Homeostasis

Homeostasis refers to a process that involves maintaining the body environment in a steady position particularly when the external environment is altered. The hypothalamus coordinates the actions of most of the hormones and automatic nervous systems. Elaine’s body thus employs a negative feedback that aims at setting a corrective mechanism that reverse the original change to get the system back to normal. The dermis shelters the sensory receptors for cold which are generally refereed to as the free nerve endings.

The thermostat of the body is the hypothalamus and is located in the area of the brain. The smooth muscle fibers contained in the tunica media layer assists the blood vessels to constrict. Shivering however, is facilitated by the skeletal muscles which cause rapid involuntary contractions and relaxation of parts such as the limbs and jaws to produce heat. Frostbite damages the skin and the underlying tissues. It affects body parts such as the nose, fingers, ears and toes. Such areas receive limited blood flow and may eventually die.

Elaine was instructed to remove her parka because it had already caught cold and would affect her internal body temperature. She was shivering due to the action of her skeletal muscles which cause involuntary movement of her body parts through rapid contraction and relaxation to facilitate the production of body heat. Elaine’s knee was swollen probably due to an increased movement of both leukocytes and plasma to the injured place from the blood. The knee thus swells due to the increased fluid collection through increased permeability and induced dilation of blood vessels.

A dorsalis pedis pulse is generally taken on the anterior part of the foot, at the lateral area of the big toe. The main reason of undertaking it is to ensure that no impairment of circulation occurred. The bones comprising of the knee joint fit together with the help of the cartilage and synovial fluid whose main purpose is to reduce friction. The bone is kept well aligned by the five ligaments located around the joint. The tendons attached to the patella and the shinbone are the cushioned by bursas. The medial surface of the knee is associated with such structures as, the medial collateral ligament, medial meniscus, medial epicondyle of the femur, and the medial tuberosity of the tibia.

Broken bones or joint dislocation are the common injuries that can be clearly identified through an X-ray since the skeletal structure is easily recognized for any alteration to such an extent. A positive Lachman maneuver test is indicated by a displacement of more than 4 mm of the tibia relative to the femur when the knee is flexed 20–30°. Leg elevation and ice are very important since they reduce swelling and also help relieve the pain. Elaine was instructed not use a hot tub because it would facilitate further swelling and bring immense pain. It is only advisable to use heat after a few days to reduce muscle spasm and to promote flexibility and circulation.

Dr. Scott ordered an MRI in order to identify tears in the menisci and the anterior cruciate ligament for appropriate reconstruction. Age is a very crucial factor in the healing process of an individual. A young person tends to heal faster than an old individual. Osteoarthritis refers to a type of arthritis that is caused by breakdown and inflammation of cartilage that wear out with time.

The primary movement of the knee joint is the constant change of angle between the upper leg and the lower leg.  When the leg bends at the knee joint this movement is referred to as knee flexion and when the leg is straightened it is referred to as knee extension. The muscle groups responsible for flexion are the hamstrings while the extension movement of the knee is controlled by the quadriceps. When muscle and bone tissues are not used there results some deficiency. Muscle atrophy for instance occurs when muscles are not used as required and the individual thus lose muscle tone.

A tendon could be used to replace a ligament because both are formed from collagen cells chains that originate from the proteins the body stores. The knee joint is lined with the synovial membrane which helps in lubrication of the joint through the secretion of the synovial fluid. The ACL heals quickest while the MCL generally takes longer to heal. Meniscus generally does not have direct blood supply and hence the difficulty for spontaneous healing.  Scarring is the healing process of a tissue. The most important cell for scar formation is the fibroblast.