WJEC Biology for A2: Student Bk

Humans have an endoskeleton, an internal structure that provides support and protection and, being jointed, it allows movement. It is made of bone and cartilage, disorders of which may have devastating effects. Some are described here. Skeletal muscle is attached to bones by tendons, and bones are held together at joints by ligaments. The structure of muscle and the ultra-structure of its cells support the sliding filament theory, which describes how muscle fibres contract. The biochemistry of muscles explains the release of energy for contraction. Joints are highly specialised structures made from a variety of tissues. Faults leading to two types of arthritis are described. By the end of this topic you will be able to: ▪ Describe the structure of three types of cartilage and two types of bone. ▪ Understand how the balance between osteoblasts and osteoclasts maintains bone structure. ▪ Describe Haversian systems. ▪ Understand the causes and treatments of rickets and osteomalacia. ▪ Explain the siding filament theory of muscle contraction in relation to muscle ultra-structure. ▪ Describe the differences between fast and slow twitch muscle fibres. ▪ Describe how muscles obtain energy, even when the oxygen availability is low. ▪ Describe the structure and functions of the human skeleton. ▪ Understand the types of fractures to which the skeleton is prone. ▪ Relate the structure of different vertebrae to their functions. ▪ Describe the causes and treatments of some postural deformities. ▪ Describe different types of joint. ▪ Understand the causes and treatment of osteoarthritis and rheumatoid arthritis. ▪ Describe joints as first, second and third order levers. ▪ Describe the structure of the synovial joint. ▪ Explain the concept of antagonistic muscles. Topic contents 279 Skeletal tissues 282 Bone disease 284 Skeletal muscle 291 Structure and function of the human skeleton 294 Postural deformities 295 Joints CH 15 Option B: Human musculoskeletal anatomy 278