Introduction A vital function of the nervous system is the gathering of sensory information. Sensory information is derived from a variety of specialized sensory nerve endings. These include: Sensory endings in the skin to detect touch (fine touch, pressure), pain…
Introduction The skin is an extensive organ covering the exterior of the body. It varies in structure from site to site according to specific functions, which include: Protection from external damaging agents (infective, mechanical, thermal) Prevention of loss of water…
Introduction The female reproductive system: Produces haploid female gametes (ova) Receives haploid male gametes (spermatozoa) before fertilization Provides a suitable environment for fertilization of ova by spermatozoa Provides a suitable physical and hormonal environment for implantation of the embryo Accommodates…
Introduction The male reproductive system is responsible for: Production, nourishment and temporary storage of the haploid male gametes (spermatozoa) Intromission of a suspension of spermatozoa (semen) into the female genital system Production of male sex hormones (androgens) Whereas the first…
Introduction The main function of the urinary system is the production, storage and voiding of urine. Urine production and the control of its composition are the responsibility of the kidneys. The pelvicalyceal systems and ureters transfer urine from the kidneys…
Introduction Cell communication is vital for any multicellular organism to function efficiently. At a local level, cells communicate via cell surface molecules and gap junctions, whereas remote communication is mediated by the secretion of chemical messengers, which activate cells by…
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…