Transcript The skeletal system
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 McGrallHil l Textbook
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/what are-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/what are-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. 3 rd 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
Sternum Ribs Ulna Carpals Phalanges Tibia Tarsals Phalange s http://kootation.com/this-actually-made-me-cry-such-humanity.html
Skull Clavicle Humerus Coxa Radius Metacarpals Femur Patella Fibula Metatarsals
Major Bones of the Body: Posterior View
Scapula Vertebral Column Sacrum Floating Ribs Coccyx http://www.clker.com/clipart-skeleton posterior.html
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
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Osteoporosis
• Thinning and weakening of the bone • More common to women • Low bone density and low dietary sodium intake • Hips, wrists, and spine • Considered a ‘silent disease’ • Can be prevented or treated with a healthy lifestyle; correct diet, exercise, and medications such as bisphonates http://1.bp.blogspot.com/-QAa7G65np08/Tcq0QVHnkrI/AAAAAAAAAWs/dZcSfC0WQYo/s1600/osteoporosis1.jpg
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.
Web. 23 Feb. 2013.