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45 Cards in this Set

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Adenohypophysis
anterior pituitary gland, which has the structure of an endocrine gland
Adrenal Glands
endocrine gland that rests on the top of each kidney; made up of cortex and medulla regions
Endocrine
secreting into blood or tissue fluid rather than into a duct; opposite of exocrine
Gonads
sex glands in which reproductive cells are formed; ovaries in women, testes in men
Hormone
substance secreted by an endocrine gland into the bloodstream that acts on a specific target tissue to produce a given response
Neurohypophysis
Posterior pituitary gland
Parathyroid
endocrine gland located in the neck on the posterior aspect of the thyroid gland; secretes parathyroid hormone
Prostaglanin (PG)
any of a group of naturally occurring lipid-based substances that act in a hormone-like way to affect many body functions, including vasodilation, uterine smooth muscle contraction, and the inflammatory response
Target Cell
cell that, when acted on by a particular hormone, responds because it has receptors to which the hormone can bind
Thymus
endocrine gland located in the mediastinum; vital part of the body's immune system
Thyroid
endocrine gland located in the neck that stores its hormones until needed; thyroid hormones regulate cellular metabolism
Tropic Hormone
hormone that stimulates another endocrine gland to secrete its hormones
Releasing Hormone
hormones produced by the hypothalamus that cause the pituitary gland to release its hormones
neuroendocrine system
When the two systems work together, they perform the same general functions: communication, integration, and control
Hormones
—carried to almost every point in the body; can regulate most cells; effects work more slowly and last longer than those of neurotransmitters
Anabolic hormones
hormones that stimulate anabolism in target cells
steroid hormone
Synthesized from cholesterol
b. Lipid soluble and can easily pass through the phospholipid plasma membrane of target cells
non-steroid hormone
Synthesized from cholesterol
b.Lipid soluble and can easily pass through the phospholipid plasma membrane of target cells
c. Examples of steroid hormones: cortisol, aldosterone, estrogen, progesterone, and testosterone wont be produced if don’t have cholesterol
Amine hormones
—synthesized by modifying a single molecule of tyrosine; produced by neurosecretory cells and by neurons; e.g., epinephrine, norepinephrine
Amino acid derivatives
produced by the thyroid gland; synthesized by adding iodine to tyrosine
Synergism—
combinations of hormones acting together have a greater effect on a target cell than the sum of the effects that each would have if acting alone
Permissiveness
—when a small amount of one hormone allows a second one to have its full effects on a target cell
Antagonism—
one hormone produces the opposite effects of another hormone; used to “fine tune” the activity of target cells with great accuracy
Mechanism of steroid hormone action
Steroid hormones are lipid soluble, and their receptors are normally found in the target cell's cytosol
b.After a steroid hormone molecule has diffused into the target cell, it binds to a receptor molecule to form a hormone-receptor complex
c.Mobile-receptor model—the hormone passes into the nucleus, where it binds to a mobile receptor and activates a certain gene sequence to begin transcription of mRNA; newly formed mRNA molecules move into the cytosol, associate with ribosomes, and begin synthesizing protein molecules that produce the effects of the hormone
d.Steroid hormones regulate cells by regulating production of certain critical proteins
e.The amount of steroid hormone present determines the magnitude of a target cell's response
f.Because transcription and protein synthesis take time, responses to steroid hormones are often slow
Mechanisms of nonsteroid hormone action
a.The second messenger mechanism—also known as the fixed-membrane-receptor model
(1)A nonsteroid hormone molecule acts as a “first messenger” and delivers its chemical message to fixed receptors in the target cell's plasma membrane
(2)The “message” is then passed by way of a G protein into the cell where a “second messenger” triggers the appropriate cellular changes
(3)Second messenger mechanism—produces target cell effects that differ from steroid hormone effects in several important ways
(a)The effects of the hormone are amplified by the cascade of reactions
(b)There are a variety of second messenger mechanisms—e.g., IP3, GMP, calcium-calmodulin mechanisms
(c)The second messenger mechanism operates much more quickly than the steroid mechanism.b. The nuclear-receptor mechanism—small iodinated amino acids (T4 and T3) enter the target cell and bind to receptors associated with a DNA molecule in the nucleus; this binding triggers transcription of mRNA and synthesis of new enzymes
Regulation of hormone secretion
Control of hormonal secretion is usually part of a negative feedback loop and is called endocrine reflexes 2.Simplest mechanism—when an endocrine gland is sensitive to the physiological changes produced by its target cells
3.Endocrine gland secretion may also be regulated by a hormone produced by another gland
4.Endocrine gland secretions may be influenced by nervous system input; this fact emphasizes the close functional relationship between the two systems
Up-regulation—
increased number of hormone receptors increases sensitivity
Down-regulation—
decreased number of hormone receptors decreases sensitivity
PROSTAGLANDINS
Unique group of lipid hormones (20-carbon fatty acid with 5-carbon ring) that serve important and widespread integrative functions in the body but do not meet the usual definition of a hormone
PROSTAGLANDINS
Called tissue hormones because the secretion is produced in a tissue and diffuses only a short distance to other cells within the same tissue; PGs tend to integrate activities of neighboring cells
Prostaglandin A (PGA)—
intraarterial infusion resulting in an immediate fall in blood pressure accompanied by an increase in regional blood flow to several areas
Prostaglandin E (PGE)—
vascular effects: regulation of red blood cell deformability and platelet aggregation; inflammation (which can be blocked with drugs that inhibit PG-producing enzymes such as COX-1 and COX-2); gastrointestinal effects: regulates hydrochloric acid secretion
Prostaglandin F (PGF)—
especially important in reproductive system, causing uterine contractions; also affects intestinal motility and is required for normal peristalsis
PITUITARY GLAND
A. Structure of the pituitary gland not considered as part of the brain, Formerly known as hypophysis. Located on the ventral surface of the brain within the skull. Infundibulum—stemlike stalk that connects pituitary to the hypothalamus. Made up of two separate glands, the adenohypophysis (anterior pituitary gland) and the neurohypophysis (posterior pituitary gland)
Three types of cells can be identified according to their affinity for certain stains
a.Chromophobes—do not stain
b.Acidophils—stain with acid stains
c.Basophils—stain with basic stains
Prolactin (PRL
Produced by acidophils in the pars anterior
b.Also known as lactogenic hormone
c.During pregnancy, PRL promotes development of the breasts, anticipating milk secretion; after the baby is born, PRL stimulates the mother's mammary glands to produce milk
Tropic hormones—
hormones that have a stimulating effect on other endocrine glands; four principal tropic hormones are produced and secreted by the basophils of the pars anterior
a. Thyroid-stimulating hormone (TSH), or thyrotropin—
promotes and maintains the growth and development of the thyroid; also causes the thyroid to secrete its hormones for example is the thyroid stimulating hormone and it tell another gland to work.
b. Adrenocorticotropic hormone (ACTH), or adrenocorticotropin—
promotes and maintains normal growth and development of the cortex of the adrenal gland; also stimulates the adrenal cortex to secrete some of its hormones
c. Follicle-stimulating hormone (FSH)—
in the female, stimulates primary graafian follicles to grow toward maturity; also stimulates the follicle cells to secrete estrogens; in the male, FSH stimulates the development of the seminiferous tubules of the testes and maintains spermatogenesis
d. Luteinizing hormone (LH)—
in the female, stimulates the formation and activity of the corpus luteum of the ovary; corpus luteum secretes progesterone and estrogens when stimulated by LH; LH also supports FSH in stimulating maturation of follicles; in the male, LH stimulates interstitial cells in the testes to develop and secrete testosterone; FSH and LH are called gonadotropins because they stimulate the growth and maintenance of the gonads
Neurohypophysis (posterior pituitary)
1.Serves as storage and release site for antidiuretic hormone (ADH) and oxytocin (OT), which are synthesized in the hypothalamus
2.Release of ADH and OT into the blood is controlled by nervous stimulation
3.Antidiuretic hormone (ADH)
PINEAL GLAND
A.Tiny, pine cone–shaped structure located on the dorsal aspect of the brain's diencephalon
B.Member of the nervous system because it receives visual stimuli and also a member of the endocrine system because it secretes hormones
C.Pineal gland supports the body's biological clock
D.Principal pineal secretion is melatonin
Aldosterone
a. Only physiologically important mineralocorticoid in the human; primary function is maintenance of sodium homeostasis in the blood by increasing sodium resorption in the kidneys
(2)Aldosterone also increases water retention and promotes the loss of potassium and hydrogen ions
(3)Aldosterone secretion is controlled by the renin-angiotensin-aldosterone system (RAAS) and by blood potassium concentration
Glucocorticoids
affect every cell in the body. Essential for maintaining normal blood pressure by aiding norepinephrine and epinephrine to have their full effect, causing vasoconstriction