Lab 10 Exercise 13 Study Sheet

Describe how nerve impulses are transferred from one neuron to the next at a synapse

At a synapse, the action potential opens calcium channels and calcium enters the synaptic knob. The calcium causes the synaptic vesicles to fuse to the neuron's cell membrane and release their neurotransmitter molecules into the synaptic cleft. The neurotransmitter molecules diffuse through the synaptic cleft and bind to receptors on the postsynaptic neuron.

Rough Endoplasmic Reticulum in a neuron

Chromatophilic bodies

short gaps in the myelin sheath along a myelinated axon

Node

Compare the CNS and the PNS by discussing the components found in each

The central nervous system is composed of the brain and spinal cord only. The peripheral nervous system includes all the nerves that arise from the central nervous system—the cranial and spinal nerves. The PNS also has motor and sensory divisions. The motor division has two parts: the somatic nervous system and autonomic nervous system. The sensory division has three components: somatic sensation, visceral sensation, and special sensation.

What is the myelin sheath?

The myelin sheath is a sheet of the lipid myelin that is wrapped multiple times around the axon of most neurons. Its presence dramatically increases the rate of impulse conduction within the myelinated neuron because the impulse jumps between nodes, which are gaps in the myelin. Consequently only those areas must depolarize, instead of the entire axon.

Nerve cell process that transmits electric impulses

axon

neuron cell process that receives impulses from other neurons

dendrite

several layers of fused cell membrane that serve as an insulation for a nerve fiber

myelin sheath

contains secretory vesicles filled with a neurotransmitter

synaptic terminals