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General Knowledge Cluster74 Verified Questions
Human Endocrine System GK Questions & Answers
The human endocrine system comprises ductless glands that synthesize biochemical signalling molecules called hormones, secreting them directly into the circulatory bloodstream to modulate target organ physiology. Hypothalamic neurosecretory cells regulate the pituitary gland (hypophysis), commonly termed the master gland, located in the sella turcica of the sphenoid bone. The anterior pituitary (adenohypophysis) secretes Growth Hormone (GH), Thyroid-Stimulating Hormone (TSH), Adrenocorticotropic Hormone (ACTH), and gonadotropins, while the posterior pituitary (neurohypophysis) releases oxytocin and vasopressin (Antidiuretic Hormone, ADH) synthesized by the hypothalamus. The thyroid gland produces tetraiodothyronine (T4) and triiodothyronine (T3) containing dietary iodine; deficiency results in simple goitre and congenital cretinism. Adrenal glands atop the kidneys possess an outer cortex producing steroid hormones (cortisol, aldosterone) and an inner medulla releasing catecholamines (adrenaline/epinephrine and noradrenaline) for sympathetic fight-or-flight responses. In the pancreas, the endocrine Islets of Langerhans contain beta cells producing insulin, which facilitates cellular glucose uptake and prevents Diabetes mellitus, while alpha cells secrete glucagon to promote glycogenolysis. Parathyroid glands secrete parathormone (PTH) to increase serum calcium concentrations antagonistically against calcitonin.
High-yield conceptual summaries for competitive exams and rapid revision.
The pituitary gland is anatomically seated in the sella turcica, divided into adenohypophysis (anterior) and neurohypophysis (posterior).
Posterior pituitary stores and releases oxytocin (parturition and milk ejection) and vasopressin/ADH (renal water reabsorption), synthesized in the hypothalamus.
Thyroid gland synthesizes T3 and T4 utilizing iodine; hyposecretion causes goitre, myxedema in adults, and cretinism in infants.
The adrenal medulla synthesizes adrenaline and noradrenaline for rapid emergency autonomic response, while the cortex produces cortisol and aldosterone.
Endocrine Islets of Langerhans in the pancreas secrete insulin from beta-cells to lower blood glucose and glucagon from alpha-cells to elevate it.
Showing 25 Curated Questions74 Total in Bank
1ID: GK-BODY-00200
hardHormones, Enzymes & Nutrition
Somatostatin (Growth Hormone-Inhibiting Hormone / GHIH), secreted by delta cells in pancreatic islets and hypothalamic neurosecretory cells, functions systemically as a potent inhibitor of:
Verified Explanation
Somatostatin acts as a universal inhibitory regulatory peptide, suppressing anterior pituitary growth hormone and TSH, as well as gastrointestinal hormones (insulin, glucagon, secretin, and gastrin).
2ID: GK-BODY-00217
easyHormones, Enzymes & Nutrition
Which primary glucocorticoid steroid hormone, synthesized in the zona fasciculata of the adrenal cortex, helps regulate blood sugar, suppress inflammation, and manage prolonged stress?
Verified Explanation
Cortisol is the body's primary glucocorticoid hormone produced by the adrenal cortex, regulating glucose metabolism, immune suppression, and circadian stress responses.
3ID: GK-BODY-00279
mediumHormones, Enzymes & Nutrition
Which endocrine hormone produced by the parathyroid glands acts to increase calcium concentration in the bloodstream when serum calcium drops?
Verified Explanation
Parathyroid hormone (PTH) stimulates osteoclasts to resorb bone calcium, increases renal calcium reabsorption, and activates Vitamin D to elevate blood calcium.
4ID: GK-BODY-00300
hardHormones, Enzymes & Nutrition
What peptide hormone secreted by adipose tissue (fat cells) binds to receptors in the arcuate nucleus of the hypothalamus to suppress appetite and stimulate energy expenditure?
Verified Explanation
Leptin is the "satiety hormone" secreted by white adipocytes in proportion to body fat mass; it acts on hypothalamic POMC and NPY/AgRP neurons to decrease food intake.
5ID: GK-BODY-00331
mediumHormones, Enzymes & Nutrition
Which iodine-containing hormone, secreted by follicular cells of the thyroid gland, contains four iodine atoms and governs basal metabolic rate in bodily tissues?
Verified Explanation
Thyroxine (T4) represents ~90% of thyroid hormone output; it is converted peripherally into active T3, binding nuclear thyroid hormone receptors to upregulate Na+/K+-ATPase and basal metabolic rate.
6ID: GK-BODY-00337
mediumHormones, Enzymes & Nutrition
Which hormone produced and secreted by lactotroph cells in the anterior pituitary gland is primarily responsible for milk production (lactogenesis) in mammary glands?
Verified Explanation
Prolactin is a polypeptide hormone secreted by anterior pituitary lactotrophs that promotes mammary gland development and milk synthesis during pregnancy and lactation.
7ID: GK-BODY-00355
easyHormones, Enzymes & Nutrition
Which hormone, secreted by four tiny parathyroid glands on the posterior surface of the thyroid, acts to increase calcium concentration in the bloodstream?
Verified Explanation
Parathyroid hormone (PTH or parathormone) elevates serum calcium levels by stimulating bone resorption, enhancing renal calcium reabsorption, and activating Vitamin D.
8ID: GK-BODY-00466
hardHormones, Enzymes & Nutrition
Which gastrointestinal peptide hormone, secreted by S-cells in the duodenal mucosa in response to acidic gastric chyme (pH < 4.5), stimulates the pancreas to secrete bicarbonate-rich fluid?
Verified Explanation
Secretin (the first hormone ever discovered, by Bayliss and Starling in 1902) is released by duodenal S-cells to stimulate pancreatic ductal secretion of water and neutralizing bicarbonate.
9ID: GK-BODY-00475
easyHormones, Enzymes & Nutrition
Which endocrine hormone, secreted by beta cells in the islets of Langerhans in the pancreas, lowers blood glucose levels?
Verified Explanation
Insulin is a peptide hormone produced by pancreatic beta cells that promotes glucose uptake by skeletal muscle and adipose tissue while inhibiting hepatic gluconeogenesis, reducing blood sugar.
10ID: GK-BODY-00534
easyHormones, Enzymes & Nutrition
Which endocrine hormone produced by the beta cells of the islets of Langerhans in the pancreas lowers blood glucose levels?
Verified Explanation
Insulin is a peptide hormone secreted by pancreatic beta cells that facilitates glucose uptake into muscle and adipose tissues, lowering blood glucose concentration.
11ID: GK-BODY-00580
hardHormones, Enzymes & Nutrition
Which neuroendocrine peptide hormone synthesized in the paraventricular nucleus of the hypothalamus and released from the posterior pituitary stimulates uterine contractions during labor and milk ejection during lactation?
Verified Explanation
Oxytocin is a nonapeptide hormone that causes smooth muscle contraction in the myometrium (Ferguson reflex during labor) and myoepithelial cells of mammary alveoli (milk ejection reflex).
12ID: GK-BODY-00620
mediumHormones, Enzymes & Nutrition
Growth Hormone (Somatotropin), which stimulates epiphyseal bone growth and protein anabolism throughout childhood and adolescence, is secreted by the:
Verified Explanation
Somatotroph cells in the anterior pituitary (adenohypophysis) synthesize and secrete human Growth Hormone (hGH) under the regulatory control of hypothalamic GHRH and somatostatin.
13ID: GK-BODY-00640
hardHormones, Enzymes & Nutrition
Calcitonin, a 32-amino acid peptide hormone that lowers blood calcium levels by inhibiting osteoclast bone resorption, is synthesized and secreted by:
Verified Explanation
Calcitonin is produced by the neural crest-derived parafollicular cells (C cells) of the thyroid gland in response to hypercalcemia, counteracting parathyroid hormone (PTH).
14ID: GK-BODY-00009
easyHormones, Enzymes & Nutrition
Insulin is a hormone produced by the beta cells of which digestive and endocrine organ?
Verified Explanation
Insulin lowers blood glucose levels by facilitating cellular uptake and glycogenesis in liver and muscles.
15ID: GK-BODY-00024
mediumHormones, Enzymes & Nutrition
Which hormone secreted by the adrenal medulla during acute stress triggers the 'Fight or Flight' response?
Verified Explanation
Adrenaline elevates heart rate, dilates bronchioles, and mobilizes blood glucose during sympathetic emergency activation.
16ID: GK-BODY-00029
mediumHormones, Enzymes & Nutrition
Which hormone regulates the human sleep-wake cycle (circadian rhythm) and is secreted by the pineal gland in darkness?
Verified Explanation
Melatonin synthesis in the pineal gland is stimulated by darkness via retinohypothalamic tract signaling from the SCN.
17ID: GK-BODY-00039
mediumHormones, Enzymes & Nutrition
Which hormone, often called the 'Love Hormone' or 'Bonding Hormone', stimulates uterine contractions during childbirth and milk ejection?
Verified Explanation
Synthesized in the hypothalamus and released from the posterior pituitary, oxytocin regulates maternal bonding and labor.
18ID: GK-BODY-00045
hardHormones, Enzymes & Nutrition
The 'Juxtaglomerular Apparatus' (JGA) in the kidneys releases which enzymatic hormone in response to decreased renal perfusion pressure?
Verified Explanation
Renin cleaves angiotensinogen into angiotensin I, activating the RAAS cascade to restore systemic blood pressure.
19ID: GK-BODY-00049
hardHormones, Enzymes & Nutrition
The 'Islets of Langerhans' contain delta cells (δ-cells) that secrete which paracrine regulatory hormone that inhibits both insulin and glucagon?
Verified Explanation
Somatostatin (SS-14) acts locally to tonically inhibit secretory output from neighboring alpha and beta endocrine cells.
20ID: GK-BODY-00088
easyAnatomy Organ Systems
Which hormone, secreted by the beta cells of the Islets of Langerhans in the pancreas, lowers blood glucose levels by promoting cellular glucose uptake?
Verified Explanation
Insulin stimulates GLUT4 glucose transporter translocation to cell membranes in skeletal muscle and adipose tissue, promoting glycogenesis in the liver.
21ID: GK-BODY-00127
mediumHormones Glands
Which hormone, synthesized from serotonin and secreted by the pineal gland in response to darkness, regulates circadian sleep-wake cycles?
Verified Explanation
Melatonin secretion is suppressed by retinal light exposure signaling via the suprachiasmatic nucleus (SCN), peaking during darkness to induce sleep.
22ID: GK-BODY-00128
mediumHormones Glands
Which hormone, secreted by four small glands embedded on the posterior surface of the thyroid, increases blood calcium levels by stimulating bone osteoclasts?
Verified Explanation
PTH elevates blood calcium by promoting bone resorption, increasing renal calcium reabsorption, and activating Vitamin D (calcitriol) synthesis.
23ID: GK-BODY-00155
easyHormones, Enzymes & Nutrition
Which peptide hormone, secreted by beta cells in the Islets of Langerhans of the pancreas, decreases blood glucose concentration by facilitating cellular glucose uptake?
Verified Explanation
Insulin promotes glucose uptake into skeletal muscle and adipose tissue while inhibiting hepatic gluconeogenesis, maintaining blood glucose homeostasis.
24ID: GK-BODY-00167
easyHormones, Enzymes & Nutrition
Which catecholamine hormone, secreted rapidly by the adrenal medulla during acute stress, triggers the classic 'fight-or-flight' response?
Verified Explanation
Adrenaline increases heart rate, dilates bronchioles, mobilizes glycogen into glucose, and redistributes blood flow to skeletal muscles in response to sympathetic nervous stimulation.
25ID: GK-BODY-00175
mediumHormones, Enzymes & Nutrition
Which iodine-containing amino acid hormone, secreted by thyroid follicular cells, regulates basal metabolic rate (BMR) and cellular oxidative energy consumption?
Verified Explanation
Thyroid follicular cells synthesize Thyroxine (T4) and Triiodothyronine (T3) using tyrosine residues and dietary iodine; these hormones elevate basal metabolic rate and protein synthesis.
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