neurones

neurone

specialised cells that carries electrical impulses around the body [nervous system is made up of neurones]

types of neurones and their role

sensory neurones

-carry nerve impulses from receptors to the CNS (central nervous system)

relay neurones

-carry impulses within the CNS

-carry nerve impulses between the sensory and motor neurones

motor neurones

-Carry impulses from the CNS to effectors

relay neurones are also called…

where is it found?

-intermediate neurones

-found within CNS

CNS (2)

brain or spinal cord

common features for all neurones

- have a cell body with a nucleus

- have an axon

- have dendrites

what does cell body contain?

- nucleus

-cytoplasm

-organelles→ mitochondria, ribosomes, RER, golgi apparatus etc

structure of sensory neurone

[- cell body branches off to the side in the middle of neurone]

structure of relay neurone

[short axon and dendrites]

structure of motor neurone

[long axon]

role of:

-dendron

-cell body

-axon

-dendron→ carry nerve impulses to the cell body

-cell body→ produce neurotransmitters

-axon→ carry nerve impulses away from the cell body

difference in structure of motor and sensory neurones (4)

-the cell body is at the end motor neurone. The cell body is in the middle of sensory neurone

-motor neurone has a longer axon

-motor neurone has no dendron

-cell body of motor neurone is in CNS. the cell body of sensory neurone is not in CNS

myelinated neurones

non-myelinated neurones

-have a myelin sheath wrapped around the axon

-they are not surrounded by myelin sheath

what is the myelin sheath made up of?

Schwann cells

what are the gaps in between the Schwann cells called?

nodes of Ranvier

role of the myelin sheath (3)

-acts as an electrical insulator and speeds up conduction of action potentials

-prevents depolarisation (prevents movement of ions into and out of neurone)

how do Schwann cells produce myelin?

they wrap themselves around the axon multiple times

is conduction faster in myelinated or non-myelinated neurones

conduction is faster in myelinated neurone

pathway of nervous communication

stimulus→ receptors→sensory neurone → relay neurone → motor neurone → effector

[receptor cells detect a stimuli. Sensory neurones carry nerve impulses from the receptors to the CNS. The CNS processes the info and sends impulses along motor neurones to effectors. Effectors carry out a response]