hair cell (har sel) Mechanoreceptor in the inner ear that lies between the basilar membrane and the tectorial membrane and triggers action potentials in fibers of the auditory nerve. p. 471

hair follicle (har fol'ï-kl) Tubelike depression in the skin in which a hair develops. p. 176 half-life (haf'llf) The time it takes for one-half of the radioactivity of an isotope to be released. p. 43 haploid (hap'loid) Sex cell with a single set of chromosomes, in humans 23. p. 979 hapten (hap'ten) A small molecule that, in combination with a larger one, forms an antigenic substance and can later stimulate an immune reaction by itself. p. 661

haustra (haws'trah) Pouches in the wall of the large intestine. p. 725 hematocrit (he-mat'o-krit) The volume percentage of red blood cells within a sample of whole blood. p. 547 hematoma (he"mah-to'mah) A mass of coagulated blood within tissues or a body cavity. p. 396 hematopoiesis (hem"ah-to-poi-e'sis) The production of blood and blood cells; hemopoiesis. p. 208 heme (hem) The iron-containing portion of a hemoglobin molecule. p. 807 hemizygous (hem"ï-zi'gus) A gene carried on the Y chromosome in humans. p. 989 hemocytoblast (he"mo-si'to-blast) A cell that gives rise to blood cells. p. 548 hemoglobin (he"mo-glo'bin) Pigment of red blood cells responsible for the transport of oxygen. p. 208 hemolysis (he-mol'ï-sis) The rupture of red blood cells accompanied by the release of hemoglobin. p. 87 hemopoiesis (he"mo-poi-e'sis) The production of blood and blood cells; hematopoiesis. p. 208 hemorrhage (hem'o-rij) Loss of blood from the circulatory system; bleeding. p. 753 hemostasis (he"mo-sta'sis) The stoppage of bleeding. p. 563 heparin (hep'ah-rin) A substance that interferes with the formation of a blood clot; an anticoagulant. p. 556 hepatic (he-pat'ik) Pertaining to the liver. p. 709

hepatic lobule (he-pat'ik lob'ul) A functional unit of the liver. p. 709 hepatic sinusoid (he-pat'ik si'nu-soid) Vascular channel within the liver. p. 709

heredity (he-red'ï-te) The transmission of genetic information from parent to offspring. p. 978 heritable gene therapy (her'ï-tah-bl jen ther'ah-pe) Manipulation of genes to cure a medical condition. p. 993 heterozygous (het"er-o-zi'gus) Different alleles in a gene pair. p. 981 hilum (hi'lum) A depression where vessels, nerves, and other structures (bronchus, ureter, etc.) enter an organ. p. 655 hilus (hi'lus) Hilum. p. 791 hindbrain (hlnd'bran) Posteriormost portion of the developing brain that gives rise to the cerebellum, pons, and medulla oblongata. p. 411

hinge joint (hinj joint) Two bones joined where the convex end of one bone fits into the complementary concave end of another. p. 276 hippocampus (hip"o-kam'pus) A part of the cerebral cortex where memories form. p. 418 histamine (his'tah-min) A substance released from stressed cells. p. 556 holocrine gland (ho'lo-krin gland) The entire secreting cell along with its secretions are released from this structure. p. 148 homeostasis (ho"me-o-sta'sis) A state of equilibrium in which the internal environment of the body remains in the normal range. p. 6 homeostatic mechanism (ho"me-o-stat'ik mek'ah-nizm) Process used to maintain normal internal environment within the body. p. 6

homozygous (ho"mo-zi'gus) Identical alleles in a gene pair. p. 981 hormone (hor'mon) A substance secreted by an endocrine gland that is transmitted in the blood or body fluids. p. 504 human chorionic gonadotropin (hu'man ko"re-on'ik gon"ah-do-tro'pin) Hormone, secreted by an embryo, that helps form the placenta; hCG. p. 916 humoral immunity (hu'mor-al i-mu'ni-te) Destruction of cells bearing foreign (nonself) antigens by circulating antibodies. p. 665 hyaline cartilage (hi'ah-lln kar'ti-lij)

Semitransparent, flexible connective tissue with an ultra-fine fiber matrix. p. 156 hydrogen bond (hi' dro-jen bond) A weak bond between a hydrogen atom and an atom of oxygen or nitrogen. p. 45 hydrolysis (hi-drol'i-sis) Splitting of a molecule into smaller portions by addition of a water molecule. p. 110 hydrostatic pressure (hi"dro-stat'ik presh'ur) Pressure exerted by fluids, such as blood pressure. p. 87 hydroxyapatite (hi-drok"se-ap'ah-tlt) A type of crystalline calcium phosphate found in bone matrix. p. 209 hydroxyl ion (hi-drok'sil i'on) OH-. p. 48 hymen (hi'men) A membranous fold of tissue that partially covers the vaginal opening. p. 906 hyperextension (hi"per-ek-sten'shun)

Extreme extension; continuing extension beyond the anatomical position. p. 276 hyperglycemia (hi"per-gli-se'me-ah) Excess blood glucose. p. 771 hyperkalemia (hi"per-kah-le'me-ah)

Elevated concentration of blood potassium. p. 771

hypernatremia (hi"per-nah-tre'me-ah)

Elevated concentration of blood sodium. p. 771

hyperparathyroidism (hi"per-par"ah-thi'roi-dizm) Excess secretion of parathyroid hormone. p. 526 hyperpolarization (hi"per-po"lar-i-za'shun) An increase in the negativity of the resting potential of a cell membrane. p. 376

hypertension (hi"per-ten'shun) Elevated blood pressure. p. 617 hyperthyroidism (hi"per-thi'roi-dizm)

Oversecretion of thyroid hormones. p. 552 hypertonic (hi"per-ton'ik) Condition in which a solution contains a greater concentration of dissolved particles than the solution with which it is compared. p. 87

hypertrophy (hi-per'tro-fe) Enlargement of an organ or tissue. p. 314 hyperventilation (hi"per-ven"ti-la'shun) Breathing that is abnormally deep and prolonged. p. 803 hypervitaminosis (hi"per-vi"tah-mi-no'sis)

Excessive intake of vitamins. p. 752 hypochondriac region (hi"po-kon'dre-ak re'jun) The portion of the abdomen on either side of the middle or epigastric region. p. 22 hypodermis (hi"po-der'mis) Mainly composed of fat, this loose layer is directly beneath the dermis; subcutaneous. p. 170 hypogastric region (hi"po-gas'trik re'jun) The lower middle portion of the abdomen. p. 22 hypoglycemia (hi"po-gli-se'me-ah)

Abnormally low concentration of blood glucose. p. 531 hypokalemia (hi"po-kah-le'me-ah) A low concentration of blood potassium. p. 771 hyponatremia (hi"po-nah-tre'me-ah) A low concentration of blood sodium. p. 77 hypoparathyroidism (hi"po-par"ah-thi'roi-dizm) An undersecretion of parathyroid hormone. p. 526 hypophysis (hi-pof'i-sis) The pituitary gland. p. 513

hypoproteinemia (hi"po-pro"te-i-ne'me-ah) A low concentration of blood proteins. p. 862 hypothalamus (hi"po-thal'ah-mus) A portion of the brain located below the thalamus and forming the floor of the third ventricle. p. 418

hypothyroidism (hi"po-thi'roi-dizm) A low secretion of thyroid hormones. p. 552 hypotonic (hi"po-ton'ik) Condition in which a solution contains a lesser concentration of dissolved particles than the solution to which it is compared. p. 87 hypoxia (hi-pok'se-ah) A deficiency of oxygen in the tissues. p. 807

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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