Chapter 3

The brief wave of electrical charge that sweeps down the axon during the transmission of a nerve impulse.

Important endocrine glands that are instrumental in regulating moods, energy level, and the ability to cope with stress.

Sensory nerves that transport information to the brain.

A drug that mimics or increases a neurotransmitter's effects.

Once an electrical impulse reaches a certain level of intensity, it fires and moves all the way down the axon without losing any of its intensity.

A drug that blocks a neurotransmitter's effects.

Region of the cerebral cortex in which the highest intellectual functions, including thinking and problem solving, occur; also called association areas.

The division of the PNS that communicates with the body’s internal organs. It consists of the sympathetic and parasympathetic nervous systems.

The part of the neuron that carries information away from the cell body to other cells.

Large clusters of neurons, located above the thalamus and under the cerebral cortex, that work with the cerebellum and the cerebral cortex to control and coordinate voluntary movements.

The region of the brain that includes most of the hindbrain (excluding the cerebellum) and the midbrain.

The part of the neuron that contains the nucleus, which directs the manufacture of substances that the neuron needs for growth and maintenance.

The brain and spinal cord.

Highest level of the forebrain, where the highest mental functions, such as thinking and planning, take place.

Threadlike structures that contain genes and DNA. Humans have 23 chromosome pairs in the nucleus of every cell. Each parent contributes one chromosome to each pair.

The large bundle of axons that connects the brain’s two hemispheres.

Branches of a neuron that receive and orient information toward the cell body; most neurons have numerous dendrites.

A complex molecule that contains genetic information; makes up chromosomes.

principle The principle that, if one gene of a pair governing a given characteristic (such as eye color) is dominant and one is recessive, the dominant gene overrides the recessive gene. A recessive gene exerts its influence only if both genes in a pair are recessive.

Motor nerves that carry the brain's output.

A set of glands that regulate the activities of certain organs by releasing their chemical products (hormones) into the bloodstream.

The highest level of the brain. Key structures in the forebrain are the limbic system, thalamus, basal ganglia, hypothalamus, and cerebral cortex.

The part of the cerebral cortex just behind the forehead that is involved in the control of voluntary muscles, intelligence, and personality.

The units of hereditary information. They are short segments of chromosomes, composed of DNA.

An individual's genetic heritage; his or her actual genetic material.

Cells that provide support and nutritional benefits in the nervous system.

The lowest portion of the brain, consisting of the medulla, cerebellum, and pons.

Chemical messengers manufactured by the endocrine glands.

Small forebrain structure involved in regulating eating, drinking, and sex; directing the endocrine system; and monitoring emotion, stress, and reward.

Loosely connected network of structures—including the amygdala and hippocampus—that play important roles in memory and emotion.

Located between the hindbrain and forebrain, a region in which many nerve-fiber systems ascend and descend to connect the higher and lower portions of the brain.

Area of the cerebral cortex that processes information about voluntary movement.

The layer of fat cells that encases and insulates most axons. The myelin sheath speeds up the transmission of nerve impulses.

The body's electrochemical communication circuitry, made up of billions of neurons.

Networks of nerve cells that integrate sensory input and motor output.

Nerve cells that are specialized for processing information. Neurons are the basic units of the nervous system.

Chemicals that carry information across the synaptic gap from one neuron to the next.

The part of the cerebral cortex at the back of the head that is involved in vision.

The division of the autonomic nervous system that calms the body.

Area of the cerebral cortex at the top of the head that is involved in registering spatial location, attention, and motor control.

The network of nerves that connects the brain and spinal cord to other parts of the body. It is divided into the somatic nervous system and the autonomic nervous system.

The expression of an individual’s genotype in observable, measurable characteristics.

An important endocrine gland at the base of the skull that controls growth and regulates other glands.

The brain's special capacity for modification and change.

The stable, negative charge of an inactive neuron.

A midbrain system that consists of a diffuse collection of neurons involved in stereotypical behaviors, such as walking, sleeping, or turning to attend to a sudden noise.

The division of the PNS consisting of sensory nerves, whose function is to convey information to the CNS, and motor nerves, whose function is to transmit information to the muscles.

Area of the cerebral cortex that processes information about body sensations.

The response of individuals to changes in circumstances and events that threaten their coping abilities.

Circumstances and events that threaten individuals and tax their coping abilities

The division of the autonomic nervous system that arouses the body.

Tiny junctions between two neurons, generally where the axon of one neuron meets the dendrites or cell body of another neuron.

The portion of the cerebral cortex just above the ears that is involved in hearing, language processing, and memory.

• Forebrain structure that functions as a relay station to sort information and send it to appropriate areas in the forebrain for further integration and interpretation.