The Human Musculoskeleton System

1. The Human Musculoskeleton System

3. Bones and Cartilage Bone is a type of connective tissue that is hard and inflexible. The bones of the human skeletal system serve a number of different purposes

4. Functions the Bones • They serve as sites of attachment for skeletal muscles and they serve as levers that make body parts move when these muscles contract. • They give the body its general shape and support body structures. • They protect delicate structures, such as the brain, spinal cord, heart and lungs. • They serve as storage places for minerals, such as calcium and phosphorus. • They serve as the places where RBCs and some WBCs are produced.

5. Bone is made up of living bone cells, connective tissue fibers and inorganic compounds. • It is an active tissue. • There is constant destruction of old tissue and laying down of new tissue. • A basic part of the structure is collagen.

6. When bones are being formed, living cells called osteoblast secrete collagen and certain polysaccharides. • The collagen forms fibers that are bound together by the calcium and phosphate ions, which act as cement. • Bone is formed when calcium and phosphate ions from the body fluids combine, forming calcium phosphate.

7. The calcium ions precipitates as crystals within the mass of collagen fibers and cement. • The hardness and heaviness of bone are due to the presence of the calcium phosphate. • The osteoblast are trapped in small cavities inside the bone substance to form bone cells called osteocytes

9. Osteoblasts Body fluid secretes secretes Calcium and phosphate ions and form calcium phosphate Collagen and polysaccharides Precipitates as crystals in collagen fibers and cement form Collagen fibers with polysaccharides which act as cement Osteoblasts are trapped in small cavities inside the bone substance to form bone cells called osteocytes

11. The structure of the bone 1.In the bone, the osteocytes are arranged in a series of smaller and smaller circles with a common center. 2. In the center of each series of circles, there is a cavity called the Haversian canal, which contains blood vessels and nerves. 3. Tiny canals connect the osteocytesto each other and to the Haversian canal. 4. The blood vessels within the Haversian canals carry oxygen and nutrients to the bone cells and remove wastes

12. Look at the layers of bone and osteocytes running around the Haversian canal.  Focus up and down and you can see tiny channels, like spider legs, extending from oblong lacunae.  The osteocytes are sitting in the lacunae and the canals are canaliculi, which interconnect the lacunae with the major vessels. This series of channels allows the osteocyte to be nourished and regulated.

16. The structure of the bone The outside of a bone, except at its ends where it connects to other bones, is covered by a tough membrane called periosteum. The main purpose of the periosteum is to make new bone for growth and repair. The periosteum is also the point at which muscles are fastened to bones. This membrane contains blood vessels and nerves that enter the bone.

17. Types of Bony Tissue Compact Bone Spongy Bone They are made of the same material, but compact bone is very dense and strong, while spongy is more porous. Most bones contain both types of tissue

19. In this photo spongy bone can be seen filling the distal end of the femur

21. Bone Marrow • Yellow Bone Marrow • It is made of fat cells. • In adults, it is found in the hollow center of long bones. • Red Bone Marrow • It makes RBCs, platelets, and some type of WBCs • In adults red marrow,is found in the spongy bone of vertebrae, ribs, breastbone, cranium and long bones.

24. The Effects of the Nagasaki Atomic Bombing on the Human Body A: The bone marrow of a person who died after exposure to the bombing 1.8 km from the hypocenter. The femur is cut longitudinally, revealing the bone marrow. The bone marrow is sponge-like in appearance because of the lack of all hematopoietic (blood-making) cells (NS196B).B: Normal for control.

25. CARTILAGE • It is like bone, is a type of connective tissue. While bone is rigid, cartilage bend easily. • In the embryo, most of the skeleton is cartilage. • As the embryo develops, minerals are laid down, and much of the cartilage slowly changes into bone. This process is called ossification, goes on into adulthood. • In adults, it is found at the ends of ribs at joints, and in the nose and outer ear. • It gives support while still allowing some bending motion. • It allows the bones to bend more easily at joints and cushions against impact or pressure

26. This is what cartilage looks like in the knee joint. It is glistening because it is very smooth and has a lubricating layer over it called synovial fluid.

29. The Human Skeleton • The Axial Skeleton • Skull : The upper part of the skull is cranium,and rest of the skull is made of facial and jaw bones • Spinal column: has 33 bones called vertebrae • Ribs: are fastened at the back to the upper vertebrae and at the front of the breastbone • Breastbone(sternum) • The Appendicular Skeleton • Arm and leg bones • Pectoral girdle: shoulder blades(scapula) and collar bones. It connects the arms to spine • Pelvic girdle: It is made up of the hip bones and connects the legs to the spine.

35. JOINTS A point in the skeleton where bones meet is called a joint.

36. At movable joints, bones are held together by tough, fibrous bands of connective tissue called ligaments . A fluid, called synovial fluid is secreted into movable joints. This fluid acts as a lubricant and reduces friction.

38. The bones of the cranium (the part of the skull that protects the brain)arejoined together by immovable joints The vertebrae are joined by slightly movable joints.

39. Freely movable joints allow the most movement gliding (wrist bones; light back and forth) ball-and-socket (shoulder; free rotation) hinge (knee; hingelike extension and flexion in one plane). pivotal (head and neck; rotation in one plane)