Nervous Communication - Neurones Flashcards
(23 cards)
define neurones
specialised cells that transmit an action potential from one part of the body to another
define sensory neurone
carry an action potential from a sensory receptor to the CNS
what is the position of the cell body of the sensory neurone
just outside the CNS (dorsal root ganglia)
what is the length of the dendrites in the sensory neurone
long (often single dendron)
what is the length of the axon in the sensory neurone
short (from just outside CNS into CNS)
define relay neurone
connect sensory and motor neurones
what is the position of the cell body in the relay neurone
within CNS
how long are the dendrites in the relay neurone
short
how long is the axon in the relay neurone
short
define motor neurone
carry an action potential from the CNS to an effector (muscle/gland)
what is the position of the cell body in the motor neurone
inside CNS
how long are the dendrites in the motor neurone
many short dendrites
how long is the axon in a motor neurone
long (from inside CNS to effector)
what are the adaptations of neurones
- long
- sodium potassium pumps
- gated ion channels
- organelles in cell body
- myelin sheath (not in all)
explain how being long helps neurones
transmit action potentials over a long distance
explain how sodium potassium pumps help neurones
actively transport sodium out of the cell and potassium into the cell (uses ATP)
explain how gated ion channels help neurones
control entry/exit of sodium/potassium/calcium ions
explain how organelles in cell body help neurones
mitochondria, nucleus, ribosomes, ER and golgi apparatus for the production of ATP of active transport and production of neurotransmitters
explain how a myelin sheath helps neurones
fatty sheath insulates neurone from other electrical activity, speeds up transmission of action potential
describe the myelin sheath
- schwann cells wrap themselves around the axon many times
- composed of myelin (lipid)
what are gaps between schwann cells called
nodes of Ranvier
are all neurones myelinated
no, only approx 1/3
what is the purpose of the myelin sheath
acts as an insulator to prevent the movement of ions across the cell membranes, which speeds up conduction
