6 Major functions of the skeletal system1. Support-Provides structural support for the entire body. Without the skeleton, muscle, and organs would not be able to support themselves.
2. Movement-Skeletal muscle is attached to the bone so that it pulls on bone when it contracts, and they would not function without bones to use. 3. Protection-Surrounds soft tissue, such as when the ribs or the sternum support the lungs and heart, and the skull protects the brain. 4. Blood cell production-Red bone marrow produces red blood cells, white blood cells, and other blood elements. 5. Calcium Storage-Calcium is added to bones by osteoblasts and removed from bones by osteoclasts, and it is essential for healthy bones, muscle contraction, heart action and normal clotting, and it is stored in bone cells. 6. Endocrine Regulation-Bone cells release osteocalcin, which contributes to the regulation of blood sugar, and lipids, which increases insulin, sensitivity and fat storage. Microscopic structures of bones1. spongy bone: Bone in which spicules form a spider web-like interconnection, with interstices filled with embryonic connective tissue or bone morrow.
2. compact bone: The compact portion of bone that consists largely of organic substances and inorganic salts, leaving only tiny spaces(lacunae), that contain osteocytes. 3. periosteum: The thick fibrous membrane covering the entire surface of a bone except its articular cartilage and serving as an attachment for muscles and tendons 4. red marrow: Found at the ends of long bones, such as the femur, and in flat bones, such as the hip. An important site for blood cell production. Here all erythrocytes (red blood cells), platelets, and most leukocytes (white blood cells) form in adults. From the red marrow, erythrocytes, platelets, and leukocytes migrate to the blood to do their special tasks. 5. yellow marrow: Found in spongy bones, and the central cavities of long bones. Has fatty connective tissue and fills the marrow cavity. During starvation, the body uses the fat in yellow marrow for energy 6. Haversian canals: Small tubes that form a network in bone and contain blood vessels, which carry blood, nutrients, and nerve cells. 7. osteoblasts: Form new bone tissue in response to more demands on bone. When a person is physically active, the rate of osteoblast activity increases, which thickens and strengthens the bones. When muscles tense and flex, their tendons pull on the bones. This action causes the osteoblasts to secrete proteins that form lamellar (compact) bone and cancellous (spongy) bone with texture that resembles trabeculae 8. Osteoclasts:A large multinucleate bone cell that absorbs bone tissue during growth and healing. Osteoclasts work with osteoblasts. These osteoclasts dissolve bone tissue by secreting enzymes. Their actions help healthy individuals keep bones light and airy. They also regulate calcium and phosphate concentrations in body fluids. 9. Osteocytes: A bone cell formed when an osteoblast becomes embedded into the matrix it has secreted. |
Types of joints
- Definition of a joint – A point at which a structure is joined in this case bones
example: Hip, shoulder (Wide range of movement)
2. Hinge
example: Knees, knuckles, elbows (Back and forth)
3. Pivot
example: Skull on neck, pelvis (180 degree range)
4. Gliding
example:Wrist, ankle, clavicle (Flattened, slightly curved surfaces)
5. Condyloid
example: Wrist (Oval condyle of one bone articulates with elliptical cavity of another)
6. Saddle
example: Base of thumb (Wide range of movement)
Vocabulary
1. Ligament: A short band of tough, flexible, fibrous tissue that either holds together a joint, or two bones or cartilages
2. Tendon: A flexible but inelastic cord that holds bone and muscle together
3. Cartilage: Whitish and firm collective tissue that can be found in the larynx, ear, respiratory tract, and in the articulating surfaces of joints. Is found in infants and is later replaced by bone
4. Ossification: The process of forming bone from cartilage.
2. Tendon: A flexible but inelastic cord that holds bone and muscle together
3. Cartilage: Whitish and firm collective tissue that can be found in the larynx, ear, respiratory tract, and in the articulating surfaces of joints. Is found in infants and is later replaced by bone
4. Ossification: The process of forming bone from cartilage.