Alveoli - Air cells of the lungs, formed by the terminal
dilation of tiny air passageways.
Antibody - A protein that is made by certain white blood
cells (lymphocytes), in the body, in response to the invasion of
a foreign substance.
Antigen - A substance that when introduced into the body
stimulates an immune response.
Aorta - The main trunk of the arterial system, carrying
blood from the left ventricle of the heart to all of the body except
Arteries - Blood vessels that carry blood from the heart
to any part of the body.
Bacteria - One-celled organisms, spherical, spiral, or rod-shaped
and appearing singly, in chains, or in clusters.
Blood - The fluid that circulates in the principal vascular
system of human being and other vertebrates: in humans consisting
of plasma in which the red blood cells, white blood cells, and platelets
Bronchi - The main branches of the trachea.
Capillaries - The tiny blood vessels between the terminations
of the arteries and the beginnings of the veins.
Chemotaxis - Movement of a cell toward of away from a chemical
Cytoplasm - A jellylike material that surrounds the nucleus
of a celland contains most of the cell's organelles.
Differentiation - (of cells or tissues) to change from relatively
generalized to specialized kinds, during development.
Erythrocyte - A red blood cell.
Fibrin - The insoluble protein end product of blood coagulation.
Germs - Any microorganisms that cause disease.
Granulocyte - A circulating white blood cell having prominent
granules in the cytoplasm and a nucleus of two or more lobes.
Hemoglobin - The oxygen-carryingprotein of red blood cells
that gives them their red color and serves to carry oxygen to the
Immunity - The condition that permits either natural or
acquired resistance to disease.
Leukocyte - A white blood cell.
Lymphocyte - A type of white blood cell having a spherical
nucleus surrounded by a thin layer of nongranular cytoplasm.
B Lymphocyte - A lymphocyte that is involved in the production
T Lymphocyte - A lymphocyte that helps in the priming of
B lymphocytes to make antibody or is directly involved in attacking
foreign cells, such as tumor cells.
Marrow - A soft, fatty, vascular tissue in the interior
cavities of bones that is a major site of blood cell production.
Megakaryocyte - A large bone marrow cell having a lobulate
nucleus (one with lobes); the source of blood platelets.
Mitosis - The usual method of cell division.
Monocyte - A large, circulating white blood cell, formed
in bone marrow and in the spleen, that ingests large foreign particles
Nucleus - The part of the cell that holds genetic information
as DNA. Bacterial cells have no nucleus.
Nutrients - Substances that give sustenance to an organism.
Organelle - A specialized part of a cell having some specific
Phagocyte - Any cell that ingests and destroys foreign particles.
Phagocytosis - The ingestion of a smaller cell or a fragment.
Plasma - The liquid part of blood or lymph, as distinguished
from the suspended elements.
Platelets - Small non-nucleated (having no nucleus) cells
which form the first plug to stop bleeding.
Red Blood Cells - One of the cells of the blood, which,
in mammals, are non-nucleated disks concave on both sides, containing
hemoglobin and carrying oxygen to the cells and tissues and carbon
dioxide back to the respiratory organs.
Spleen - A highly vascular, glandular, ductless organ, situated
in humans at the cardiac end of the stomach, serving chiefly in
the formation of mature lymphocytes, in the destruction of worn-out
red cells, and as a reservoir for blood.
Stem Cells - Cells that upon division replace their own
numbers and give rise to cells that differentiate further into one
or more specialized types, such as various B cells and T lymphocytes.
Transfusion - The direct transferring of blood, plasma,
or the like into a blood vessel.
Veins - Branching vessels or tubes carrying blood from various
parts of the body to the heart.
Vessel - A tube or duct such as an artery or vein, which
contains or conveys blood or some other body fluid.
Virus - A tiny object that is composed of RNA or DNA and
is surrounded by a protein cap or capsid.
White Blood Cells - Any of various nearly colorless cells
of the immune system that circulate mainly in the blood and lymph.