Biology Ch. 26 Vocabulary Definitions

Neuron

Neuron

nerve cell; specialized for carrying messages throughout the nervous system

Stimulus

signal to which an organism responds

Sensory Neuron

type of nerve cell that receives information from sensory receptors and conveys signals to the central nervous system

Interneuron

type of neuron that processes information and may relay information to motor neurons

Response

specific reaction to a stimulus

Motor Neuron

type of nerve cell that carries directions from interneurons to either muscle cells or glands

Ganglion

group of interneurons

Cerebrum

part of the brain responsible for voluntary activities of the body; includes the “thinking” regions of the brain

Cerebellum

part of the brain that coordinates movement and controls balance

Hydrostatic skeleton

skeleton made of fluid-filled body segments work with muscles to allow the animal to move

Exoskeleton

external skeleton; tough external covering that protects and supports the body of many invertebrates

Endoskeleton

internal skeleton; structural support system within the body of an animal

Joint

place where one bone attaches to another bone

Placenta

specialized organ that enables exchange of respiratory gases, nutrients, and wastes between the mother and her developing young

Metamorphosis

a developmental process that involves dramatic changes in shape and form

Amniotic egg

egg composed of shell and membranes that creates a protected environment in which the embryo can develop out of water

Mammary gland

gland in female mammals that produce milk to nourish the young

Endocrine gland

gland that releases its secretions (hormones) directly into the blood, which transports the secretions to other areas of the body

Ectotherm

animal whose body temperatures is determined by the temperature of its environment

Endotherm

animal whose body temperature is regulated, at least in part, using heat generated within its body