Endocrinology Flashcards
endocrine system
acts as means of internal communication, coordinating the activities of organ systems
hormones
chemical substances synthesized and secreted by endocrine glands directly into the circulatory system.
Exocrine glands
secrete substances that are transported by ducts
two chemical structures of hormones
peptide hormones and steroid hormones.
Peptide hormones
act as first messengers binding to specific extracellular receptors on the surface of their target cells, they rigger a series of enzymatic reactions within the cell. causing a cascade effect usually fast acting and short lived
Cyclic AMP
acts a second messenger from the enzymatic conversion of ATP, which was catalyzed by membrane bound enzyme adenylate cyclase.
it relays messages from the extracellular peptide hormone enzymes.
-inactivated by cytoplasmic enzyme phosphodieterase.
Steroids hormones
belong to a class of lipid derived molecules, because the are lipid soluble, steroid hormones enter their target cells directly and bind to intracellular receptor proteins in cytoplasm -this complex enter the nucleus and directly activates expression. longer and longer effect
endocrine glands
pituitary, hypothalamus, thyroid, parathyroid, adrenals, pancreas, testes, ovaries, pineal, kidneys, gastrointestinal glands, heart and thymus
adrenal glands
are situated on top of the kidneys and consist of the adrenal cortex and adrenal medulla
adrenal cortex
in response to stress ATCH stimulates the adrenal cortex to synthesize and secrete the steroid hormones which are collectively known as corticosteroids.
corticosteroids
derived from cholesterol include glucocorticoids, mineralcorticoids and cortical sex hormones.
glucocorticoids
cortisol and cortisone, involved in glucose regulation and protein metabolism. Rasing blood glucose levels by promoting protein breakdown and using the products in gluconeogenesis. also raises the plasma glucose levels and decreases protein synthesis
gluconeogenesis
a metabolic pathway that generates glucose from non carbohydrates
mineralcorticoids
particularly aldosterone regulates plasma levels of sodium and potassium and the total extracellular water volume.
aldosterone
causes active re-absorption of sodium and passive re-absorption of water in the nephron. results in the rise in both blood volume and blood pressure. this excess retention leads to hypertension
corical sex hormones
the adrenal cortex secretes small quantities fo androgens (male hormones) like androstendione and dehydropieandrosterone in males and females. has no real effect in males due to its already present. but over production in females leads to masculinizing effects
adrenal medulla
produces epinephrine and norepinephrine both of which belong to a class of amino acid derived compounds called catecholamines
epinephrine
increases the conversion of glycogen to glucose in liver and muscle tissue, causing a rise in blood glucose levels and increase in basal metabolic rate. along with norepinephrine it increases the strength of the heart beat to assist in “fight or flight”
control of adrenal hormones
release of adrenal cortical hormones is under the control of ACTH, aldosterone is controlled by renin angiotensisn mechanism.
Pituitary gland
(hypophysis) small trilobed gland lying at the base of the brain. the two main lobes, anterior and posterior are functionally distinct.
anterior pituitary
synthesizes both direct and tropic hormones. the hormonal secretions of this portion of the pituitary is regulated by hypothalamic secretion called releasing and inhibiting hormones or factors.
direct hormones
anterior pituitary hormones that directly synthesize their target organs. (PEG) prolactin, endorphins, growth hormone
Growth Hormone
GH (somatotrophin) promotes the bone and muscle growth
acromegaly
a disorder caused from GH over production in humans that have disproportionate over growth
prolactin
stimulates mile production and secretion in female mammary glands.
endorphins
neurotransmitters that behave like opoids, providing internal pain relief and production of pleasure sensations