Endocrine Hormone Regulation Quiz

High glucose stimulates insulin release from pancreatic beta cells, promoting glucose uptake and glycogen storage. Low glucose triggers glucagon release to mobilize glycogen. Homeostasis remains near 90 mg/100 mL, allowing stable energy regulation through coordinated hormone responses.

Alpha cells in the pancreatic islets secrete glucagon when blood glucose drops. Their primary function is to signal the liver to release stored glucose, ensuring stable plasma glucose levels during fasting or extended energy demand.

Beta cells produce insulin during high blood sugar, lowering glucose by promoting uptake. Glucagon is released during low glucose and acts on the liver to increase plasma glucose. This reciprocal control ensures stable metabolic regulation.

Glucagon specifically targets the liver, where it activates glycogenolysis and gluconeogenesis. These processes release glucose back into circulation, preventing hypoglycemia during fasting or intense metabolic demand.

High calcium stimulates calcitonin release from the thyroid, shifting calcium into bone and promoting renal excretion. Calcitonin counteracts PTH, helping prevent dangerously elevated calcium levels and maintaining mineral homeostasis.

Low blood calcium triggers PTH release from the parathyroid glands. PTH increases calcium by stimulating bone resorption, increasing renal reabsorption, and activating vitamin D to enhance intestinal absorption.

Hypothalamic neurohormones such as oxytocin and ADH are transported to and stored in the posterior pituitary. They are released directly into systemic circulation in response to neural signals, bypassing endocrine intermediates.

The anterior pituitary is the adenohypophysis, responsible for producing tropic hormones like TSH, ACTH, GH, and LH/FSH. It receives hormonal regulation through the hypothalamic portal system rather than neuronal storage.

Tropic hormones act on other endocrine glands but may also exert direct physiological effects on target tissues. This dual activity makes them both tropic (gland-stimulating) and non-tropic (acting on peripheral tissues), depending on the specific hormone.

Hypothalamic releasing hormones travel through the hypophyseal portal system to the anterior pituitary. This direct vascular link enables rapid regulation of pituitary output, maintaining coordinated endocrine signaling across multiple hormone axes.