MUSCULAR SYSTEM

Muscular system is formed by the set of skeletal muscles, whose mission is the movement of body. Along with the bones is the musculoskeletal system, which is the active part, as the muscles are responsible for the movements of the bones.

Skeletal muscles contract in response to nerve impulses. These impulses travel through ner-motor nerves that terminate in the muscles. The contact area between a rib and a striated muscle fiber skeletal neuromuscular junction is known as motor or plate.

The human body has over 600 muscles. These muscles are attached directly or indirectly (through tendons) to bone and generally work in antagonistic pairs when
one contracts the other relaxes

 

MUSCULAR SYSTEM FUNCTIONS

The main functions of the muscular system are: Body movement (locomotion) or any of its parts. Heat production. The muscles produce 40% of body heat at rest and up to 80% during the exercise. Maintaining the posture. Mimicry: a share of certain muscles, especially of the face, you can take certain gestures used to express feelings.

TYPES OF MUSCLES

Depending on the type of movement they make, one can distinguish the following types of muscles:

Flexors and extensors: closer or apart, respectively, two parts of a member.

The application of these terms in relation to the hip and shoulder requires a special definition. The bending in these structures is a movement by which the thigh and arm are moved front, by extension, thigh and arm move back.

Abductors and adductors: away or moving parts come to a central axis.

Rotator: a bone rotated around a longitudinal axis. Pronation and supination are two special forms of rotation.

Pronation is the joint rotation of the forearm and hand, leaving the palms facing backwards. Supination is the opposite movement. Elevators or depressants: raise or lower a body part.

Disorder

Presynaptic Location: Interference for the release of ACh by autoAb directed against the calcium channel the presynaptic terminal (paraneoplastic syndrome of Eaton-Lambert) or botulinum toxin (botulism).

- Location postsynaptic: Lock and destruction of the postsynaptic receptor-mediated Ach Ach of antireceptor autoantibodies, causing less muscle response to it.

Alterations of ion channels

- Periodic paralysis: rare syndromes in which there is a change in the resting potential and a loss of action potentials, so that the muscle cell is unable to propagate action potentials. Most cases are inherited, but also acquired abnormalities of potassium and calcium can cause generalized weakness, and depending on the levels of K are divided into hipopotasémicas, normopotasémicas and hiperpotasémicas.

- Myotonia: This phenomenon is the inability to relax muscles after contraction, by a defect in the uptake of calcium into the endoplasmic reticulum by a malfunction of ion channels. It is manifested by the myotonic phenomenon.

 

Structural alterations of muscle fibers (myopathy)

- Muscular dystrophies: hereditary diseases that cause a structural alteration of different proteins in the muscle cell. Duchenne and Becker are due to the alteration of a gene encoding dystrophin, a membrane protein of muscle cells, whose role seems to be to connect the external contractile proteins in the cell.

- Inflammatory Myopathies: Inflammation of autoimmune nature. Two types: polymyositis (cytotoxic T lymphocyte) and dermatomyositis (autoantibodies and cutaneous).

- Metabolic myopathies: For alteration in the mechanisms of energy production, either by alterations in the metabolism of carbohydrates (source of energy at beginning of year), alterations in lipid metabolism (fatty acid oxidation for ATP is an important energy mechanism exercises held, of> 30 min) or mitochondrial disorders (mitochondrial respiratory chain is the final link in the energy).

TUMOR

A tumor is an abnormal growth of body tissue. Tumors can be cancerous (malignant) or noncancerous (benign).

In general, tumors occur when cells divide excessively in the body. Typically, cell division is strictly controlled. New cells are created to replace older ones or to perform new functions. Cells that are damaged or no longer needed die to make room for healthy replacements.

If the balance of cell division and death is disturbed, a tumor may form.

Problems with the body's immune system can lead to tumors. Tobacco causes more deaths from cancer than any other environmental substance. Other causes include:

• Benzene and other chemicals and toxins
• Drinking too much alcohol
• Environmental toxins, such as certain poisonous mushrooms and a type of poison that can grow on peanut plants (aflatoxins)
• Excessive sunlight exposure
• Genetic problems
• Obesity
• Radiation
• Viruses

Symptoms

Symptoms depend on the type and location of the tumor. For example, lung tumors may cause coughing, shortness of breath, or chest pain. Tumors of the colon can cause weight loss, diarrhea, constipation, iron deficiency anemia, and blood in the stool.

Some tumors may not cause any symptoms. In certain tumors, such as pancreatic cancer, symptoms often do not start until the disease has reached an advanced stage.

The following symptoms occur with most tumors:

• Chills
  
• Fatigue
• Fever
  
• Loss of appetite
• Malaise
  
• Night sweats
• Weight loss

Signs and tests

Like the symptoms, the signs of tumors vary based on their site and type. Some tumors are obvious, such as skin cancer. However, most cancers cannot be seen during an exam because they are deep inside the body.

When a tumor is found, a biopsy is performed to determine if the tumor is noncancerous (benign) or cancerous (malignant). Depending on the location of the tumor, the biopsy may be a simple procedure or a serious operation.

Most patients with tumors have CT or MRI scans to determine the exact location of the tumor and how far it has spread. More recently, positron emission tomography (PET) scans have been used to find certain tumor types.

Other tests include:

• Biopsy of the tumor
• Blood tests (to look for chemicals such as tumor markers)
• Bone marrow biopsy (most often for lymphoma or leukemia)
• Chest x-ray
  
• Complete blood count (CBC)

Treatment varies based on:

• The type of tumor
• Whether it is noncancerous or cancerous
• Its location

If the tumor is benign (meaning it has no potential to spread) and is located in a "safe" area where it will not cause symptoms or affect the function of the organ, sometimes no treatment is needed.

Sometimes benign tumors may be removed for cosmetic reasons, however. Benign tumors of the brain may be removed because of their location or harmful effect on the surrounding normal brain tissue.

If a tumor is cancerous, possible treatments include:

• Chemotherapy
• Radiation
• Surgery
• A combination of these methods

If the cancer is in one location, the goal of treatment is usually to remove the tumor with surgery. If the tumor has spread to local lymph nodes only, sometimes these can also be removed. If all of the cancer cannot be removed with surgery, the options for treatment include radiation and chemotherapy, or both. Some patients need a combination of surgery, radiation, and chemotherapy.

Lymphoma (cancer of the lymph glands) is rarely treated with surgery. Chemotherapy and radiation therapy are most often used for treating lymphoma.