Neurology

Question 1

What are the supporting cells of the nervous system?

What are the 4 main functions of glial cells?

Answer 1

THE GLIA

to surround neurons and give the cells some structure to supply nutrients and oxygen to neurons,
to insulate one neuron from another,
to clear up dead neurons, remove the debris.

Question 2

Macroglia are

Answer 2

Gives the brain structure by supporting, seperating and sometimes insulating neurons, neuronal groups and synaptic connections.

During the development of teh brain ‘radial glia’ direct migrating cells and direct the direction of the outgrowths of the axons.

They insulate and nourish the brain.

C) Provide support and insulation to axons in both the central and peripheral nervous system of vertebrates. OLIGODENDROCYTES are found in the central nervous system (CNS), and SCHWANN CELLS are in the peripheral nervous system (PNS). Oligodendrocytes do this by creating the myelin sheath, which is 80% lipid and 20% protein.

They make the speed of neuronal firing quicker than the unmyelinated axons, due to the insulated regions with gaps in between, so the action potential and nerve message can bounce from gap to gap rather than wait to travel the length of the axon with the chemical and electrical gradients.

Question 3

Which is the most numerous of glial cell and what is their form and function?

Answer 3

Most numerous of glial cells. The star like projections do form part of the cytoskeleton, giving more rigidity, form and structure to the cytoplasm.

Nutrients:
Astrocytes are also responsible for local metabolic support of neurons. With this contact on the blood vessels, they take up glucose from the blood, convert it to lactate, release it and thus provide an energy substrate to neurons. Astrocytes are the only cells in the brain which can synthesize glycogen and thus can serve as an energy reservoir.

Question 4

What are the thing a nerve needs to survive and thrive?

Answer 4

1. Oxygen
2. Nutrients
3. Frequency of Firing-promotes an increase in mRNA expression for synthesis of proteins.

Question 5

What is the frequency of firing of neuron dependant on?

Answer 5

HE FREQUENCY OF FIRING OF A NEURON IS DEPENDENT ON THE FREQUENCY OF FIRING OF ITS PRE-SYNAPTIC NEURONS AND/OR RECEPTORS (PRE-SYNAPTIC POOL).

Question 6

How does the cell membrane of a neuron maintains its negative charge?

Answer 6

By movement of Na+ out of the cell and K+ back into it. This sodium potassium pump keeps the concentration of Na+ 10x higher on the outside and the concentration of K+ about 20x higher on the inside.

Question 7

Synapses: 2 types what are they and how do they work?

Answer 7

1. Electric Synapses: much more rapid transfer of signal from one cell to the next.
2. Chemical: The majority of synapses are actually chemical in the NS. It activates voltage gated calcium channels. Ie by neurotransmitter.

Question 8

What is Summation?

What are the 2 types of Summatio?

Answer 8

Summation is reaching the threshold.

Excitation of many terminals at the same time is needed to summate and depolarize a neural membrane. (summation).

1. Temporal Summation:
   This is where one presynamptic neurons sens multiple nerve impulses to one post sunaptic terminal. These nerve impulses are one directional, but fast and frequent. The membrane potential is raised incrementally, instead of all at once
2. Spatial Summation:
   This is where there are lots of presynaptic neurons, all synapsing on one post synaptic neuron, so the membrane potential is raised all at once, instead of incrementally.

Question 9

Speed of Action Potentials.

What is the classification of MSC
GTO
Joint mechanoreceptors

Answer 9

Classification systems is that the small the number or letter, the bigger, better, and most importantly FASTER, the neuron fires.

Musles Spindle cells: 1A -proprioception
GTO: IB Proprioception
Mechanoreceptors: II -proprio

NOCICEPTORS (small diameter)
C Afferent- Pain and temp
A -

Question 10

What is Plasticity?

Answer 10

Greatly increases the efficiency of. neural pathway.

In a number of ways:
1. Chemically- amount of neurotransmitter etce tc

2. Structural
3. Function/ Cortical Plasticity.: Activity dependant alteration of the size and connectibity of specific areas in the brain (Cortex)
   Cortical Plasticity describes changes that can occur all over the brain, not just in the cortex.

Plasticity can increase or decrease rapidly.