Specialized Cells


action potential

rapid change in membrane potential due to changes in the flux of potassium and sodium ions inside and outside the cell


star-shaped glial cell in the CNS (central nervous system) that supports neurons by connecting them to nutrient supplies and repairing nervous tissue after injury


extension from the neuronal cell body that transmits the signal to receiving cells

B cell

lymphocyte that originates and matures in the red bone marrow and produces antibodies, which bond to pathogens and neutralize them


type of white blood cell that releases histamine and heparin to promote inflammatory reactions such as in allergic reactions, anaphylaxis, and asthma. Basophils make both histamine and serotonin.


rapid mitotic divisions of the zygote during the three days postfertilization that produce cells called blastomeres

cytoplasmic determinant

maternal influence of early cell differentiation


extension from the neuronal cell body that receives input from other cells


neurotransmitter that regulates motor behavior and the brain's pleasure and reward centers


leukocyte (white blood cell) from the myeloid lineage that contains granules, releases cytotoxic chemicals to kill large parasites, and plays a role in allergies and asthma

ependymal cell

type of glial cell, in the CNS, that lines the spinal cord and ventricles of the brain, as well as produces cerebrospinal fluid (CSF)

gamma aminobutyric acid (GABA)

neurotransmitter that works in neurons within the brain's cortex to influence motor control and vision and regulate the body's reaction to anxiety


cells that support and protect neurons


immune cell that contains granules in the cytoplasm, specifically the eosinophil and basophil


type of protein that can be secreted from or bound to the surface of B cells and recognize antigens


type of formed elements in blood that aids the immune process and protects the body from infections and foreign invasion. Leukocytes lack hemoglobin and are therefore colorless, or "white," which is why they are also referred to as white blood cells.


one of a family of several different types of leukocytes (white blood cells), including B cells, T cells, and natural killer (NK) cells. Lymphocytes are found in lymphoid organs, such as lymph nodes.


monocyte that has migrated from the bloodstream into any tissue in the body


type of leukocyte (white blood cell) that can change as needed into a macrophage targeted to destroy specific foreign substances, such as bacteria and viruses

myelin sheath

lipid-rich material that wraps around the axon, acting like insulation around an electrical wire


chemical that binds to neuronal receptors and excites or inhibits postsynaptic cells


white blood cell that can travel anywhere in the body and is the first to arrive at the site of inflammation or injury. They often cause swelling to protect damaged cells.


glial cell that generates myelin, which wraps around axons in the CNS


process by which cells such as macrophages engulf and digest pathogens and other material

satellite cell

glial cell in the PNS that surrounds the cell bodies of neurons in sensory, sympathetic, and parasympathetic ganglia

Schwann cell

glial cell in the PNS that provides myelination to axons in the PNS


space found between two nerve cells, across which neurotransmitters travel

synaptic vesicle

structure that holds neurotransmitters

T cell

leukocyte produced by red bone marrow that migrates to the thymus gland, where it matures. T cells play a role in eliciting the adaptive immune response.

voltage-gated channel

ion pathway that opens and closes when an electrical signal is received and activated by changes in membrane potential