U1B nervous tissue

structure/function of

what is myelin sheath made up of

made up of specialised cells called Schwann cells

what do Schwann cells do?

wrap themselves around axons insulating them making action potential travel faster through saltatory conduction

what is the difference between unmyelinated cells and myelinated cells?

unmyelinated cells don’t have nodes of Ranvier, Gray in colour and lose the nerve impulse during conduction.

what is the difference between unmyelinated cells and myelinated cells?

myelinated cells have nodes of Ranvier have lipid rich Schwann cells around axon making them conduct faster and are white in colour.

what is meant by resting potential?

membrane is polarized (-70 mV) maintained by sodium potassium pump

what is meant by depolarisation?

sudden temporary change in the membrane potential of a neurone in response to transmission of a nerve impulse (inside of the axon is less negative than the outside)

what is meant by hyperpolarisation

A decrease in the membrane potential of an axon (more negative than the resting potential)

what is meant by repolarisation?

The re-establishment of the resting potential (-65mV)

what is an synapse

junction between 2 neurons

what is meant by the synaptic cleft

gap between cells used when action potential reaches a synapse

what is meant by a presynaptic neurone

when action potential reaches and end of a neurone

what is meant by a synaptic knob

the end of the axon of the presynaptic neurone

what is a synaptic vesicle

vesicles located in the synaptic knob that contains neurotransmitters

what are neurotransmitters?

chemicals that allow an action potential to transfer across a synapse

what is meant by an agonist

• mimic effect of a neurotransmitter

• does this by binding to stimulating receptors

what is meant by antagonist

• prevent neurotransmitters from binding to and then stimulating receptors

why do we use antagonists and agonists

these are drugs used to treat neurological conditions such as parkinson’s