Chapter 43: Animal Nervous System

sodium channels

sodium channels

The ________ that trigger action potentials in a neuron are typically located near the place where the axon emerges from the cell body, a site called the axon hillock.

central nervous system

A(n) ________ (CNS) includes large numbers of neurons aggregated into clusters called ganglia.

Neurotoxins

________ are poisons that affect neuron function often resulting in convulsions, paralysis, or unconsciousness.

autoimmune disease multiple sclerosis

The ________ (MS) develops when the immune system targets oligodendrocytes, destroying myelin in the CNS.

brainstem

The ________ connects the brain to the spinal cord and contains the midbrain and parts of the hindbrain.

CNS

All neurons and other components of the nervous system that are outside the ________ are considered part of the peripheral nervous system, or PNS.

Oligodendrocytes

________ and Schwann cells are two examples of glia, which are nervous system cells that support neurons.

Memory

________ is the retention of learned information.

cell body

A(n) ________, or soma, contains the nucleus.

cerebellum

The ________ is a structure in the hindbrain that coordinates complex motor patterns.

sensory information

It relays ________ to the cerebrum and functions in maintaining homeostasis.

synaptic plasticity

A change in the responsiveness or structure of a synapse is termed ________.

volt

The ________ (V) is the standard unit of electrical potential, and a millivolt (mV) is 1 /1000 of a(n) ________.

diencephalon

The ________ is also part of the forebrain.

autonomic center

It is the ________ for regulating cardiovascular, digestive, and other involuntary functions.

efferent division carries

The ________ commands from the CNS to the rest of the body.

diffuse arrangement of cells

The ________ is called a nerve net, is found in cnidarians (jellyfish, hydra, anemones) and ctenophores (comb jellies)

long projections

One or more relatively ________ are called axons.

electrical potential

A difference in charge between any two points creates a(n) ________ or voltage.

Positive feedback

________ is rare in organisms: It can not be employed as a regulatory mechanism under many circumstances, because often leads to uncon oiled events.

Motor neurons

________ and sensory neurons are bundled together into long strands of nervous tissue called nerves.

oligodendrocytes

When ________ or Schwann cells wrap around the axon，they form a myelin sheath, which acts as a type of electrical insulation.

Positive feedback is rare in organisms

It cannot be employed as a regulatory mechanism under many circumstances, because often leads to uncon oiled events