Intro To Neurophysiology

Question 1

Outline the differences between neurons and glial cells.

Answer 1

Neurons:
- CNS contains more than 100 billion neurons
- have a basic structure
- mostly myelinated
- generate electrical potentials

Glial cells:
- 2-10 times more glia than neurons
- no dendrites or axons
- arise from same precursor cells but have functional differences
- not electrically excitable and do not take part in electrical signalling

Question 2

What are the basic components that make up a neuron?

Answer 2

Dendrites, cell body, axon, telodendria, synaptic terminals

Question 3

List the characteristics of neurons

Answer 3

• have high metabolic rate
• require continuous and abundant supply of glucose and oxygen
• have extreme longevity
• most neurons formed during foetal development remain functional even in old age
• typically non mitotic (mitotic activity lost during foetal development)

Question 4

What are the three structural classifications of neurons?

Answer 4

1. Unipolar
   - single primary process
   - pseudounipolar neurons carry somatosensory information
2. Bipolar
   - two distinct processes
   - eg. In the retina and olfactory
3. Multipolar
   - single axon but multiple dendrites
   - most predominant type in vertebrates

Question 5

What are the different types of glial cells found in the CNS?

Answer 5

Astrocytes, ependymal cells, microglia and oligodendrocytes

Question 6

What is the function of astrocytes in the CNS?

Answer 6

• star like cells that is in contact with neurons and capillaries
• help form the BBB
• regulate tissue fluid composition
• provide structural support
• replace damaged neurons
• regulate neural development

Question 7

What is the function of ependymal cells in the CNS?

Answer 7

• simple cuboidal epithelial cells which line the cavities in the brain and spinal cord, have cilia on their apical surfaces
• line ventricles of brain and central canal of spinal cord
• assist in conduction and circulation of CSF

Question 8

What is the function of microglia in the CNS?

Answer 8

• small cells (least common)
• mediate immune functions
• clear cellular debris
• clear dead neurons
• influence synaptic transmission and synpatogenesis

Question 9

What is the function of oligodendrocytes in the CNS?

Answer 9

• rounded cells with slender cytoplasmic extensions which wrap around CNS axons
• serve to myelinate and insulate axons which allow faster nerve impulse conduction

Question 10

Outline the functions of the glial cells found in the PNS

Answer 10

Satellite cells
- flattened cells cluster around neuronal cell bodies in a ganglion
- protect and regulate nutrients for cell bodies in ganglia

Schwann cells (nuerolemmocytes)
- myelinate axons in the peripheral NS
- one Schwann cell = one segment of myelin sheath of an axon
- gaps between myelin sheaths = nodes of Ranvier

Question 11

List the different lobes of the brain.

Answer 11

Frontal, parietal, temporal, occipital and insula

Question 12

What is the structure which separates the brain into a left and right hemisphere called?

Answer 12

Longitudinal fissure

Question 13

What is the structure which separates the frontal lobe from the parietal lobe called?

Answer 13

Central sulcus

Question 14

What structures does the lateral sulcus separate?

Answer 14

Frontal and parietal lobe from the temporal lobe

Question 15

Describe the term hemispheric laterization.

Answer 15

It refers to a functional dominance of one hemisphere over the other, to which one is more responsible or entirely responsible for control of a function in comparison to the other

Question 16

Describe what is meant by the term “homonculus”.

Answer 16

It is a map along the cerebral cortex of where each part of the body is processed. The sizing is according to the amount of cortical area dedicated to the processing sensory or motor information related to those body parts

Question 17

List 3 hypothalamic nuclei and the functions each is involved in.

Answer 17

Mammillary body - processes sensations related to smelling
Paraventricular nucleus & supraoptic nucleus - produce oxytocin and ADH

Question 18

What are the 3 cranial meninges? Describe how these interact with one another.

Answer 18

1. Pia mater - innermost of the cranial meninges, thin layer of delicate areolar connective tissue which tightly adheres to the brain (follows every contour on the surface), highly vascularised
2. Arachnoid mater - composed of a delicate web of collagen and elastic fibres called the arachnoid trabeculae (where CSF flows)
3. Dura mater - an external tough dense and irregular connective tissue layer composed of 2 fibrous layers (meningeal layer - deep; periosteal layer - superficial)

Question 19

Where is CSF produced?

Answer 19

Brain ventricles

Question 20

What is one of the consequences of CSF not being tightly regulated?

Answer 20

Infant with hydrocephalus
- increased CSF resulting in the swelling of the cranial area