Endocrine system Flashcards
Endocrine glands
synthesize and secrete chemical substances called HORMONEs directly into the circulatory system
-include: pituitary, hypothalamus, thyroid, parathyroids, adrenals, pancreas, testes, ovaries, pineal glands, kidneys, gastrointestinal glands, heart and thymus
Exocrine Glands
such as the gallbladder,
-secrete substances transported by ducts
Adrenal Glands
located on the top of the Kidneys and consists of the adrenal cortex and the adrenal medulla
What stimulates the adrenal cortex and what is the result of the stimulation?
-ACTH (adrenocorticotropic mormon which is produced by the anterior pituitary stimulates the adrenal cortex to produce more than 2 dozen different steroid hormones called ADRENOCORTICAL STEROIDS or CORTICOSTEROIDS
Transcortins
the complex that is formed in the blood, when the corticosteroids are bound to transport proteins \
What are the three major classes of corticosteroids?
1) Glucocorticoids
2) Mineralocorticoids
3) Corticol Sex Hormones
Glucocorticoids
-such as cortisol and cortisone are involved in glucose regulation and protein metabolism
- raise blood glucose levels by promoting protein breakdown and gluconeogenesis and decreasing protein synthesis
- increase plasma glucose levels
- antagonistic to the effects of insulin
- release amino acids from skeletal muscle as well as lips from adipose tissue
- also promote the peripheral use of lipids and have anti-inflammatory effects
Mineralcorticoids
- ALDOSTERONE-
- regulate plasma levels of sodium and potassium and consequently the total extracelular fluid volume
- Aldosterone causes active reabsorption of sodium and passive reabsorption of water in the nephron of the kidney. This results in an increase in BLOOD VOLUME AND BP
- stimulated by angiotensen II and inhibited by ANP (Atrial natriuretic peptide)
Excess production of Aldosterone causes?
results in excess retention of water with resulting hypertension (High BP)
Corticol Sex hormones
-in both men and some the adrenal cortex secretes small amounts of ANDROGENS (male sex hormones) like andiostenedioine and dehydroplandrosterone
- in men, most of the androgens are produced by the testes
- in women, overproduction of the adrenal androgens may have maculating effects, such as excessive facial hair
Adrenal Medulla
-produces EPINEPHRINE (adrenaline) and noreepinephrine (noradrenaline)
What class does epinephrine and norepinephrine belong to?
CATECHOLAMINES
Epinephrine
- increases the conversion of glycogen to glucose in the liver and muscle tissue causing an increase in blood glucose levels and an increase in the basal metabolic rate
- inhibits other functions, such as digestion, that are not immediately important for survival
Epinephrine and Norepinephrine SImiliarities
both increase the rate and strength of the heartbeat and dilate and constrict blood vessel in such as way to increase the blood supply to the kidneys, skin, and digestive tract
- also promote the release of lipids by adipose tissue
- THese effects are known as the “fight or flight response”
- both are also NEUROTRANSMITTERS
Pituitary Gland
hypophysis
- a small, trilled gland at the basis of the brain
- the two main lobes are anterior and posterior
- Pituitary gland hangs below the hypothalamus and is connected to it by a slender cord call infundibulum
Anterior Pituitary
- synthesize both direct hormones which directly acts on their target organs
- also synthesize tropic hormones which stimulate other endocrine glands to release hormones
what regulates the hormonal secretion of the anterior pituitary?
regulated by the hypothalamic hormones called releasing/inhibiting hormones or factors
Direct hormones of the anterior pituitary
- Growth Hormone (GH, somatotropin)
- Prolactin
Growth Hormone
- (GH, somatotropin)
- promotes bone and muscle growth
- promotes protein synthesis and lipid mobilization and catabolism
In children what can a deficiency in growth hormone result in?
stunted growth (Dwarfism)
In children what can an excess of growth hormone result in?
Gigantism
In adults what can overproduction of Growth Hormone cause?
Acromegaly, a disorder characterized by disproportionate overgrowth of bone, especialy in the skull, jaw, feet, and hands
Prolactin
stimulates milk production in female mammary glands
Tropic hormones of the Anterior Pituitary
- adrenocorticotropic Hormone (ACTH)
- Thyroid Stimulating Hormone (TSH)
- Lenteinizing Hormone (LH)
- Follicle-stimulating hormone (FSH)
- Melanocyte-stimulating hormone (MSH)
- Endorphins
Adrenocorticotropic Hormone
ACTH
- stimulates the adrenal cortex to synthesize and secrete gulcocorticoids
- regulated by corticotrophin-releasing-factor (CRF)
Thyroid Stimulating Hormone
stimulates the thyroid gland to synthesize and release thyroid hormone, including thyroxine