Unit 7 Reflection

In this unit we learned about the skeletal system and different disorders that can occur. Bones are divided into the axial system, which is composed of the skull, spine, and ribcage, and the appendicular skeleton, which is composed of all the other bones. With in the two different divisions, bones are classified in different ways. There are short bones, which are shorter than they are wide; long bones, which are longer than they are wide; flat bones, which are thin and flattened; and irregular bones, which have an irregular shape and do not fit into any of the other categories. In our Owl Pellet Lab we were able to dissect an actual owl pellet and identify the organism that it had eaten based off of what the bones looked like. Two types of bone tissue are compact and spongy bones. Compact bones are strong, while spongy bones are full of small spaces and are more flexible. There are different types of bone cells within the bones themselves. Osteocytes are mature bone cells. Osteoblasts are bone-forming cells, while osteoclasts are bone destroying cells. The balance of all of these cells allows the bones to grow and stay healthy and strong. Bones receive nutrients from blood vessels that run through them. The Haversian canal contains at least one blood capillary which is the source of nutrients and means of waste disposal.

There are many different disorders that can occur in the skeletal system. Arthritis is the inflammation of the joints, which is caused by age, infection of the joints, and trauma from the joints. Unlike what many people believe, cracking one's knuckles does not lead to arthritis. Osteoporosis is the condition in which bones have lost minerals and the holes become too large, allowing the bones to become brittle. Scoliosis is when there is an abnormal curvature of the spine. This is more common in girls than boys. Kyphosis is when the spine may develop a hump, affecting people of all ages. Lordosis is the excessive curvature of the lumbar spine and forward pelvic tilt. This is common in gymnasts and dancers. Rickets is the softening and weakening of bones, which is common in children with vitamin D deficiency.

Ossification is the process by which a bone forms. This process usually continues until the individual is 25 years of age. Epiphyseal Disks are responsible for longitudinal growth. The calcium that is stored inside bones helps maintain the blood pH levels and body fluids, heart function, muscle contractions, nerve function, and blood clotting. The osteoblasts in the bones produce osteocalcin, which is a calcium binding cell. The osteoclasts secrete enzymes that help function in reabsorption. The hormone Parathyroid hormone increases the number of active osteoclasts, which will increase the amount of calcium. Calcitonin is secreted to lower the level of calcium by inhibiting the osteoclasts. While calcium is necessary for bones, it cannot be absorbed without the help of vitamin D. An excess amount of sodium and protein can lead to an increase of calcium excretion because of the build up of amino acids in the blood. Overall, it is vital to keep your bones healthy through exercise and a well balanced diet. Bone fractures may occur if a more force is put on a bone than it can hold. There are different types of bone fractures. A complete fracture is when the bone is broken completely through. An incomplete or greenstick fracture is when the fracture does not extend through the bone. A closed fracture is when the bone does not tear through the skin. A compound fracture is when skin is pierced. A comminuted fracture is when the bone is fragmented into three or more pieces. An oblique fracture occurs when the bone breaks at an angle. Once the bone breaks, it bleeding and inflammation occurs, producing a blood clot. The clot then softens after about 48 hours, producing a procallus. Then, fibroblasts arrive and secrete dense connective tissue that replaces the procallus. Chrondroblasts and osteoblasts are next to arrive. After the first week cartilage and bone appear throughout the site. An osseous callus acts as an internal splint for the site. Once the osseous callus has undergone remodeling to restore the bone, it is healed.

A joint is the point of connection between two bones or elements. There are three classifications of levers for joints: First-class lever, which have a fulcrum in the middle between effort and resistance; second-class lever, which has resistance between fulcrum and effort; and third-class lever, which have effort between resistance and fulcrum. In terms of movement, joints can be synarthroses, immovable; amphiarthroses, or slightly movable; diarthroses, or freely movable. Structurally, bones can be fibrous, which are generally immovable; cartilagenous, which are immovable or slightly movable; or synovial, which are freely movable. A joint that is fibrous and synarthroses is an immovable fibrous joint. An example of this would be the skull. A fibrous and amphiarthoses joint would be bones that are only connected to ligaments. a cartilagenous and synarthroses joint would be bones that are joined by the hyaline cartilage. These are generally immovable. A cartilagenous and amphiarthoses joint is bound by the fibrocartilage and is slightly movable. a synovial and diarthroses joint is a joint between two tones separated by a space called a joint cavity. A bursar is a small fluid-filled sac that is linked by synovial membrane with inner capillary layer of slimy fluid. This provides a cushion between the bone and tendons and reduces the friction.

I want to learn more about topics that are relevant to me. For example, I want to know about what a stress fracture would be. Also I'm curious about common injuries in the joints, such as torn ACLs menisci. I still struggle in distinguishing between the different joints and the combinations of them together. Also, I'm curious about how the different ligaments in the knee helps keep it stable.

I think I have grown throughout this whole unit as a student. During the Owl Pellet Lab, I learned the importance of patience and considering many different options because the bones were scrambled and there could have been more than one organism in the pellet. I also have more of an appreciation for what we are learning because I hurt my knee and we learned about the different joints in this unit. Also, the fractures section relates to me because I fractured one of my fingers when I was in elementary school. The swelling of the finger makes much more sense now since before I never really knew the reason behind it. I can make sure to keep my bones healthy by making sure I go outside enough and get vitamin D so that the calcium that I take in can be absorbed into bones. My goal of running is going to be difficult for the next 6ish months since I am unable to run with my bad knee. I could just work on strengthening my legs instead.