Unit 7 Reflection

This unit was all about the skeletal system, bones, and our joints, and how they work to allow our body to move. We started off the unit by discussing how bones are classified based on their shape - long, short, flat, or irregular. Long bones are typically longer than they are wide and have a shaft with circular heads on both ends and contain mainly compact bone. These bones generally have a diaphysis (the shaft) with an epiphysis on either end that is composed mainly of spongy bone. The image below illustrates and labels the major parts of a typical long bone.

Short bones, on the other hand, are generally cube shaped (wider than they are long) and contain mostly spongy bone. Another type of bone - flat bones - are thin and flattened bones that are usually curved and have thin layers of compact bone around a layer of spongy bone. Lastly, irregular bones are the ones that don't fit into any of the above three categories and so are considered irregular in shape. The image below depicts the various shape-categories that bones are classified into.

Continuing the theme of this class (learning about the function of a part of the body by first exploring its disfunction), we then learned about the various disorders of the skeletal system. Arthritis, as we learned, is caused by the inflammation of the joints. Osteoporosis, another disorder, is a condition in which the bones have lost their minerals and so become weak and more brittle. Scoliosis (abnormal curvature of the spine), kyphosis (excessive curvature of the thoracic vertebrae of the spine), and lordosis (excessive curvature of the lumbar spine) are all problems that the "Assessment of Stresses in the Cervical Spine Caused by Posture and Position of the Head" reading discussed. These three disorders in particular have become increasingly more prominent in our population - and adolescents, especially - as we constantly have bad posture when using technological gadgets like phones and laptops. 

We also learned about the different types of bone cells we have and how they play a role in a process known as bone remodeling. Osteocytes are what actually make up bones and are the mature bone cells. Osteoblasts are the bone building cells of the body. Osteogenic cells (also known as osteoprogenitor cells) are dividing cells that are at the growth plates of bones and eventually develop into osteoblasts. And osteoclasts are the bone-destroying cells that breakdown the bone matrix in order for bone remodeling and the release of calcium to occur.

As we learned how these cells make up bones, we began talking about how the bones also behave as the body's reservoir for calcium, which is necessary in many body processes. Parathyroid hormone (PTH) and calcitonin are the two hormones that work together to regulate the blood calcium levels in the body. Vitamins (Vitamin D, especially) are also needed in order to regulate blood calcium and make sure the bones are healthy. In addition we learned about bone remodeling (explained more in depth in the video below), which is the process by which bones are rebuilt after a bone injury and also occurs throughout the day to maintain homeostasis. Basically, in this process, osteoclasts resorb bone so that osteoblasts can refill the cavities left by osteoclasts. The osteoblasts that get trapped inside the matrix they secrete become osteocytes. Ossification, the process by which new bones are formed, occurs in a similar way.

Then we talked more about the different bones in our body and how they make up the skeletal system. Before we did this though, we once again learned about the disfunction of bones and the various types of fractures that can occur: complete fractures where the bone is completely broken through, incomplete fractures where the fracture does not extend through the bone), and closed/simple fractures where the bone does not tear through the skin. The way that bone repair after a fracture occurs is just like the bone remodeling process. First, bleeding and inflammation occurs to produce a blood clot. Then, the blood clot softens and produces a mass of protein fibers, called a procallus. Fibroblasts arrive and secrete dense connective tissue that replaces the procallus. Finally, chondroblasts and osteoclasts arrive and trigger the bone remodeling process. Pictures of some typical bone fractures are shown below:

We discussed the skeletal system in even more depth and even did an Owl Pellet Dissection to compare how our skeletal systems are similar or different to those of other animals and to see if we could put together the pieces of another organism's skeleton. We also discussed the joints in this unit. We can functionally classify joints into synarthroses or immovable joints, amphiarthroses which are slightly movable joints, and diarthroses which are completely freely movable joints. Structurally, joints can be classified even further into fibrous joints which are made of connective tissue or collagen, cartilaginous joints which are made of hyaline tissue - also known as cartilage - and synovial joints which have a membrane containing synovial fluid. These joints can be classified into different types even further as shown in the image below: 

I still want to learn more about how we can fix bad posture and whether or not back rests and chiropractic stretches actually help with fixing back problems. In addition, I want to know more about how the muscles shift and adapt to back problems and whether muscular problems can also lead to back problems. In addition, I would like to learn more about to what extent drinking milk can help small children grow taller and what limits a person's growth - when do the growth plates of bones start to fuse. Lastly, I want to know whether or not sleeping can help a person's bones grow so that he/she can grow taller and how it would do that.

As I've been pretty busy visiting colleges and then catching up on my school work, I must admit I've been falling behind on my New Years' Resolution - I have actually been sleeping later, rather than earlier. Now that I've caught it, though, I will definitely start trying to sleep earlier. In addition, work on my 20 Time Project has been going pretty smoothly. I have come across some bumps in the road, but am working to find solutions. In addition, I've moved on to Month 2 (the month of eating healthier) and it's been going pretty smoothly; however, it has been pretty difficult to remind myself to eat healthier. I guess the bad habits of eating unhealthy are a little to ingrained! I've been working a lot on my study habits, though, in preparation for college next year. The VARK Questionnaire that we did earlier this semester has really helped me in that respect, as I've been taking advantage of diagrams and flowcharts to help me study in almost ever class and have seen a difference. When we did the Bone Lab and the Owl Pellet Lab, for example, we drew out the different bones and labelled them and were able to visualize them. This really helped me internalize the concepts we had been learning throughout the unit, so I have high hopes for the upcoming test!