A2 Nervous system Flashcards
what is the central nervous system made up of
brain and spinal cord
what is the peripheral nervous system made up of
All other nerves outside the brain and spinal cord
what is an axon
a long neuron that action potential ( electrical impulses) travel along
what is a myelin sheath
layer of fat around the axon
what is the node of ranvier
the gap where impulses can jump from node to node
what is depolarised
there is a influx of sodium ions into the axon making the inside more positive
What is repolarised
Potassium ions move rapidly out the axon restoring the negative charge
What is polarised
A neurone is at resting potential and the inside of the membrane is negatively charged
What is the name for a nerve travelling down an axon
Action potential
What is the role of a sodium potassium pump
Move 3 sodium ion out the neurone for every 2 potassium ions that move in
What is hyper polarised
When too many potassium ions diffuse out of the neurone
What restores hyper polarised
Sodium potassium pump return the rate back to resting potential
What is the effect of mylenation of transmittion speed
faster because only need to depolarise the node of Ranvier
What does the sensory neurone do
Connect receptors to the coordinator
What does the relay neurone do
These coordinate the correct response to the stimulus
What does the motor neurone do
These send the signal from the coordinator to the effector
What is a stimulus
A change to the body’s internal or external environment
What is are the coordinators
Brain and spinal cord
What are the effectors
Muscle or glands
What are the reasons for reflexes
To protect you tissues from harm
Keep you safe and alive
Where does the ‘thinking’ take place
Central nervous system
What is a reflex
An automatic response to a stimulus
What is a synapse
A gap between neurones
What is the term for the process where the action potential leaps from Node of Ranvier to Node of Ranvier?
Saltatory Conduction
What is the gap from one neurone to the next called?
Synapse
Name the components of the synapse.
- Presynaptic neurone
- Synaptic cleft
- Post synaptic neurone
What is found in the presynaptic neurone?
- Neurotransmitters
What happens when an action potential arrives at the presynaptic neurone
Synaptic vesicles move towards and fuse with the cell membrane in the synaptic cleft
What process releases neurotransmitters from synaptic vesicles?
Exocytosis
What occurs to neurotransmitters after they are released into the synaptic cleft?
They diffuse across the synaptic cleft
What must happen for an action potential to be generated in the post synaptic neurone?
Enough neurotransmitters must bind to receptors
What is the correct term for a nerve impulse travelling down an axon?
Action potential
What controls the sodium and potassium ion levels in a neurone?
Sodium potassium pump
What state is a neurone in when it has a higher concentration of sodium ions outside than potassium ions inside?
Polarised
What must occur before an action potential can be generated?
Neurone must be at resting potential
What happens during depolarisation?
Rapid influx of sodium ions into the axon
What effect does depolarisation in one area of the neurone’s axon have?
Causes depolarisation in the next region
What occurs during repolarisation?
Potassium ions move rapidly out of the axon
What is the refractory period?
Time during which no new action potentials can be transmitted
What restores the resting potential after an action potential?
Sodium potassium pump
How does myelination affect the transmission speed of action potentials?
Increases speed by allowing depolarisation only at the Nodes of Ranvier
Fill in the blank: The _______ creates a myelin sheath around axons.
Schwann cells
What is the result of a neurone being depolarised?
Inside of the membrane becomes more positive
Explain why the speed of transmission of impulses is faster along a myelinated axon than a non myelinated axon
Myelinated means myelin sheath this allows impulses to jump from node of ranvier to node of ranvier this is called saltatory conduction, only need to depolarise the node of ranvier
Non myelinated depolarise the whole length of the membrane
