Bio: Endocrinology
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- where are the adrenal glands?
- right above the kidneys
- what hormones does the adrenal gland adrenal cortex secrete?
- corticosteroids: glucocorticoids (cortisol and cortisone): increase the amount of glucose in the blood, mineralocorticoid (aldesterone): increase blood volume, and small amounts of cortical sex hormones (androgens): affect females more than males.
- how are the hormones secreted by the adrenal cortex regulated?
- the hormone ACTH, adrenocorticotropic hormone, which is secreted by the anterior pituitary, regulates glucocorticoids and mineralocorticoids secreted by the adrenal cortex.
- what hormones are secreted by the adrenal medulla in the adrenal gland?
- epinephrine and norepinephrine (neurotransmitters) are secreted by the adrenal medulla. they are involved in the fight/flight response which increases blood circulation to muscles and the brain and slows down metabolic processes that are not vital to survival.
- what hormones are secreted tropically (causing other hormones to be secreted by other endocrinological organs) by the anterior pituitary?
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FSH (follicle stimulating hormone)
LH (Luteinizing hormone)
Adrenaline
Thyroid-stimulating hormone - what hormones are secreted directly by the anterior pituitary?
- Prolactin
- what hormones are secreted by the posterior pituitary?
- oxytocin and ADH (antidiuretic hormone): increases blood volume by increasing the permeability of the nephron to water, caused by hormonal signal from the hypothalamus (the neurosecretory cells). oxytocin and ADH are not synthesized by the posterior pituitary. only stored and secreted by posterior pituitary. they are synthesized by the hypothalamus.
- order of glands from top to bottom of body
- pineal, hypothalamus, pituitary, parathyroid/thyroid, thymus, adrenal, kidneys, ovaries, testes
- what hormones regulate secretions of the anterior and posterior pituitary?
-
a)hypothalamus hormones such as FSH and LH regulate the secretion of the anterior pituitary and are sent directly to the anterior pituitary through the portal vein, thus causing the anterior pituitary to increase/decrease hormone secretion (flat peg). a feedback system is incorporated.
b)hypothalamus hormones oxytocin and ADH are synthesized by the hypothalamus and are transported through the axon into the posterior pituitary, which then stores and releases these same hormones. - Thyroid hormones
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a) thyroxine and triiodothyronine are derived from the iodination of the aa tyrosine. have neurological development and growth functions. hyperthyroidism, and hypothyroidism are diseases caused by thyroid.
b) calcitonin decreases the release of Ca2+ from the bone - pancreas: exocrine and endocrine functions
-
an exocrine and endocrine organ.
a) exocrine functions are to secrete through ducts, digestive enzymes into the small intestine
b) endocrine function involeves Islets of Langerhans: composed of alpha and beta cells: alpha cells secrete glucagon and beta cells secrete insulin. - insulin is antagonistic to
- glucagon and glucocorticoids (adrenal cortex)
-
calcitonin is antagonistic to
what does calcitonin do? -
PTH parathyroid hormone
calcitonin (which decreases the release of Ca from bone) is secreted by the thyroid, PTH (which increases the concentration of Ca by increasing the release of Ca from bone) is secreted by the parathyroid. - PTH does what
- increases Ca concentration in blood and decreases excretion of Ca in kidneys
- Kidneys do what when blood volume starts to fall
- secrete renin, an enzyme which causes the adrenal cortex to produce a mineralocorticoid (aldosterone) which causes sodium levels and blood volume to increase by increasing their permeability in the nephron.
- an excess of aldosterone can cause
- hypertension (due to high blood volume and sodium levels)
- adrenal cortex secretes small amounts of
- cortical sex hormones (androgens)
- Renin does what
- when kidneys sense a low blood volume and renin is produced, it converts plasma protein angiotensin into angiotensin I which turns into angiotensin II, which stimultates the adrenal cortex to secrete aldosterone.
- gastrointestinal hormones
- food enters stomache, causes secretion of gastrin. gastrin signals to gastric glands to secrete HCl. chyme (partially digested acidified food) reaches small intestine, causes secretion of secretin, which causes secretion of alkaline bicarbonate from the pancreas (exocrine action). pancreas also secretes cholecystokinin (in response to fat) to cause gall bladder to secrete bile (to digest fat)
- pineal gland is located at
- the base of the brain; secretes melatonin, thought to regulate circadian rhythms (light and dark, sleep)
- what are the two kinds of mechanisms for hormone action?
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peptides (extracellular) bind to specific receptors located on the surface of cells, cause ATP to be converted to cAMP by adenylate cyclase which in turn causes a cascade of reactions to take place.
Steroids, which are lipid soluble (estrogen, aldosterone, glucocorticoids secreted by the testes, ovaries, adrenal cortex, and placenta) can pass through the lipid bilayer and bind to internal receptors to signal the DNA directly to change mRNA transcription and protein synthesis.