Psych 2e Chapter 3

Gene

A sequence of DNA that controls or partially controls physical and psychological traits.

Allele

A specific version of a gene.

Gene

A sequence of DNA that controls or partially controls physical and psychological traits.

Allele

A specific version of a gene.

Chromosome

A long strand of genetic information made up of DNA.

Genotype

A person’s genetic makeup.

Phenotype

A person’s observable physical characteristics.

Dominant allele

An allele whose trait is expressed whenever it is present.

Recessive allele

An allele whose trait is expressed only when a person is homozygous for that allele.

Homozygous

Having two identical alleles for a given trait.

Heterozygous

Having two different alleles for a given trait.

Mutation

A sudden, permanent change in the sequence of DNA.

Epigenetics

The study of how genes and the environment interact to influence phenotype.

Polygenic

Characteristic influenced by multiple genes.

Range of reaction

The idea that genes set boundaries and the environment determines where within them a person falls.

Neuron

A nervous system cell that processes and transmits information through electrical and chemical signals.

Glial cell

A supportive cell in the nervous system that helps neurons and maintains homeostasis.

Soma

The cell body of a neuron containing the nucleus.

Dendrite

Branch-like extensions of the neuron that receive information.

Axon

The extension of a neuron that sends electrical impulses.

Myelin sheath

A fatty layer that insulates axons and speeds neural transmission.

Node of Ranvier

Gaps in the myelin sheath that facilitate rapid signal conduction.

Terminal button

The endpoint of an axon where neurotransmitters are released.

Synaptic vesicle

A small sac in the terminal button that stores neurotransmitters.

Neurotransmitter

A chemical messenger released by neurons at the synapse.

Receptor

A protein on the neuron’s surface that binds neurotransmitters.

Synaptic cleft

The narrow gap between neurons at a synapse.

Action potential

The electrical signal that moves down the axon following an all-or-none principle.

All-or-none principle

The concept that once initiated, an action potential travels full strength.

Resting potential

The electrical charge difference across a neuron’s membrane when inactive.

Membrane potential

The charge difference across the neuronal membrane at any given moment.

Reuptake

The process of neurotransmitter molecules being reabsorbed into the sending neuron.

Agonist

A drug or molecule that mimics or enhances a neurotransmitter’s effect.

Antagonist

A drug or molecule that blocks or diminishes a neurotransmitter’s effect.

Dopamine

A neurotransmitter involved in mood, motivation, reward, and motor control; associated with Parkinson’s disease and schizophrenia.

Serotonin

A neurotransmitter involved in mood regulation, sleep, and appetite; low levels are linked to depression.

Acetylcholine

A neurotransmitter involved in muscle movement, memory, and learning; deficits linked to Alzheimer’s disease.

Norepinephrine

A neurotransmitter important for arousal and alertness; also functions as a hormone.

GABA (gamma-aminobutyric acid)

The brain's main inhibitory neurotransmitter; reduces neuronal excitability and anxiety.

Glutamate

The brain's main excitatory neurotransmitter; involved in learning and memory.

Endorphins

Natural pain-relieving neurotransmitters; linked to pleasure and exercise.

Biological perspective

The view that biological processes influence behavior and disorders.

Central nervous system (CNS)

The brain and spinal cord.

Peripheral nervous system (PNS)

The network of nerves that connects the CNS to the body.

Somatic nervous system

The PNS division transmitting sensory and motor signals to and from the CNS.

Autonomic nervous system

The PNS division controlling internal organs and glands.

Sympathetic nervous system

The “fight or flight” branch of the autonomic nervous system.

Parasympathetic nervous system

The “rest and digest” branch of the autonomic nervous system.

Fight-or-flight response

The body's automatic response to stress via sympathetic activation.

Frontal lobe

Region of the cerebral cortex involved in reasoning, motor control, emotion, and language.

Parietal lobe

Region that processes sensory information such as touch, temperature, and pain.

Temporal lobe

Region associated with hearing, memory, emotion, and language.

Occipital lobe

The visual processing center of the brain.

Motor cortex

The strip of cortex that controls voluntary movement.

Somatosensory cortex

The strip of cortex that processes sensory information from the body.

Gyrus

A ridge on the cerebral cortex.

Sulcus

A groove on the cerebral cortex.

Longitudinal fissure

The deep groove separating the brain's two hemispheres.

Corpus callosum

The band of neural fibers connecting the hemispheres.

Forebrain

The brain area containing the cortex, thalamus, and limbic system.

Thalamus

A sensory relay station for all senses except smell.

Limbic system

A set of brain structures involved in emotion and memory.

Amygdala

A structure in the limbic system involved in emotion and fear.

Hippocampus

A limbic structure critical for learning and memory.

Midbrain

The region between forebrain and hindbrain; includes reticular formation.

Reticular formation

A structure essential for sleep/wake cycles and arousal.

Substantia nigra

A midbrain structure that produces dopamine and helps control movement.

Ventral tegmental area (VTA)

A dopamine-producing area involved in mood, reward, and addiction.

Hindbrain

The rear part of the brain; includes brainstem and cerebellum.

Brainstem

The structure controlling automatic functions like breathing and heartbeat.

Medulla

A brainstem structure that controls vital functions like breathing and heart rate.

Pons

A brainstem structure involved in sleep regulation and relaying neural signals.

Cerebellum

A hindbrain structure that coordinates movement and procedural memory.

Neuroplasticity

The ability of the nervous system to change structure and function in response to experience.

Electroencephalography (EEG)

A method to record electrical activity of the brain via scalp electrodes.

CT scan (Computerized Tomography)

An imaging technique using X-rays to create brain structure images.

PET scan (Positron Emission Tomography)

A method that uses mild radioactive tracers to visualize brain activity.

MRI (Magnetic Resonance Imaging)

A method using magnetic fields to create detailed brain images.

fMRI (Functional Magnetic Resonance Imaging)

An MRI variant that shows changes in brain activity by tracking blood flow.

Endocrine system

A collection of glands that release hormones to regulate body functions.

Hormone

A chemical messenger secreted by endocrine glands and carried through the bloodstream.

Gland

An organ that produces and releases hormones.

Hypothalamus

A brain structure that links the nervous and endocrine systems and regulates homeostasis.

Pituitary gland

The "master gland" that controls hormone secretion by other glands.

Thyroid gland

A gland that secretes thyroxine for metabolism and growth.

Adrenal gland

A gland producing stress-related hormones like adrenaline and cortisol.

Pancreas

A gland that secretes insulin and glucagon to regulate blood sugar.

Gonads

The sex glands (ovaries and testes) that produce hormones affecting reproduction and behavior.

Adrenaline (epinephrine)

A hormone and neurotransmitter involved in the fight-or-flight response.

Cortisol

A hormone released by the adrenal glands in response to stress; increases blood sugar and suppresses the immune system.

Homeostasis

The maintenance of internal biological balance.