Endocrine System and Calcium Regulation

Flashcards covering calcium regulation, adrenal gland layers, pancreatic hormones, and cellular communication methods based on the lecture transcript.

Calcitonin

A hormone released from the c cells of the thyroid gland when blood calcium is too high; it stimulates osteoblasts to build bone, reducing blood calcium.

Parathyroid hormone (PTH)

A hormone secreted by the chief cells of the parathyroid gland when blood calcium is too low; it stimulates osteoclasts to break down bone and promotes calcium retention at the kidney and intestines.

Renal calculi

The medical term for kidney stones, which can be caused by having too much calcium in the blood.

Adrenal medulla

The middle portion of the adrenal gland controlled by the nervous system; it is responsible for the synthesis of epinephrine and norepinephrine part of the short-term stress response.

Adrenal cortex

The outer portion of the adrenal gland made of three layers of tissue that produce different classes of hormones involved in the long-term stress response.

Zona glomerulosa

The outermost layer of the adrenal cortex that produces mineralocorticoids, specifically aldosterone, which causes the body to retain salt and water.

Zona fasciculata

The middle layer of the adrenal cortex responsible for producing glucocorticoids, specifically cortisol, which regulates the metabolism of fats, proteins, and carbohydrates.

Zona reticularis

The innermost layer of the adrenal cortex that produces gonadocortivoids, such as DHEA, which promotes the synthesis of testosterone and estradiol.

POMC (pro-opium-melanocortin)

A molecule produced in response to stress that breaks down into endorphins (analgesics), MSH (melanocyte-stimulating hormone), and cortin to produce cortisol.

Addison's disease

A condition resulting from low cortisol production characterized by nervousness, weight loss, and hyperpigmentation or bronzing of the skin due to a positive feedback loop involving MSH.

Cushing's syndrome

A condition caused by hypersecretion of glucocorticoids from the adrenal cortex, often characterized by weight gain in the trunk and potentially caused by an adrenal tumor.

Islets of Langerine

The endocrine portion of the pancreas, comprising approximately $2 \%$ of the organ, which contains alpha and beta cells responsible for blood sugar regulation.

Insulin

A hormone produced by the beta cells of the pancreas that lowers blood glucose by storing excess glucose as glycogen.

Glucagon

A hormone produced by the alpha cells of the pancreas that raises blood glucose levels by stimulating the breakdown of glycogen.

Type 1 diabetes

A genetic autoimmune condition where the body destroys its own beta cells, leading to an inability to produce insulin.

Type 2 diabetes

A condition traditionally associated with lifestyle factors like diet and exercise, where the body's glycemic index fluctuates or the pancreas experiences endocrine fatigue.

Thymosins

Hormones secreted by the thymus gland that aid in the conversion of immature T lymphocytes into mature ones.

Melatonin

A hormone produced by the pineal gland that regulates sleep and wake cycles based on environmental light and darkness.

Zygabers

Environmental cues or timekeepers, such as light, sound, or smell, that either suppress or increase the synthesis of melatonin.

Erythropoietin

A hormone secreted by the kidney that promotes red blood cell synthesis in response to low blood oxygen levels.

Leptin

A hormone made by adipocytes (fat cells) that is released when the stomach distends to signal satiety or feelings of fullness to the brain.

Peptide hormones

Water-soluble hormones derived from amino acids or polypeptides that bind to membrane receptors on the outside of the cell and require a second messenger.

Steroid hormones

Lipid-soluble hormones derived from cholesterol and fats that bind to the hormone responsive element on the DNA inside the cell to influence transcription.

Transcription

The biological process of sequence conversion where DNA is used to create messenger RNA.

Translation

The biological process where messenger RNA is used to synthesize proteins.

Second messenger

A molecular mechanism, such as cyclic AMP, that translates and amplifies an extracellular hormone signal into an intracellular physiological response.