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.
Sensory neurone:
- 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
Motor neurone:
- 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
Synapses:
- 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.
References: https://www.researchgate.net/profile/Guoyuan-Li-2/publication/263858109/figure/fig1/AS:669025763872785@1536519580639/Reflex-arc-It-consists-of-a-receptor-a-sensory-neuron-a-reflex-center-spinal-cord-a.png
Drafted by Catrina (Biology)