6. Basic Neuroscience

Question 1

Briefly describe communication by nervous system and the benefits

Answer 1

Neuron -> nerve impulse -> neurotransmitter -> target cells

Faster signalling

Neuron smallest functional unit in body

Question 2

Briefly describe endocrine system and benefits?

Answer 2

Endocrine cells -> hormone in bloodstream -> target cells

Small amount of hormone needed for whole body

Question 3

Describe the prototypical neuron?

Answer 3

Neurons are highly polaried, very different one end to other, made up of axon, soma (cell body) and dendrites

Question 4

What are the two major cell types in the nervous system?

Answer 4

Neurons and Glia

Question 5

Describe the axon?

Answer 5

Gap in the myelin = node (of ranvier)

Myelin sheath on axon = white electrical insulator

Question 6

Describe the glia?

Answer 6

Glial cell not quite as polarised

Outnumber neurons by 10:1

May mediate some signalling in brain

Primary role is to support neurons

Can divide unlike neurons

Also known as neuroglia

Question 7

Name the CNS glial cells and PNS glial cells?

Answer 7

CNS glial cells: astrocytes (astroglia), oligodendrocytes, ependymal (make csf) and microglia (immune function)

PNS glial cells: Schwann cells

Question 8

Describe oligodendrocytes/schwann cells and their function?

Answer 8

Make myelin from cholesterol and myelinate axons of neurons

Oligodendrocytes=Many branches/axons=CNS

Schwann cells=Single axon=PNS

Question 9

What is the support for the nervous system?

Answer 9

There is no internal connective tissue for support, the supporting cells are all Glia.

Question 10

What is the grey matter?

Answer 10

Grey matter = nerve cell bodies

Outside of the brain e.g. cortex and basal nuclei and inner part of the spinal cord

Question 11

What is white matter?

Answer 11

White matter = axons and myelin

Inner part of the brain and outer part of the spinal cord

White is from fatty tissue in myelin

Question 12

What are the types of neuron?

Answer 12

Unipolar (Psuedo)

Bipolar

Multipolar

Question 13

Which direction do signals travel along a neuron?

Answer 13

Dendrites receive

Cell body integrates

Synapse Transmits

Question 14

What is the role of axons?

Answer 14

Specialised for transmission of information

Question 15

What is the role of dendrites?

Answer 15

Specialised for receipt of information

Question 16

What similarities and differences are there between neurons and other cells?

Answer 16

Similarities:

• cell body with cytosol and organelles including a nuclus
• cell membrane (plasmalemma)

Uniquie(ish):

• can’t reproduce
• can trigger action potentials (excitable cells)

Question 17

What other cells to nerve cells communicate with?

Answer 17

Nerve cell -> nerve cell

Nerve cell innovates muscle

Nerve cell innovates glands

Question 18

Movement of charges ions across cell membranes depends on what?

Answer 18

Diffusion and electricity

Question 19

Which way do charged ions want to move?

Answer 19

From areas of high to low concentrations

Question 20

What charge to charged ions move towards?

Answer 20

Charged ions move to areas of opposite charge

Question 21

How can ions be kept outside of inside the cell against their concentration gradients?

Answer 21

Channels and pumps that can be made to stay closed or forced to work

Question 22

What is voltage/membrane potential?

Answer 22

The difference in charge from different ions outside and inside the cell

Question 23

Is neuron polarised?

Answer 23

Inside of a neuron is negative compared to outside (polarised) typically -70 or -80 mV

Question 24

What ions are inside and outside the resting cell?

Answer 24

Sodium Na+ - Positive charge - Outside cell

Protein - Negative charge - Inside cell

PO4 3- - Negative charge - Inside cell

Maintained by sodium-potassium pump

Question 25

Describe the resting cell membrane?

Answer 25

Polarised Negative inside (lots of protein) Positive outside (lots of sodium)

Question 26

Describe the stimulation phase of an action potential?

Answer 26

Depolarisation Sodium channels open Sodium moves in Reversal of electrical ppotevntial (inside becomes +ve)

Question 27

Describe the repolarisation phase of an action potential?

Answer 27

Repolarisation Sodium channels close Potassium channels open Potassium moves out Return of electrical potential inside to -ve

Question 28

What happens if stimulation is below threshold for action potential?

Answer 28

No action potential All or nothing

Question 29

What happens if stimulation is above threshold for action potential?

Answer 29

Fixed size of action potential whether it's just above threshold or miles above hreshold

Question 30

What does myelin do?

Answer 30

Myelin does the job of electrical tape - it insulates the axon so the flow of Na+ ionns in the action potential can travel quickly without dissipating out of the cell

Question 31

What is MS?

Answer 31

Multiple Sclerosis is a disease affecting the myeling. Myelin is attacked by the body's own immune system and degraded

Question 32

What does no myelin mean for the action potential?

Answer 32

No myelin means the action potential will move more lowly down the neuron. Many problems in nerve function then happen, depending on the location of myelin attack.

Question 33

What do you call the neuron before and after the synapse?

Answer 33

Presynaptic neuron Postsynaptic neuron

Question 34

Describe a chemical synapse?

Answer 34

Action potential in nerve terminal opens Ca2+ channels Ca2+ entry causes vesicle fusion and transmitter release Receptor-channels open, Na+ enters the postsynaptic cell and vesicle recycle

Question 35

Name some neurotransmitters?

Answer 35

Serotonin Acetyl choline Glutamate Dopamine GABA noradrenaline adrenaline

Question 36

How are neurons classified?

Answer 36

1. ) Sensory (afferent: somatic or visceral) neurons originate from senory receptors to the processor 2. ) Motor (efferent: somatic or visceral) neurons conduct signals that originate in the CNS 3. ) Interneurons are between sensory and motor neurons

Question 37

Name 3 problems with neurons that can cause clinical problems?

Answer 37

- Paralysis - damage to the spine means action potentials can't travel down neurons to/from areas below the damage usually crush or severing of spinal cord - Stokes and head injuries - regions of cell death in the brain stop signals being generated or interpreted in that area usually cell death due to brain starvation of blood or oxygen - Alzheimer's disease - make too much protein, tangles up, means signalling can't occus

Question 38

Give examples of neurological exams?

Answer 38

Glasgow coma scale, pupillary light reflexes, tests for normal cranial nerve and midbrain function, muscle tone and strength

Question 39

Describe glasgow coma scale?

Answer 39

Rapid assessment of level of coma/consciousness especially useful following acute head injuries Best GCS=15 Comatose GCS \< 8 Totally unresponsive = 3 3 categories: eye opening response, best verbal response, best motor response