neurons

Node of Ranvier

A space between segments of the myelin sheath

Create the myelin sheath in the PNS

Schwann cells

Myelin sheath

A fatty sheath found around certain axons that increases the speed of conduction of an action potential

Synaptic vesicle

A vesicle containing neurotransmitters in the axon terminal of a neuron

What is the difference between an excitatory postsynaptic potential and an inhibitory postsynaptic potential?

An excitatory postsynaptic potential creates a local depolarization in the membrane of the postsynaptic neuron that brings it closer to threshold. An inhibitor postsynaptic potential does the opposite; it hyperpolarizes the membrane and brings it farther away from threshold.

Anchor neurons and blood vessels, maintain extracellular environment around neurons, assist in the formation of the blood-brain barrier

Astrocytes

Dendrite

Branchlike parts of a neuron that are specialized to receive information.

Ciliated cells in the CNS that form and circulate cerebrospinal fluid

Ependymal cells

Synaptic cleft

Fluid-filled space at a synapse through which neurotransmitters diffuse

An action potential is generated at the

trigger zone of the axon.

Axon

Process of the neuron that generates and transmits action potentials

Axon terminal

Swollen area found at the end of each telodendrion that contains synaptic vesicles

cell body

The biosynthetic center of the neuron

Neuron

The cells of nervous tissue that generate and transmit action potentials

neuroglial cells

The cells of nervous tissue that surround and support neurons

Multiple sclerosis is a demyelinating disease, in which the patient's immune system attacks and destroys the cells that form the myelin sheath in the central nervous system. What types of symptoms would you expect from such a disease? Why? Would Schwann cells or oligodendrocytes be affected? Explain

The myelin sheath increases the speed of action potential conduction within the CNS. As MS results in the destruction of the myelin sheath, it causes slowing of action potential conduction. This causes muscle weakness and eventual paralysis and can cause cognitive impairment. MS affects oligodendrocytes because these neuroglial cells myelinate axons of the CNS.

Postsynaptic neuron

The neuron that receives the message; its plasma membrane contains receptors for neurotransmitters

Presynaptic neuron

The neuron that sends the message; its axon terminals contain synaptic vesicles with neurotransmitters

You are examining another neuron, and find that it has two processes, both of which generate action potentials. What is the structural class of this neuron? How did you come to this conclusion?

This is a pseudounipolar neuron, in which it has two axons, a central process and a peripheral process. Both processes are capable of generating action potentials, and so both are axons.

The neuron pictured is a

multipolar neuron

The bacterium Clostridium tetani produces a toxin called tetanospasmin, the causative agent of the disease tetanus. The toxin prevents the release of inhibitory neurotransmitters in the CNS and so blocks the resulting IPSPs they would normally generate. What are some of the functions of inhibitory synapses? Considering this, what symptoms would you expect from the disease tetanus, and why?

Inhibitory synapses perform several functions, including preventing antagonist muscles from contracting while agonist muscles are simultaneously contracting. When inhibitory synapses are prevented by tetanospasmin, antagonist and agonist muscles contract at the same time. This leads to painful muscle contractures, a situation in which all muscles are in spasm and movement is impossible.

Synapse

Junction between neurons and target cells

Where are synaptic vesicles located?

axon terminals

The main function of an axon is to

generate and transmit signals in the form of action potentials

What triggers exocytosis of synaptic vesicles?

influx of calcium ions into the axon terminal.

Phagocytic cells of the CNS

microglia

Form the myelin sheath in the CNS

oligodendrocytes

Surround the cell bodies of neurons in the PNS

satellite cells