Chapter 13 - Nervous System: Final Exam

How many divisions are there in the nervous system?

2

Central Nervous System (CNS)

Brain and spinal cord

Peripheral Nervous System (PNS)

Nerves and ganglia (collections of cell bodies)

What are the three ways that the nervous system functions by communication between cells?

Sensory input, integration of data, and motor output

What are the two cell types in the nervous system?

Neurons and neuroglia

What are the three types of neurons

Sensory, interneuron, and motor

Sensory Neurons

Takes impulses from sensory receptor to CNS

Interneurons

Receives information in the CNS and sends it to a motor neuron

Motor Neurons

Takes impulses from the CNS to an effector like a gland or a muscle fiber

Cell Body

Main cell where nucleus and most organelles reside

Dendrites

Many short extensions that carry impulses to a cell body

Axon (Nerve Fiber)

Single, long extension that carries impulses away from the cell body

Myelin Sheath

A lipid covering on long axons that acts to increase the speed of nerve impulse conduction, insulation, and regeneration in the PNS

Schwann Cells

Neuroglia that make up the myelin sheath in the PNS

Nodes of Ranvier

Gaps between myelination on the axons

Saltatory Conduction

Conduction of the nerve impulse from node to node

Resting Potential

When the axon is not conducting a nerve impulse

Are there more positive ions on the inside or the outside of the membrane during resting potential?

Outside

What is the charge inside of the axon during resting potential?

-70 mV

Is there more Na⁺ outside or inside the axon during resting potential?

Outside

Is there more K⁺ outside or inside the axon during resting potential?

Inside

Action Potential

Rapid change in axon membrane that allows a nerve impulse to occur

What opens first during action potential?

Sodium gates which let Na⁺ in

What happens when the sodium gates open during action potential?

Depolarization occurs and interior of axon loses negative charge

What does the charge turn into when the sodium gates open during action potential?

-55 mV → +35 mV

What opens after the sodium gates open during action potential?

Potassium gates open letting K⁺ out

What happens when the potassium gates open during action potential?

Repolarization occurs, interior of axon regains negative charge, and wave of depolarization/repolarization travels down the axon

What does the charge turn into when the potassium gates open during action potential?

-70 mV

How is resting potential restored after action potential?

By moving potassium inside and sodium outside

Synapse

A small gap between the sending neuron (presynaptic membrane) and the receiving neuron (postsynaptic membrane)

How is transmission accomplished in a synapse?

Across this gap by a neurotransmitter like ACh, dopamine, or serotonin

Where are neurotransmitters stored?

Synaptic vesicles in the axon terminals