A&PII Endocrine System

Q: What is the endocrine system, and what role does it play?

A: A system of glands that secrete hormones into the bloodstream to regulate growth, metabolism, reproduction, stress, fluid balance, and homeostasis.

Q: How does the endocrine system differ from the nervous system?

A: Nervous system = fast, short-acting (electrical signals); Endocrine system = slower, long-lasting (hormones).

Q: How are hormones produced, released, and transported?

A: Glands produce hormones → released into blood → travel to target cells with specific receptors.

Q: What are lipid-soluble hormones? Give examples.

A: Steroid hormones (cortisol, aldosterone, estrogen, testosterone) and thyroid hormones (T3/T4). They require carrier proteins, cross membranes, act on intracellular receptors, and change gene expression (long-lasting effects).

Q: What are water-soluble hormones? Give examples.

A: Most peptide/protein hormones (insulin, glucagon, ADH, epinephrine). They dissolve freely in blood, bind to surface receptors, and trigger second messenger cascades (fast, short-lived effects).

Q: Which hormones have longer half-lives, lipid-soluble or water-soluble?

A: Lipid-soluble (slow breakdown in the liver).

Q: What is negative feedback? Example?

A: Hormone secretion stops when levels normalize. Example: Insulin lowers blood glucose → insulin release stops.

Q: What is positive feedback? Example?

A: Hormone secretion amplifies until an endpoint. Example: Oxytocin during childbirth increases contractions → more oxytocin release.

Q: Why is the hypothalamus important in endocrine regulation?

A: Links the nervous and endocrine systems by controlling pituitary hormone release.

Q: Why is the pituitary gland called the “master gland”?

A: It releases tropic hormones that control other endocrine glands (TSH, ACTH, LH/FSH).

Q: What does the HPG axis regulate?

A: Reproduction (GnRH → LH, FSH → sex hormones, gamete production).

Q: What does the HPA axis regulate?

A: Stress (CRH → ACTH → cortisol, epinephrine/norepinephrine).

Q: What does the HPT axis regulate?

A: Metabolism (TRH → TSH → T3, T4).

Q: What does the HPS axis regulate?

A: Growth (GHRH → GH → IGFs).

Q: What hormones are produced by the thyroid gland?

A: T3 & T4 (increase metabolism, protein synthesis, ATP use) and calcitonin (lowers blood calcium by building bone).

Q: What is the function of the parathyroid gland?

A: Produces PTH, which raises blood calcium by stimulating bone resorption, kidney reabsorption, and calcitriol activation.

Q: What hormones are secreted by the adrenal cortex?

A: Aldosterone (salt/water balance), Cortisol (stress & blood glucose regulation), Androgens (sex hormones).

Q: What hormones are secreted by the adrenal medulla?

A: Epinephrine and norepinephrine (fight-or-flight response).

Q: How does the pancreas regulate blood glucose?

A: Insulin (β-cells) lowers glucose by promoting uptake/storage. Glucagon (α-cells) raises glucose by glycogen breakdown & gluconeogenesis.

Q: What is the role of the pineal gland?

A: Produces melatonin, regulates circadian rhythms, released in darkness.

Q: What hormone does the thymus produce, and what is its function?

A: Thymosin → stimulates T-cell maturation for immune defense.

Q: What is diabetes mellitus, and what are the types?

A: Type I = no insulin (autoimmune destruction of β-cells). Type II = insulin resistance. Symptoms: polyuria, polydipsia, polyphagia, blurred vision, weight loss.

Q: What is hyperthyroidism (Graves’ disease)?

A: Excess thyroid hormone → increased metabolism, weight loss, heat intolerance, anxiety.

Q: What is hypothyroidism?

A: Low thyroid hormone → fatigue, weight gain, cold intolerance. Children: cretinism; Adults: myxedema/goiter.

Q: What are adrenal disorders?

A: Cushing’s (too much cortisol, weight gain, hypertension, immunosuppression) and Addison’s (too little cortisol, fatigue, hypotension, hypoglycemia).

Q: What happens with excess or deficient GH?

A: Childhood excess = gigantism; Adult excess = acromegaly; Childhood deficiency = dwarfism.

Q: How does stress affect the endocrine system?

A: Activates HPA axis → cortisol release. Short-term stress = protective; chronic stress = ↑BP, diabetes risk, immune suppression.

Q: How do diet, exercise, and toxins affect endocrine health?

A: Diet affects glucose, thyroid (iodine), calcium/vitamin D. Exercise ↑insulin sensitivity, regulates GH/cortisol. Environmental toxins (like BPA) can mimic/block hormones, causing reproductive and metabolic issues.