Biopsychology Anatomical Terms - Fall 2026

Membrane

surface of the cell separating it from the outside environment

Nucleus

contains chromosomes/genetic material

Mitochondrion

performs metabolic activities and provides energy, has mtDNA separate from autosomal DNA

Ribosomes

synthesize new protein molecules

endoplasmic reticulum

network of thin tubes to transport synthesized proteins

Neuron

Brain cells

Motor Neurons

conducts impulses along axon to a muscle

Sensory Neurons

specialized, highly sensitive to a type of stimulation

Dendrites

branching fibers lined with synaptic receptors to receive information from other neurons. The greater the surface area, the more information it can receive.

Dendritic spines

small nubs along dendrites that increase the surface area

Soma

cell body of a neuron, containing the nucleus, ribosomes, and mitochondria -- the center for metabolic work

Axon

thin fiber with consistent diameter, conveys electrical impulse toward other neurons, organ, or a muscle

Myelin sheath

insulating material on vertebrate axons with interruptions called Nodes of Ranvier, lipids/fatty tissue

Nodes of Ranvier

interruptions along the myelin sheath of a neuron

Presynaptic Terminal

swelling on the end of axon branches where exons release chemicals that cross through junction between neuron cells

Efferent Axon

carries information away from a structure

Afferent Axon

brings information to a structure

intrinsic neuron

when a neuron cell's axons and dendrites are entirely contained within a single structure

Glia

non-neuronal cells in the brain that use chemical signaling instead of electrical signaling

Astrocytes

star-shaped glia that wrap around synapses of functionally related neurons, shielding them from chemicals. They take up and re-release ions released by axons. They synchronize closely related neurons, enabling message waves and rhythm mechanisms. They also dilate blood vessels in the brain to increase nutrient flow and activity of neurons

Tripartite Synapse

when the tips of an axon releasing chemicals causes a neighboring astrocyte to release its own chemicals, magnifying or modifying the message to the next neuron

Microglia

immune agents of the brain, they remove virus/fungi, dead or damaged neurons post brain damage, and the weakest synapses.

Oligodendrocytes

In the CNS, build myelin sheaths that insulate axons and supply axons with nutrients

Schwann Cells

In the PNS, build myelin sheaths that insulate axons and supply axons with nutrients

Radial Glia

guide the migration of new neurons during embryonic development, and they turn to neurons/astrocytes/oligodendrocytes after that stage of brain development is finished

Active transport

protein-mediated process, expending energy to pump chemicals from the blood into the brain

Sodium-Potassium Pump

protein complex that transports sodium ions out and potassium ions into the neuron using active transport

Action Potential

electrical messages sent by axons

Central Nervous System (CNS)

the brain and spinal cord

Peripheral Nervous System (PNS)

motor and sensory neurons

Extracellular fluids

salty from sodium, fluids in the body not contained in cells

Reflex Arc

the circuit from a sensory neuron to muscle response, found by Charles Scott Sherrington

Presynaptic Neuron

neuron that delivers transmission in reflex arc

Postsynaptic Neuron

neuron that receives transmission in reflex arc

Interneuron

an intermediate neuron or relay neuron, specialized nerve cells that connect other neurons in the CNS, mainly linking sensory neurons to motor neurons

Neurotransmitters

chemicals that affect another neuron

Vesicles

tiny, nearly spherical packets where neurotransmitters are stored

Glutamate

most abundant excitatory neurotransmitter released by nerve cells in your brain, found in ctenophores/least-evolved creatures like jellies as well as other animals, meaning it evolved very early on

Nitric Oxide

neurotransmitter that dilates blood vessels, increasing blood flow to the brain

Catecholamines

compounds containing a catechol and an amine group

Tryptophane

precursor to serotonin

Insulin

takes competing amino acids against tryptophane out of the bloodstream and into body cells, has high permeability

L-DOPA

precursor to dopamine and increases dopamine, used as treatment for Parkinson's Disease

MAO

monoaminoxidase, breaks down serotonin, dopamine, or norepinephrine after synaptic signaling

GABA

gamma-aminobutyric acid, used in most inhibitory ionotropic(fast-acting) synapses but also in some metabotropic

Glycine

common inhibitory transmitter found primarily in the spinal cord

Acetylcholine

often excitatory and found in many ionotropic(fast-acting) synapses, widens the sodium channels

Dopamine

neurotransmitter known for its role in the "reward system", metabotropic(slow-acting) processes

Norepinephrine

neurotransmitter also known as adrenaline, used in metabotropic synapses

Serotonin

neurotransmitter used in metabotropic processes, carries messages between nerve cells in the brain and throughout your body

Monoamine Neurotransmitter

neurotransmitters and neuromodulators that contain one amino group connected to an aromatic ring by a two-carbon chain. Examples are dopamine, norepinephrine and serotonin.

G Protein

protein coupled to guanosine triphosphate(GTP), an energy storing molecule. It results in increased second messaging concentration during a synaptic reaction

Neuropeptide/neuromodulators

synthesized in the cell body and slowly transported to other parts of the cell, released by dendrites and other parts of the neuron. They require repeated stimulation to be released

Synapse

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron

Ionotropic Receptors

allow change in postsynaptic cell to happen directly and quickly, ligand-gated ion channels open

Metabotropic Receptors

allow change after postsynaptic cell to happen gradually and more indirectly, through a sequence of cellular messages

Monoamines

serotonin, dopamine, norepinephrine, and epinephrine; associated with movement, learning, memory, mood, etc..

Lamina

row or layer of cell bodies separated from other cell bodies by a layer of axons and dendrites

Column

a set of cells perpendicular to the surface of the cortex, with similar properties

Tract

set of axons within the CNS, also known as a projection, they extend from one structure to another

Nerve

set of axons in the PNS, either from the CNS to a muscle/gland or from a sensory organ to the CNS

Nucleus (neuroanatomy)

cluster of neuron cell bodies within the CNS

Ganglion

cluster of neuron call bodies usually outside the CNS (in the sympathetic nervous system)

Gyrus

protuberance/bump on the brain surface

Sulcus

fold/groove separating gyruses

Fissure

a long, deep sulcus

Dorsal

toward the back

Ventral

toward the stomach

Anterior

toward the front end

Posterior

toward the back end

Superior

above another part

Inferior

below another part

Lateral

toward the side, away from the midline

Medial

toward the midline, away from the side

Proximal

approximate/close to the point of origin

Distal

distant from the point of origin

ipsilateral

on the same side of the body

Contralateral

on the opposite side of the body

Somatic Nervous System

PNS, axons conveying messages from the sense organs to the CNS and from the CNS to the muscles -- regulation of voluntary control

Autonomic Nervous System

PNS, controls the heart, intestines, and other organs. Some cell bodies within the brain or spinal cord, and some clustered along the sides of the spinal cord -- regulation of involuntary control

Spinal Cord

CNS, within spinal column. It communicates with all the sense organs and muscles except those of the head

Dorsal Root Ganglion

clusters of neurons of cell bodies of sensory neurons outside the spinal cord

Gray Matter (spinal cord)

H-shaped center of the cord, packed densely with cell bodies and dendrites

White Matter (spinal cord)

around the gray matter, contains myelinated axons

Sympathetic Nervous System

network of nerves that prepare the organs for a burst of vigorous activity, consisting of ganglia chains just to the left and right of the spinal cord's central regions. It helps prepare for "fight or flight"

Parasympathetic Nervous System

facilitates vegetative, nonemergency responses. Generally, the opposite of the sympathetic nervous system -- "rest and digest"

Hindbrain

posterior part of the brain, consists of the medulla, pons, and cerebellum (brainstem)

Medulla

enlarged extension of the spinal cord, moderates breathing, blood pressure, and heart rate

Cranial Nerves

12 pairs of nerves in the medulla which control vital reflexes like breathing, heart rate, vomiting, salivation, coughing, and sneezing

Pons

anterior and ventral to the medulla, also contains nuclei for several cranial nerves. It's the "bridge" between the left and right hemispheres with opposite sides of the spinal cord

Cerebellum

control of movement, shifting attention between stimuli, judging timing, and some types of learning and conditioning. It's sometimes called the "mini brain", and has a unique "tree of life" pattern inside

The Midbrain

in the middle of developing brains, but is dwarfed and surrounded by the forebrain in mammalian adulthood

Tectum

roof of the midbrain

superior and inferior colliculi

swellings on each side of the tectum, important for sensory processing. Inferior = hearing and superior = vision

Tegmentum

under tectum, intermediate level of the midbrain

Substantia Nigra

gives rise to dopamine, and contains a pathway that facilitates readiness for movement

The Forebrain

most prominent part of the mammalian brain, consists of two cerebral hemispheres - one left and one right - with each hemisphere organized to receive sensory information, mostly from the opposite(contralateral) side of the body

Cingulate Gyrus

on the prefrontal cortex interface, assists with conflict resolution and error detection (when reality doesn't align with what's expected)

Cerebral Cortex

outer portion of the forebrain

Limbic System

"limbus"=border, around the brainstem. it includes the olfactory bulb, hypothalamus, hippocampus, amygdala, and the cingulate gyrus of the cerebral cortex