Biology 30: Nervous System and Neuron

What are the 2 main divisions of the nervous system?

Central nervous system (CNS) and peripheral nervous system (PNS).

What makes up the CNS?

Brain and spinal cord.

What makes up the PNS?

Nerves outside the brain and spinal cord.

What are the 2 divisions of the PNS?

Somatic and autonomic nervous systems.

What does the somatic nervous system control?

Voluntary actions and skeletal muscles.

What does the autonomic nervous system control?

Involuntary body functions.

What are the 2 divisions of the autonomic nervous system?

Sympathetic and parasympathetic.

What does the sympathetic nervous system do?

Prepares the body for intense activity ("fight or flight").

What does the parasympathetic nervous system do?

Relaxes the body ("rest and digest").

What is a neuron?

An electrically excitable cell that processes and transmits information.

What do dendrites do?

Receive stimuli and transfer information to the neuron.

What does the cell body do?

Powers and nourishes the neuron.

What does the axon do?

Carries electrical impulses away from the cell body.

What does myelin do?

Insulates the axon and speeds up impulse transmission.

What do Schwann cells make?

Myelin.

What are nodes of Ranvier?

Gaps in the myelin sheath that speed up impulse transmission.

What are synaptic knobs (axon terminals)?

The ends of the axon where signals transfer to another neuron or muscle.

What is the neurilemma?

A structure used to regenerate damaged neurons.

Where is the neurilemma found?

Only in the PNS.

What is white matter?

Myelinated parts of neurons.

Where is white matter found?

In the CNS.

What is grey matter?

Unmyelinated parts of neurons.

Where is grey matter found?

In the CNS.

What is a reflex arc?

The simplest nerve pathway that produces a quick response.

Does a reflex arc require coordination by the brain?

No; the spinal cord coordinates the response.

What is the order of a reflex arc?

Receptor → sensory neuron → interneuron → motor neuron → effector.

What does the receptor do in a reflex arc?

Receives the stimulus.

What does the sensory neuron do?

Carries information from the receptor to the spinal cord.

What does the interneuron do?

Relays information to a motor neuron.

What does the motor neuron do?

Carries the impulse to the effector.

What does the effector do?

Produces the response.