Biology Vocabulary and Practice Study Set Ch. 27

Dendrite

A short, branched neuron fiber that receives signals and conveys them from its tip inward, toward the rest of the neuron.

What part of a neuron sends the signal to the next neuron?

Axon. (Conducts signals to another neuron or to a muscle or gland cell.)

How are signals sent from one neuron to another?

Neurotransmitters.

What is the basic anatomy of a neuron

1. Cell body 2. Dendrites 3. Axon 4. Myelin Sheath 5. Nucleus 6. Synpatic Terminals

Myelin Sheath

A chain of bead-like supporting cells that insulate the axon of a nerve cell in vertebrates. This insulation helps to speed electrical transmission along the axon.

Neurotransmitter

A chemical messenger that carries information from a transmitting neuron to a receiving cell, which is another neuron, muscle cell, or gland cell.

Synapse

A junction, or relay point, between two neurons: or between a neuron and a muscle, or gland cell. Electrical and chemical signals are relayed from one cell to another at a synapse.

Synaptic Cleft

A narrow gap at a synapse separating the synaptic terminal of a transmitting neuron from a receiving cell, which is another neuron, a muscle cell, or a gland cell.

Neuron

A nerve cell; The fundamental structural and functional unit of the nervous system, specialized for carrying signals from one location in the body to another.

Axon

A neuron fiber that extends from the cell body and conducts signals to another neuron or to a muscle or gland cell.

Action potential

A self-propagating change in the voltage across the plasma membrane of a neuron; A nerve signal that carries information along a neuron.

What part of a neuron receives the signal from the previous neuron?

Dendrites extend from the cell body and receive nerve impulses from other neurons.

Do neurons actually touch?

No, they do not physically touch, they are separated by the synaptic cleft.

In general terms, how does an action potential happen and propagate down a neuron?

Stimulating the neuron's plasma membrane can trigger the use of the membrane's potential energy. It is like tipping a domino in a standing row; There is a change in polarity across the membrane. If the stimulus is strong enough, a sufficient number of Ion channels open and close as the membrane reaches the threshold potential, allowing more positive ions to rush in and to diffuse.

Synapatic Terminal

The bulb-like structure at the tip of a transmitting neuron's axon, where signals are sent to another neuron or to muscle or gland cell.

Resting potential

The voltage across the plasma membrane of a resting neuron, positively charged outside and negatively charged inside.