Ib bio C2.2 - D. 2.3

what are 2 adaptations nerves have?

1. Increased diameter size in animals to provide less resistance of the impulse because of the wider fibers

2. Myleniation by coating nerve fibers with Schwann cells to allow impulse to jump from node to node, speeding it up

what is a synapse?

junction between two neurons

what are the three types of neurons and examples?

1. sensory receptors —> neurons

2. neuron —> neuron

3. neuron —> muscle fibers and gland cells

what’s the presynaptic neuron?

it brings the signal as an impulse/action potential to the post synaptic neuron

what’s a neurotransmitter?

chemical that transmits signals across fluid filled gap between pre and post synaptic gap

what’s the post synaptic membrane?

carrie’s the signal away from synapse as an impulse

how is a neurotransmitter released from the presynaptic membrane?

1. Nerve impulse goes along presynaptic neuron until it reaches the membrane

2. Depolarization of presynaptic membrane causes calcium cons to diffuse through channels in membrane into the neuron

3. Influx of Calcium (Ca+)causes vesicles containing the neurotransmitter to move to presynaptic membrane and fuse with it

4. Neurotransmitter is released into gap by exocytosis

how is an action potential potential propagated in the post synaptic neuron?

1. NT difuses across synaptic gap

2. NT binds to receptors in postsynaptic membrane, causing ton channel to open

3. Ions difuse with concentration gradient into post synaptic neuron, causing membrane

potential to become more positive

4. If potential is enough, it triggers action potential, going away from synapse

5. NT is broken down and removed from gap