Lesson 2- Structure & Function of Sensory, Relay & Motor Neurons Flashcards
What are neurons?
Neurons- specialised nerve cells that move ⚡️ impulses to and from CNS
How do neurons communicate with other cells around the body?
Neurons receive & transmit info via⚡️ impulses to other cells
What does the cell body of a neutron contain?
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
Define cell body
Cell Body- control centre of neuron
Define nucleus
Nucleus- contains genetic material of cell
Define dendrites
Dendrites- branch like structures- receive an electrical impulse (action potential) from other neurons or sensory receptors
Define axon
Axon- long fibre- carries⚡️ impulses away from cell body to axon terminal
Define synapse
Synapse- ending of a neuron
Define synaptic knob
Synaptic knob- swelling at end of neuron (synapse)- contains vesicles- release neurotransmitters
Define synaptic cleft
Synaptic cleft- small microscopic gap between 1 neuron and next (pre-synaptic and post-synaptic)
Define myelin sheath
Myelin Sheath- insulating layer that protects axon and speeds up transmission of⚡️ impulse
Define Schwann cells
Schwann cells- make up myelin sheath
Define nodes of ranvier
Nodes of Ranvier- gaps in myelin sheath- speed up⚡️ impulse along axon and force impulse to jump across gaps
Define neurotransmitters
Neurotransmitters- chemicals released form one neuron within synaptic knob- pass synaptic cleft to next neuron
Define receptor sites
Receptor sites- proteins on surface of cell receive neurotransmitters – 🔒 & 🔑
What are the functions of the sensory neuron?
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 🧠
What are the functions of the relay neuron?
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)
What are the functions of the motor neuron?
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
Where are sensory neurons found?
Found in sensory receptors e.g. 👂, 👀, 👅 etc
Where are motor neurons found?
Found in CNS BUT project their axons outside of CNS
Where are relay neurons found?
Found in CNS
