Biopsychology

Neurons

Specialized cells that transmit electrical impulses and translate them into chemical signals.

Soma (Cell Body)

Contains the neuron’s nucleus and maintains cell health.

Dendrites

Receive incoming messages from other neurons.

Axon Hillock

Integrates signals from the soma and determines if an action potential will be fired.

Axon

Carries electrical impulses away from the soma to other neurons, muscles, or glands.

Myelin Sheath

Fatty covering on the axon that increases the speed of neural transmission.

Nodes of Ranvier

Gaps in the myelin sheath where ion exchange occurs during impulse transmission.

Nerve Terminal

End of axon that releases neurotransmitters to communicate with other neurons.

Synaptic Cleft

Gap between presynaptic and postsynaptic neurons where neurotransmitters travel.

Synapse

The junction including presynaptic terminal, synaptic cleft, and postsynaptic membrane.

Sensory Neurons (Afferent)

Carry sensory information from receptors to the CNS.

Motor Neurons (Efferent)

Carry motor commands from the CNS to muscles and glands.

Interneurons

Connect neurons within the CNS; involved in reflexes.

Multipolar Neuron

Neuron with multiple extensions from the soma.

Bipolar Neuron

Neuron with two extensions.

Unipolar Neuron

Neuron with one extension.

Astrocytes

Glial cells that nourish neurons and form the blood-brain barrier.

Ependymal Cells

Line ventricles and produce cerebrospinal fluid (CSF).

Microglia

Phagocytic cells that remove waste and pathogens from the CNS.

Oligodendrocytes

Produce myelin in the CNS.

Schwann Cells

Produce myelin in the PNS.

Resting Potential

The difference in charge across a neuron’s membrane, typically -70mV.

Depolarization

Increase in membrane potential due to excitatory input.

Hyperpolarization

Decrease in membrane potential due to inhibitory input.

Threshold

The membrane potential (around -55mV) needed to trigger an action potential.

Repolarization

Restoration of negative membrane potential after depolarization.

Refractory Period

Period after firing when a neuron cannot fire again.

Saltatory Conduction

Jumping of action potential between nodes of Ranvier.

Neurotransmitters

Chemical messengers released from neurons to communicate across synapses.

Reuptake

Process where neurotransmitters are reabsorbed by the presynaptic neuron.

Enzymatic Degradation

Breakdown of neurotransmitters by enzymes (e.g., ACh by acetylcholinesterase).

Acetylcholine (ACh)

Enables muscle action, learning, and memory; low levels linked to Alzheimer’s.

Dopamine

Influences movement, learning, attention, emotion; excess linked to schizophrenia, low to Parkinson’s.

Serotonin

Affects mood, hunger, sleep; low levels linked to depression.

Norepinephrine

Controls alertness and arousal; low levels can depress mood.

GABA

Main inhibitory neurotransmitter; low levels cause seizures, tremors, insomnia.

Glutamate

Main excitatory neurotransmitter; oversupply causes migraines or seizures.

Endorphins

Natural painkillers and pleasure enhancers; oversupply from opioids suppresses natural production.

Agonist

Molecule that increases a neurotransmitter’s action.

Antagonist

Molecule that blocks or inhibits a neurotransmitter’s action.

Central Nervous System (CNS)

Brain and spinal cord; controls decision-making.

Peripheral Nervous System (PNS)

Connects the CNS to the body via sensory and motor neurons.

Somatic Nervous System

Controls voluntary skeletal muscle movement.

Autonomic Nervous System (ANS)

Controls involuntary functions (glands, organs).

Sympathetic Nervous System

Arouses body and expends energy (fight-or-flight).

Parasympathetic Nervous System

Calms the body and conserves energy (rest-and-digest).

Endocrine System

Glands that secrete hormones into the bloodstream.

Pituitary Gland

Master gland that controls hormone release.

Hypothalamus

Links nervous and endocrine systems; regulates hunger, thirst, temperature, and sex drive.

Cortisol

Stress hormone released by adrenal glands; increases blood sugar.

Brainstem

Central core of the brain; controls automatic survival functions.

Medulla

Regulates heartbeat and breathing.

Pons

Coordinates movement and controls sleep.

Cerebellum

“Little brain”; coordinates movement, balance, and nonverbal learning.

Reticular Formation

Filters information and controls arousal.

Thalamus

Directs sensory messages to the cortex and transmits replies to the cerebellum and medulla.

Amygdala

Processes emotions such as fear and aggression.

Hippocampus

Forms and processes conscious memories; shrinks with age.

Cerebral Cortex

Outer layer of the brain; responsible for higher thought and processing.

Frontal Lobe

Involved in movement, speaking, planning, and decision-making.

Parietal Lobe

Processes sensory information from touch and body position.

Occipital Lobe

Processes visual information.

Temporal Lobe

Processes auditory information.

Motor Cortex

Controls voluntary muscle movements.

Somatosensory Cortex

Receives sensory input from the body.

Visual Cortex

Processes visual input.

Auditory Cortex

Processes sound input.

Association Areas

Integrate information; involved in judgment, planning, and memory.

Lateralization

Specialization of brain hemispheres.

Left Hemisphere

Responsible for language and positive emotions.

Right Hemisphere

Handles spatial abilities and negative emotions.

Brain Plasticity

Brain’s ability to adapt or reorganize, especially during development.

EEG (Electroencephalogram)

Records electrical activity of the brain.

ERP (Event-Related Potential)

Measures brain response to specific stimuli.

CAT Scan

X-ray that provides detailed 2D brain images.

MRI

Uses magnetic fields to create clear 3D brain images.

DTI (Diffusion Tensor Imaging)

Measures integrity of white matter.

PET Scan

Uses radioactive tracer to show brain activity via blood flow.

fMRI

Measures brain activity by detecting oxygenated blood flow.