The Nervous System, Synapses, reflex arcs.🤨
A coordinated response is similar to a reflex arc in the sense that they both use stimuli, however a reflex arc is involuntary.
STRUCTURES + FUNCTIONS: you will need to know the 3 main ones in I/GSCE Biology
Dendrons + dendrites - carry nerve impules towards the cell body
Axons - carry impulses away from the cell body
Myelin Sheath - some axons are surrounded by a myelin sheath, it acts as an electrical insulator, speeding up the electrical impulse
The longer the neurone the quicker the impulse.
- one long dendron carries nerve impulses from receptor cells to the cell body, which is located in the middle of the neurone
- one short axon carries nerve impulses from the cell body to the CNS
- Many short dendrites carry nerve impulses from the CNS to the cell body
- One long axon carries nerve impulses from the cell body to the effector cells
- It is the connection between two neurones.
- the nerve signal is transferred by chemicals called neurotransmitters, which diffuse across the gap
- The neurotransmitters then set off a new electrical signal in the next neurone.
- Transmission is very fast but it is slowed down at the synapse because the diffusion of neurotransmitters takes time.
Drafted by Catrina (Biology)