ch 9 Flashcards
the endocrine system: function
system that works with nervous system to MAINTAIN HOMEOSTASIS by releasing chemical hormones from various glands
- composed of endocrine glands and hormones
function of endocrine glands
secrete chemical messengers (HORMONES) directly into bloodstream
there are over 200 hormones in the human body, with various functions that regulate
- growth and development
- metabolism
- blood pressure
- immune response
- blood glucose levels
- water-salt balance
glands + tissues
some glands are exclusively endocrine glands:
- pituitary
- pineal
- thyroid
- parathyroid
- adrenal glands
some tissues/organs secrete hormones, but aren’t exclusively endocrine glands:
- hypothalamus
- thymus
- panreas
- testes
- ovaries
endocrine hormones
define + types
chemicals secreted by endocrine glands directly into the blood
- classified according to their activation site
NON-TARGET HORMONES: affect many cells throughout body (ex. insulin, epinephrine)
TARGET HORMONES: affect specific cells/target tissues (parathyroid hormone, gastrin)
chemical control systems: compared to the RAPID actions of the nervous system,
endocrine system has SLOWER and LONGER ACTING EFFECTS + affects a BROADER RANGE of CELL TYPES
- hypothalamus regulates PITUITARY GLAND through nerve stimulation, but pituitary gland is what stimulates the glands of the endocrine system to release hormones
- scientists discovered the hormones that are low concentration in the blood by trial and error (usually removing an organ and seeing what goes wrong lmao)
types of hormones
- steroid hormones
made from cholesterol
- complex CHO rings, fat soluble, easily diffuse DIRECTLY through lipid bilayer of target cell + activate specific genes to elicit response (1. diffuse into target cell 2. bind to receptor protein in cytoplasm 3. hormone-receptor complex activates specific genes to elicit response 4. affect gene expression) - peptide hormones
made from a.a. chains
- water soluble
- can’t diffuse across membrane (1. bind to receptor on membrane surface, causing chain reaction inside target cell 2. peptide hormones affect metabolic enzyme activity- enzyme cascade)
adenylyl cyclase catalyzes conversion of ATP to cyclic AMP
- cAMP (cyclic AMP) = cyclic adenosine monophosphate = secondary chemical messenger that directs protein synthesis by ribosomes
- production of cyclic AMP can be stopped by a 2nd type of G protein which inhibits the activity of adenylyl cyclase
major glands of the endocrine system: pituitary gland
pea sized gland in bony cavity attached by thin stalk to hypothalamus at base of brain
- controls other endocrine glands + regulates body growth (coordinates endocrine and nervous)
- releases hormones important for metabolism, growth, development, reproduction, and other critical life functions
- composed of posterior pituitary/lobe and anterior pituitary/lobe
major glands of the endocrine system: pituitary gland: posterior pituitary
- considered part of nervous system
- doesn’t produce any hormones- STORES AND RELEASES hormones ADH and oxytocin (childbirth) which are produced in the hypothalamus
major glands of the endocrine system: pituitary gland: anterior pituitary
true hormone-synthesizizng gland
produces and releases 6 main hormones:
- TSH (thyroid-stimulating hormones)
- ACTH (adrenocorticotropic hormone)
- PRL (prolactin)
- hGH (human growth hormone)
- FSH (follicle-stimulating hormones)
- LH (luteinizing hormone)
hypothalamus controls secretions of anterior pituitary + hormones are secreted into bloodstream
major glands of the endocrine system: thyroid gland
butterfly-shaped gland in front of neck that secretes a hormone that CONTROLS the SPEED at which the body cells work, e.g.
- bone growth
- mental development
- metabolic use of energy
- blood pressure and heart rate
- muscle tone
- digestion
- reproduction
secretion of thyroid hormones is under NEGATIVE CONTROL (feedback) from hypothalamus (via TSH)
- goiter: iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine (T4, which = tyrosine + iodine, which comes from seafood, milk, ionized salt)
major glands of the endocrine system: parathyroid glands
four small glands in thyroid gland that regulate the CA2+ content in blood. Calcium’s functions:
- bone and teeth structure
- cell signaling
- nerve conduction
- muscle contraction
- blood clotting
the adrenal glands
located above each kidney (tiny lil hats) (left vs right adrenal gland)
- regulate use of carbs and salts + prepares the body for emergency by producing epinephrine (adrenaline)
- two glands (each made of cortex + medulla encased in one shell): ADRENAL CORTEX (outer) and ADRENAL MEDULLA (inner)
adrenal glands: adrenal cortex (outer)
- involved in long-term stress response
- produces glutocorticoids and mineralocorticoids
cortisol: glucocorticoid (adrenal cortex) that raises blood glucose by promoting breakdown of muscles to a.a., prompts breakdown of fat cells - chronic stress => impaired thinking, heart damage, high blood pressure, infection, death
- natural anti-inflammatory + supresses immune system + inhibits regeneration of connection tissue
aldosteron: mineralocorticoid (adrenal cortex) that increases the absorption of sodium into the blood (inc. ion sodium concentration in blood, more osmosis, inc. blood pressure) (water always follows sodium) (increases volume)
adrenal glands: adrenal medulla (inner)
- produces epinephrine and norepinephrine (adrenaline and noradrenaline)
- regulates the short-term stress response (fight/flight)
- hormonal effects similar to sympathetic system, but influence lasts about 10 times longer
