Heredity: The passing of traits from parents to offspring, either through asexual or sexual reproduction.

Evolutionary perspective: A psychological approach that emphasizes the role of evolutionary processes in shaping behavior and mental processes.

Natural selection: The process by which organisms better adapted to their environment tend to survive and produce more offspring.

Eugenics: A social philosophy advocating for the improvement of the genetic quality of the human population, often through selective breeding.

Central nervous system (CNS): The part of the nervous system consisting of the brain and spinal cord, responsible for processing and transmitting information.

Peripheral nervous system (PNS): The part of the nervous system outside the CNS, including nerves and ganglia, that connects the CNS to limbs and organs.

Autonomic nervous system: A subdivision of the PNS that controls involuntary functions like heart rate, digestion, and respiratory rate.

Somatic nervous system: The part of the PNS that controls voluntary movements and transmits sensory and motor information to and from the CNS.

Sympathetic nervous system: A division of the autonomic nervous system that prepares the body for "fight or flight" responses during stressful situations.

Parasympathetic nervous system: A division of the autonomic nervous system that promotes "rest and digest" functions, conserving energy and calming the body.

Glial cells: Non-neuronal cells in the nervous system that support and protect neurons, playing roles in nutrient supply and maintenance of the extracellular environment.

Reflex arc: The neural pathway that controls a reflex, involving sensory input, processing in the spinal cord, and motor output without involving conscious brain activity.

Sensory neurons: Neurons that transmit sensory information (e.g., touch, pain, temperature) from receptors to the CNS.

Motor neurons: Neurons that transmit signals from the CNS to muscles or glands to initiate movement or actions.

Interneurons: Neurons that connect sensory and motor neurons within the CNS, playing a role in reflexes and neural communication.

All-or-Nothing principle: The concept that a neuron either fully fires or does not fire at all; action potentials have the same strength regardless of stimulus intensity.

Depolarization: A reduction in the electrical charge difference across a cell membrane, typically leading to an action potential.

Refractory period: The period following an action potential during which a neuron is unable to fire again until it returns to its resting state.

Resting potential: The electrical charge across the membrane of a neuron when it is not active, typically around -70 mV.

Reuptake: The process by which neurotransmitters are absorbed back into the presynaptic neuron after being released into the synapse, stopping the signal transmission.

Multiple sclerosis (MS): A chronic disease affecting the CNS, where the immune system attacks the myelin sheath covering nerves, leading to communication problems between the brain and body.

Myasthenia gravis: An autoimmune disorder where antibodies block or destroy acetylcholine receptors, leading to muscle weakness and fatigue.

Dopamine: A neurotransmitter involved in regulating mood, pleasure, and reward, as well as motor control.

Serotonin: A neurotransmitter involved in mood regulation, sleep, appetite, and emotional well-being.

Norepinephrine: A neurotransmitter and hormone involved in arousal, attention, and the fight-or-flight response.

Glutamate: The most abundant excitatory neurotransmitter in the CNS, involved in cognitive functions like learning and memory.

GABA (gamma-aminobutyric acid): The primary inhibitory neurotransmitter in the CNS, reducing neuronal excitability and helping control anxiety and stress.

Endorphins: Neurotransmitters that act as natural painkillers, reducing pain and promoting feelings of pleasure or well-being.

Acetylcholine: A neurotransmitter involved in muscle contraction, memory, and learning.

Substance P: A neurotransmitter involved in transmitting pain signals to the brain.

Leptin: A hormone that regulates energy balance by inhibiting hunger, often called the "satiety hormone."

Ghrelin: A hormone that stimulates appetite, often called the "hunger hormone."

Melatonin: A hormone produced by the pineal gland that regulates sleep-wake cycles.

Oxytocin: A hormone and neurotransmitter involved in social bonding, reproduction, childbirth, and trust.

Agonist: A substance that binds to a receptor and activates it, mimicking the effect of a neurotransmitter.

Antagonist: A substance that binds to a receptor but blocks or dampens the effect of a neurotransmitter.

Stimulants: Drugs that increase nervous system activity, leading to increased alertness, energy, and mood (e.g., caffeine, amphetamines).

Depressants: Drugs that decrease nervous system activity, leading to relaxation and reduced anxiety (e.g., alcohol, benzodiazepines).

Hallucinogens: Drugs that cause perceptual distortions, hallucinations, and altered sensory experiences (e.g., LSD, psilocybin).

Medulla: The lower part of the brainstem that controls vital life-sustaining functions such as breathing, heart rate, and blood pressure.

Reticular activating system (RAS): A network of neurons in the brainstem involved in arousal and regulating wakefulness and sleep.

Cerebellum: The part of the brain involved in coordination, balance, and fine motor skills.

Cerebral cortex: The outer layer of the brain, responsible for complex cognitive functions, including thought, perception, and decision-making.

Limbic system: A group of brain structures involved in emotions, memory, and motivation, including the hippocampus and amygdala.

Thalamus: A brain structure that acts as a relay station for sensory information, directing it to the appropriate areas of the cortex.

Hypothalamus: A small region of the brain involved in regulating body temperature, hunger, thirst, and other homeostatic functions, as well as linking the nervous and endocrine systems.

Pituitary gland: The "master gland" of the endocrine system, regulating hormone production and secretion in other glands.

Hippocampus: A brain structure involved in the formation and retrieval of long-term memories.

Amygdala: A brain structure involved in processing emotions, particularly fear and aggression.

Corpus callosum: A bundle of nerve fibers connecting the two hemispheres of the brain, enabling communication between them.

Occipital lobes: The region of the brain responsible for processing visual information.

Parietal lobes: The region of the brain responsible for processing sensory information related to touch, temperature, and body position.

Temporal lobes: The region of the brain involved in processing auditory information and memory.

Frontal lobes: The region of the brain involved in decision-making, problem-solving, planning, and voluntary movement.

Association areas: Regions of the cerebral cortex that integrate information from various parts of the brain, involved in higher cognitive functions.

Somatosensory cortex: A part of the parietal lobe that processes sensory information from the body, including touch, pressure, and pain.

Motor cortex: A part of the frontal lobe that controls voluntary movements.

Broca’s area/aphasia: A region in the frontal lobe responsible for speech production; damage to this area results in Broca’s aphasia, characterized by difficulty in producing speech.

Wernicke’s area/aphasia: A region in the temporal lobe responsible for language comprehension; damage results in Wernicke’s aphasia, characterized by difficulty understanding language.

Brain plasticity: The brain's ability to change and adapt by forming new neural connections, particularly after injury or in response to learning.

EEG (Electroencephalogram): A test that measures electrical activity in the brain, often used to study sleep patterns and diagnose epilepsy.

fMRI (Functional Magnetic Resonance Imaging): A brain imaging technique that measures blood flow to different parts of the brain to identify areas of activity.

Left hemisphere: The left side of the brain, typically involved in language, logical thinking, and analytical tasks.

Right hemisphere: The right side of the brain, typically involved in spatial abilities, face recognition, and creativity.

N-REM 1-3: The non-rapid eye movement stages of sleep, from light sleep (NREM-1) to deep sleep (NREM-3), where restorative processes occur.

REM (Rapid Eye Movement): The stage of sleep characterized by rapid eye movements, vivid dreams, and increased brain activity.

Circadian rhythm: The body's internal clock that regulates sleep-wake cycles, typically on a 24-hour cycle.

Hypnogogic sensations: Vivid, dream-like sensations that occur as a person is falling asleep.

REM rebound: The phenomenon where the amount of REM sleep increases following periods of REM sleep deprivation.

Insomnia: A sleep disorder characterized by difficulty falling asleep or staying asleep.

REM sleep behavior disorder: A sleep disorder in which a person physically acts out vivid dreams during REM sleep, often involving violent movements.

Sleep apnea: A disorder characterized by repeated interruptions in breathing during sleep, often leading to poor sleep quality.

Narcolepsy: A sleep disorder characterized by excessive daytime sleepiness and sudden, uncontrollable episodes of falling asleep.

Somnambulism (sleepwalking): A disorder in which a person walks or performs other activities while asleep, usually during deep sleep.

Activation synthesis theory: A theory suggesting that dreams are the brain's attempt to make sense of random neural activity during sleep.