Psychology: Biology and Behavior

Neurons

Neurons

The specialized cells that conduct impulses through the nervous system and contain three major parts -a cell body, dendrites, and an axon.

Cell Body

The part of a neuron that contains the nucleus and carries out the metabolic functions of the neuron.

Dendrites

In a neuron, the branchlike extensions of the cell body that receive signals from other neurons.

Axon

The slender, tail-like extension of the neuron that transmits signals to the dendrites or cell bodies of other neurons and muscles, glands, and other parts of the body.

Axon Terminal

Bulbous end of the axon where signals move from the axon of one neuron to the dendrites or cell bodies of another.

Synapse

The junction where the axon terminal of a sending neuron communicates with a receiving neuron across the synaptic cleft.

Neurotransmitters

Chemical substances that are released into the synaptic cleft from the axon terminal of a sending neuron, cross a synapse, and bind to appropriate receptor sites on the dendrites or cell body of a receiving neuron, influencing the cell either to fire or not to fire.

Dopamine

A neurotransmitter that plays a role in learning, attention, movement, and reinforcement; neurons in the brains of those with Parkinson's disease and schizophrenia are less sensitive to its effects.

Norepinephrine

A neurotransmitter affecting eating, alertness, and sleep.

Epinephrine

A neurotransmitter that affects the metabolism of glucose and causes nutrient energy stored in muscles to be released during strenuous exercise.

Serotonin

A neurotransmitter that plays an important role in regulating mood, sleep, impulsivity, aggression, and appetite.

Glutamate

Primary excitatory neurotransmitter in the brain.

GABA

Primary inhibitory neurotransmitter in the brain.

Endorphins

Chemicals produced naturally by the brain that reduce pain and the stress of vigorous exercise an positively affect mood.

Central Nervous System

The part of the nervous system comprising the brain and the spinal cord.

Peripheral Nervous System

The nerves connecting the central nervous system to the rest of the body.

Spinal Cord

An extension of the brain, from the base of the brain through the next and spinal column, that transmits messages between the brain and the peripheral nervous system.

Hindbrain

A link between the spinal cord and the brain that contains structures that regulate physiological functions, including heart rate, respiration, and blood pressure.

Brainstem

The structure that begins at the point where the spinal cord enlarges as it enters the brain and handles functions critical to physical survival. It includes the medulla, the pons, and the reticular formation.

Medulla

The part of the brainstem that controls heartbeat, blood pressure, breathing, coughing, and swallowing.

Reticular Formation

A structure in the brainstem that plays a crucial role in arousal and attention and that screens sensory messages entering the brain.

Pons

Structure that connects the halves of the cerebellum.

Cerebellum

The brain structure that helps the body execute smooth, skilled movements and regulates muscle tone and posture.

Midbrain

Area that contains structures linking the physiological functions of the hindbrain to the cognitive functions of the forebrain.

Forebrain

The largest part of the brain, where cognitive functions as well as many of the motor functions of the brain are carried out.

Thalamus

The structure, located above the brainstem, that acts as a relay station for information flowing into or out of the forebrain.

Hypothalamus

A small but influential brain structure that regulates hunger, thirst, sexual behavior, internal body temperature, other body functions, and a wide variety of emotional behaviors.

Limbic System

A group of structures in the forebrain, including the amygdala and hippocampus, that are collectively involved in emotional expression, memory, and motivation.

Amygdala

A structure in the limbic system that plays an important role in emotion, particularly in response to unpleasant or punishing stimuli.

Hippocampus

A structure in the limbic system that plays a a central role in the storing of new memories, the response to new or unexpected stimuli, and navigational ability.

Somatic Nervous System

All the sensory and motor neurons that transmit messages between the brain and the parts of the body that make it possible to sense the environment and to move. (e.g., the skin and joints).

Autonomic Nervous System

Nerves that transmit messages between the brain and the parts of the body that are not under voluntary control (e.g., the heart).

Sympathetic Nervous System

The division of the autonomic nervous system that mobilizes the body's resources during stress and emergencies, preparing the body for action.

Parasympathetic Nervous System

The division of the autonomic nervous system that brings the heightened bodily responses back to normal following an emergency.

Cerebrum

The largest structure of the human brain, consisting of the two cerebral hemispheres connected by the corpus callosum and covered by the cerebral cortex.

Cerebral Cortex

The gray, convoluted covering the cerebral hemispheres that is responsible for the higher mental processes of language, memory, and thinking.

Left Hemisphere

The hemisphere that controls the right side of the body, coordinates complex movements, and, in most people, handles most of the language functions.

Right Hemisphere

The hemisphere that controls that left side of the body and, in most people, is specialized for visual-spatial perception.

Split-Brain Operation

A surgical procedure performed to treat severe cases of epilepsy, in which the corpus callosum is cut, separating the cerebral hemispheres.

Frontal Lobes

The largest of the brain's lobes, which contain the motor cortex, Broca's area, and the frontal association areas.

Motor Cortex

The strip of tissue at the rear of the frontal lobes that controls voluntary body movement and participates in learning and cognitive events.

Broca's Area

The area in the frontal lobe, usually in the left hemisphere, that controls the production of speech sounds.

Parietal Lobes

The lobes that contain the somatosensory cortex (where touch, pressure, temperature, and pain register) and other areas that are responsible for body awareness and spatial orientation.

Somatosensory Cortex

The strip of tissue at the front of the parietal lobes where touch, pressure, temperature, and pain register in the cerebral cortex.

Occipital Lobes

The lobes that are involved in the reception and interpretation of visual information; they contain the primary visual cortex.

Temporal Lobes

The lobes that are involved in the reception and interpretation of auditory information; they contain the primary auditory cortex, Wernicke's area, and the temporal association areas.

Wernicke's Area

The language area in the left temporal lobe involved in comprehending the spoken word and in formulating coherent speech and written language.

Pruning

The process through which the developing brain eliminates unnecessary or redundant synapses.

Plasticity

The capacity of the brain to adapt to changes such as brain damage.

Electroencephalogram (EEG)

A record of brain-wave activity made by a machine called the electroencephalograph.

Computerized Axial Tomography (CT Scan)

A brain-scanning technique that uses a rotatin, computerized X-ray tube to produce cross-sectional images of the structures of the brain.

Magnetic Resonance Imaging (MRI)

A diagnostic scanning technique that produces high-resolution images of the structures of the brain.

Position-Emission Tomography (PET Scan)

A brain-imaging technique that reveals activity in various parts of the brain, based on patterns of blood flow, oxygen use, and glucose consumption.

functional MR (fMRI)

A brain-imagining technique that reveals both brain structure and brain activity more precisely and rapidly than PET.

Endocrine System

A system of ductless glands in various parts of the body that manufacture hormones and secrete them into the bloodstream, thus affecting cells in other parts of the body.

Hormones

Chemical substances that are manufactures and released in one part of the body and affect other parts of the body.

Pituitary Gland

The endocrine gland located in the brain that releases hormones that activate other endocrine glands as well as growth hormone; often called the "master gland."

Adrenal Glands

A pair of endocrine glands that release hormones that prepare the body for emergencies and stressful situations and also release corticoids and small amounts of the sex hormones.

Genes

The segments of DNA that are located on the chromosomes and are the basic units of the transmission of all hereditary traits.

Chromosomes

Rod-shaped structures in the nuclei of body cells, which contain all the genes and carry all the genetic information necessary to make a human being.

Genotype

An individual's genetic makeup.

Phenotype

An individual's actual characteristics.

Behavioral Genetics

A field of research that uses twin studies and adoption studies to investigate the relative effects of heredity and environment on behavior.

Testosterone

the most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty. produced by the testes and ovaries

thyroid gland

produces hormones that regulate metabolism, body heat, and bone growth - thyroxine

Epigenetics

the study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself.

identical (monozygotic) twins

develop from a single fertilized egg that splits in two, creating two genetically identical organisms

fraternal twins (dizygotic twins)

twins who develop from separate fertilized eggs. They are genetically no closer than brothers and sisters, but they share a fetal environment.

stress

the reaction of the body and mind to everyday challenges and demands