Neurons and synapses
- Created by: lavithedemon
- Created on: 14-04-16 07:59
View mindmap
- Neurons and synapses
- neurons transmit electrical impulses
- dendrites - short branched nerve fibres
- axons - elongated nerve fibres
- the myelination of nerve fibres allows for saltatory conduction
- schwann cells are covered in myelin.
- node of Ranvier
- impulse can jump from one node to the other
- saltatory conduction
- impulse can jump from one node to the other
- Neurons pump sodium and potassium ions across their membranes to generate a resting potential
- sodium (3) out for every 2 potassium in.
- potassiums leak back in the membrane - charge imbalance
- resting membrane potential of - 70 mV
- outside more positive than inside
- resting membrane potential of - 70 mV
- potassiums leak back in the membrane - charge imbalance
- sodium (3) out for every 2 potassium in.
- An action potential consists of depolarisation and repolarisation of the neuron
- depolarisation
- sodium ions get back in its concentration gradient
- reversing of balance - inside more positive than outside (30 mV)
- sodium ions get back in its concentration gradient
- repolarisation
- potassium channels make potassium ions go out from the membrane
- inside more negative than outside
- potassium channels make potassium ions go out from the membrane
- depolarisation
- Nerve impulses are action potentials propagated along the axons of neurons
- ion movements that depolarize one part of the neuron trigger depolarisation in the next part of neuron
- refractive period
- prevents propagation backwards
- refractive period
- ion movements that depolarize one part of the neuron trigger depolarisation in the next part of neuron
- propagation of nerve impulses is the result of local currents that cause each successive part of the axon to reach the threshold potential
- due to movement of sodium ions
- local currents reduce concentration gradient
- synapses are junctions between neurons and between neurons and receptor or effector cell
- effector - the thing that carries out a response to a stimulus
- neurotransmitters
- pre synaptic and post synaptic cells
- when pre-synaptic neurons are depolarised they release a neurotransmitter into the synapse
- nerve impulse is propagated along the pre synaptic neuron
- depolarisation of the pre-synaptic cell causes calcium ions to diffuse in the neuron
- calcium makes vesicles containing neurotransmitters to fuse with the membrane of the cell
- neurotransmitter released in the synaptic cleft by exocytosis
- nt binds to receptors in the post synaptic cell membrane
- sodium channels open and sodium ions diffuse in through their concentration gradient
- action potential
- sodium channels open and sodium ions diffuse in through their concentration gradient
- nt binds to receptors in the post synaptic cell membrane
- neurotransmitter released in the synaptic cleft by exocytosis
- calcium makes vesicles containing neurotransmitters to fuse with the membrane of the cell
- depolarisation of the pre-synaptic cell causes calcium ions to diffuse in the neuron
- nerve impulse is propagated along the pre synaptic neuron
- secretion and reabsorption of acetylcholine by neurons at synapses
- a nerve impulse is only initiated if the threshold potential is reached
- neurons transmit electrical impulses
Comments
No comments have yet been made