grey matter
The site where there is very little to no myelin sheath and a lot of cell bodies
- Interneuron
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.
- Muscle
Band of fibrous tissue that can contract and relax either voluntary or involuntary to bring about movement of the body and support the body
- Nerve (neuron)
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.
- Neurilemmal / Schwann cells
Glial cells in the PNS that are responsible for producing the myelin sheath
- Neuroglia / glial cells
Supporting cells of the nervous system. They regulate the extracellular components, protect (microglia), nourish and insulate the nerve
- Neuromuscular junction
The junction/gap between the muscle and neuron which allows for coordinated communication between the two
- Node of Ranvier
A space of no myelin sheath between two consecutive myelin sheaths, which increases the speed pf conduction through saltatory conduction
- Nucleolus
Site of DNA production and the actual command center of the cells, located within the nucleus
- Nucleus
A circular structure which carries the nucleolus and the nucleoplasm. It is surrounded by the nuclear pore
- Receptor
Any cell that receives stimuli and converts it into an electrical impulse to be transmitted to the brain where it will be interpreted
- Sensory neurons
The afferent neuron where sensation is felt. Receptors are located here and send the electrical stimuli throght the sensory neurons
- Spinal cord
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
- Taste bud
The circular structure which houses the gustation receptor cells
- Taste pore
The opening of the taste buds
- Transduction
The conduction of the stimuli
- Ventral
The anterior side
- Ventral (anterior) root
Side going out of the interneuron to the effector muscle/gland. This is usually the motor neuron
- Ventral fissure
The anterior groove of the spine
- Ventral horn
The anterior side of the grey matter of the spinal cord
- White matter
The component of the cns which has lots of myelin sheaths which make it appear white
