Cells Of NS

Question 1

What is the hierarchical structure of the brain?

Answer 1

Molecules, Cells, Circuits - Systems, Behaviour, Cognition

Question 2

Who proposed the reticular theory?

Answer 2

Camillo Golgi

Question 3

What did Golgi believe about neurites?

Answer 3

That they were fused together to form a network (this is wrong)

Question 4

What is the neuron doctrine?

Answer 4

Each neuron is a discrete cell

Question 5

What are the two principles of the neuron doctrine?

Answer 5

• Principle of dynamic polarisation (to transmit information in one direction)
• Principle of connectional specificity

Question 6

What advancement confirmed the existence of synapses?

Answer 6

Development of the electron microscope

Question 7

What is a disadvantage of using an electron microscope?

Answer 7

Cells are fixed, i.e., dead

Question 8

What technique uses tagged antibodies to visualize proteins in tissue?

Answer 8

Immunofluorescence labelling methods

Question 9

What is the resolution of an electron microscope?

Answer 9

0.1 nm

Question 10

What is the primary role of glia in the nervous system?

Answer 10

To support neurons

May mediate some signalling in the brain

Question 11

How do glia outnumber neurons in the thalamus?

Answer 11

17:1

Question 12

What are astrocytes and their role?

Answer 12

Majority of glia
Star-shaped glial cells that regulate the composition of extracellular fluid & fill space between neurons
Play an important role in directing proliferation & differentiation of neural stem cells

Question 13

What is the function of oligodendrocytes?

Answer 13

Myelinate axons in the CNS

Question 14

What do Schwann cells do?

Answer 14

Myelinate a single axon in the PNS

Question 15

What do ependymal cells produce?

Answer 15

Cerebrospinal fluid (CSF)

Question 16

What is the function of microglia?

Answer 16

Act as immune scavengers in the brain = can migrate & have phagocytes/immune function

Question 17

What is a unique feature of neuronal cells?

Answer 17

They cannot divide

Question 18

What are the two types of processes in a neuron?

Answer 18

• Dendrites
• Axons

Question 19

What is the primary function of dendrites?

Answer 19

Specialized for receipt of information

Question 20

What is the primary function of axons?

Answer 20

Specialized for transmission of information

Question 21

What are the main cytosolic organelles found in neurons?

Answer 21

• Peroxisomes
• Mitochondria
• Ribosomes
• Endoplasmic reticulum
• Golgi complex

Question 22

What is the role of the neuronal cytoskeleton?

Answer 22

• Structural support (shape & diameter of axons and dendrites)
• Transport cargo to and from axons & dendrites
• Tethering components at membrane surface

Question 23

What are the three types of neuronal classification based on structure?

Answer 23

• Unipolar = 1 process from cell body (I.e. dorsal root ganglion neuron)
• Bipolar = 2 processes from cell body
• Multipolar = have multiple dendrites coming off cell body & branched axon

Question 24

What are the two functional classifications of neurons?

Answer 24

• Sensory (afferent) neurons - originate from sensory receptors to the ‘processor’
• Motor (efferent) neurons - conduct signals that originate in the CNS
• Interneurons - between sensory and motor neurons, found in spinal cord

Question 25

True or False: Neurons can divide.

Answer 25

False

Question 26

Fill in the blank: The _______ are the supporting cells in the nervous system.

Answer 26

glia

Question 27

Process of immunofluoresence labelling

Answer 27

1. Prepare selective antibody/drug tagged with fluorescent label 2. Add to target protein in tissue and allow to bind strongly 3. Wash off free labelled antibody/drug 4. Image distribution of fluorescence

Question 28

Disadvantage of immunofluoresence labelling

Answer 28

Limited by range of antibodies available

Question 29

Confocal microscopes

Answer 29

Involves focusing laser at different levels in a piece of tissue labelled with a fluorescent probe Can examine living cells Disadvantage; resolution of 0.1 um

Question 30

Role of ependymal cells

Answer 30

Line ventricles (where CSF is) and direct cell migration during development of the brain Produce CSF Reserve of cells for regeneration (can turn into neurons)

Question 31

Neuronal structure

Answer 31

Can be in different forms but most have a cell body (soma/perikaryon) and 2 types of processes (neurites) - Dendrites = specialised for receipt of information - Axons = specialised for transmission of information

Question 32

Structures common in almost all cells

Answer 32

- Cell body with Cytosol and organelles including the nucleus - Cell membrane (plasmalemma)

Question 33

Structures unique to neuronal cells

Answer 33

Cannot divide Can trigger action potentials (excitable cells)

Question 34

Features of Axons (5 marks)

Answer 34

- Propagate information - Have synaptic vesicles as the only organelle - Long and untapered, branch at 90 degree angle - Have terminals - Often myelinate

Question 35

Features of dendrites (5 marks)

Answer 35

- Receive information - Organelles including the rough ER, ribosomes and Golgi - Short, tapered and branched - Have dendritic spines - Never myelinate

Question 36

Cytosolic organelles

Answer 36

- Peroxisomes & mitochondria - Ribosomes - Vacuolar apparatus (secretory pathway/endocytic pathway) 1. ER 2. Secretory vesicles 3. Golgi complex 4. Endosomes 5. Lysosomes - Division at axon hillock 1. Synaptic vesicles 2. Mitochondria 3. Smooth ER

Question 37

Axons vs Dendrites in membrane & cytoplasm

Answer 37

Dendrites = Ca2+ channels, Ligand-gated ion channels (glutamate receptors) and G-Protein coupled receptors Axons = G-Protein coupled receptors (terminals), Ca2+ channels (terminals) and Na+ & K+ channels (axon shafts)

Question 38

Microtubules in the neuronal cytoskeleton

Answer 38

- Role = structure & transport - Run longitudinally down axons & dendrites - Big, 20 nm wide, tubulin polymers - Change shape due to polymerisation/depolymerisation - Microtubule associated proteins e.g. MAP-2 —> involved in immunofluorescent imaging Tau, Kinesin & Dynein —> motor proteins that help move cargo enclosed in vesicles down Microtubules towards axon terminal and from terminal to cell body

Question 39

Neurofilaments in neuronal cytoskeleton

Answer 39

- Role = mechanical strength - 10 nm wide filamentous protein threads

Question 40

Microfilaments in neuronal cytoskeleton

Answer 40

- Smallest element - Role = mediate shape change - Made of actin polymers - 5 nm wide actin polymers - Tethered to membrane