Histology of Endocrine Organs Flashcards
What is humoral stimuli? Give an example
Release controlled by monitoring levels of ions and nutrients in blood and body fluids
Ex: release of parathyroid hormone stimulated by low serum calcium levels
What is neuronal stimuli? Give an example
Release stimulated by nerve signals
Ex: release of epinephrine from adrenal gland in response to a signal from sympathetic nerve fibers
What is hormonal stimuli? Give an example
Release caused by a hormone secreted into bloodstream by another endocrine organ or cell
Ex: release of thyroid hormone stimulated by the release of the hormone, TSH, from the pituitary
Describe epithelioid cells. Where are they derived from?
Lack free surface and arranged as cords/follicles and some as isolated individual cells; well vascularized vessels often have fenestrated endothelium; derived from epithelia
What are the direct targets of hypothalamic hormones?
Anterior pituitary gland, kidney and uterus, adrenal medulla
What are the indirect targets of hypothalamic hormones?
Thyroid gland, adrenal cortex, mammary gland, gonads (testes/ovaries), bone and other organs
What are somatotropic cells?
Cells that secrete GH
What are thyrotropic cells?
Cells that secrete TSH that regulates thyroid gland secretion
What are corticotropic cells?
Secrete ACTH and melanocyte-stimulating hormone (MSH), which stimulates melanocytes to produce melanin
What are gonadotropic cells?
Secrete FSH and LH
What are mammotropic cells?
Cells that secrete prolactin that stimulates milk production
What are the cells found in the pars distalis of the anterior pituitary?
Acidophils, basophils, chromophobes
What are the acidophils and basophils?
Acidophils: somatotrophs, mammotrophs
Basophils: corticotrophs, thyrotrophs, gonadotrophs
What is the antidiuretic hormone?
Targets the kidney; regulates sodium and water retention
What is oxytocin?
Targets uterine smooth muscle and stimulates lactation; induces birth; may be involved in sexual arousal and pair and social bonding
What is Grave’s disease?
Abnormal antibodies stimulating TSH receptors causing over-secretion of T3 and T4; symptoms are elevated metabolism, sweating, rapid heart rate, weight loss, eyeballs may protrude; 4-8x more common in women
What is hypothyroidism?
Insufficient T3 and T4 production often an autoimmune disease-causing follicle cell death; symptoms are low metabolic rate, weight gain, lethargy, chilliness, edema, mental sluggishness
What is goiters?
Thyroid enlargement most commonly due to iodine deficiency; follicle cells keep producing thyroglobulin but cannot iodinate to make TH
What cells are found in the parathyroid gland?
Chief (principle) cells and oxyphil cells
What is the function of chief (principle) cells in the parathyroid?
Release PTH; secretion occurs when the blood concentration of calcium falls below the normal range of 9.5-10.5 mg/dL; secretion stops when the level of calcium returns to normal
What is the mechanism by which PTH regulates calcium?
Calcium blood levels drop below 9.5 mg/dL:
1) Stimulates osteoclasts to resorb bone and release its calcium stores
2) Increase calcium retention by the kidneys
3) Stimulates kidney to convert an inactive form of vitamin D to calcitriol (active vitamin D)
4) Calcitriol increases calcium absorption by the intestines
5) Blood calcium levels increase and inhibits further PTH release
Describe epinephrine and norepinephrine chromaffin cells
Epi: smaller with granules less electron dense than norepinephrine cells
Norepi: larger with granule more electron dense
What cells are found in the endocrine pancreas?
Alpha cells, beta cells, delta cells, F-cells
What is the function of alpha cells in the endocrine pancreas?
Secrete glucagon when blood glucose levels drop; stimulates release of glucose from liver glycogen stores
What is the function of beta cells in the endocrine pancreas?
Secrete insulin when blood glucose levels are elevated and promotes glycogen storage in liver and entry into cells
What is the function of delta cells in the endocrine pancreas?
Secrete somatostatin slowing the release of insulin and glucagon thereby controlling the rate of nutrient entry into the bloodstream and cells; stimulated by high levels of nutrients in the bloodstream
What is the function of F-cells in the endocrine pancreas?
Secrete pancreatic polypeptide that inhibit the release of somatostatin
