Ch. 11 Review Questions
Why is estrogen called the "feminizing hormone" while testosterone is called the "masculinizing hormone"?
Each of these hormones contributes to the development and maturation of the external genitals and body contours typical of an adult male or female.
explain the function of ADH
accelerates the reabsorption of water from urine in kidney tubules back into the blood; acts to decrease urine volume and thus prevent dehydration
explain the difference between prostaglandins (PGs) and hormones. list some of the body functions that can be influenced by prostaglandins
also called tissue hormones, prostaglandins are powerful lipid substances found in a variety of tissues. they are different from typical hormones in that a PG is produced in a tissue and then diffuses only a short distance to act on cells within that tissue. typical hormones influence and control activities of widely separated organs; typical PGs influence activities of neighboring cells. body functions: respiration, blood pressure, GI secretions, inflammation, and the reproductive system.
pick a body function (regulation of glucose or calcium levels in the blood) and explain how the interaction of hormones is used to help maintain homeostasis
calcitonin, a hormone produced by the thyroid gland, decreases calcium levels in the blood by first acting on bone to inhibit its breakdown and preventing bone reabsorption of calcium. high levels of calcium stimulate the thyroid gland to release calcitonin, which inhibits the release of calcium from the bone, thus lowering serum calcium levels
explain the function of aldosterone
chief mineralocorticoid that increases the amount of sodium and decreases the amount of potassium in the blood; it causes the kidney tubules to speed up their reabsorption of sodium back into the blood so that less of it will be lost in the urine. also causes the tubules to increase their secretion of potassium so that more of it will be lost in the urine; speed up the kidney's reabsorption of water
describe the structure of the pituitary gland and where it is located
contains two glands-- the adenohypophysis and the neurohypophysis. it sits securely within the sella turcica; the pituitary stalk attaches the gland to the undersurface of the brain, or more specifically, attaches the pituitary body to the hypothalamus.
differentiate between endocrine and exocrine glands
endocrine: ductless glands that secrete hormones into intercellular spaces that diffuse directly into the blood and are carried throughout the body; belong to the endocrine system exocrine: secrete products into ducts that empty onto a surface or into a cavity (sweat & salivary glands); do not belong to the endocrine system
explain the function of glucocorticoids
help maintain normal blood glucose concentration; increase gluconeogenesis, a process in liver cells that converts amino acids or glycerol to glucose. also play an essential part in maintaining normal blood pressure. produce an anti-inflammatory effect. the normal adrenal cortex responds during stress by increasing its secretion of glucocorticoids.
define or explain the terms hormone, target cell, hypersecretion, and hyposecretion
hormone: substance secreted by an endocrine gland target cell: cell in which a hormone molecule binds to that has specific receptors for that hormone, triggering a reaction in the cell hypersecretion: production of too much hormone by a diseased gland hyposecretion: production of too little hormone by a diseased gland
list conditions that may occur from hyposecretion and hypersecretion of the adrenal cortex
hyposecretion: Addison disease hypersecretion: Cushing syndrome
list conditions that may occur from hyposecretion and hypersecretion of the pancreas
hyposecretion: Diabetes mellitus
list conditions that may occur from hyposecretion and hypersecretion of the growth hormone
hyposecretion: dwarfism hypersecretion: gigantism
list conditions that may occur from hyposecretion and hypersecretion of the thyroid gland
hyposecretion: hypothyroidism, cretinism (pre-adult), myxedema (adult), goiter hypersecretion Grave's disease, hyperthyroidism
list the primary endocrine glands and identify the major hormones produced by each
1. ANTERIOR PITUITARY: thyroid-stimulating hormone (TSH), follicle-stimulating hormone (ACTH), growth hormone (GH), etc. 2. POSTERIOR PITUITARY: antidiuretic hormone (ADH), oxytocin (OT) 3. HYPOTHALAMUS: releasing hormones, inhibiting hormones 4. THYROID: thyroxine and triiodothyronine, calcitonin (CT) 5. PARATHYROID parathyroid hormone (PTH) 6. ADRENAL CORTEX: mineralocorticoids (MCs), glucocorticoids (GCs), androgens 7. ADRENAL MEDULLA: epinephrine (Epi) and norepinephrine (NR) 8. PANCREATIC ISLETS: glucagon, insulin 9. OVARY: estrogens, progesterone 10. TESTIS: testosterone 11. THYMUS: thymosins 12. PLACENTA: chorionic gonadotropin, estrogens, progesterone 13. PINEAL GLAND: melatonin 14. HEART (ATRIA): atrial natriuretic hormone (ANH) 15. GI TRACT: ghrelin 16. FAT-STORING CELLS: leptin
name the four tropic hormones released by the anterior pituitary gland and briefly explain their function
1. thyroid-stimulating hormone (TSH): acts on the thyroid gland and stimulates it to increase the secretion of thyroid hormone 2. adrenocorticotropic hormone (ACTH): acts on the adrenal cortex and stimulates it to increase in size and to secrete larger amounts of its hormones, especially cortisol 3. luteinizing hormone (LH): causes ovulation; stimulates the formation of the corpus luteum from the ruptured follicle (luteinization) and stimulates the corpus luteum to produce progesterone. 4. growth hormone (GH): speeds up the movement of digested proteins from the blood and into the cells, which accelerates the cells' anabolism of amino acids to form tissue proteins; increases blood glucose 5. prolactin (PRL): stimulates breast development necessary for lactation
What are the two hormones secreted by the pancreas? What type of cell releases each? What do these hormones do?
Alpha cells secrete glucagon, which accelerates glycogenolysis in the liver. Glucagon increases blood glucose concentration. Beta cells secrete insulin, which decreases blood glucose concentration by accelerating its movement out of the blood, through cell membranes, and into cells. (The only hormone that can decrease blood glucose concentration.)
What are the two hormone secreting structures in a female's ovaries? What hormones do they secrete?
Ovarian follicles are little pockets in which egg cells, or ova, develop, They also secrete estrogen, which is involved in the development and maturation of the breasts and external genitalia. The corpus luteum chiefly secretes progesterone but also some estrogen.
explain the difference between T3 and T4. what is unique about the thyroid gland?
T4 is more abundant, containing 4 atoms of iodine, while T3, although more potent and considered to be the principal thyroid hormone, has only 3 atoms of iodine; these thyroid hormones stimulate cellular metabolism. the thyroid gland is unique in that it stores considerable amounts of the thyroid hormones in the form of molecules suspended in the colloid, unlike most endocrine glands which instead secrete their hormones directly into the blood as they are produced and do not store them. additionally, T3 and T4 are nonsteroid hormones that can enter their target cell to find their receptors without the use of an internal second messenger
The thymus gland is associated with what body system?
lymphatic system
explain the mechanism of action of nonsteroid hormones
nonsteroid hormones serve as first messengers, providing communication between endocrine glands and target organs. another molecule (cyclic AMP) acts as the second messenger, providing communication within a hormone's target cells.
name the hormones produced by the zones or areas of the adrenal cortex
outer zone: mineralocorticoids middle zone: glucocorticoids innermost: small amounts of sex hormones
explain and give an example of a positive feedback loop for the regulation of hormone secretion
positive feedback mechanisms amplify changes rather than reverse them. example: during labor, the muscle contractions that push the baby through the birth canal become stronger and stronger by means of a positive feedback mechanism that regulates secretion of the oxytocin hormone.
explain the function of the hypothalamus in the endocrine system
produces releasing hormones (RHs) and inhibiting hormones (IHs); produced in the hypothalamus and then directly released into a unique blood capillary system, which carries the hormones to the anterior pituitary gland, where they stimulate or inhibit the release of anterior pituitary hormones into the general circulation.
explain the functions of prolactin and oxytocin
prolactin: stimulates the breast development necessary for eventual lactation oxytocin: stimulates contraction of the smooth muscle of the pregnant uterus and initiates and maintains labor; it is sometimes injected to induce labor. it also causes the glandular cells of the breast to release milk into ducts from which a baby can obtain by sucking.
explain the function of growth hormone
promotes normal growth by anabolic action
explain why a second messenger system is necessary for nonsteroid hormones but not for steroid hormones
steroid hormones are lipid-soluble and can therefore pass intact directly through the plasma membrane of the target cell-- nonsteroid hormones are not lipid-soluble.
explain the mechanism of action of steroid hormones
steroid hormones pass through the plasma membrane and enter the nucleus to form a hormone-receptor complex that acts on DNA. as a result, a new protein that produces specific effects in the target cell is formed in the cytoplasm.
what would be the effect on the body if the thyroid gland were removed?
the body would need T3 and T4 hormones
Where is melatonin produced? What is its primary function?
the pineal gland; it receives and responds to sensory information from the light-sensitive ganglion cells of the eye's retina, and uses this information regarding changing light levels to adjust its output of melatonin.
if a doctor discovered that a patient had very low levels of thyroxine but high levels of TSH, would the patient's problem be in the thyroid gland or the pituitary gland?
the problem would be in the thyroid gland and result in hypothyroidism, which is the undersecretion of thyroid hormones
explain and give an example of a negative feedback loop for the regulation of hormone secretion
the secretion of most hormones is regulated by negative feedback mechanisms that tend to reverse any deviations from normal. example: an increase in blood glucose triggers the secretion of insulin by the pancreas. because insulin promotes glucose uptake by cells, the blood glucose level is restored to its lower, normal level.