Functional Neuroanatomy

Question 1

Glial cells are a type of cell that provides physical support to neurons and maintain their environment. T/F

Answer 1

False! Glial cells provde both physical and chemical support to neurons & maintain their environment

Question 2

What are the three glial cells in the CNS and what are their main functions?

Answer 2

1) Oligodendrocytes (big brother): creates myelin sheathes in CNS and provides scaffolding and support structures.
2) Astrocytes (star shaped): exists where oligodendrocytes are not, and are the largest and creates “blood-brain” barriers (seals of capillaries).
3) Microglia (first aid): response to injury/disease > anti-inflammartory response, e.g., often response to strokes, and eliminates excessive neurotransmitters

Question 3

Fill in the word: _____ are most common, (40-50% of brain tumours). Fast growing and arises from any type of glial cells.

Answer 3

Glimomas!

Question 4

Unipolar sensory neurons are efferent neurons. T/F

Answer 4

False! Unipolar sensory neurons are afferent neurons. They ARRIVE at the CNS with sensory information

Question 5

Describe the characteristics of the multipolar motor neuron

Answer 5

Multipolar motor neurons are neurons with multiple dendrite branches which collect motor informating EXITING (efferent neurons) TOwards central organ/point.

Question 6

Interneurone (relay) relay message from sensory neurons to motor neurons and make up the brain and spinal cord. T/F

Answer 6

True!

Question 7

Match the following neuron structures to their functions.
1) Dendrites, 2) Ribosomes & Endoplasmic Reticulums , 3) Mitochondria, 4) Golgi complex
A) Energy release, B) Contains Neurotransmitters, C) Bring info from connecting neurons, D) To transport packaged N. transmitter down axons, E) To generate proteins (neurotransmitters), F) To package proteins into vesicles
Point out where they exist in the diagram

Answer 7

Answer: 1 C, 2 E, 3 A, 4 F

Question 8

Match the following neuron structures to their functions.
1) Synaptic vesicles, 2) Microtubules, 3) Myellin, 4) Terminal Buttons
A) To collect neurotransmitters into vesicles, while they await release, B) Energy release, C) Contains neurotransmitters, D) To generate protein, E) To protect axon & promote transmission down axon, F) To generate protein, G) To transport packaged neurotransmitter down axon.
What do the incorrect functions match to? Can you point out where these exist in the diagram?

Answer 8

Answer: 1 C, 2 G, 3 E, 4 A

Question 9

What are the neuropathological changes associated with Alzheimer’s Dementia?

Answer 9

Alzheimer’s Disease results in cerebral astrophy (wasting away), such as: neuronal death, and widened sulci and gyri narrowed

Question 10

What is identified in areas of lots of synapses, causing degeneration of synapses?

Answer 10

Amyloid plaques

Question 11

What looks like twisted ropes within swollen cell body and creates tangles? What does it consist of?

Answer 11

Tangles, consiting of “tau” protein.

Question 12

Name the most characteristic marker of idiopathic
(spontaneously and unknown cause) Parkison’s Disease & Lewy Body Dementia

Answer 12

Lewy body

Question 13

What are the three broad phases of neuronal communication?

Answer 13

1. Collection & integration of signal
2. Transmission of signal along the axon
3. Transmission of signal from the axon terminal

Question 14

What is the process of active and passive movement of ions in neurons called?

Answer 14

Transport & diffusion

Question 15

Name the 3 ions: Na+ K+ CI-

Answer 15

Sodium, Potassium (both positive) and chlorine (negative)

Question 16

Describe “resting potential”

Answer 16

When a neuron is idle, it is considered as possessing resting potential as it sits at -70mv and is “polarised” as it holds the potential to send a signal (awaiting local change)

Question 17

Describe how a neuron becomes less polarised

Answer 17

A neuron becomes less polarised from its original polarised state (with resting potential) due to a local change (another neuron sending a signal etc.). That is, a neighbouring neurons signal causes the neuron’s ion levels to shift due to positive ions transported in, and thus it then becomes depolarised as it voltage reaches closer to 0

Question 18

Describe how a neuron becomes more polarised?

Answer 18

A neuron becomes hyperpolarised in a similar process to depolarisation. Specifically, a neuron experiences a local change whereby ions levels shift, causing the neuron to hold more negative ions within, and thus moves further away from zero mV

Question 19

Explain absolute refractory and relative refractory

Answer 19

Absolute refractory refers to a state neurons experience after firing an action potential whereby it will not respond to stimulus (cannot refire).
Relative refractory refers to the state after absolute refractory whereby it can respond to new stimulus if the stimulus is stronger than the original one

Question 20

Explain the three phases of an action potential using, rising phase, repolarisation, and hyperpolarisation.

Answer 20

The rising phase occurs after neurons experience an excitory stimulus. Sodium channels, then potassium channels open, causing the neuron to be depolarised as the neuron becomes more positive. At its peak, the sodium channel closes and enters the repolarisation phase as the neuron returns to its polarised state, which then the potassium channel finally closes. The final phase of an actional potential is reached when the neuron becomes more negative than -70mV, or otherwise known as hyperpolarisation

Question 21

Potassium (K+) is responsible for excitatory/inhibitory responses?

Answer 21

Inhibitory. Increase in potassium levels causes neurons to be hyperpolarised

Question 22

Sodium (Na+) is responsible for excitatory/inhibitory responses?

Answer 22

Excitatory. Increase in sodium levels causes neurons to be depolarised

Question 23

Neurons hold excitatory synapses to promote further excitation.

Answer 23

False! Neurons hold both excitatory and inhibitory synpases to BALANCE excitatory and inhibitory levels

Question 24

What is saltatory conduction?

Answer 24

Saltatory conduction is the process whereby a passive conduction is generated at ea

Question 25

Explain saltatory conduction

Answer 25

Due to myelination, the action potential travels through the axon (cytoplasm) and at each node of Ranvier, the action potential is regenerated, repeatedly successively through each node. In essence, “jumping” and propagating down axon.

Question 26

Name the three parts of the synapse and its functions

Answer 26

1. Presynaptic terminal: With vesicles containing neurotransmitters AND receptors for re-uptake
2. Junction: Where the neurotransmitters ‘float’ briefly after release
3. Post-synaptic terminal: With receptors for the transmitters

Question 27

What is an axoaxonic synapse

Answer 27

An axoaxonic synapse is a type of synapse that synapses between the presynaptic neuron and the postsynaptic neuron. Axoaxonic synapses can have inhibitory or excitatory effects on the postsynaptic neuron, and as well, regulate the amount of neurotransmitter released by the presynaptic neuron

Question 28

Neurons can produce just one neurotransmitter, T/F

Answer 28

False! Can produce two or more

Question 29

Which of two molecules is this?
- Synthesized in cytoplasm of terminal button
- packaged in vesicles by Golgi complex
- vesicles stored in clusters next to pre-synaptic membrane, waiting for trigger to be released

Answer 29

Small molecules

Question 30

Which of two molecules is this?
- all neuropeptides
- assembled in the cell body by ribosomes
- packaged by Golgi complex
- transported to the axon terminal via microtubules

Answer 30

Large molecules

Question 31

What are the four small-molecule neurotransmitter?

Answer 31

1. Amino acids
2. Monoamines
3. Achetycholine (ACh)
4. Unconventional neurotransmitter - soluble gases and endocannabinoids

Question 32

Amino acid neurotransmitters are usually found at _____ _____ _____ synapses in the CNS.
Name the three types of amino acid neurotransmitters

Answer 32

Fast-acting directed
1. glutamate - most prevalent excitatory neurotransmitter
2. gaba - most prevalent inhibitory neurotransmitter
3. aspartate & glycine

Question 33

Effects of monoamines tend to be ______, _______

Answer 33

Diffuse, non-directed
1. Catecholamines (sythensied from tyrosine)
- dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline)
2. Indolamines (synthesized from trytophan)
- seratonin, melatonin

Question 34

Explain the exocytosis process of neurotransmitters

Answer 34

1. Neurotransmitters are sythesised and packaged into synaptic vesicles
2. Calcium ion levels in cells increase from calcium channels opening, which triggers docking of synaptic vesicles
3. Calcium contrentation triggers docking of synaptic vesicles