ENDOCRINE Flashcards
What is the function of the endocrine system?
To chemically control body functions by secreting hormones into the bloodstream.
What are the major organs of the endocrine system?
Thyroid, pineal, pituitary, adrenal glands, pancreas, ovaries/testes.
How do endocrine and nervous systems differ?
Endocrine uses hormones (slow, long-lasting); nervous uses impulses (fast, short-term).
Difference between endocrine and exocrine glands?
Endocrine: ductless, secrete into blood. Exocrine: ducts, secrete onto body surfaces or into cavities.
How do hormones affect cells?
Change membrane permeability, enzyme activity, protein synthesis, secretion, and mitosis.
What is up-regulation?
Increased receptors on target cells to heighten hormone sensitivity (e.g., uterus and oxytocin).
What is down-regulation?
Decreased receptors on target cells to reduce hormone sensitivity (e.g., insulin resistance in Type 2 diabetes).
How are hormone levels typically regulated?
Mostly via negative feedback.
What are examples of lipid-soluble hormones?
Steroids like testosterone, estrogen, aldosterone; thyroid hormone.
What are examples of water-soluble hormones?
Peptides, proteins (GH, insulin), amines (epinephrine).
How do lipid-soluble hormones act?
Cross cell membrane → bind intracellular receptors → gene activation.
How do water-soluble hormones act?
Bind membrane receptors → use second messengers (cAMP, Ca²⁺) → enzyme activation.
What are synergist hormones?
Hormones that amplify each other’s effects (e.g., glucagon + epinephrine).
What are antagonist hormones?
Hormones with opposite effects (e.g., insulin vs. glucagon).
What is permissiveness?
One hormone needs another to exert full effect (e.g., thyroid hormone and GH).
What are tropic hormones?
TSH, ACTH, FSH, LH, MSH – they regulate other glands.
What are non-tropic hormones?
GH and prolactin.
What does ADH do?
Reduces urine, raises BP.
What does oxytocin do?
Stimulates uterine contractions and milk ejection.
Functions of thyroxine (T₄)?
Increases metabolism, temp, protein synthesis.
What does calcitonin do?
Lowers blood calcium.
What does PTH do?
Increases blood calcium, decreases phosphate.
Function of insulin?
Lowers blood glucose by promoting uptake/storage.
Function of glucagon?
Raises blood glucose via glycogenolysis & gluconeogenesis.
What are the three zones and their hormones?
Zona glomerulosa → Aldosterone
Zona fasciculata → Cortisol
Zona reticularis → Androgens (e.g., DHEA)
What does the adrenal medulla secrete?
Epinephrine & norepinephrine.
What are the stages of GAS?
Alarm (fight/flight)
Resistance (long-term hormone release)
Exhaustion (system breakdown)
Which hormones are involved in the resistance stage?
Cortisol, GH, TSH, aldosterone.
