The pancreas is an elongated, fleshy organ posterior to the stomach. It functions both as an exocrine (with ducts) gland to secrete digestive enzymes and as an endocrine (ductless) gland. The endocrine portion of the pancreas makes up only about 1% of the gland. This portion synthesizes, stores, and secretes hormones from clusters of cells [...]
In mammals, two adrenal glands rest on top of the kidneys. Each gland consists of two separate glandular tissues. The inner portion is the medulla, and the outer portion, which surrounds the medulla, is the cortex. Adrenal Cortex -The adrenal cortex secretes three classes of steroid hormones: glucocorticoids (cortisol), mineralocorticoids (aldosterone), and sex hormones (androgens, [...]
The parathyroid glands are tiny, pea-sized glands embedded in the thyroid lobes, usually two glands in each lobe. The parathyroids secrete parathormone (PTH), which regulates the concentrations of calcium (Ca2+) and phosphate (HP02-4) ions in the blood. When the calcium concentration in the blood bathing the parathyroid glands is low, PTH secretion increases and has [...]
The thyroid gland is in the neck, anterior to the trachea. Two of its secretions are thyroxine and triiodothyronine, both of which influence overall growth, development, and metabolic rates. Another thyroid hormone, calcitonin, helps control extracellular levels of calcium ions (Ca2+) by promoting the deposition of these ions into bone tissue when their concentrations rise. [...]
Zoologists know more about the endocrine organs, hormones, and target tissues of mammals than of any other animal group. This is especially true for the human body. A brief overview of mammalian endocrinology follows. Pituitary Gland (Hypophysis) The pituitary gland (also known as the hypophysis) is directly below the hypothalamus. The pituitary has two distinct [...]
