Chapter 4 Flashcards
(24 cards)
Functions of the skeletal system: composed of 206 bones
- SUPPORT: the skeleton is the body framework that supports internal tissues and organs
- PROTECTION: the skeleton forms a firm, cagelike structure that protects many internal structures.
- MOVEMENT: skeletal muscles are attached to the bones, which enables the bones to provide leverage for movement.
- MINERAL STORAGE: the bones serve as a storage area for various minerals, particularly calcium and phosphorus.
- HEMATOPOIESIS: blood cell formation, takes place in the red bone marrow.
Structure of bones: 4 groups:
- Long: found in extremities
- Short: found in hands and feet
- Flat: found in skull and sternum
- Irregular: make up the vertebrae
Bones cannot bend without damage. To allow movement, individual bones join at joint sites. The joint is the point of contact between the individual bones. The structure of the individual bones depends on the function the area. Every bone in the body (except the hyoid bone, which anchors the tongue) connects with at least one other bone.
Articulations (joint)
Perform two important functions: they hold bones together to form the skeleton, and they allow movement and flexibility of the skeleton
Joints
3 types of joints: no movement
Synarthrosis
3 types o joints: slight movement
Amphiarthrosis
3 types o joints: free movement
Diarthrosis
Measures the angle of a joint. Is is used to determine the degree of joint mobility
Goniometer
Axial skeleton: cranium, ear bones, face
Skull
Axial skeleton: vertebrae
Spine
Axial skeleton: ribs, sternum
Thorax
Appendicular skeleton: shoulder (pectoral) girdle, arms, wrists, hands
Upper extremities
Appendicular skeleton: hip (pelvic girdle), legs, ankles, feet
Lower extremities
As muscles contract, they perform 3 vital functions:
- Motion
- Maintenance of posture
- Production of heat
Functions of the muscular system
- More than 600 muscles, making up approximately 40% to 50% of the body weight
- Movement rely on the integrated function of the bones, joints, muscles.
- Muscle tissue is under voluntary or involuntary control.
- Produce body heat when skeletal muscles contract, up to 85% of body heat.
Skeletal muscle structure
- 3 layers of surrounding connective tissue covering: epimysium, perimysium and endomysium
- Connective tissue extends to form tough cord call tendons that anchor muscles to bones.
- Tendons in the ankle and wrist are enclosed in tendon sheaths (sleeves or tubelike structures of connective tissue contain synovial fluid)
All the body’s tendons, ligaments (which are like tendons, but anchoring bone to bone) and aponeuroses (very broad, flat, tendons) are composed by connective tissue in various sizes, shapes, and densities. Collectively known as:
Fasciae
Usually one artery, two veins, and one nerve penetrate a particular muscle. Each muscle cell comes in contact with several capillaries and a portion of a nerve cell. The muscle cells, in union with the nerve cell that controls them are called:
Motor unit
The impulse from the nerve cell must travel across a small gap because the nerve cell and the muscle cell do not directly touch each other. This small gap is called___ and is filled with tissue fluid.
Synaptic cleft
A special chemical travels through the tissue fluid to stimulate the muscle fiber.
Neurotransmitter
The neurotransmitter for skeletal muscle tissue
Acetycholine
An enzyme that breaks down the acetylcholine one it has transferred the message. This allows the muscle to cell to relax between impulses
Cholinesterase
Muscle cells are governed by the “all or none” law; that is, when a muscle cell is stimulated or shocked adequately, it will contract completely
Muscle stimulus
Because each skeletal muscle is composed of thousands of muscle cells that react to many different nerve cells, the muscle as a whole contracts according to the principle of graded response. The strength of the muscle contraction therefore depends on the number of individual muscle responding.
Muscle contraction
