Calcium and Phosphate Balance Calcium plays a critical role in many cellular processes, including hormone secretion, muscle contraction, nerve conduction, exocytosis, and the activation and inactivation of many enzymes. As described in Chapter 3 , calcium also serves as an…
The islets of Langerhans are endocrine and paracrine tissue The pancreas contains two types of glands: (1) exocrine glands, which secrete digestive enzymes (see p. 882 ) and (see pp. 885–886 ) into the intestinal lumen; and (2) endocrine glands,…
The human adrenal glands, each weighing only ~4 g, are located above the upper pole of each kidney in the retroperitoneal space. They produce four principal hormones: cortisol, aldosterone, epinephrine (adrenaline), and norepinephrine. Each adrenal gland is composed of an inner…
The thyroid gland is located in the anterior neck, lying like a small bow tie across the front of the trachea. In adults, the normal thyroid weighs ~20 g. It is composed of left and right lobes and a small connecting…
Growth from the fertilized ovum to the adult is an exceedingly complex process involving both hyperplasia (an increase in the number of cells) and hypertrophy (an increase in the size of cells) as well as turnover of the cellular elements…
With the development of multicellular organisms that have specialized tissues and organs, two major systems evolved to communicate and coordinate body functions: 1 The nervous system integrates tissue functions by a network of cells and cell processes that constitute the…