Endocrine System Flashcards
Glands the secrete products into the interstitial fluid, most of which diffuse into the blood and are carried throughout the body are called what?
Endocrine glands
Glands that secrete products into body cavities, the lumen of organs, or to the outer surface of the body are called what?
Exocrine glands
Name the five endocrine glands of the body.
Pituitary, thyroid, parathyroid, adrenal, and pineal glands
Name the thirteen organs and tissues that, in addition to their other functions, also secrete hormones.
SPLIT KOSH PATH
Skin, pancreas, liver, intestine (small), thymus, kidneys, ovaries, stomach, hypothalamus, placenta, adipose tissue, testes, and heart
A decrease in the number of target-cell receptors for a hormone is called what?
Down-regulation
An increase in the number of target-cell receptors is called what?
Up-regulation
Hormones that act on the cell that secreted them are called what?
Autocrines
Hormones that act on neighbouring cells to the one from which they are secreted, but that do not diffuse into the blood are called what?
Paracrines
Autocrines and paracrines, together are known as what?
Local hormones
Hormones that diffuse into the blood and travel throughout the body are known as what?
Circulating hormones
What are the three types of fat-soluble hormones?
Steroid hormones, thyroid hormones, and nitric oxide (NO)
What are the three kinds of water-soluble hormones?
Amine hormones, peptide hormones, and eicosanoid hormones
In order to travel through the blood, lipid-soluble hormones often attach to what?
Transport proteins
What gland secretes melatonin?
Pineal gland
Name the seven hormones secreted by the anterior pituitary gland.
HGH, TSH, ACTH, FSH, LH, MSH, and …
Human growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, luteinizing hormone, melanocyte-stimulating hormone, and prolactin
All releasing and inhibiting hormones are secreted by what organ?
Hypothalamus
When a water-soluble hormone binds to a receptor on its target cell membrane, it becomes known as what?
First messenger
The first messenger activates the production of a second messenger inside the cell. One common second messenger is cyclic AMP (cAMP).
In the process, what does adenylate cyclase convert into cAMP?
ATP
What does cAMP stand for?
Cyclic adenosine monophosphate
What are the three factors that determine the responsiveness of a target cell to a hormone?
Concentration of hormone in the blood, number of receptors on the target cell, and the influence of other hormones
When one hormone requires recent or simultaneous exposure to another hormone in order to carry out their function, this is known as what?
Permissive effect
When two different hormones acting together increase the effect of either hormone acting alone, this is known as what?
Synergistic effect
When one hormone opposes the action of another hormone, this is known as what?
Antagonistic effect
What three types of signals control hormone secretion?
Signals from nervous system, chemical changes in blood, and the actions of other hormones
What connects the hypothalamus to the pituitary gland?
Infundibulum
The adenohypophysis is another name for what gland?
Anterior pituitary
Neurohypophysis is another name for what?
Posterior pituitary
The anterior pituitary is composed of epithelial tissue and the posterior pituitary is composed of what?
Nervous tissue
What system transports hormones from the hypothalamus to the pituitary gland?
Hypophyseal portal system
What is the name of the cells in the hypothalamus that produce the releasing and inhibiting hormones?
Neurosecretory cells
The pituitary gland rests in a cavity of what bone?
Shpenoid
Anterior pituitary hormones that act on other endocrine glands are called what?
Tropic hormones
What cells secrete human growth hormone?
Somatotrophs
What cells secrete thyroid-stimulating hormone?
Thyrotrophs
What cells secrete the gonadotropins FSH and LH?
Gonadotrophs
What cells secrete prolactin?
Lactotrophs
What cells secrete adrenocorticotropic hormone?
Corticotrophs
Melanocyte-stimulating hormones are secreted by what cells?
Corticotrophs
What are the five releasing hormones secreted by the hypothalamus?
GHRH, TRH, GnRH, PRH, and CRH
What are the two inhibiting hormones released by the hypothalamus?
GHIH and PIH
Human growth hormone promotes the synthesis and secretion of what small protein hormone?
Insulin-like growth factor
What are found within the hypothalamohypophyseal tract?
Axons of the neurosecretory cells of the hypothalamus
What are the four functions carried out by insulin-like growth factors?
Increases uptake of amino acids,
decreases breakdown of proteins,
enhances lipolysis in adipose tissue,
and decreases glucose uptake into cells
What do PRL, PRH, PIH, and CRH stand for?
Prolactin, prolactin-releasing hormone, prolactin-inhibiting hormone (dopamine), and corticotropin-releasing hormone
Abnormally low blood glucose concentration is a condition known as what?
Hypoglycemia
Abnormally high blood glucose concentration is known as what?
Hyperglycemia
Hypoglycemia stimulates the hypothalamus to secrete what hormone?
GHRH
Hyperglycemia stimulates the hypothalamus to secrete what hormone?
GHIH
In addition to the secretion of HGRH by the hypothalamus, identify three more stimuli that promote the secretion of HGH by somatotrophs in the anterior pituitary gland.
Decreased fatty acids with increased amino acids in the blood,
deep sleep (stages 3 & 4),
increase activity of the sympathetic nervous system (exercise),
other hormones such as glucagon, estrogen, cortisol, and insulin
What are the three zones of the adrenal cortex, from outer to inner?
Zona glomerulosa, zona fasciculata, and zona reticularis
Mineralocorticoids, such as aldosterone, are secreted by what layer of the adrenal cortex?
Zona glomerulosa
What three things does the follicle-stimulating hormone stimulate?
Development of ovarian follicles,
secretion of estrogen,
production of sperm
What hormone triggers ovulation?
Luteinizing hormone (LH)
After estrogens, progesterone, glucocorticoids, human growth hormone, thyroxine, and insulin exert their permissive effects, what hormone is then effective in stimulating mammary glands to produce milk?
Prolactin (PRL)
What hormone is also known as dopamine?
Prolactin-inhibiting hormone (PIH)
Hyper secretion of prolactin causes what?
Galactorrhea (inappropriate lactation) and amenorrhea (absence of menstrual cycles)
What two hormones does the posterior pituitary store and release?
Oxytocin and antidiuretic hormone (ADH)
Antidiuretic hormone is also known as what?
Vasopressin
What vessel supplies blood to the posterior pituitary?
Inferior hypophyseal arteries, which branch from the internal carotid arteries
What two main things does oxytocin stimulate?
Uterean contractions (with stretching of the cervix) and milk ejection (with suckling stimulus)
What five related effects does antidiuretic hormone (ADH) have on the kidneys?
Increase in water reabsorption, decrease in urine production, decreased sweating, smooth muscle constriction of arteriole walls, all of which contribute to increased blood pressure
What cells in the hypothalamus monitor blood osmotic pressure?
Osmoreceptors
What cells in the thyroid gland secrete T3 and T4?
Follicular cells
What are the other names for T4 and T3?
Thyroxine (or tetraiodothyronine) and triiodothyronine
What do the parafollicular cells of the thyroid gland produce?
Calcitonin
What large glycoprotein do the follicular cells of the thyroid produce in addition its hormones?
Thyroglobulin (TGB)
What is the amino acid on the thyroglobulin protein to which iodine molecules attach when in the lumen of thyroid follicles?
Tyrosine
What is the transport protein that binds to T3 and T4 when these hormones enter the bloodstream?
Thyroxine-binding globulin (TBG)
What are some of the actions of thyroid hormones?
Increases metabolic rate
Stimulates synthesis of sodium-potassium pumps
Increases body temperature
Stimulates protein synthesis
Increases the use of glucose and fatty acids for ATP production
Stimulates lypolysis
Regulates growth of nervous and bone tissue
Enhances some actions of epinephrine and norepinephrine
How does calcitonin decrease blood calcium levels?
By inhibiting osteoclasts from breaking down the extracellular matrix of bone
When calcium levels in the blood are low, what three ways does parathyroid hormone act to bring the calcium levels back up?
By increasing the number and activity of osteoclasts,
by slowing the loss of calcium to the urine,
and by stimulating the kidneys to release calcitriol which increases absorption of calcium from the gastrointestinal tract
The zona fasciculata secretes glucocorticoids; what is the primary glucocorticoid it secretes?
Cortisol
The deepest layer of the adrenal cortex, the zona reticularis, secretes what hormones?
Androgens
What are three stimuli that will initiate the renin-angiotensin-aldosterone (RAA) pathway?
Dehydration, sodium deficiency, and hemorrhage
Decreased blood pressure stimulates juxtaglomerular cells of the kidneys to secrete renin, which converts angiotensinogen into angiotensin I.
Primarily in what organ does angiotensin-converting enzyme (ACE) convert angiotensin I into angiotensin II?
Lungs
Angiotensin II stimulates the zona glomerulosa of the adrenal cortex to secrete aldosterone;
What two things does aldosterone do in the kidneys?
Increases reabsorption of sodium into the blood, thus causing increased water reabsorption,
and increases secretion of potassium and hydrogen ions into the urine
The most abundant glucocorticoid (95%) is cortisol; what are two others?
Corticosterone and cortisone
What are six effects of glucocorticoids?
Increased protein breakdown Gluconeogenesis Lipolysis Stress resistance Anti-inflammatory effects Depressed immune response
Dehydroepiandrosterone (DHEA) is formed in the zona reticularis of the adrenal cortex. In adult females, what are its functions?
Promotes libido and are converted into estrogens, the sole source after menopause
What tissue type makes up the adrenal medulla?
Nervous tissue
What are the cells of the adrenal medulla that produce and release epinephrine (80%) and norepinephrine(20%)?
Chromaffin cells
What are the other names of epinephrine and norepinephrine?
Adrenaline and noradrenaline
What is the essential function of the hormones epinephrine and norepinephrine?
Intensifies/augments sympathetic (fight-or-flight) nervous system response
99% of pancreatic cells are exocrine, and called what?
Acini
What is another name for the endocrine pancreatic islets?
Islets of Langerhans
What are the four types of hormone secreting cells found in the pancreatic islets, and what do each produce?
Alpha cells (17%of islet cells): glucagon Beta cells (70%): insulin Delta cells (7%): somatostatin (aka GHIH) F cells (6%): pancreatic polypeptide
Glucagon stimulates glycogenolysis and what?
Gluconeogenesis
Insulin stimulates the uptake of glucose into cells and what two other processes?
Glycogenesis and lipogenesis
Somatostatin (GHIH) inhibits the secretion of growth hormone and what else?
Glucagon & insulin
Insulin release is also stimulated by acetylcholine released by the parasympathetic vagus nerve fibres that innervate the pancreatic islets, by the amino acids arginine and leucine, and by what hormone?
GIP
Glucose-dependent insulinotropic peptide (GIP)
Glucagon release is also stimulated by what?
Exercise (increased sympathetic nervous system activity) and high amino acid concentration in the blood, as after a high-protein meal
What are four hormones secreted by ovaries?
Estrogens (estradiol and estrone), progesterone, inhibin, and relaxin.
What hormone is related to the muscle atrophy that occurs with aging?
Human growth hormone
Hyposecretion of human growth hormone during the growth years slows bone growth and closes epiphyseal plates before normal height is reached. This condition is called what?
Pituitary dwarfism
Hypersecretion of human growth hormone during childhood causes what condition?
Giantism
Hyperscretion of human growth hormone during adulthood is known as what condition?
Acromegaly
Diabetes insipidus results from faulty receptors (nephrogenic DI) or lack of secretion (neurogenic DI) of what hormone?
Antidiuretic hormone (ADH)
The most common form of hyperthyroidism is what condition?
Graves’ disease, an autoimmune disorder in which the person produces antibodies that mimic the action of thyroid-stimulating hormone (TSH)
Graves’ disease patients often develop edema behind the eyes, which is called what?
Exophthalmos, which causes the eyes to protrude
An enlarged thyroid gland is called what?
Goiter
Hypersecretion of the glucocorticoid cortisol by the adrenal cortex produces what?
Cushing’s syndrome, with symptoms of spindly arms and legs, “moon face”, a “buffalo hump” on the back, and a hanging abdomen
Hyposecretion of glucocorticoids and aldosterone is what condition?
Addison’s disease,
What is the most common endocrine disorder?
Diabetes mellitus, caused by an inability to produce or use insulin
