Neurones and Neuroglia

Question 1

What are the features of neurones?

Answer 1

Dendrites
Cell body/ perikaryon/ soma
Axon
Synapse

Question 2

What are dendrites?

Answer 2

Short processes arising from the cell body
May contain dendritic spines
Site of synaptic contacts

Question 3

What happens at the cell body?

Answer 3

Houses the nucleus
Site of protein, hormone and neurotransmitter production
Gives rise to a single axon

Question 4

What is an axon?

Answer 4

Long cylindrical and slender process, with an axon hillock and initial segment
Axolemma (plasma membrane)
Axoplasm (cytoplasm)
Can be myelinated or unmyelinated

Question 5

What are the features of a neuronal synapse?

Answer 5

Presynaptic terminal
Synaptic cleft
Post synaptic terminal

Question 6

What controls the ion permeability of cells?

Answer 6

Gated ion channels
Alternate between open and closed to allow/ prevent movement

Question 7

What types of gated ion channels are there?

Answer 7

Mechanically gated
Chemically gated
Voltage gated

Question 8

What types of electrical signals are there?

Answer 8

Graded potentials (short distance)
Action potentials (rapid over long distances)

Question 9

What are the features of graded potentials?

Answer 9

They can vary in strength
Lose strength over distance
Slower than APs
Can be excitatory
Can be inhibitory

Question 10

What ways can you describe a graded potential?

Answer 10

Subthreshold - too weak (No AP)
Suprathreshold - generates AP

Question 11

What types of neurones are there?

Answer 11

Pseudounipolar
Bipolar
Multipolar
Anaxonic

Question 12

Describe pseudounipolar neurons

Answer 12

A single process arises from the cell body and divides into two branches, one travels to the PNS and the other to the CNS.
Information at the PNS terminal is transmitted to the CNS (bypasses the cell body)
Signals are relayed from the receptor to the CNS without modification

Question 13

Describe bipolar neurons

Answer 13

They have two processes which arise from the elongated cell body
One process ends in dendrites
The other forms an axon
They integrate multiple inputs
The modified, processed information passes onto the next neuron in the chain

Question 14

Describe multipolar neurons

Answer 14

The possess three or more dendrites which branch off directly from the cell body
They also have a single long axon issuing from the axon hillock

Question 15

Describe what anaxonic neurons are

Answer 15

They are a form of interneuron in the CNS
They only have dendrites
No axon can be determined

Question 16

Describe the movement of anterograde transport

Answer 16

Towards the synapse / nerve terminal

Question 17

Describe the movement of retrograde transport

Answer 17

Towards the cell body

Question 18

What types of neurogoial cells are found within the CNS?

Answer 18

Astrocytes
Oligodendrocytes
Microglia
Polydendrocytes
Ependymal cell

Question 19

Which neuroglial cells are found in the PNS?

Answer 19

Satellite cells
Schwann cells

Question 20

Describe the appearance of astrocytes

Answer 20

They’re the largest glial cell
With stellate appearance and centrally located nuclei

Question 21

What types of astrocytes are found where?

Answer 21

Fibrous - white matter
Protoplasmic- gray matter
Muller cells - the retina

Question 22

What are the functions of astrocytes and how do they do these?

Answer 22

They shuttle excess ions
Pick up metabolites and glucose from vasculature and carry to neurons
Have a major role in the tripartite synapse
Dues to their processes making contact with thousands of neurons
And forming ‘feet’ on blood vessels

Question 23

What happens at tripartite synapses?

Answer 23

Glutamate released from presynaptic membranes activates metabotropic receptors
Calcium is released from astrocytes
Releases of gliotransmitters
Which modulates neuronal function
And can regulate local circulation of the brain

Question 24

Describe oligodendrocytes

Answer 24

Smaller than astrocytes and with fewer processes
myelinating cells within the CNS
Can myelinated multiple axons

Question 25

Describe microglia

Answer 25

Smallest of all glial cells
Derived from monocyte-macrophage lineage
Immune cells of CNS
Activated by inflammatory markers
Phagocytic function

Question 26

Describe polydendrocytes

Answer 26

Recently defined
Stem cell pool
Recruited as oligodendrocyte precursors in remyelination
Can provide link between neuronal signalling network and glial cells

Question 27

Describe ependymal cells and their different types

Answer 27

Epithelial cells (EP) that separate CSF from tissue
Ependymocytes - line ventricle and central canal, posses microvilli and cilia
Tanycytes- found in 3rd ventricle, transport hormone from CSF to capillaries
Choroidal EP - choroid plexus, produce and secrete CSF

Question 28

Describe satellite cells and where there found

Answer 28

Similar to Schwann cells
Found in sensory, sympathetic and parasympathetic ganglia

Question 29

Describe Schwann cells and where they’re found

Answer 29

They are myelinating cells of the PNS
One Schwann cell per axon
Found at neuromuscular junction and can take up excessive neurotransmitter

Question 30

Why is white matter white?

Answer 30

It is the myelinated processes of axons

Question 31

What is found in the gray matter of the brain?

Answer 31

Nerve cell bodies
Dendrites
Axon terminals
Bundles of unmyelinated axons
Neuroglia

Question 32

What are the resting membrane potentials of:
Neurons
Smooth muscle
Cardiac muscle

Answer 32

Neuron = -70mV
Smooth muscle = -40mV
Cardiac muscle =-90mV

Question 33

What maintains the difference between electrical charges on the inside compared to the outside of the cell?

Answer 33

Na+/K+ ATPase pump
3 Na+ pushed out, 2K+ taken in