THE SKELETAL SYSTEMBy 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 McGrallHill 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://www.tumblr.com/tagged/elastic%20cartilage

http://tissueslides.blogspot.com/2009/10/fibrocartilage.html

http://washington.uwc.edu/about/wayne.schaefer/TissuesPage.htm

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:

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.

• 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

Primary Ossification Center

Secondary Ossification Center

• Replacement of hyaline cartilage with bony tissue.

• Most of the bones of the skeleton are formed in this manner.

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

Femur

Humerus

Fibula

Tibia

RadiusUlna

Skull

Sternum

Ribs

Carpals

Phalanges

Coxa

Metacarpals

Tarsals

MetatarsalsPhalanges

Clavicle

Patella

http://kootation.com/this-actually-made-me-cry-such-humanity.html

Major Bones of the Body:Posterior View

Scapula

Sacrum

Coccyx

Floating RibsVertebral Column

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

HINGE

Condyloid

Gliding

PIVOT

BALL-AND-SOCKET

SADDLE

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/2511097-1-eng-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

http://1.bp.blogspot.com/-QAa7G65np08/Tcq0QVHnkrI/AAAAAAAAAWs/dZcSfC0WQYo/s1600/osteoporosis1.jpg

• 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

OSTEOPOROSIS=POROUS BONE

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

"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.

Work Cited