Muscular and Skeletal Systems
Introduces the use of muscles and bones for movement. Links | Back to Top. Skeleton "Click the bones and they will speak"; The Muscular System from Human. The muscular system is responsible for the movement of the human body. Attached to the bones of the skeletal system are about named.
Located in long bones are two distinctions of bone marrow yellow and red. The yellow marrow has fatty connective tissue and is found in the marrow cavity. During starvation, the body uses the fat in yellow marrow for energy. From the red marrow, erythrocytes, platelets, and leukocytes migrate to the blood to do their special tasks.
Another function of bones is the storage of certain minerals. Calcium and phosphorus are among the main minerals being stored. The importance of this storage "device" helps to regulate mineral balance in the bloodstream. When the fluctuation of minerals is high, these minerals are stored in bone ; when it is low it will be withdrawn from the bone. Muscle The body contains three types of muscle tissue: On the anterior and posterior views of the muscular system above, superficial muscles those at the surface are shown on the right side of the body while deep muscles those underneath the superficial muscles are shown on the left half of the body.
For the legs, superficial muscles are shown in the anterior view while the posterior view shows both superficial and deep muscles. There are three types of muscles— cardiacskeletaland smooth. Smooth muscles are used to control the flow of substances within the lumens of hollow organsand are not consciously controlled. Skeletal and cardiac muscles have striations that are visible under a microscope due to the components within their cells.
Only skeletal and smooth muscles are part of the musculoskeletal system and only the skeletal muscles can move the body. Cardiac muscles are found in the heart and are used only to circulate blood ; like the smooth muscles, these muscles are not under conscious control. At this plate, cartilage is continuously formed and then turned into bone.
This process is called ossification. This stops when a person reaches the adult age. Bone Development Even though bones stop growing in length in early adulthood, they can continue to increase in thickness or diameter throughout life in response to stress from increased muscle activity or to weight.
The increase in diameter is called appositional growth. Osteoblasts in the periosteum form compact bone around the external bone surface. At the same time, osteoclasts in medullary cavity break down bone on the internal bone surface, around the medullary cavity.
- What is the functional relationship between skeletal muscles and bones?
- The Skeleton and Muscles
These two processes together increase the diameter of the bone and, at the same time, keep the bone from becoming excessively heavy and bulky. Factors that affect bone growth: Stress on the bones by physical activity. Lack of Stress causes bones to become thin. Growth hormone and sex hormones increase bone size.
Joints A joint is the junction between two or more bones. There are three major types of joints: These joints include the skull, sacrum, pelvis, and coccyx.
As the name suggests, these joints are points where joints fuse or grow together. The place where they grow together is called the suture. These joints provide strength, support, and protection. These joints are located between the vertebrae of the upper spine. There is cartilage within the joints. They help pad and protect the bones. The bones are held together by ligaments. The ligaments are tightly bound and limit the movement of the bones. This protects the spinal cord.
Freely Moveable or Synovial Joints: At these joints the ends of the bones are covered with cartilage and there is a cavity that separates the bones. The bones are held in place by ligaments which stop the bones from moving too much. In addition to the ligaments the two bones are joined together by sleeve-like capsule.
The capsule encloses the synovial cavity. The outer layer of the capsule is composed of ligaments. As stated previously, the ligaments keep bones together preventing dislocation and control the range of movement.
Human musculoskeletal system
The inner layer of the capsule is the synovial membrane. The synovial membrane secretes the lubricating synovial fluid. Lubrication is essential to prevent frictional wear and tear.
The cartilage at the contact ends of the bones also reduces friction. The cartilage pads also acts as shock absorbers against mechanical damage. Classes of Synovial Joints 1. The bones of these joints move across each other, back-and-forth and side-to-side. Examples are between the carpals of the wrist and tarsals of the ankle.
These joints allow a turning movement. Examples are between the first and second vertebras when turning the head, between the ulna and the radius of the lower arm when turning the palm of the hand up or down. These joints allow movement in one plane during flexion and extension. They act, as the name implies, like the hinge of a door. Examples are bending the elbow or knee. This type of joint permits movement in three planes, i.
Examples are the shoulder and hip joints. Ligaments Ligaments are strong, slightly elastic tissues that connect bone to bone at joints. These tissues are more flexible when warm. That is why you should gently warm up before exercising. Ligaments prevent dislocation of the joint and control the range of movement of the bones at the joint. Tendons Tendons are strong inelastic cords or bands of connective tissue that connect muscle to bone. The perichondriuma connective tissue, forms around the cartilage and begins forming compact bone while the above changes are occurring.
Blood vessels form and grow into the perichondrium, transporting stem cells into the interior. Two bands of cartilage remain as the bone develops, one at each end of the bone. During childhood, this cartilage allows for growth and changes in the shape of bones. Eventually the elongation of the bones stops and the cartilage is all converted into bone. Growth of a long bone. Bones continue to change as adults, to adapt to the stresses generated by physical activity. Exercise can increase the diameter and strength of bone; inactivity can decrease them.
Age is a factor: Increasing calcium intake, reducing protein intake, exercise and low doses of estrogen are effective treatments for osteoporosis.
The Skeleton and Muscles
Joints Back to Top There are three types of joints: Immovable joints, like those connecting the cranial bones, have edges that tightly interlock. Partly movable joints allow some degree of flexibility and usually have cartilage between the bones; example: Synovial joints permit the greatest degree of flexibility and have the ends of bones covered with a connective tissue filled with synovial fluid; example: The outer surface of the synovial joints contains ligaments that strengthen joints and hold bones in position.
The inner surface the synovial membrane has cells producing synovial fluid that lubricates the joint and prevents the two cartilage caps on the bones from rubbing together. Some joints also have tendons connective tissue linking muscles to bones.
Bursae are small sacs filled with synovial fluid that reduce friction in the joint. The knee joint contains 13 bursae Joints of the human body. Skeletal Disorders Injury, degenerative wear and tear, and inflammatory disorders affect joints.
Sprains are common injuries that cause ligaments to rip of separate from the bone. Tendinitis such as tennis elbow and bursitis are inflammations of the tendon sheaths. Osteoarthritis is a degenerative condition associated with the wearing away of the protective caps of cartilage covering the bone-ends.
Bony growths or spurs develop as the cartilage degenerates, causing restriction of movement and pain. The cause is not known and may just be wear-and-tear associated with aging. Rheumatoid arthritis is a severely damaging arthritis that begins with inflammation and thickening of the synovial membrane followed by bone degeneration and disfigurement.
More women than men are affected. There may be a genetic predisposition to rheumatoid arthritis. Joint replacement may in some cases restore function. Tendons attach many skeletal muscles across joints, allowing muscle contraction to move the bones across the joint. Muscles generally work in pairs to produce movement: Ligaments and tendons of the arm and leg. Muscles have both electrical and chemical activity.[MEDICAL] 3D Anatomy and Physiology Animations : Bones and Skeletal Muscles
There is an electrical gradient across the muscle cell membrane: Stimulus causes an instantaneous reversal of this polarity, causing the muscle to contract the mechanical characteristic producing a twitch or movement.
Organization of a muscle. Skeletal Muscle Structure Muscle fibers are multinucleated, with the nuclei located just under the plasma membrane.
Most of the cell is occupied by striated, thread-like myofibrils. Within each myofibril there are dense Z lines. A sarcomere or muscle functional unit extends from Z line to Z line. Each sarcomere has thick and thin filaments.
The thick filaments are made of myosin and occupy the center of each sarcomere. Thin filaments are made of actin and anchor to the Z line. Fine structure of a muscle fiber. Muscles contract by shortening each sarcomere. The sliding filament model of muscle contraction has thin filaments on each side of the sarcomere sliding past each other until they meet in the middle.
Myosin filaments have club-shaped heads that project toward the actin filaments. Electron micrograph of the banding of a muscle fiber. Myosin heads attach to binding sites on the actin filaments.
The myosin heads swivel toward the center of the sarcomere, detach and then reattach to the nearest active site of the actin filament.