Steam project: How does Arthritis affect the bones?

  Olivia Tucker

University of Fairbanks, Alaska 

Human Anatomy & Physiology

Professor Larson 

          November 15, 2023

The course objectives for my STEAM project to go over are: 

• Identify the 7 functions of bone
• Bone development/growth 
• Functions of joints and cartilage
• Skin – Epidermis and the different layers that are most likely to be affected by arthritis 
• How does arthritis affect bones, joints and skins overall  

For my project I would like to take my objectives and relate them to different types of arthritis, specifically rheumatoid arthritis and how it affects the bones, joints, cartilage, and the skin. 

Bones have many different functions for our bodies they include: Support, the body is supported by its bones, which also act as cradles for its soft organs. Protection, the brain is shielded by the skull’s fused bones. The rib cage aids in protecting the thorax’s important organs, while vertebrae encircle the spinal cord. Movement, skeletal muscles which are connected to bones by tendons, move the body and its components by using the bones as levers. Mineral and growth storage, when required by every organ of the body, stored minerals are gradually released into the bloodstream in their ionic state. “Deposit” along with “withdrawals” significant growth factors are stirred by mineralized bone matrix.  Triglyceride (fat) storage, Adipose tissue, or fat, is the body’s energy reserve and is kept in bone cavities. Blood cell formation, certain bones have red bone marrow chambers where (hematopoiesis) takes place. The last function of bones are hormone production, osteocalcin is a hormone that is produced by bones and aids in controlling insulin secretion, glucose homeostasis, and energy expenditure. Knowing these functions are vital for understanding how and where arthritis can affect bones and their functions.  

Bones and their development take years to fully form, from infants to adults our bones fuse and cartilage changes to bone.   When first born infants aren’t born with bones, they have different types of cartilage.  During pregnancy, the cartilage, a solid tissue that is softer and more flexible than bone, begins to develop into the skeletal structure that will eventually support the entire body of your unborn child. This makes it possible for the infant to pass through the birth canal and permits growth after birth.  Around 16, the majority of the excess cartilage has grown into bone. Every long bone in children has growth plates in it. These plates are regions of soft bone at each end of the long bones. As a child grows, growth plates allow the bone to expand. By the time a child reaches the age of 14 or 18, the growth plates fuse.  Most bones are fully fused by 18 years of age. 

Bone development or ossification is broken down into 5 stages; there are also regions comprising long bones. A long bone’s diaphysis, or shaft, makes up the majority of its length. Most of the bone is compact. A long bone’s epiphysis is located at both ends. The majority of the bone is porous. The portion of a long bone that is between the growth plate and the diaphysis is called the metaphysis. In diaphysis the next stage of growth, the central cartilage calcifies and then becomes hollow. Next periosteal buds enter cavities, and a spongy bone is formed. Then bud is composed of osteogenic cells, osteoclasts, red marrow, blood vessels, and nerves. The diaphysis lengthens as the medullary cavity (contains the bone marrow) develops.  Only in articular cartilage and epiphyseal plates does hyaline cartilage persist. 

Cartilage functions are what shield your bones and joints. It encircles the tips of your bones and fills in the gaps where your bones meet at joints. Cartilage performs three tasks: Shock absorption: Your bones and joints are cushioned by cartilage during movement and use. It lessens the amount of stress an impact places on your bones by absorbing force. Consider the contrast between running shoes and bare feet when you hop up and down. On the interior of your joints and around your bones, cartilage functions similarly to the cushion in your sneakers. Cartilage lubricates your joints, reducing friction. It facilitates the smooth passage of your bones past one another. This lessens wear and strain on your joints and enables them to function as smoothly as they should. Supporting your body’s structures: Cartilage keeps your joints shaped throughout movement. It also joins your bones and other tissues together. All over your body, cartilage connects muscles, tendons, and ligaments. 

The connective tissues that keep your bones together, such as ligaments, tendons, cartilage, and nerves, make up your joints. Based on the amount of connective tissue present, joints are divided into three types: cartilaginous, synovial, and fibrous joints. The flexibility of fibrous joints is low. A few of them remain still. Their name accurately describes what they are composed of: dense, closely woven fiber-like connective tissue. Collagen is generally abundant in fibrous joints. A layer of cartilage that connects the bones cushions cartilaginous joints. The majority of cartilaginous joints can move, although not very much or in many different directions.  The cartilaginous joints connect your ribs to your sternum, or breastbone. “Another cartilaginous junction is the pubic symphysis joint, which connects your left and right pelvic bones”.  (NCBI) There is the greatest range of motion in synovial joints. They are composed of one bone having a hollow that another bone can fit into. A synovial joint is composed of ends of bones covered in slick hyaline cartilage. “The gap between the bones is lined with a synovial membrane, a fluid-filled sac that lubricates and shields the joint.” (Medical News Today) Synovial joints can move with the least amount of friction possible because of this additional cushioning. 

Rheumatoid arthritis, often known as RA, is an inflammatory and autoimmune illness. It arises when your body’s immune system unintentionally targets healthy cells, leading to painful swelling in the affected areas of the body. “The joints are the primary target of RA, often several joints at once. It is distinguished by the development of pannus, or invasive synovial tissue, and persistent synovitis.” (Tanaka, Y.) In the end, this causes the subchondral bone, cartilage, and soft tissues of the afflicted joint to be destroyed. The most typical skin symptom is the development of rheumatoid nodules. These are hard lumps that form right under the skin, not a rash, they vary in size from a pea’s approximation to a golf ball’s. They can appear on a person’s hands, fingers, elbows, or other bony or fleshy body parts. Inflammation of the arteries that supply blood to the body’s organs, including the skin and nerves, can also result in RA rashes. Rheumatoid vasculitis rashes can occasionally turn into excruciating ulcers. Further difficulties may arise if the ulcers become infected. Deep sores may also develop on the fingers, legs, or anywhere RA is affecting the body.

Treatments for rheumatoid arthritis include disease-modifying antirheumatic drugs (DMARDs), which are the first-line treatment for all newly diagnosed cases of RA (PubMed)  Biological response modifiers, which are targeted agents that specifically inhibit particular immune system molecules. Nonsteroidal anti-inflammatory drugs (NSAIDs), which are used to manage pain and inflammation. 

References

Cartilage and bone damage in rheumatoid arthritis. (2018, May 9). NCBI. Retrieved November 21, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5974634/

Li, M. R. (n.d.). Rheumatoid arthritis rash: Causes, symptoms, and images. Medical News Today. Retrieved November 21, 2023, from https://www.medicalnewstoday.com/articles/319869

Tanaka, Y. (2020, September 7). Rheumatoid arthritis | Inflammation and Regeneration | Full Text. Inflammation and Regeneration. Retrieved November 21, 2023, from https://inflammregen.biomedcentral.com/articles/10.1186/s41232-020-00133-8

Treatment of rheumatoid arthritis. (n.d.). PubMed. Retrieved November 21, 2023, from https://pubmed.ncbi.nlm.nih.gov/17158693/