Ap Biology Chapter 45 Vocabulary

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adenohypophysis

Back 1

portion of the pituitary that develops from nonneural tissue; consists of endocrine cells that synthesize and secrete several tropic and nontropic hormones.

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adrenal gland

Back 2

One of two endocrine glands located adjacent to the kidneys in mammals. Endocrine cells in the outer portion (cortex) respond to ACTH by secreting steroid hormones that help maintain homeostasis during long-term stress. Neurosecretory cells in the central portion (medulla) secrete epinephrine and norepinephrine in response to nervous inputs triggered by short-term stress.

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adrenocorticotropic hormone (ACTH)

Back 3

A tropic hormone produced and secreted by the anterior pituitary that stimulates the production and secretion of steroid hormones by the adrenal cortex.

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androgen

Back 4

Any steroid hormone, such as testosterone, that stimulates the development and maintenance of the male reproductive system and secondary sex characteristics.

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anterior pituitary

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Also called the adenohypophysis; portion of the pituitary that develops from nonneural tissue; consists of endocrine cells that synthesize and secrete several tropic and nontropic hormones.

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antidiuretic hormone (ADH)

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A hormone produced in the hypothalamus and released from the posterior pituitary. It promotes water retention by the kidneys as part of an elaborate feedback scheme that helps regulate the osmolarity of the blood.

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brain hormone

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A hormone, produced by neurosecretory cells in the insect brain, that promotes development by stimulating the prothoracic glands to secrete ecdysone.

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calcitonin

Back 8

A hormone secreted by the thyroid gland that lowers blood calcium levels by promoting calcium deposition in bone and calcium excretion from the kidneys.

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catecholamine

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Any of a class of compounds, including the hormones epinephrine and norepinephrine, that are synthesized from the amino acid tyrosine.

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corticosteroid

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Any steroid hormone produced and secreted by the adrenal cortex.

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cytokine

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Any of a group of proteins secreted by a number of cell types, including macrophages and helper T cells, that regulate the function of lymphocytes and other cells of the immune system.

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diabetes mellitus

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An endocrine disorder marked by inability to maintain glucose homeostasis. The type I form results from autoimmune destruction of insulin-secreting cells; treatment usually requires insulin injections several times a day. The type II form most commonly results from reduced responsiveness of target cells to insulin; obesity and lack of exercise are risk factors.

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ecdysone

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A steroid hormone, secreted by the prothoracic glands, that triggers molting in arthropods.

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endocrine gland

Back 14

A ductless gland that secretes hormones directly into the interstitial fluid, from which they diffuse into the bloodstream.

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endocrine system

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The internal system of chemical communication involving hormones, the ductless glands that secrete hormones, and the molecular receptors on or in target cells that respond to hormones; functions in concert with the nervous system to effect internal regulation and maintain homeostasis.

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endorphin

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Any of several hormones produced in the brain and anterior pituitary that inhibits pain perception.

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epinephrine

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A catecholamine hormone secreted from the adrenal medulla that mediates fight-or-flightresponses to short-term stress; also functions as a neurotransmitter.

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estrogen

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Any steroid hormone, such as estradiol, that stimulates the development and maintenance of the female reproductive system and secondary sex characteristics.

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follicle-stimulating hormone (FSH)

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A tropic hormone produced and secreted by the anterior pituitary that stimulates the production of eggs by the ovaries and sperm by the testes.

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glucagon

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A hormone secreted by pancreatic alpha cells that raises blood glucose levels. It promotes glycogen breakdown and release of glucose by the liver.

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glucocorticoid

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A steroid hormone secreted by the adrenal cortex that influences glucose metabolism and immune function.

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gonadotropin

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A hormone that stimulates the activities of the testes and ovaries. Follicle-stimulating hormone and luteinizing hormone are gonadotropins.

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growth factor

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A protein that must be present in the extracellular environment (culture medium or animal body) for the growth and normal development of certain types of cells; a local regulator that acts on nearby cells to stimulate cell proliferation and differentiation.

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growth hormone (GH)

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A hormone produced and secreted by the anterior pituitary that has both direct (nontropic) effects and tropic effects on a wide variety of tissues.

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hormone

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In multicellular organisms, one of many types of circulating chemical signals that are formed in specialized cells, travel in body fluids, and act on specific target cells to change their functioning.

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hypothalamus

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The ventral part of the vertebrate forebrain; functions in maintaining homeostasis, especially in coordinating the endocrine and nervous systems; secretes hormones of the posterior pituitary and releasing factors that regulate the anterior pituitary.

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insulin

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A hormone secreted by pancreatic beta cells that lowers blood glucose levels. It promotes the uptake of glucose by most body cells and the synthesis and storage of glycogen in the liver and also stimulates protein and fat synthesis.

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insulin-like growth factor

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A hormone produced by the liver whose secretion is stimulated by growth hormone. It directly stimulates bone and cartilage growth.

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islets of Langerhans

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Clusters of endocrine cells within the pancreas that produce and secrete the hormones glucagon (alpha cells) and insulin (beta cells).

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juvenile hormone

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A hormone in arthropods, secreted by the corpora allata glands, that promotes the retention of larval characteristics.

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luteinizing hormone (LH)

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A tropic hormone produced and secreted by the anterior pituitary that stimulates ovulation in females and androgen production in males.

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melanocyte-stimulating hormone (MSH)

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A hormone produced and secreted by the anterior pituitary that regulates the activity of pigment-containing cells in the skin of some vertebrates.

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melatonin

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A hormone secreted by the pineal gland that regulates body functions related to seasonal day length.

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mineralocorticoid

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A steroid hormone secreted by the adrenal cortex that regulates salt and water homeostasis.

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negative feedback

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A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation.

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neurohypophysis

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an extension of the hypothalamus composed of nervous tissue that secretes oxytocin and antidiuretic hormone made in the hypothalamus; a temporary storage site for these hormones.

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neurosecretory cell

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A specialized nerve cell that releases a hormone into the bloodstream in response to signals from other nerve cells; located in the hypothalamus and adrenal medulla.

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nitric oxide (NO)

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A gas produced by many types of cells that functions as a local regulator, a neurotransmitter, and an antibacterial agent.

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norepinephrine

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A hormone that is chemically and functionally similar to epinephrine.

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oxytocin

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A hormone produced by the hypothalamus and released from the posterior pituitary. It induces contractions of the uterine muscles and causes the mammary glands to eject milk during nursing.

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pancreas

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A gland with dual functions: The nonendocrine portion secretes digestive enzymes and an alkaline solution into the small intestine via a duct; the endocrine portion secretes the hormones insulin and glucagon into the blood.

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parathyroid gland

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Any of four small endocrine glands, embedded in the surface of the thyroid gland, that secrete parathyroid hormone.

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parathyroid hormone (PTH)

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A hormone secreted by the parathyroid glands that raises blood calcium level by promoting calcium release from bone and calcium retention by the kidneys.

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pineal gland

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A small gland on the dorsal surface of the vertebrate forebrain that secretes the hormone melatonin.

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pituitary gland

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An endocrine gland at the base of the hypothalamus; consists of a posterior lobe (neurohypophysis), which stores and releases two hormones produced by the hypothalamus, and an anterior lobe (adenohypophysis), which produces and secretes many hormones that regulate diverse body functions.

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posterior pituitary

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Also called the neurohypophysis; an extension of the hypothalamus composed of nervous tissue that secretes oxytocin and antidiuretic hormone made in the hypothalamus; a temporary storage site for these hormones.

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progestin

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One of a family of steroid hormones, including progesterone, that prepare the uterus for pregnancy.

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prolactin (PRL)

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A hormone produced and secreted by the anterior pituitary with a great diversity of effects in different vertebrate species. In mammals, it stimulates growth of and milk production by the mammary glands.

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prostaglandin (PG)

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One of a group of modified fatty acids secreted by virtually all tissues and performing a wide variety of functions as local regulators.

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signal transduction pathway

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A mechanism linking a mechanical or chemical stimulus to a specific cellular response.

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testosterone

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The most abundant androgen hormone in the male body.

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thyroid gland

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An endocrine gland, located on the ventral surface of the trachea, that secretes two iodine-containing hormones, triiodothyronine (T3) and thyroxine (T4), and calcitonin.

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thyroid-stimulating hormone (TSH)

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A tropic hormone produced and secreted by the anterior pituitary that regulates the release of thyroid hormones.

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thyroxine (T4)

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One of two iodine-containing hormones that are secreted by the thyroid gland and help regulate metabolism, development, and maturation in vertebrates.

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triiodothyrodine (T3)

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One of two iodine-containing hormones that are secreted by the thyroid gland and help regulate metabolism, development, and maturation in vertebrates.

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tropic hormone

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A hormone that has another endocrine gland as a target.

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vitamin D

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One of the fat-soluble vitamins. The active form functions as a hormone, acting in concert with parathyroid hormone in bone and promoting the uptake of calcium from food within the intestines.