Nervous System

Question 1

What type of signal is used throughout the nervous system?

Answer 1

Electrical

Question 2

Name the two parts of the nervous system

Answer 2

Central nervous system; Brain and spinal cord

Peripheral Nervous System: Nerves extending from the brain / spinal cord.

Question 3

`Describe features of a neuron

Answer 3

Cell body, Nucleus, dendrites, Node of ranvier, Myelin sheath, Axon, Schwann’s Cell, Axon terminals.

Question 4

What is the key feature of a dendrite?

Answer 4

Provide a large surface area for the neuron allowing it to recieve information from other cells towards its cell body.

Question 5

Another name for afferent neurone

Answer 5

Sensory Neurone

Question 6

Another name for the motor neurone

Answer 6

Efferent neurone

Question 7

What is a ganglion?

Answer 7

A grouping of neuron cell bodies

Question 8

Name the two types of supporting cells in the PNS

Answer 8

Schwann cells

Satellite cells or ganglion gliocytes

Question 9

Name the four types of supporting cells in the CNS

Answer 9

Olligodendrocytes
Astrocytes
Microglia
Ependymal cells

Question 10

What do oligodendrocytes do?

Answer 10

Form the myelin sheaths around the CNS axons.

Question 11

What cell are used to phagocytose foreign material in the CNS?

Answer 11

Microglial cells

Question 12

What is the use of astrocytes?

Answer 12

Help regulate the external environment of the CNS forming the blood brain barrier, removing and adding products and nutrients between the nerve cells and blood vessels)

Question 13

What are ependymal cells?

Answer 13

Line the ventricles of the brain and central canal and spinal cord.

Question 14

Explain the difference between grey matter and white matter

Answer 14

White matter is the fatty part of the brain (Lots of myelin) this is where the connection of the different parts of the brain are found. Grey matter is the ‘storage areas of the brain’ containing cell bodies and dendrites.

Question 15

What is a Glial cell?

Answer 15

non-neural support cell which are closely associated with neurones.

Question 16

Describe the cell body of a neurone

Answer 16

Encompasses the nucleus surround by the cytoplasm, Free ribosomes and RER are seen and are responsible for protein production. i.e. neurotrasmitters

Question 17

What is a multipolar neurone?

Answer 17

Have more than two cell processes (e.g. motor neurones)

Question 18

What is a bipolar neurone?

Answer 18

Have one dendrite and one axon found only in specialized sensory areas such as olfactory and retina areas.

Question 19

What is a node of ranvier?

Answer 19

A gap between schwann cells that allows depolarization of that neurone to occur only at these specific points, speeding up the transfer of action potential.

Question 20

Action potentials are said to be what?

Answer 20

All or nothing responses

Question 21

What is the resting membrane potential?

Answer 21

-70mV

Question 22

What part of the neurone is more negative during the resting state?

Answer 22

Inside of the cell, This is due to the concentration difference of potassium ions. (K+) concentration high within the cell.

Question 23

Name 3 ways in which the extra cellular K+ concentrations can be increased?

Answer 23

Kidney disease
Major Soft tissue damage
Medication Error
American lethal injection

Question 24

What happens when the nerve cell becomes permeable to Na+

Answer 24

Depolarisation occurs and an action potential is fired if the threshold potential is reached.

Question 25

What does Na+ do to the inside of nerve cell?

Answer 25

Makes it more positive.

Question 26

How is the resting membrane potential restored?

Answer 26

K+ diffuses out of the cell

Question 27

Chemical synapses are used for what?

Answer 27

pass the action potential to other or multiple nerve cells

Question 28

How is the signal carried across these chemical synapases?

Answer 28

Via a neurotransmitter for example, acetylcholine this neurotransmitter than binds to receptors found on the post synaptic membrane.

Question 29

Explain briefly how the neurotransmitter is released into the synaptic cleft.

Answer 29

Action potential reaches the presynaptic knob, This causes depolarization of the knob and causes voltage dependent calcium channels to open. Ca2+ flows into the cell and causes the movement of vesicles of the NT to the presynaptic membrane and exocytosis of the NT.

Question 30

How is the strength of a stimulus determined via an action potential?

Answer 30

It's frequency, so how quickly between each action potential is fired.

Question 31

What is saltatory conduction?

Answer 31

Depolarization only at the node of Ranvier

Question 32

What is the refactory period?

Answer 32

A period of time where the neurone is resistant to firing another action potential.

Question 33

Action potentials can only fire one way what is this called?

Answer 33

Orthodromic conduction

Question 34

Name the two things than can help speed up the rate of action potential

Answer 34

Diameter increase- causing cytoplasmic resistance to decrease (local current flow is faster and conduction velocity is faster) Myelination of nerve cell- minimizes electrotonic current decay. Also node of ranvier present allowing the action potential to 'jump' between nodes speeding up conduction up to 50x.

Question 35

Name the 7 steps required to move an action potential across a synpase.

Answer 35

1: Transmitter synthesis 2:Uptake 3:Synaptic storage 4:Action potential 5:Voltage gated Calcium channels open 6:release of NT 7:Receptor activation (Cellular effect.)

Question 36

What is an inhibitory neurone?

Answer 36

a neurone that can synpase onto either a pre- or post-synaptic terminal. NT are released i.e GABA which act to hyperpolarise the neurone, reducing its likelihood of depolarization. Stopping neurotransmitter release.

Question 37

What is a facilitatory neurone?

Answer 37

A neurone that can synapse on the pre-synaptic terminal which acts to increase the amount of NT released.

Question 38

What are four types of interneuronal synapses?

Answer 38

Convergence Divergence Positive Feedback Negative Feedback