What is the target and function of PTH (Parathyroid hormone)?
Target: bone, intestines, kidneys
Function: regulates calcium and phosphorus blood levels, promotes bone demineralization and increases intestinal absorption of calcium, increases serum calcium levels
What gland secretes Epinephrine (adrenaline)?
What is the target and function of Epinephrine (adrenaline)?
Target: sympathetic effectors
Function: response to stress; enhances and prolongs effect of SNS
What gland secretes norepinephrine?
What is the target and function of norepinephrine?
Target: sympathetic effectors
Function: response to stress; enhances and prolongs effects of SNS
What gland secretes Corticosteroids (cortisol, hydrocortisone)?
What is the target and function of corticosteroids?
Target: all body tissues
Function: promotes metabolism; response to stress
What gland secretes androgens (testosterone, androsterone) and estrogen?
What is the target and function of androgens and estrogen?
Target: reproductive organs
Function: masculinization in men; growth and sexual activity in women
What gland secretes mineralocorticoids (aldosterone)?
What is the target and function of mineralocorticoids?
Function: regulates Potassium and Sodium balance and thus water balance
What secretes insulin?
Beta cells of pancreas
What is the target and function of insulin?
Function: promotes movement of glucose out of blood and into cells
What secretes glucagon?
Alpha cells of pancreas
What is the target and function of glucagon?
Function: promotes movement of glucose from glycogen (glycogenolysis) and into blood
What secretes Somatostatin?
What is the target and function of somatostatin?
Function: inhibits insulin and glucagon secretion
What secretes pancreatic polypeptide?
What is the target and function of pancreatic polypeptide?
Function: influences regulation of pancreatic exocrine function and metabolism of absorbed nutrients
What secretes estrogen?
What is the target and function of estrogen?
Target: reproductive system, breasts
Function: stimulates development of secondary sex characteristics, preparation of uterus for fertilization and fetal development; stimulates bone growth
What secretes progesterone?
What is the target and function of progesterone?
Target: reproductive system
Function: maintains lining of uterus necessary for successful pregnancy
What secretes testosterone?
What is the target and function of testosterone?
Target: reproductive system
Function: stimulates development of secondary sex characteristics; spermatogenesis
What are the characteristics and roles of hormone receptors?
located within cells of target tissues
specificity of hormone-target interation is determined by receptors in a "lock and key" type of mechanism
hormone only acts on cells that have receptors specific to that hormone
location of receptor sites affect the hormones mechanism of action
Where are steroid hormone receptors located?
inside the cell
What happens once lipid-soluble (steroid and thyroid) hormones enter into the cell?
They diffuse through the membrane and bind to receptor sites in the cytoplasm or nucleus. The complexes bind to DNA to stimulate or inhibit synthesis of mRNA. This can stimulate the synthesis of a new protein which has specific effects on the target cell.
Where are protein hormone receptors located?
target cell membrane
Which hormone-receptor complex is a two step process?
What occurs when protein hormones activate receptors on the cell membrane?
The interaction stimulates the production of a second messenger which activates enzymes to regulate intracellular activity
Which feedback system involves communication via hormones among several glands to turn on or turn off target organ hormone secretion?
Which feedback system involves a gland that responds to a stimulus by increasing or decreasing the secretion of a hormone based on feedback from various factors?
What feedback system increases target organ action beyond normal?
What sort of stimuli cause the nervous system to modulate hormone secretion?
Pain, emotion, sexual excitement, and stress
Neural involvement is initiated by the CNS and implemented by the ______
Sympathetic nervous system
What is an example of neural involvement in the endocrine system?
Stress is sensed by CNS, the SNS secretes catecholamines that increase BP and HR to deal w/stress more effectively
Oxytosin release causes an increase in uterine contractions. The pressure sensors in the vagina then stimulate more oxytocin to be released which causes stronger contractions. What feedback is this an example of?
Example of negative feedback
Increased blood glucose stimulates insulin secreation which decreases blood glucose, then the stimulation decreases.
Example of complex feedback
regulation of thyroid hormones - synthesis and release of TSH from anterior pituitary is stimulated by thyrotropin-releasing hormone (TRH) which is secreted by the hypothalamus, T3 and T4 have an inhibitory effect on secretion of TRH and TSH
What is the effect of aging on the thyroid gland?
Atrophy of the thyroid gland, TSH and T3 secretion is decreased
What is the effect of aging on the parathyroid glands?
Increased basal level of PTH and increased secretion
What are the effects of aging on the adrenal cortex?
Adrenal cortex becoms more fibrotic and slightly smaller
higher plasma levels of cortisol
decreased plasma levels of adrenal androgens and aldosterone
What are some effects of aging on the adrenal medulla?
increased secretion and basal level of norepinephrine; no change in plasma epinephrine levels with aging
decreased beta adrenergic receptor response to norepinephrine
What are the effects of aging on the pancreas?
Increase in fibrosis and fatty deposits in pancreas
Increased glucose intolerance and decreased sensitivity to insulin
What is the purpose of an MRI for evaluating the pituitary gland?
Identifies tumors involving the hypothalamus or pituitary
What is the purpose of a TSH test?
measures levels for TSH. considered the most sensitive method fro evaluating thyroid disease. generally recommended as first diagnostic test for thyroid dysfunction
What is the purpose of a Thyroxine (T4) total?
Measures total serum level of T4, useful in evaluating thyroid function and monitoring thyroid therapy.
What is the purpose of measuring T3?
Measures serum levels of T3, helpful in diagnosing hyperthyroidism if T4 levels are normal
What is the purpose of measuring readioactive iodoine uptake?
provides direct mesure of thyroid activity. useful for evaluation of functional activity of solitary thyroid nodules
How is the procedure done for radioactive iodine uptake (RAIU)
Patient is given radioactive iodine either orally or IV, the uptake by the thyroid gland is measured with a scanner at several time intervals such as 2-4 hours and at 24 hours
What is the purpose of measuring total serum calcium?
Helps detect bone and parathyroid disorders. Hypercalcemia = hyperparathyroidism. Hypocalcemia = hypoparathyroidism.
What is the purpose of a thyroid scan?
Used to evaluate nodules of the thyroid. Radioactive isotopes are given orally or IV. Scanner passes over thyroid and makes graphic record of radiation emitted. Malignant tumors appear as cold spots because they tend not to toake up the radionuclide