Nerones & Action Potentials Flashcards
What’s are sensory neurones
The carry nervous impulses from receptors to the CNS
What are motor neurones
They carry impulses from the CNS to effector organs such as muscles
What are relay neurones
Carry impulses from the sensory neurone and relay them to the motor neurone
What is the function of dendrites
They carry nervous impulses towards the cell body
What is the function of axon
Axon carries nervous impulses away from the cell body
What is the Schwann cell
It wraps around the axon forming a myelin sheath
The myelin sheath insulates neurones increasing speed of impulse transmission
What are gaps between Schwann cells called
Nodes of Ranvier
What is resting potential
The state at which an axon is at rest
It’s potential difference at this state is -70mv neurone is said to be polarised
Sodium potassium channels pump sodium out of the axon and potassium into the axon
Potassium ion channels open to allow potassium to diffuse back out
What is an action. Potential
When a stimulus is introduce to the receptor the energy causes a temporary reversal in the charge inside the membrane causing -70mv charge to become a +40 charge
The membrane is depolarised
When is membrane depolarised
When PD surpasses threshold -55mv
What is depolarisation
Na channels channels close an K channels open allowing K ions to diffuse out of the axon membrane making it more negative
What is hyerpolarisation / refractory period
When potential difference is slightly more negative than resting potential in order to prevent re stimulation of a neutron
