The skeletal system
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THE SKELETAL SYSTEM By Susan Song, Julienne Kim and Kelsey Osborn BONE FUNCTION: Support and Protection Give shape and provide protection to head, face, thorax, and limbs Structural support for heart, lungs and marrow Protection for brain, uterus, and other internal organs Attachment sites for muscles allowing movement of limbs BONE FUNCTION: Body Movement Movement is possible through of the attachment of bones to muscles. (Tendons) Bones and muscles interact as mechanical devices called levers. 4 basic components of levers: 1) rod or bar 2) pivot point 3) object moving against resistance 4) force supplying energy l Textbook McGrallHil BONE FUNCTION: Blood Cell Formation 3 groups of blood cells: red blood cells, white blood cells, and platelets Also called hematopoiesis Begins in the yolk sac, later occurs in the liver and spleen, and finally in bone marrow Marrow: soft mass of connective tissue found within medullary cavities of long bones, spongy bone, and central canals of compact bone tissue 2 kinds of bone marrow: Red marrow and yellow marrow Continued… Red marrow: formation of red blood cells, white blood cells and platelets. In infants, red marrow occupies the cavities of bones Yellow marrow: stores fat. Is not active in blood formation However, if needed, can become red marrow, then reverts back to yellow marrow www.propofs.com BONE FUNCTION: Storage of Inorganic Salts • • • • • The extracellular matrix of bone tissue is rich in calcium salts Vital Metabolic processes require calcium When blood is low in calcium, osteoclasts break down bone tissue, which releases calcium salts into the blood High blood calcium activates osteoclasts and causes the release of calcitonin, which stimulates osteoblasts to form bone tissue. Excess calcium is stored in the extracellular matrix Bones • • • • • • Bone tissue is a type of dense connective tissue. Come in a variety of shapes and have a complex internal and external structure Lightweight, yet strong and hard Rigid and has a honeycomb-like, three-dimensional internal structure. Includes marrow, endosteum and periosteum, nerves, and blood vessels There are 206 bones in the adult human body and 270 in an infant. Ligaments • • • • • Connect bone to another bone Allow most joints to move help control their range of motion Stabilize them so that the bones move in proper alignment Collagen makes up the tissue in most ligaments. Collagen fibers allow to stretch significantly when they move, such as when the elbow is bent or straightened. http://www.wisegeek.com/whatare-ligaments.htm Tendons • • • • Tough band of fibrous connective tissue that usually connect muscle to bone Capable of withstanding great tension. Similar to ligaments and fasciae as they are all made of collagen but ligaments join one bone to another bone, and fasciae connect muscles to other muscles. Tendons and muscles work together http://www.wisegeek.org/whatare-tendons.htm#slideshow Cartilage • • • • • • • Flexible connective tissue found in many areas in the body like the rib cage, the ear, the nose. Provide support, frameworks, and attachments Protect underlying tissues Form structural models for developing bones Not as hard and rigid as bone but is stiffer and less flexible than muscle. 3 types: elastic cartilage, hyaline cartilage and fibrocartilage Do not contain blood vessels and as a result, heals very slowly. http://washington.uwc.edu /about/wayne.schaefer/TissuesPage.htm http://www.tumblr.com/tagged/el astic%20cartilage http://tissueslides.blogspot.com /2009/10/fibrocartilage.html Bone Development and Growth The skeletal systems begins to grow during prenatal development Continues to grow into adulthood Form by replacing existing connective tissues 2 types of bone formation: Intramembranous and endochondral Bone Development and Growth: Intramembranous Ossification Formation of flat bones like the skull Connective tissue forms in sheets at sites of future bones Highly invested with blood vessels. The future bones are first formed as connective tissue membranes. Osteoblasts migrate to the membranes and deposit bony matrix around themselves. As a result, spongy bone tissue forms in all directions within the membrane layers Periosteum: cells of the membranous tissues that lie outside the developing bone Osteoblasts lie within the periosteum and form compact bone around spongy bone Endochondral Ossification: • Replacement of hyaline cartilage with bony tissue. • Most of the bones of the skeleton are formed in this manner. Primary Ossification Center Future bones first form as hyaline cartilage models. 3rd month after conception: the perichondrium that surrounds the hyaline cartilage models fills with blood vessels and osteoblasts and changes into a periosteum. The osteoblasts form a collar of compact bone around the diaphysis. Cartilage in the center of the diaphysis begins to disintegrate. Osteoblasts penetrate the disintegrating cartilage and replace it with spongy bone. Secondary Ossification Center • • • • Continues from the center toward the ends of the bones. After spongy bone is formed in the diaphysis, osteoclasts break down the newly formed bone to open up the medullary cavity. As the developing bone increases in length, cartilage continues to disintegrate When secondary ossification is complete, the hyaline cartilage is totally replaced by bone but a region of hyaline cartilage remains over the surface of the epiphysis as articular cartilage McgrawHill Textbook Features of a Typical Long Bone (Shier) Axial v. Appendicular Skeletons Axial: Head, neck and trunk Appendicular: Upper and lower limbs http://bodyorgans.blogspot.com/2012_09_01_archive.html Major Bones of the Body: Anterior View Skull Sternum Clavicle Ribs Humerus Coxa Ulna Radius Metacarpals Carpals Phalanges Femur Tibia Tarsals Phalange s Patella Fibula Metatarsals http://kootation.com/this-actually-made-me-cry-such-humanity.html Major Bones of the Body: Posterior View Scapula Vertebral Column Floating Ribs Sacrum Coccyx http://www.clker.com/clipart-skeleton- Joints of Different Tissue http://www.infovisual.info/03/img_en/026%20Types%20of%20joints%20found%20in%20the%20human%20body.jpg Joints Fibrous Lie closely between one another Thin layer of dense conn. tissue I.e. sutures on skull bones Cartilaginous Hyaline cartilage or fibrocartilage Separate the vertebral column Synovial Mostly of all joins Allows free movement Complex structures Six Synovial Joints http://classconnection.s3.amazonaws.com/404/flashcards/1237404/jpg/slide321333990034923.jpg http://www.medtrng.com/flexionextension.gif http://www.medtrng.com/flexionextension.gif http://frankduffy93.files.wordpress.com/2012/10/abductionadduction.gif http://www.usi.edu/science/biology/mkhopper/hopper/BIOL2401/LABUNIT2/01Ex12Joints/Ex.13Images/DorsiPlantar.jpg http://people.emich.edu/pbogle/PHED_200/overheads/ch7_art/07_40.jpg http://d3j7fudf8o8iuo.cloudfront.net/var/ezwebin_site/storage/images/media/images/e-anatomy/anatomical-terms-of-location-position-motion/inversion-eversion/2511097-1eng-GB/inversion-eversion_imagelarge.jpg http://www.baileybio.com/plogger/images/anatomy___physiology/04._powerpoint_-_skeletal_system/protraction___retraction.jpg http://www.usi.edu/science/biology/mkhopper/hopper/BIOL2401 /LABUNIT2/01Ex12Joints/Ex.13Images/DorsiPlantar.jpg http://www.baileybio.com/plogger/images/anatomy___physiology/04._powerpoint_-_skeletal_system/elevation___depression.jpg Osteoporosis •Thinning and weakening of the bone •More common to women •Low bone density and low dietary sodium intake •Hips, wrists, and spine http://1.bp.blogspot.com/-QAa7G65np08/Tcq0QVHnkrI/AAAAAAAAAWs/dZcSfC0WQYo/s1600/osteoporosis1.jpg •Considered a ‘silent disease’ •Can be prevented or treated with a healthy lifestyle; correct diet, exercise, and medications such as bisphonates Osteogenesis Imperfecta Congenital Disease More common within shorter stature Bones become weaker Damages in the gene for type 1 collagen Blue tint to the whites of the eye, hearing losses, and multiple fractures No definite cure http://www.primehealthchannel.com/wp-content/uploads/2011/08/Osteogenesis-Imperfecta.jpg Bone Tumor Abnormal growth of bones Genetics, radiation, injury Symptoms: Pain (night) and fractures Treated like most cancers http://www.magmire.net/wp-content/uploads/Dog-Bone-Tumors.jpg Work Cited "Bone tumor - PubMed Health." National Center for Biotechnology Information. N.p., n.d. Web. 26 Feb. 2013. <http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002210/> "Osteogenesis imperfecta - PubMed Health." National Center for Biotechnology Information. Web. 23 Feb. 2013. <http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002540> "NIHSeniorHealth: Osteoporosis - What Is Osteoporosis?." NIHSeniorHealth Home Page. N.p., n.d. Web. 24 Feb. 2013. <http://nihseniorhealth.gov/osteoporosis/whatisosteoporosis/01.html> Shier, David, Jackie Butler, and Ricki Lewis. Hole's essentials of human anatomy and physiology. 9th ed. Boston: McGraw-Hill, 2006. Print.
