Ch. 10: Endocrine Function Flashcards
how do hormones influence processes?
by binding to receptors on the surface or within their target cells. only small amounts of these potent substances are required to make a significant impact at the cellular and organism levels
what are hormones classified or described based on?
their action, source, or chemical structure
when the end product of a biochemical process inhibits it’s own production - the hormone is released only when its levels decline, and production stops when its levels rise
negative feedback loop
rare and occurs when one hormone product stimulates the production of more
positive feedback loop
what is the difference between tropic and nontropic hormones?
tropic hormones- regulate endocrine glands to produce other hormones
nontropic hormones - directly stimulate cellular metabolism and other activities
what happens once the hormone has acted upon the target cell?
the liver metabolizes and the kidneys excrete it to prevent an accumulative effect
“master gland”, located at the base of the brain, regulated by the hypothalamus
pituitary gland
basal portion of the diencephalon which regulates the pituitary gland. connects the nervous and endocrine systems. contains receptors that monitor hormone, nutrient, and ion levels
hypothalamus
what is the difference between the anterior and posterior pituitary with how they are regulated?
the anterior pituitary is regulated by hormones released by the hypothalamus. the brain controls the posterior pituitary gland by neurohormones in this region
what are the endocrine functions of the pancreas carried out by?
the islest of langerhan
which cells secrete glucagon and which secrete insulin?
alpha cells secrete glucagon and beta cells secrete insulin. these are in the islets of langerhan
what hormones are secreted by the anterior pituitary gland?
thyroid-stimulating hormone, adrenocorticotropin, prolactin, growth hormone, gonadotropins
what hormones are secreted by the posterior pituitary gland?
antidiuretic hormone and oxytocin
released when serum glucose levels fall and stimulates the breakdown of glycogen to glucose which raises serum glucose levels
glucagon
released when serum glucose levels increase. stimulates cellular uptake of glucose, which in turn decreases serum glucose levels
insulin
hormones are produced within the follicles of the thyroid. what are these hormones?
thyroxin or T4, triiodothyronine or T3, and thyrocalcitonin or calcitonin.
two hormones together that regulate cellular metabolism as well as growth and development
T3 and T4 together
how does the hypothalamus influence the thyroid gland?
it stimulates the pituitary gland to release thyroid-stimulating hormone, using a negative feedback loop. TSH drives the thyroid to produce T3 and T4
what does the thyroid require in order to synthesize T3 and T4
iodine
this, along with parathyroid hormone, regulates serum calcium levels
calcitonin
how does calcitonin regulate serum calcium levels?
inhibits osteoclast activity and stimulates osteoblast activity.
when is calcitonin secreted?
when serum calcium levels are high
usually four of theses, on the posterior surface of the thyroid gland
parathyroid glands
works in the opposite way of calcitonin to regulate serum calcium levels. secreted when calcium levels drop
parathyroid hormones (PTH)
how does PTH regulate serum calcium levels?
by increasing osteoclast activity (which increases calcium release from the bone) as well as increasing the absorption of calcium in the GI tract and kidneys
what is the difference between the ways that the hypothalamus stimulates the adrenal medulla and the cortex?
adrenal cortex is regulated by negative feedback involving the hypothalamus and adrenocorticotropic hormones. the medulla is regulated by nerve impuleses from the hypothalamus
part of the adrenal gland that produces epinephrine and norepinephrine in times of stress.
adrenal medulla
what are the three separate regions of the adrenal cortex? what hormones do they secrete?
outermost region of the adrenal cortex secretes mineralocorticoids (adlosterone acts to conserve sodium and water in the body)
middle region of the adrenal cortex secretes gluocorticoids (cortisol increases serum glucose levels)
inner region secretes gonadocorticoids (sex hormones)
rare, complex condition in which the pituitary gland does not produce sufficient amounts of some or all of its hormones
hypopituitarism
what are the causes of hypopituitarism?
congenital defects, cerebral or pituitary trauma, autoimmune conditions, infections of the brain and tissues that support the brain, TB, pituitary tumors, hemochromatosis, histiocytosis X, sarcoidosis, hypothalamic dysfunction (the only secondary cause)
what can hypopituitarism cause? what are they?
dwarfism - short stature caused by deficient levels of growth hormone, somatoropin, or somatotropin-releasing hormone
diabetes insipidus - excessive fluid excretion in the kidneys caused by deficient antidiuretic hormone levels
does hypopituitarism develop slowly or suddenly?
it can develop suddenly, but most often develops slowly
what are the clinical manifestations of hypopituitarism?
fatigue, headache, cessation of menstruation, infertility, decreased libido, low tolerance for stress, hypotension, muscle weakness, nausea, constipatoin, weight loss or gain, anorexia, abdominal discomfort, cold sensitivity, visual disturbances, loss of body or facial hair, joint stiffness, hoarseness, facial edema, thirst, excessive urination, short stature, delayed growth and development
condition in which the pituitary gland secretes excessive amounts of one or all of the pituitary hormones. most commonly caused by tumors that secrete hormones or hormone-like substances
hyperpituitarism
what conditions can be caused by hyperpituitarism?
gigantism, acromegaly, syndrome of inappropriate antidiuretic hormone (SIADH), hyperprolactinemia, Cushing’s syndrome, hyperthyroidism
tall stature caused by excessive grotwth hormone levels prior to puberty
gigantism
increased bone size caused by excessive growth hormone levels in adulthood
acromegaly
increased renal water retention caused by excessive antidiuretic hormone levels
SIADH
excessive prolactin levels that result in menstrual dysfunction and galactorrhea (inappropriate lactation)
hyperprolactinemia
excessive cortisol levels that result from the increased ACTH levels
Cushing’s syndrome