Introduction The musculoskeletal system, which provides mechanical support and permits movement, is composed of skeletal muscle, tendons, bones, joints and ligaments. Skeletal muscles act as contractile levers and are connected to bone by tendons. Bones act as rigid levers, articulating…
Introduction The liver acts as a vast biosynthetic chemical factory, synthesizing large complex molecules from substances brought to it in the blood, particularly substances recently absorbed by the intestine and transported by a portal blood system. The liver has a…
Introduction The alimentary tract is best considered as a muscular tube lined internally by an epithelium that varies in structure according to specialized functions required at particular sites along its length; with a few local variations, the structure of the…
Introduction The respiratory system transfers oxygen from the air into the blood and carbon dioxide from the blood into the air. Blood oxygen is used for cellular respiratory processes that generate carbon dioxide as a by-product. The gaseous exchange occurs…
Introduction The main transport systems are the circulatory systems, in which substances are dissolved or suspended in liquid and carried from one part of the body to another in a series of tubes (vessels). There are two main circulatory systems:…
Introduction The immune system is part of an array of defence systems used to combat disease. The body must constantly protect itself from invasion by a variety of pathogens, which may gain entry via the skin, gut, respiratory tract and…
Introduction The blood is a mixture of cellular elements, fluid, proteins and metabolites. Blood has four major elements: Red blood cells (erythrocytes) transport oxygen from the lungs to the peripheral tissues. White blood cells (leukocytes) have a defensive role, destroying…
Introduction The nervous system allows rapid and specific communication between widely spaced areas of the body by the action of specialized nerve cells (neurons), which gather and process information and generate appropriate response signals. The nervous system is divided into…
Introduction Several cell types are specialized to generate motile forces through contraction. This chapter presents an overview of the main types of contractile cells. The general structure of each type of cell is described, together with details of their fine…
Introduction The cells that form tissues can be divided into two types: parenchymal cells , which provide the main function of a tissue, and support cells , which provide the structural scaffolding of a tissue. Support cells comprise a set…