11.1 Overview The integument, the largest organ of the body, is composed of skin and skin appendages — nails, hair, sweat glands, and sebaceous glands. The total weight and overall surface area of skin in the adult are 3-5 kg and…
10.1 Overview The endocrine system comprises glands and tissues composed of parenchymal cells, which synthesize and secrete products called hormones. The term hormone derives from a Greek word meaning to set in motion. Like the nervous system, the endocrine system…
9.1 Overview The extensive lymphoid —or immune — system protects the body against potentially harmful effects of pathogens, foreign substances, infectious agents (bacteria and viruses), and abnormal cells. Its major functions are thus to serve as a source of immunocompetent…
8.1 Overview The cardiovascular system consists of the heart —a muscular pump—and closed vessels through which blood circulates in the body. Arteries leave the heart, branch repeatedly, and have smaller diameters as they course toward the periphery. They deliver blood…
7.1 Overview Blood is a specialized type of connective tissue that consists of cells suspended in a circulating fluid known as plasma. The total amount of circulating blood in men is 5-6 L; that in women, 4-5 L. Fresh blood is a…
6.1 Overview Cartilage and bone are specialized forms of connective tissue that have critical roles in providing the skeletal framework of the body. Although they share similarities, many important differences set them apart. As with other connective tissues, they derive…
5.1 Overview The nervous system is divided anatomically into the central (CNS) and peripheral (PNS) nervous systems. The CNS comprises the brain, brainstem , and spinal cord ; the PNS, all nerve fibers ( axons and dendrites ), nerve endings…
4.1 Overview Muscle tissue in the body is classified into one of three major categories according to structure, function, and location. Skeletal muscle is the most common and characteristic type; the other two kinds are cardiac muscle and smooth muscle.…
3.1 Overview Adult connective tissue comprises a diverse family of tissues whose major function is to provide form and support to the body and organs and to connect and anchor parts. It is also a medium for exchange of nutrients,…
2.1 Overview Epithelium is one of the four basic tissues, with a wide distribution and many functions. It consists of continuous sheets of cells that cover exposed body surfaces. It also lines internal cavities, such as those of the digestive,…