1. Bone is a very active tissue. Please explain the pathway of how the bone cells get nutrients and oxygen from the blood vessels using the following terms: Periosteum, endosteum, lacunae, lamellae, canaliculi, perforating canals, osteon, Haversian canal (central canal) and trabeculae.
Periosteum is enriched with blood vessels and a small artery which supply the bone tissue with blood. Bone shaft marrow cavity is lined with the endosteum. Concentrated layers of lamellae have fluid-filled cavities (lacunae) and are covered and connected to the haversian canals by canaliculi, a system of interconnecting canals. All together they form a long cylinder of osteon ( Diaz-Curiel, 2009).
The bone is penetrated with blood vessels from outside to inside layers through the perforating canals. Blood circulates through blood vessels in the spaces between the trabeculae (bony bars), providing nutrients and oxygen to the bone cells.
2. In general compare and contrast the three functional classifications of joints according to movement. What are two characteristics that make synovial joints unique and different from other joints? Which joint is stronger-the shoulder or hip joint and why is it?
- A synarthrosis joint permits no movement and can be either a fibrous or cartilaginous joint.
- An amphiarthrosis joint permits only slight movement and can be either fibrous or cartilaginous joint.
- A diarthrosis joint is a freely movable joint and is always a synovial joint:
- Allows considerable movement;
- Contains synovial fluid in a joint cavity (Phillips, 2004).
The hip and shoulder joints have different structure and mission: the hip has a weight bearing structure to allow controlled movement but retain strength and stability, as the shoulder is mainly designed for a much wider range of controlled movements and is not as stable and strengthened as the hip.
3. Please explain how the muscle cell’s anatomy of the cytoplasm is unique from other cells.
The cytoplasm of muscle cells is called sarcoplasm and occupies 25-30% of the muscle’s size. The sarcoplasm consists of nutrients, glycogen, capillaries, and mitochondria proliferation. Through the sarcoplasm there is an intricate network of membranous channels known as the sarcoplasmic reticulum. Perpendicular to the sarcoplasmic reticulum is the system of transverse tubules ( Boccardi, 2007).
4. With your knowledge of how a muscle cell contracts please describe three mechanisms (problems) that could inhibit or disrupt the process of muscle contraction. Think about the process and the steps involved in muscle contraction.
Contraction can be disrupted by the following sequence:
- if acetylcholinesterase breaks down the acetylcholine at the neuromuscular junction, muscle fiber’s action potential is terminated;
- if sarcoplasmic reticulum ceases to release calcium ions, all the released calcium ions immediately start to be sequestered;
- contraction ceases in the absence of calcium ions, as myosin molecule heads are blocked with the change of troponin’s and tropomyosin’s configuration
Troponin and tropomyosin start to move and enable myosin molecule heads as the Ca++ ions in sarcoplasmic reticulum are released, and cause muscle contraction (Goldring, 2002).
5. What is the difference between osteoarthritis and osteoporosis?
Osteoarthritis is a disease, which is characterized with the defeat of all the components of the joint, in the first place – the cartilage, but also synovium, ligaments, capsule, periarticular muscles. Usually, osteoarthritis develops slowly and starts with the destruction of one joint, but after a while other joints are included in the process, which most often compensatory take on increased mechanical load to unload the originally diseased joint.
Osteoporosis is a systemic disease that affects all the bones of the skeleton, accompanied by a decrease in density and bone strength, which leads to a high risk of fractures even with minimal trauma, such as falling from stature height or lifting weights about 10 kg (Rosen, 2002).
Diaz-Curiel, M., Alvarez, J.M., Serrano Morales, R., Diaz M. (2009). Nutrition and Bone Health: Its Relationship to Osteoporosis. Current Nutrition & Food Science, 5(3), pp. 193-195.
Phillips, F. (2004). Diet and bone health. Nutrition Bulletin, 29(2), pp. 99-101.
Rosen, C. (2002). Nutrition and bone health in the elderly. Clinical Review in Bone and Mineral Metabolism, 1(3), pp. 249-260.
Goldring, K., Partridge, T., Watt, D. (2002). Muscle stem cells. The Journal of Pathology, 197(4), pp. 457-467.
Boccardi, C., Cecchettini, A., Caselli, A., Camici, G. (2007). A proteomic approach to the investigation of early events involved in the activation of vascular smooth muscle cells. Cell and Tissue Research, 329(1), pp. 119-128.