Biology 30 - Nervous System (Unit Test #1)

What is the purpose of the nervous system?

Allow our bodies to read and respond to changes in the external environment

Name the two types of nervous system cells

Neurons and Glial Cells

What is the function of neurons?

Transmits impulses, integrates information

What is the function of Glilal Cells?

Nourish the neurons

What are the three types of neurons?

Sensory, motor, and interneurons

What is the function of sensory neurons?

Send impulses TO the Central Nervous System (ex. smell, taste, hearing, etc.)

What is the function of motor neurons?

Send impulses AWAY from the Central Nervous System (ex. voluntary movement of limbs)

What is the function of interneurons?

Integrate information and generate a response (ex. reflex arcs)

List all parts of the neuron

Dendrite, cell body, axon, myelin sheath, node(s) of Ranvier, Schwann cell, axon terminal, Neurilemma

What is the function of the Dendrite?

Sends impulses to cell body

What is the function of the Cell Body?

Control centre of the neuron

What is the function of the Axon?

Send impulses away from the cell body

What is the function of the Myelin Sheath?

Insulate and protect the axon

What is the function of the Nodes of Ranvier?

Gaps in Myelin Sheath where nerve impulses move

What is the function of Schwann Cells?

Secrete/create the myelin sheath

What is the function of the Axon Terminal?

End of axon; where nerve impulses leave

What is the function of Neurilemma?

Promotes regeneration of Myelin Sheath

What is the difference between a neuron and a nerve?

A neuron is one cell; a nerve is thousands of neurons held together by connective tissue.

What is the name of the process of an impulse traveling through a neuron?

Action Potential

How does action potential move down the neuron? (Brief explanation)

Na+ in high external concentration moves into the axon via Na+ channels. Then, these (Na+) channels close. Next, K+ channels open, and K+ moves out, then these (K+) channels close.

What is a reflex arc?

Involuntary response to an external stimulus.

Does the reflex arc involve the brain?

No, the spinal cord does the integration and response.

List the five parts of the reflex arc (in order by reaction to stimulus)

Receptor, sensory neuron, interneuron, motor neuron, effector.

What is the voltage of resting potential?

-70mV

What is the placement of ions like during resting potential?

Na+ concentrated on the outside, K+ on the inside.

What is the other term for "resting potential"?

Polarized

What is the other term for "action potential"?

Depolarization

What is the refractory period?

A period immediately following stimulation during which a nerve is unresponsive to further stimulation.

Why is the refractory period necessary?

Put Na+ and K+ back into their original locations so another action potential can take place

Why can a nerve impulse only travel in one direction?

After an action potential the placements of Na+ and K+ are inverted, therefore it cannot travel backwards.

What are threshold levels?

The minimum intensity of a stimulus to cause an action potential to occur

What is the all or nothing response?

A neuron either fires or not. All channels open or they don't.

What are the two ways the intensity of a response can increase

-More than one neuron fires

-Neuron fires more per minute

What are the parts of the synapse?

Axon terminal, presynaptic neuron, vesicles, neurotransmitters, dendrites, post-synaptic neuron

How does a nerve impulse cross the synapse?

1. Nerve impulse reaches the axon terminal

2. Vesicles containing neurotransmitters release the neurotransmitter into the empty space

3. Neurotransmitters diffuse across the synapse to receptors on the dendrites of the post-synaptic area

4. Nerve impulse (action potential) is generated in the second neuron

5. Cholinesterase eats away excess neurotransmitters

What is the difference between an excitatory and inhibitory nerve transmission? (Voltage and permeability)

Excitatory - increases permeability to Na+ channels, voltage becomes more positive.

Inhibitory - increases permeability to K+ Channels, voltage becomes more negative.

What is the term to describe a membrane that has received an inhibitory transmission?

Hyperpolarized