Fundamentals of Neuroscience

Question 1

What are the two broad classes of cells in brain tissue?

Answer 1

1) Neurons
2) Neuroglia / Glial cells

Question 2

Roughly how many neurons are in the human brain?

Answer 2

100 billion

Question 3

Roughly how many glial cells are in the human brain?

Answer 3

Outnumber neurons 10:1

Question 4

What is the general structure of a neuron?

Answer 4

Cell body / soma
Axon
Dendrites

Question 5

What is an axon?

Answer 5

Output side of a neuron, with an excitable membrane specialised for the generation and propagation of action potentials. Can travel distances ranging from microns to metres.

Question 6

What is the axon hillock?

Answer 6

A conical shaped thickening on the cell body from where the axon arises

Question 7

What are dendrites?

Answer 7

Input side of cell. Usually thicker / shorter than axon, highly branched giving rise to a dense network of dendritic processes (spines)

Question 8

What is a synapse?

Answer 8

A point of specialised contact between two neurons

Question 9

How can neurons be classified?

Answer 9

1) Number of processes
2) Length of axon
3) Shape of cell body

Question 10

What are the four classifications of neurons relating to number of cellular processes?

Answer 10

1) Multipolar
2) Bipolar
3) Unipolar
4) Pseudounipolar

Question 11

What are the two classifications of neurons relating to length of axon?

Answer 11

1) Golgi type 1
2) Golgi type 2

Question 12

What are the three classifications of neurons relating to shape of cell body?

Answer 12

1) Ovoid
2) Fusiform
3) Triangular

Question 13

What is a multipolar neuron?

Answer 13

A neuron with more than one dendrite

Question 14

What is a bipolar neuron?

Answer 14

A neuron with only 1 dendrite

Question 15

What is a unipolar neuron?

Answer 15

A neuron with no dendrites (eg, skin receptor cells, the receptor acts like a dendrite and the axon goes to the spinal cord)

Question 16

What is a pseudounipolar neuron?

Answer 16

A neuron that originally developed as a bipolar neuron but the two processes fuse

Question 17

What is a Golgi type 1 neuron?

Answer 17

One with a long and large axon

Question 18

What is a Golgi type 2 neuron?

Answer 18

One with a short axon

Question 19

What are the main components of the perikaryon (cell body)?

Answer 19

1) Membrane
2) Cytoplasm
3) Nucleus
4) Smooth ER
5) Rough ER
6) Golgi complex
7) Cytoskeleton
8) Lysosomes
9) Mitochondria

Question 20

What is the structure of the neuronal membrane?

Answer 20

Phospholipid bilayer containing proteins (ion channels, ion exchangers, neurotransmitter receptors etc)

Question 21

What is the role of the cytoplasm?

Answer 21

Contain variety of organelles

Question 22

Describe the nucleus of a neuron

Answer 22

Large and round, centrally located

Neuronal cell nuclei have less heterochromatin than other types, meaning most of the genome is active in these cells

Pale stained with a large, clear, nucleolus

Question 23

What is endoplasmic reticulum?

Answer 23

System of sheets, channels and membrane enclosed spaces; partly continuous with nuclear membrane

Question 24

Describe the rough endoplasmic reticulum

Answer 24

Has attached ribosomes, together with free ribosomes = Nissl substance

Many functions including protein synthesis

Question 25

Describe the smooth endoplasmic reticulum

Answer 25

Ribosome free

Many functions including lipid synthesis and regulating intracellular Ca2+ levels to avoid excitotoxicity and cell death

Question 26

Describe the Golgi complex

Answer 26

Specialised type of endoplasmic reticulum

Many functions including packaging molecular products into vesicles for storage or transport

Question 27

Describe the cytoskeleton

Answer 27

Proteins (neurofilaments, microfilaments and microtubules) which form internal skeletal structure of neuron

Question 28

What are lysosomes?

Answer 28

Specialised vesicles that “digest” material from inside and outside the cell

Question 29

What is the role of mitochondria?

Answer 29

Energy production, respiration, TCA cycle and oxidative phosphorylation to generate ATP

Question 30

Describe the structure of dendrites

Answer 30

Similar structure to that of perikaryon

Spines: membrane limted organelles that project from the surface

Have a neck and ovoid bulb or head
Contain filaments (actin and α and β tubulins)
Average length 2μm

Question 31

Describe the role of dendrites

Answer 31

Receive most of the excitatory input
Dynamic (constantly moving and changing shape, changing impact of input signals)

Question 32

Describe the structure of the axon

Answer 32

No Nissl substance or Golgi complexes but has SER, mitchondria, cytoskeleton and vesicles

Leaves cell body from conical shaped swelling (axon hillock)

Question 33

Describe the role of the axon

Answer 33

Cytoskeletal elements are involved in axonal transport (how the cell body communicates with the extremities and vice versa)

Question 34

What are the two rates of axonal transport?

Answer 34

Fast (100-400mm/day) - continuous fast movement - moves vesicles

Slow (1-4 mm/day) - jumps along and stops - moves various proteins

Question 35

What cells form the neuroglia?

Answer 35

CNS
Oligodendrocytes
Astrocytes
Microglia

PNS
Schwann cell

Question 36

What are oligodendrocytes?

Answer 36

The myelinating cells of the CNS

Question 37

Describe the structure of oligodenrocytes

Answer 37

Single sheet of oligodendrocyte plasma membrane wraps tightly around an axonal segment

Myelinated segments = internodes, speeds up conduction

Question 38

What are astrocytes