Compendium Review Unit 3/ Topic 2- Movement

Compendium Review- Unit 3- Environmental Interactions- Topic 2-Movement

Chapter 11- Skeletal System

11.1- Overview of Skeletal System
11.2- Bone Growth, Remodeling, and Repair
11.3- Bones of the Axial Skeleton
11.4- Bones of the Appendicular Skeleton
11.5- Articulations

11.1- Overview of Skeletal System
There are 206 bones in the adult body. The skeleton is what supports the body, produces blood cells, protects soft body parts, stores minerals and fat, and permits flexible body movement. The main part of the bone is the diaphysis which has a medullary cavity that’s walls are composed of compact bone. The cavity is filled with yellow bone marrow that stores fat. The part of the bone that’s at the end of a long bone is the epiphyses which is made of spongy bone that has red bone marrow, where blood cells are made. Articular cartilage occurs at a joint. Periosteum is the connective tissue that covers the long bone, besides at the ends. Osteons are the tubular units that make up compact bone. Osteocytes are the bone cells that pass on nutrients and collect wastes from other cells. Spongy bone has thin plates separated by unequal space, this bone is better for strength. Red bone marrow is what fills the spaces in spongy bone. Cartilage is gel like, has no nerves and makes good padding for joints. Cartilage doesn’t heal fast because it has no blood vessels. There are three types- Hyaline cartilage- firm and flexible, Fibrocartilage- stronger, withholds tension and pressure and elastic cartilage- more flexible than hyaline cartilage. Fibrous connective tissue makes up ligaments and tendons.
Anatomy of a long bone shown below:








11.2- Bone Growth, Remodeling, and Repair
Some bones grow in length and width through adolescence but some continue until the age of 25, at six weeks the embryo skeleton starts to form. Some cells that help in bone growth, remodeling and repair are osteoblasts, osteocytes, and osteoclasts. Osteoclasts remove matrix from the bone and osteoblasts build it up, these turn in to osteocytes when surrounded by calcified matix. Formation of the bone is known as ossification. Intramembranous ossification are bones that develop between sheets of fibrous connective tissue. Endochondral ossification is what most of the bones of the skeleton are formed by. The growth plate or the epiphyseal plate is a band of cartilage. Four layers make up the plate, layer closest to the plate is the resting zone where cartilage remains. Next is the proliferating zone where chondrocytes produce new cartilage cells. Third layer is the degenerating zone where the cartilage cells die and the final layer is the ossification zone where bone is forming (this is what makes the bone length increase.) Hormones are chemical messengers that act on different parts of the body that have an affect on bone growth. Growth hormone (GH) is what stimulates bones growth, too little can lead to being a dwarf and too much can lead to being a giant.
Bone remodeling is the process of bone renewal, 18% of bone is recycled each year. This process keeps bones strong and the recycling helps the body to regulate the amount of calcium in the blood. The parathyroid hormone and calcitonin hormone help to regulate this level. Parathyroid speeds up bone recycling and calcitonin acts opposite of that.
After a bone suffers a break or fracture a repair is needed. There are four steps for a fracture repair that takes place during a few months 1- hematoma which is a mass where blood escapes from a ruptured blood vessel after a fracture, 2- fibrocartilaginous callus which is where tissue repair begins, 3- bony callus which joins the broken bones together and 4- remodeling spongy bone is absorbed and compact bone is built.
Bone fracture and repair shown below
















11.3- Bones of the Axial Skeleton
The axial skeleton is in the midline of the body consisting of the skull, hyoid bone, vertebral column and the rib cage. The braincase and facial bones form the skull. Eight bones make up the cranium or braincase. Major bones of the cranium are the frontal bone- forms the forehead, parietal bones- extend to the sides, occipital bone- curves to form the base of the skull and the foramen magnum- where the spinal cord passes and becomes the brain stem. The temporal bone leads to the middle ear. Sphenoid bone is the keystone of cranial bones- all other bones articulate with it. This bon makes the eye sockets and sides of the skull. Lower jaw bone is the mandible an is the only moveable bone of the skull. Tooth sockets are located here and on the maxillae- the bones that form the upper jaw. Zygomatic bones are the cheekbone prominences and the nasal bones make the bridge of the nose. The only bone in the body that does not articulate with another bone is known as the hyoid bone, which is part of the axial skeleton but not the skull.
33 vertebrae make up the vertebral column. Four curves of the column provide strength and resilience. When vertebrae join the column is formed. Spinal nerves control skeletal muscle contractions. Cervical vertebrae are in the neck, first one is the atlas which holds up the neck. Second one is the axis which allows the rotation of the neck. Intervertebral disks are in between the vertebrae and act as padding. The disks help us bend either way and move side to side.
Thoracic vertebrae make up the rib cage which is part of the axial skeleton. The rib cage protects the heart and lungs. Flattened bones make up the ribs, there are twelve pairs connected to the thoracic vertebrae in the back. The top seven pairs connect to the sternum by way costal cartilage, known as true ribs. Next three pairs are false ribs, they connect to the sternum by way of common cartilage. Last two pairs are floating ribs because they don’t attach to the sternum, they attach to the vertebrae T12. Midline of the body is the sternum, which also helps protect the lungs and the heart. Three bones make up the sternum the manubrium, the body, and the xiphoid process. Manubrium occurs at the level of the second rib which allows the ribs to be counted. Apex of the heart is located between the fifth and sixth ribs.

11.4- Bones of the Appendicular Skeleton
Bones of the pectoral and pelvic girdles and the attached limbs make up the appendicular skeleton. Pectoral girdles are on both side of the body and are made up of a scapula and a clavicle. Clavicle goes across the top of the thorax, scapula is a visible bone in he back. Rotator cuff is made of tendons extending to the humerus from four small muscles. Eight carpal bones make up the wrist, five metacarpal bones form the palm. Phalanges are the finger and thumb bones.
Hip bones make up the pelvic girdle. The pelvis bears the weight of the body, protects organs with the pelvic cavity and is what attaches the legs. Three parts make up the coxal bone, the ilium, ischium, and the pubis. Hip socket occurs where these three meet. Ilium is the largest part. Ischium is what we sit on. Pubic bone is the anterior part of the coxal bone. Thighbone is known as the femur and is the longest and strongest bone in the body. Tibia is the region of the knee and kneecap. Quadriceps tendon is what holds the kneecap in place. Slender bone in the leg is the fibula, forms at the outer bulge of the ankle. Seven tarsal bones make up the ankle, one of these the talus, can move freely where it joins the tibula and fibula. Heel bone is known as the calcaneus is considered part of the ankle. This and the talus support the weight of our bodies.

11.5- Articulations

Bones joined at the joints are classified as fibrous cartilaginous. Fibrous joints like the sutures in between the cranial bones are immoveable. Hyaline cartilage is what connects the cartilaginous joints. These joints are slightly moveable. Synovial fluid fills the synovial joint which is freely moveable. This fluid is a lubricant for the joint.
Synovial joints shown below:






Ball and socket joints at the hips and the shoulders allow movement in all planes. Elbow and knee joints are synovial joint known as hinge joints, they allow movement only one way. Tendons are what attach intact skeletal muscles to bones.

Chapter 12- Muscular System

12.1- Overview of Muscular System
12.2- Skeletal Muscle Fiber Contraction
12.3- Whole Muscle Contraction
12.4- Muscular Disorders
12.5- Homeostasis

12.1- Overview of Muscular System
There are three types of muscle tissue first there is smooth muscle which has muscle fibers that are spindle shaped cells and is located in the walls of the hollow internal organs. Contraction of this muscle in involuntary. Second type is cardiac muscle which forms the heart walls. This muscle contracting is involuntary as well. Last there is the skeletal muscle which can be long. This type of muscle is voluntary. This muscle supports the body, helps keep a regular body temperature, is responsible for making the body move, and this muscle keeps blood moving through the cardiovascular veins and lymph moving through lymphatic vessels. Skeletal muscles also assist in keeping internal organs safe and joints stabilized.
Fascicles are skeletal muscle fibers that make up a whole muscle. Connective tissue surrounds the fascicles inside and out. Tendons are the fascia, a connective tissue that covers muscles that extend beyond the muscles. Tendons anchor muscles to bones. Muscles contract-pulling on the tendon-bone moves. Muscles work in pairs but the one that does most of the work in known as the prime mover. Synergists are the muscles that help the prime mover. Muscles pull not push, they become shorter when contracted. Antagonist are the muscles that work opposite the prime mover.

12.2- Skeletal Muscle Fiber Contraction
The plasma membrane for muscle fibers is known as sarcolemma, cytoplasm known as sarcoplasmic reticulum. Myofibrils are in the reticulum and are the contractile portions of a muscle. Sarcomeres are the units responsible for muscle contraction. Two protein myofilaments myosin and actin make up sarcomeres. Myosin is thick filament while actin is thin filament. When a muscle contraction occurs sarcomeres shorten allowing actin filaments to slide past myosin filaments. Energy for muscle contraction is supplied by ATP. Myosin does the work, it breaks down ATP. Motor neurons are what stimulate contraction in muscle fiber. ACh fills synaptic vesicles in axon terminals. ACh is release when nerve impulses moving down a motor neuron arrive at the axon terminal. Once it is released it diffuses across the cleft and binds to receptors in the sarcolemma. Calcium being released from the reticulum leads to sarcomere contraction. Tropomyosin is a protein that winds about an actin filament while troponin, another protein occurs along the threads. Myosin can bind to actin when calcium is released and combines with troponin.

12.3- Whole Muscle Contraction
Motor units are made up of nerve fiber and muscle fiber. The all or none law is what motor units go by, once a motor unit is stimulated they either all contract or not. Muscle twitches are a response to infrequent electrical impulses. Three stages make up a twitch, first the latent period which is the time between stimulation and initiation of the contraction, next the contraction period, shortening of the muscle and last the relaxation period which is the muscle going back to the previous length. Tetanus is maximal sustained contraction and continues until the muscle fatigues. Sustained contractions occur when some motor units contract maximally while others are resting to keep all muscles from fatiguing at once. Four types of energy sources for muscles are muscle triglycerides, plasma fatty acids, blood glucose and muscle glycogen. Glycogen and triglycerides are stored in muscle the other two come from blood. A limited amount of ATP is stored in muscle cells and if more is needed they can get it from formation of ATP by creatine phosphate pathway, formation of ATP by fermentation and/or formation of ATP cellular respiration.
Slow twitch fibers prefer cellular respiration while fast twitch prefer fermentation and creatine phosphate pathway for ATP. Fast twitch muscle fibers are anaerobic, fatigue easily and have huge power. Slow twitch is aerobic, has steady power and endurance. Delayed onset muscle soreness can occur 24-48 hours after hard exercise. This can be avoided with stretching before exercising and when starting something new to take it slow building up your strength and endurance avoiding straining yourself.

12.4- Muscular Disorders
Sudden and involuntary muscle contractions that can sometimes be painful are known as spasms. If this occurs in the intestinal tract a bellyache can occur. If these come in multiples then seizures or convulsions can result. Long painful spasms are known as cramps. With a lot of effort a person can control facial tics. If a muscle is stretched or torn a strain can occur. If a joint is twisted a sprain can occur. If a tendon becomes injured or inflamed movement of a joint can be painful and tendonitis can result. Myalgia and fibromyalgia are two types of muscular diseases. Myalgia can result from overstretching or overworking muscles or can come from viral infections. The result is achy muscles. Fibromyalgia is chronic and causes achy pain, tenderness and stiffness of muscles. A progression of degenerating and weakening muscles is muscular dystrophy. Lou Gehrig’s disease has no cure and causes the inability to chew, talk, walk and swallow.

12.5- Homeostasis
Skeletal and muscular systems work together in maintain homeostasis, one assists the other with eating and moving, keeping the heart pumping, and breathing. While the skeletal system protects the soft organs the muscular system protects the abdominal organs. The skeletal system produces red bone marrow and regulates blood calcium while the muscular system helps regulate the body temperature, keeping it stable.