Unit 3. Compendium 2- Movement

Table of Contents
I. Skeletal System
A. Overview of the Skeletal System
B. Bone Growth, Remodeling, and Repair
C. Bones of the Axial Skeleton
D. Bones of the Appendicular Skeleton
E. Articulations
II. Muscular System
A. Overview of the Muscular System
B. Skeletal Muscle Fiber Contraction
C. Whole Muscle Contraction
D. Muscular Disorders
E. Homeostasis



I. Skeletal System
A. Overview of the Skeletal System
1. Functions of the Skeletal System
a. Supports and protacts the body
b. Produces blood cells
c. Stores mineral salts, particularly calcium phosphate, and fat
d. Along with the muscles, permits flexible body movement
2. The bones of the skeleton are composed of bone tissues and cartilage. Ligaments composed of fibrous connective tissue connect bones at joints. In a long bone:
a.Hyaline cartilage covers the ends of a long bone
b. Perioteum (fibrous connective tissue) covers the rest of the bone
c. Spongy bone (containing red bone marrow) is in the epiphyses
d. Yellow bone marrow is in the medullary cavity of the diaphysis
e. Compact bone makes up the wall of the diaphysis
B. Bone Growth, Remodeling, and Repair
1. Cells involved in growth, remodeling, and bone repair are:
a. Osteoblasts- bone-forming cells
b. Osteocytes- mature bone cells derived from osteoblasts
c. Osteoclasts- break down and absorb bone
2. Bone Development and Growth
a. Intramembranous Ossification: bones develop between sheets of fibrous connective tissue (flat bones such as skull bones)
b. Endochondral Ossification: cartilaginous models of the bones are replaced by calcified bone matrix.
c. Bone growth is affected by vitamin d, growth hormone, and sex hormones
3. Bone remodeling and its role in Homeostasis
a. Bone Remodeling- the renewal of bone; Osteoclasts breakdown bone and osteoblasts re-form bone (some bone is recycled each year)
b. Bone recycling allows the body to regulate blood calcium
4. Bone Repair
a. Repair of a fracture requires four steps: Hematoma formation, Fibrocartilaginous callus, Boney callus, and then Healed Facture, or remodeling.
C. Bones of the Axial Skeleton
1. The axial skeleton consists of the skull, the hyoid bone, the vertibral column, and the rib cage.
a. Skull- formed by the cranium, which protects the brain and the facial bones.
b. Hyoid Bone- anchors the tongue and is the site of attachment of muscles involved with swallowing.
c. Vertebral Column- Composed of vertebrae separated by shock-absobing disks, which make the column flexible; supports the head and trunk, protects the spinal cord, and is a site for muscle attachment.
d. Rib Cage- composed of the thoracic vertebrae, ribs, costal cartilages, and the sternum; protects the heart and lungs.
D. Bones of the Appendicular Skeleton
1.The Appendicular skeleton consists of the thones of the pectoral girdles, upper limbs, pelvic girdle, and lower limbs.
a. Pectoral girdles and upper limbs are adapted for flexability.
a1. Pectoral Girdle- provides support and attachment for an arm; consists of a scapula and a clavicle.
b. The pelvic girdle and lower limbs are adapted for supporting weight; the femur is the longest and strongest bone in the body.
b1. Pelvic Girdle- portion of the skeleton to which the legs are attached; consists of the coxal bones.
E. Articulations
1. Bones are joined at joints, of which there are three types:
a. Fibrous Joints (such as the sutures of the cranium) are immovable.
b. Cartilaginous Joints (such as those between the ribs and sternum and the pubic symphysis) are slightly movable.
c. Synovial Joints (which have a synovial membrane) are freely movable.
II. Muscular System
A. Overview of the Muscular System
1. Three types of muscle tissue:
a. Smooth- involuntary and is found in the walls of the intestines
b. Cardiac- involuntary and is found in the walls of the heart
c. Skeletal- voluntary, contains bundles of muscle fibers called fascicles, and is usually attached by tendons to bones.
2. Skeletal muscle functions:
a. Helps maintain posture
b. Provides movement and heat
c. protects underlying organs
3. When achieving movement, some muscles are prime movers, some synergists, and others antagonists.
4. Muscles are named for their size, shape, location, direction of fibers, number of attachments, and action.
B. Skeletal Muscle Fiber Contraction
1. Muscle fibers contain myofibrils, which contain actin and myosin filaments
2. Muscle contraction occurs when sarcomeres shorten and actin filaments slide past myosin filaments.
C. Whole Muscle Contraction
1. Muscles have motor units
a. Contractions described in terms of a muscle twitch, summation, and tetanus
b. Motor units- several fibers under the control of a single motor axon
c. The strength of the contraction varies according to recruitment of motor units
d. A continuous slight tension (called muscle tone) is maintained by muscle motor units that take turns contracting
2. A muscle fiber has three ways to aquire ATP for muscle contraction:
a. Creatine phosphate transfers a phosphate to ADP, and ATP results.
b. Fermentation also produces ATP quickly; Fermentation is associated with an oxygen debt because oxygen is needed to metablize the lactate that accumulates.
c. Cellular respiration provides most of the muscles ATP, but takes longer because much of the glucose and oxygen must be transported in blood to mitochondria. Cellular respiration occurs during aerobic exercise and burns fatty acids in addition to glucose.
3. Fast-twitch and Slow-twitch muscle fibers
a. Fast-twitch Fibers: (for weight lifting) rely on an anaerobic means of aquiring ATP; have few mitochondria and myoglobin, but motor units contain more muscle fibers; are known for explosive power, but fatigue quickly.
b. Slow-twitch Fibers: (for swimming and running) rely on aerobic respiration to aquire ATP; have a plentiful supply of mitochondria and myoglobin, which give them a dark color.
D. Muscular Disorders
1. Common Conditions
a. Spasm- convulsion, cramp, facialtics
b. Strain
c. Sprain
d. Tendinitis
e. Bursitis
2. Muscular Diseases
a. Myalgia (achy muscles) and Fibromyalgia
b. Muscular Dystrophy (degeneration and weakening of muscles)
c. Myasthenia Gravis (autoimmune disease characterized by weakness in muscles of eyelids, face, neck, and extremities)
d. Amyotrophic Lateral Sclerosis- ALS, or Lou Gehrig's disease (gradual loss of the ability to walk, talk, chew, and swallow)
E. Homeostasis
1. The muscles and bones produce movement and protect body parts
2. The bones produce red blood cells and are involved in the regulation of blood calcium levels
3. The muscles produce the heat that gives us a constant body temperature.