Endocrine, General Flashcards
What are the three classes of hormones?
Steroid, Tyroisine-derived, protein/peptide
What are the steroid hormones?
Cortisol, aldosterone, Ovarian, testicular, and placental
What are the tyrposine-derived hormones?
Triiodothyronine, thyroxine, epinephrine, norepinephrine
What are the peptide hormones?
GH, ACTH, TSH, FSH, LH, PRL, ADH, oxytocin, PTH, insulin, glucagon, somatostatin
What are the six anterior pituitary hormones?
GH, ACTH, TSH, FSH, LH, prolactin
What are the two posterior pituitary hormones?
ADH, oxytocin
What are the 5 main functions of GH?
- Opposes insulin
- Stimulates amino acid uptake
- Stimulates release of fatty acid from storage sites
- Mediates immunoglobulin F synthesis
- Stimulates growth of nearly all tissues
What are 7 stimulators of GH?
- GHRH
- Hypoglycemia
- Arginine
- Exercise
- L-dopa
- Clonidine
- Propranolol
What inhibits GH?
somatostatin
What is the main function of ACTH?
Stimulates secretion of adrenocortical hormones
What two factors stimulate release of ACTH?
CRH and stress
What inhibits ACTH secretion?
Cortisol
Main function of TSH?
Regulates secretion of T3 and T4
What stimulates TSH?
TRH
What inhibits TSH?
increased T3 and T4
What are four main functions of LH?
- Induces ovulation (female)
- Induces lutenization of follicle (female)
- Stimulates production of estrogen and progesterone (female)
- Promotes production of testosterone (male)
What stimulates release of LH?
GnRH
What is the main function of prolactin?
Facilitates breast development in preparation for milk production
What four factors simulate prolactin secretion?
TRH, estrogen, stress, exercise
What inhibits release of prolactin?
Bromocriptine
What are two main functions of ADH?
- Promotes water absorption in collecting ducts of kidney
2. Vasoconstriction of peripheral arterioles, increasing blood pressure.
What are two main functions of oxytocin?
- Increases frequency and strength of uterine contractions
2. Stimulates breast milk ejection
What stimulates release of oxytocin?
Suckling, vaginal stimulation
What are the major functions of T3 and T4?
- Increase basal metabolic rate and oxygen consumption
- Increase protein synthesis, lipolysis, glycogenolysis, gluconeogenesis
- Increase heart rate and contractility
- Increase catecholamine sensitivity
- Stimulate release of steroid hormones
- Stimulate erythropoiesis and 2,3-DPG production
- Increase bone turnover
What are four major functions of calcitonin?
- Inhibits Ca absorption in the intestine
- Inhibits osteoclast activity in bone
- Inhibits renal tubular cell resorption of Ca, allowing for excretion in urine
- Inhibits phosphate resorption by renal tubular cells
What stimulates calcitonin?
- Increased serum calcium
2. Gastrin and pentagastrin
What are the major functions of PTH?
- Increases calcium resorption in the proximal convoluted tubule
- Increases excretion of Na, K, Ph, and HCO3
- Increases calcium mobilization from bone
- Increases absorption of vitamin D in the GI tract (indirect)
What stimulates release of PTH?
Low serum Ca
What inhibits the release of PTH?
High serum Ca
What cell type secretes insulin?
Beta cells in the pancreas
What are the major functions of insulin?
Stimulates glycogenesis, glycolysis, synthesis of protein, triglycerides, cholesterol, and VLDL in the liver
- Inhibits glycogenolysis, ketogenesis, and gluconeogenesis in the liver
- Increases protein systensis and glycogen synthesis in muscle
- Promotes triglyceride storage in fat
What cell type secretes glucagon?
Alpha cells of the pancreas
What are the major effects of glucagon?
- Glycogenolysis, gluconeogenesis, ketogenesis, lipolysis, insulin secretion
- Inhibition of gastric acid and pancreatic exocrine secretion
- Inhibition of peristalsis
- Increase HR and force of contractions
What cell type secretes somatostatin?
Delta cells of the pancreas
What are the major functions of somatostatin?
Inhibition of gastric acid, pepsin, pancreatic exocrine secretions
- Inhibition of ion secretion
- Inhibition of motility
- Reduction of splanchnic blood flow
- Inhibition of insulin, glucagons, pancreatic polypeptide secretions.
What cell type secrets pancreatic polypeptide?
F cells of the pancreas
What is the major function of pancreatic polypeptide?
Function unknown, but levels rise after a meal.
What cells secrete cortisol?
Adrenal cells within the zona reticularis
What are the major functions of cortisol?
- Stimulation of hepatic gluconeogenesis, inhibition of protein synthesis, increased protein catabolism, lipolysis, inhibition of peripheral glucose uptake
- Inhibition of fibroblast activity, inhibition of bone formation, reduction of GI calcium absorption
- Inhibition of leukocytes, decreased migration of inflammatory cells to site of injury, decreased production of mediators of inflammation.
What stimulates secretion of cortisol?
ACTH circadian rhythm, and stress
What non-sex cells secrete androgens?
Adrenal cells of the zona fasciculata
What are the major functions of adrenal androgens?
DHEA and DHEA sulfate are converted to testosterone and DHT in the periphery
What percentage of total testosterone production do adrenal androgens contribute in a male?
<5%
What cells produce aldosterone?
Adrenal cells of the zona glomerulosa
What are the major functions of aldosterone?
Stimulates renal tubular sodium absorption in exchange for potassium and hydrogen, causing fluid reabsorption and intravascular volume expansion
What cells produce catecholamines?
Cells of the adrenal medulla
What are the major functions of epinephrine and norepinephrine?
- Increase oxygen consumption
- Increased heat production
- Stimulation of glycogenolysis and lipolysis
- Inhibition of insulin secretion
What three organs are affected by MEN I?
Pituitary adenomas, parathyroid hyperplasia, and pancreatic islet cell tumors
What is the chromosomal defect of MEN I?
11q12-13 deletion
What percent of patients with MEN I have involvement of 2 glands?
50%
What percentage of MEN I patients have involvement of 3 glands?
20%
What is the average age at presentation of patients with MEN I without known affected family members?
20-40
What is the average age at presentation of patients with MEN I with known affected family members?
Prior to 20 yo with screening
What mutations have been associated with MEN IIA?
- RET oncogene mutation on chromosome 10q11.2
2. Missense mutations on chromosome 1
What tumors are associated with MEN IIA
- Parathyroid hyperplasia
- Medullary thyroid carcinoma
- Pheochromocytoma
What mutation is associated with MEN IIB?
RET oncogene mutation on chromosome 10q11.2
What tumors are associated with MEN IIB?
- Medullary thyroid carcinoma
- Pheochromocytoma
- Mucosal neuroma
- Marfanoid habitus