Ch. 3 Biological Basis of Behavior

Neurons

Individual nerve cells that make up the central nervous system.

Dendrites

Rootlike parts of the neuron that stretch out from the cell body and make synaptic connections with other neurons.

Cell Body

Contains the nucleus and other parts needed to keep the neuron alive.

Axon

Wire-like structure extending from the cell body, ending in terminal buttons.

Myelin Sheath

A fatty covering around the axon of some neurons.

Terminal Buttons

The branched end of the axon that contains neurotransmitters.

Neurotransmitters

Chemicals that enable neurons to communicate, fitting into receptor sites like a key in a lock.

Nodes of Ranvier

Small gaps between the myelin sheath where neural transmission takes place.

Synapse

The gap between the terminal button and the dendrite.

Action Potentials

An electrical signal that travels down an axon, triggered by neurotransmitters fitting into receptor sites.

All-or-Nothing Principle

Neurons either fire or do not fire.

Serotonin

A neurotransmitter involved in mood, sleep, pain sensitivity, and arousal.

GABA

An inhibitory neurotransmitter.

Glutamate

An excitatory neurotransmitter.

Norepinephrine

A neurotransmitter involved in alertness and arousal.

Afferent Neurons

Sensory neurons that take information from our senses to the spinal cord.

Interneuron

Neurons that relay signals between afferent and efferent neurons in the spinal cord.

Efferent Neurons

Conducting cells that carry information from the central nervous system to muscles and organs.

Reflexes

Quick and involuntary responses to environmental stimuli.

Central Nervous System (CNS)

Composed of the brain and spinal cord.

Peripheral Nervous System (PNS)

Consists of all nerves outside the brain and spinal cord; divided into somatic and autonomic systems.

Somatic Nervous System

Controls voluntary muscle movements.

Autonomic Nervous System

Controls involuntary bodily functions like breathing and heart rate.

Sympathetic Nervous System

Mobilizes the body to respond to stress, known as the Fight or Flight System.

Parasympathetic Nervous System

Responsible for slowing down the body after stress, also called the Rest and Digest System.

Lesions

Removal or destruction of brain tissue, providing clues about brain functions.

Electroencephalogram (EEG)

A test that detects electrical activity in the brain to examine different stages of consciousness.

Computerized Axial Tomography (CAT)

A sophisticated x-ray that creates detailed three-dimensional images of brain structure.

Magnetic Resonance Imaging (MRI)

Uses magnetic fields to measure brain density and location of material without x-ray exposure.

Positron Emissions Tomography (PET)

Allows researchers to see areas of brain activity during tasks using radioactive glucose.

Functional Magnetic Resonance Imaging (fMRI)

Combines MRI and PET scans to show brain structure alongside blood flow and function.

Hindbrain

Controls basic biological functions; includes the medulla, pons, and cerebellum.

Medulla

Controls vital functions such as blood pressure and breathing.

Pons

Connects the hindbrain with the midbrain and forebrain and is involved in facial expressions.

Cerebellum

Coordinates habitual muscle movements, located at the bottom rear of the brain.

Thalamus

Receives sensory signals from the spinal cord and sends them to the appropriate areas of the forebrain.

Hypothalamus

Regulates body temperature, hunger, and biological rhythms.

Hippocampus

Vital for memory processing; memories must pass through here to be encoded.

Amygdala

Important for emotions such as fear and aggression.

Cerebral Cortex

Packed with neurons, it is responsible for higher brain functions and divided into two hemispheres.

Frontal Lobe

Located at the top front of the brain, essential for thought processes and emotional control.

Broca’s Area

In the frontal lobe, it controls the muscles involved in producing speech.

Wernicke’s Area

Located in the temporal lobe, it interprets both written and spoken language.

Parietal Lobe

Contains the sensory cortex, receiving incoming touch sensations.

Motor Cortex

Involved in the planning, control, and execution of voluntary movements.

Sensory Cortex

Processes signals from the sensory receptors in a top-down organized manner.

Temporal Lobe

Processes sound and audio information from the ears.

Occipital Lobe

Processes visual information from the eyes.

Endocrine System

A set of glands that secrete hormones affecting various biological processes.

Adrenal Glands

Produce adrenaline, triggering the fight or flight response.

Reproductive Glands

Ovaries and testes produce sex hormones, influencing behavior and physical development.

Genotype

All possible combinations of genes in an organism.

Phenotype

The observable traits of an organism, resulting from genetic and environmental interactions.

Dominant Trait

A trait that is more likely to be expressed than a recessive trait.

Identical Twins

Develop from one fertilized egg and exhibit genetic similarities.

Turner’s Syndrome

A chromosomal abnormality where an individual has a single X chromosome.

Klinefelter’s Syndrome

A condition in males characterized by an extra X chromosome (XXY).

Down Syndrome

A condition caused by an extra chromosome on the twenty-first pair, leading to distinctive physical traits and intellectual difficulties.