Lesson 2- Structure & Function of Sensory, Relay & Motor Neurons

Question 1

What are neurons?

Answer 1

Neurons- specialised nerve cells that move ⚡️ impulses to and from CNS

Question 2

How do neurons communicate with other cells around the body?

Answer 2

Neurons receive & transmit info via⚡️ impulses to other cells

Question 3

What does the cell body of a neutron contain?

Answer 3

1) Nucleus
2) Dendrites
3) Axon
4) Synapse
5) Synaptic knob
6) Synaptic cleft
7) Myelin sheath
8) Schwann cells
9) Nodes of Ranvier
10) Neurotransmitters
11) Receptor sites

Question 4

Define cell body

Answer 4

Cell Body- control centre of neuron

Question 5

Define nucleus

Answer 5

Nucleus- contains genetic material of cell

Question 6

Define dendrites

Answer 6

Dendrites- branch like structures- receive an electrical impulse (action potential) from other neurons or sensory receptors

Question 7

Define axon

Answer 7

Axon- long fibre- carries⚡️ impulses away from cell body to axon terminal

Question 8

Define synapse

Answer 8

Synapse- ending of a neuron

Question 9

Define synaptic knob

Answer 9

Synaptic knob- swelling at end of neuron (synapse)- contains vesicles- release neurotransmitters

Question 10

Define synaptic cleft

Answer 10

Synaptic cleft- small microscopic gap between 1 neuron and next (pre-synaptic and post-synaptic)

Question 11

Define myelin sheath

Answer 11

Myelin Sheath- insulating layer that protects axon and speeds up transmission of⚡️ impulse

Question 12

Define Schwann cells

Answer 12

Schwann cells- make up myelin sheath

Question 13

Define nodes of ranvier

Answer 13

Nodes of Ranvier- gaps in myelin sheath- speed up⚡️ impulse along axon and force impulse to jump across gaps

Question 14

Define neurotransmitters

Answer 14

Neurotransmitters- chemicals released form one neuron within synaptic knob- pass synaptic cleft to next neuron

Question 15

Define receptor sites

Answer 15

Receptor sites- proteins on surface of cell receive neurotransmitters – 🔒 & 🔑

Question 16

What are the functions of the sensory neuron?

Answer 16

1) Carry ⚡️ impulses from sensory receptors to CNS (spinal cord and 🧠) via PNS
2) Sensory neurons convert info from sensory receptors into ⚡️ impulses- when impulses reach 🧠, converted into sensations e.g. heat, pain etc allows body to react appropriately
3) Some sensory impulses terminate at spinal cord- allows reflexes to occur quickly without delay of sending impulse to 🧠

Question 17

What are the functions of the relay neuron?

Answer 17

1) Connect sensory neurons to motor neurons to communication between them
2) During reflex arc (e.g. put 🤚 on hot hob)- relay neurons in spinal cord involved in analysis of sensation and decide how to respond (e.g. to lift 🖐) without waiting for 🧠 to process pain (NOTE- sensation still goes to 🧠 BUT after- 🧠 confirms after that good decision made by relay neurons in spinal chord)

Question 18

What are the functions of the motor neuron?

Answer 18

1) Send⚡️ impulses via long axons from CNS to glands/muscles to function- effectors
2) When motor neurons stimulated- release neurotransmitters that bind to receptors on muscles 💪 to trigger response-> movement

Question 19

Where are sensory neurons found?

Answer 19

Found in sensory receptors e.g. 👂, 👀, 👅 etc

Question 20

Where are motor neurons found?

Answer 20

Found in CNS BUT project their axons outside of CNS

Question 21

Where are relay neurons found?

Answer 21

Found in CNS