Structures and Cells

Question 1

Describe the organisation of the NS.

Answer 1

The NS can be divided into and afferent and efferent branch. The afferent division conducts sensory and visceral stimuli to the CNS. The efferent division is further divided into an autonomic and somatic division. The autonomic division is further subdivided into the sympathetic, parasympathetic and enteric divisions.

Question 2

Distribution of neurons and glial cells.

Answer 2

The CNS contains more than 100 billion neurons

2-10 times more glia than neurons

Question 3

What is the difference between neurons and glial cells?

Answer 3

Neurons generate electrical potentials

Glial cells are not electrically excitable and do not take part in electrical signalling

Question 4

What are the four compartments of a neuron?

Answer 4

Dendrite
Cell Body
Axon
Synapse

Question 5

What are the characteristics of a neuron?

Answer 5

Have a high metabolic rate
Require continuous and abundant supply of glucose and oxygen – aerobic respiration
Have extreme longevity
Most neurons that are formed during foetal development remain functional even in old age
They are typically non-mitotic
Mitotic activity is lost during foetal development

Question 6

Unipolar neuron

Answer 6

Single primary process; pseudounipolar neurons carry somatosensory information

Question 7

Bipolar neuron

Answer 7

Two distinct processes, e.g. in the retina and in the olfactory system

Question 8

Multipolar neurons

Answer 8

Single axon but multiple dendrites; most predominant type in vertebrates

Question 9

Astrocytes

Answer 9

Star like cells that is in contact with neurons and capillaries
Help form blood brain barrier (BBB)
Regulate tissue fluid composition
Provide structural support
Replace damaged neurons
Regulate neural development

Question 10

Microglia

Answer 10

Small cells, least common
Mediate immune functions
Clear cellular debris
Clear dead neurons
Influence synaptic transmission and synaptogenesis

Question 11

Ependymal Cells

Answer 11

Simple cuboidal epithelial cells, these 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 cerebrospinal fluid (CSF)

Question 12

Oligodendrocytes

Answer 12

Rounded cells with slender cytoplasmic extensions which wrap around CNS axons
Serve to myelinate and insulate CNS axons which allow faster nerve impulse conduction

Question 13

Satellite Cells

Answer 13

Flattened cells clustered around neuronal cell bodies in a ganglion
Protect and regulate nutrients for cell bodies in ganglia

Question 14

Schwann Cells (Neurolemmocytes)

Answer 14

Myelinate axons in the peripheral nervous system
One Schwann cell = one segment of myelin sheath on an axon
Gaps between myelin sheaths = nodes of Ranvier

Question 15

What is the advantage of having gyri and sulci?

Answer 15

Surface area

Question 16

Explain hemispheric lateralisation.

Answer 16

Lateralisation is the idea that the two halves of the brain are functionally different and that each hemisphere has functional specialisations, e.g. the left is dominant for language, and the right excels at visual motor tasks

Question 17

What are association areas?

Answer 17

Association areas integrate incoming information and coordinate motor response
Associative areas of the cortex integrate current states with past states to predict proper responses based on sets of stimuli

Question 18

White matter vs Grey matter

Answer 18

Grey matter is distinguished from white matter in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively few cell bodies and is composed chiefly of long-range myelinated axons
Cells in the grey matter are composed of chromatophilic substances

Question 19

What comprises the diencephalon?

Answer 19

The caudal (posterior) part of the forebrain, containing the epithalamus, thalamus, hypothalamus, and ventral thalamus and the third ventricle

Question 20

What are the functions of CSF

Answer 20

Protection
Buoyancy
Excretion of waste products