Types of Neurones

Question 1

What are neurones?

Answer 1

Nerve cells

Question 2

What is function of neurones?

Answer 2

Fast transmission of chemical/electrical signals

Question 3

What is structure of neurones?

Answer 3

1. Dendrites
2. Axon
3. Synaptic terminals

Question 4

Function of dendrites?

Answer 4

Signal input as receive messages from other neurones

Can give rise to dendrite spines that spread out over large volume of brain tissue –> ‘dendritic tree’

Question 5

What is function of dendritic tree?

Answer 5

Increased SA for neurone to receive signal inputs

Question 6

Dendrites and axons are both types of neurite. What is a neurite?

Answer 6

Projections from neurone cell body

Question 7

Describe transmission of signal between neurones?

Answer 7

One neurone’s axon will connect chemically to another’s dendrite at synapse between them

Signal flows from 1st neurone’s axon –> 2nd neurones dendrite –> down its axon –> across synapse –> into 3rd neurone’s dendrites

Question 8

Function of axon?

Answer 8

Signal conduction away from cell body

Question 9

Function of synapse?

Answer 9

Chemical junction between axon terminal of one neurone and dendrites of another

Question 10

Function of myelin sheath?

Answer 10

Surrounds axon

1. Insulation - minimises dissipation of signal
2. Conduction - Fat prevents electricity leaking out

Speeds up transmission

Question 11

What are nodes of Ranvier?

Answer 11

Periodic gaps in myelin sheath

Question 12

What are the 3 main types of neurones?

Answer 12

1. Sensory
2. Motor
3. Interneurones

Question 13

Structure of multipolar neurones?

Answer 13

• Single long axon

- Many dendrites emerging from cell body (motoneurons)

Question 14

Structure of unipolar neurones (psuedo-unipolar)? Where are they found?

Answer 14

• Cell body attached to side

- Found in sensory ganglia (periphery sensory neurones)

Question 15

Structure of bipolar neurones? Where are they found?

Answer 15

• Cell body in middle

- Found in sensory structures (e.g. retina)

Question 16

What are 2 variations on multipolar type?

Answer 16

1. Pyramidal - Christmas tree

2. Stellate - star shaped

Question 17

What are glial cells?

Answer 17

Non-neuronal cells that provide support for nervous system

Produce myelin to form myelin sheath

Glia cells in CNS –> oligodendrocytes
Glia cells in PNS –> Schwann cells

Question 18

Where are motor neurones located? What is their structure?

Answer 18

CNS

Multipolar (single axon, multiple dendrites)

Question 19

What is function of motor neurones?

Answer 19

• Most common type of neurone

- Project their axons outside CNS to directly/indirectly control muscles

Question 20

Function of sensory neurones?

Answer 20

Convert external stimuli into corresponding internal stimuli

Activated by physical (light, sound, heat) or chemical (smell, taste) signals not inputs from other neurones (like motor neurones)

Question 21

Structure of sensory neurones?

Answer 21

Most are pseudo-unipolar (one axon that branches into 2 extensions - one receives information and is connected to dendrites, other transmits information to spinal cord)

Question 22

Function of interneurones?

Answer 22

Connections between sensory and motor neurones

Question 23

Structure and location of interneurones?

Answer 23

CNS and operate locally

Multipolar

Question 24

What are glial cells in CNS called?

Answer 24

Oligodendrocytes

Question 25

What are glial cells in PNS called?

Answer 25

Schwann cells