Lecture 1: Cellular Components

Question 1

What are the different types of glia?

Answer 1

oligodendrocytes, microglias, astrocytes, ependymal cells and radial glias

Question 2

How are neurones classified?

Answer 2

based on morphology / structure, location, function, chemical

Question 3

What type of cells are neurones?

Answer 3

excitable cells which have specialised membrane properties

Question 4

What does the functional phenotype of a neurone describe?

Answer 4

what the cell does e.g. motor neurone which excites skeletal muscle cells for motor function

Question 5

What are different types of functional phenotype?

Answer 5

motor neurone, excitatory neurone

Question 6

How can the functional phenotype of a neurone be identified?

Answer 6

electrophysiologically (measuring and directly recording the activity) -> observing the effect of exciting the neurone

Question 7

What does the chemical phenotype of a neurone describe?

Answer 7

which neurotransmitter is produced by the neurone e.g. acetylcholine (cholinergic neurone)

Question 8

How can the chemical phenotype of a neurone be identified?

Answer 8

direct labelling (immunohistochemistry), mRNA (in situ hybridisation) and genetic markers

Question 9

What are the most important regions of a neurone?

Answer 9

dendrites, cell body / soma, axon hillock, axon and synapse

Question 10

How does information flow occur in neurones?

Answer 10

information flow is generated by graded potentials produced by the axon of a presynaptic neuron and passes through the neurone in the form of action potentials to reach the axons where this information is passed on to the dendrites of a postsynaptic neuron
dendrites -> cell body -> axon

Question 11

What is the role of the cell body of a neurone?

Answer 11

information is integrated and sent out through the axon

Question 12

What are synaptic processes?

Answer 12

communication between neurones, can be axo-dendritic and axo-somatic

Question 13

What is myelin characterised by?

Answer 13

specialised properties for electrical conduction

Question 14

Are there more neurones or glia in the nervous system?

Answer 14

there are more glia in the nervous system

Question 15

What is the role of satellite cells?

Answer 15

supports cell bodies

Question 16

What is the role of Schwann cells (PNS) and oligodendrocytes (CNS)?

Answer 16

forms myelin sheaths

Question 17

What is the role of microglia?

Answer 17

modified immune cells which act as scavengers

Question 18

What is the role of ependymal cells?

Answer 18

create barriers between compartments and are a source of neural stem cells

Question 19

What is the role of astrocytes?

Answer 19

involved in NT uptake as they have glutamate transporters
possess an array of ion transporters to clean up extracellular spaces between neurones (EC homeostasis)
regulate local micro-vasculature and blood flow
important for the BBB

Question 20

Why do astrocytes depolarise after neurones?

Answer 20

levels of extracellular potassium increases dramatically following the depolarisation of neurones and is taken up by astrocytes which become activated

Question 21

Why don’t astrocytes suffer from potassium toxicity?

Answer 21

because they are connected to other astrocytes by gap junctions which allows for potassium to move down its concentration gradient into cells which do not contain as much potassium

Question 22

Why do arterioles dilate as neural activity increases?

Answer 22

activation of neurones results in increased metabolic demand, production of metabolic waste and dilation of the arterioles

Question 23

What is the role of astrocytic end-feet?

Answer 23

surround arterioles and capillaries

Question 24

What are tripartite synapses?

Answer 24

astrocytic foot processes contact both pre- and post-synaptic areas

Question 25

What are gliotransmitters?

Answer 25

chemical transmitters released by astrocytes -> not only are they passive cleaners but astrocytes actively participate in cellular communication in the brain

Question 26

What stimulates the release of gliotransmitters?

Answer 26

increased activity in adjacent neurones and astrocytes -> increased [Ca2+] in astrocyte -> release gliotransmitters (e.g. glutamate, ATP)

Question 27

What are characteristics of a neural circuit?

Answer 27

essential for complex functions, output varies depending on constituent components

Question 28

What is the functional phenotype of a neurone usually determined by?

Answer 28

the NT released -> effect on post-synaptic receptor (however exact effect of NT can depend on the post-synaptic receptor esp. GPCRs)

Question 29

What is a convergent circuit?

Answer 29

when multiple neurones send axons to a single neurone

Question 30

What is a divergent circuit?

Answer 30

when a neurone sends axons to multiple neurones

Question 31

What are different types of circuits?

Answer 31

convergent, divergent, feedback, lateral excitation, feedforward inhibition, feedback inhibition and disinhibition