A STUDY OF THE HUMAN BODY SYSTEMS:

SKELETAL & MUSCULAR

Lauren Young8th Block3/22/13

Skeletal System

OrgansBone: hard connective tissue forming the skeleton of most

vertebrates, composed of a collagen-rich organic matrix (calcium, phosphate, and other minerals). There are two types of bone: Spongy and compact.

Ligaments: a band of (usually white) fibrous tissue that connects bones to other bones.

Tendons: a cord or band of dense, tough, inelastic, fibrous tissue, serving to connect a muscle with a bone or other muscle.

Cartilage: a firm, elastic, flexible type of connective tissue of a translucent, whitish, or yellowish color. Cartilage between bones cushions the two bones and prevents them from grinding against one another.

Bone: General Info- - Bones are classified by shape: long, short, irregular, and round. - - When humans are born, there is very little to no bone in their

bodies. The skeletons consist of cartilage. - -The skeleton is made up of 206 bones by the time humans

reach adulthood. There are close to 300 or more during a human’s adolescent years.

- - The five functions of the skeletal system are (1) providing shape and support; (2) allowing the body to move; (3) protecting internal organs such as the heart, spinal cord and lungs; (4) producing red blood cells; and (5) storing minerals like calcium and phosphorus for use in other parts of the body. There are two types of bone marrow: yellow and red.

- -Yellow Bone Marrow is found in the shaft of long bones. Red Bone Marrow is found in the spongy bone.

- -Yellow Marrow contains fat. Red Bone marrow produces red blood cells.

Bone CellsThings dealing with bone often have the prefix “Osteo-,” which was the Greek

word for “Bone”- Osteoclasts: Large cells that dissolve bone. They come from the bone

marrow and are related to white blood cells. Osteoclasts usually have more than one nucleus because they were formed from two or more bone cells that fused together. These cells are usually found on the surface of the bone mineral next to dissolving bone.

- Osteoblasts: Cells that form new bone. They come from bone marrow and are related to structural cells. Unlike Osteoclasts, these cells have only one nucleus. Osteoblasts work in teams to build bone. They produce new bone called "osteoid" which is made of bone collagen and other protein. Then they control calcium and mineral deposition. They are found on the surface of the new bone.

- Osteocytes: cells inside the bone. They also come from osteoblasts. Some of the osteoblasts turn into osteocytes while the new bone is being formed, and the osteocytes then get surrounded by new bone. They are not isolated, however, because they send out long branches that connect to the other osteocytes. These cells can sense pressures or cracks in the bone and help to direct where osteoclasts will dissolve the bone.

Bone Cells

Compact Bone Structure

-The compact bone forms the outer layer of most bones and the shaft of long bones. -- Compact bone is not well veined. If injured, the bone takes a while to repair itself. -- Bone is constantly being regenerated, Osteoclasts “eat away” the damaged bone and release calcium into the blood. Osteoblasts help create new cells by removing the calcium from the blood and creating a new matrix.

Spongy Bone Structure

-Red Blood Cells are produced in the Red Bone Marrow that’s found in the spongy bone. - Spongy bone is found at the ends of the bones. - The flat pieces of mineralized bars (spicules) that create the honeycomb look of spongy bone are called trabeculae.

SkeletonBy the time a human reaches adulthood, he/she will have about 206 bones. -Bones are connected to one another by ligaments.-

Joints-Ball and socket: most movable type of joint in your body (shoulder)-- Saddle joint: enable you to grasp (thumb) -- Fixed joints: don’t allow any movement (skull bones)-- Ellipsoidal: Allow bending, extending, rocking from side-to-side, but limit rotation (base of index finger)-- Gliding Joints: occur between the surfaces of flat bones that are held together by ligaments (wrist and ankle) -- Hinge Joint- allow movement in only one direction (knee and elbow)-- Pivot Joint: allows movement side-to-side, up and down (neck)

Ligament

Tendon

Cartilage

Skeletal system and Body: The skeletal and muscular systems work together to provide stable oxygen levels in the blood by producing red blood cells to carry the oxygen in the circulatory system, to provide an open space for the lungs to inflate and deflate during respiration, and to provide the movement of the diaphragm that actually inflates and deflates the lungs, thus exchanging carbon dioxide and oxygen. They work together to maintain stable blood sugar levels, by helping the digestive system to get food, and break it down mechanically by chewing and swallowing it.

Skeletal System & Evolution

About 100,000 years ago, there were more than one “type” of human on the Earth. In Asia, there were the Homo erectus. In Africa and the Middle East, there were the Homo sapien. In Europe, there were the Homo neanderthalensis. By about 30,000 years ago, the diversity vanished and all humans developed into the anatomically and behaviorally modern form. It is still being debated what caused this shift to one single form. There are two popular theories; however.

The Multiregional Theory states that Homo erectus left Africa 2 million years ago and became Homo sapien in other parts of the world.

The Out of Africa Theory states that Homo sapiens arose in Africa and migrated to other parts of the world to replace other hominid species, including Homo erectus.

Human evolution

Muscular System

OrgansMuscles: a tissue composed of cells or fibers, the contraction

of which produces movement in the body. Somatic: dealing with movement of bone or

cartilageVisceral: dealing with organs

Tendons: a cord or band of dense, tough, inelastic, white, fibrous tissue, serving to connect muscle to bone.

**Most organs in the body are composed of one of three types of muscle.

Types of MuscleSmooth: found lining the walls of blood vessels, visceral organs (such as the digestive

tract and uterus) and are also found attached to hairs in the integument (involuntary) -Two types: -Unitary: self-initiated (myogenic contraction) to help sustain the rhythm of the organ with which it is involved. Multiunit-: neurogenic contraction requires action potential sent by neurons to regulate its action.

Cardiac: Found only in the heart. In cardiac muscle, the branching of the cells increase its overall connectivity, and the cells are firmly united with each other through intercalated disks Cardiac muscle does not fatigue easily Action of the cardiac muscle fibers shows mixed control, such that the myogenic rhythm of the heart is maintained by neurogenic control and the entire unit of the cardiac muscle acts as a syncytium, or single functional unit. (involuntary)

Skeletal: Closely associated with the skeleton and used in locomotion (voluntary) each skeletal muscle fiber is also a syncytium due to the close connection between cellular units fibers are closely associated with connective tissues and are under voluntary control by the nervous system.

Types of Muscle

Hierarchy of Muscle Tissue

Muscles & HomeostasisMuscles help maintain homeostasis by generating heat that helps maintain body temperature, by moving materials through the body, and by pulling on bones to move the body.

Evolution of Muscles It has not been determined exactly what the evolutionary history of muscles is, but

tests have shown a distinct similarity between the muscle development of amniotes (birds, reptiles, and mammals ) and a Xenopus (highly aquatic frog) embryo: superficial muscle fibers, a large number of mitochondria, and fast muscle fibers.

Characterization of the differentiation of the two types of muscle showed a remarkable difference in the tail somites (muscle cells), which are committed to cell death, and the trunk somites in the anterior region, which will eventually form most of the adult muscles. In trunk cells, fast muscle appears first, while in tail cells, slow muscle appears first then moves to the surface where most of it differentiates into fast muscle.

Later in development of the Xenopus, a second wave of slow muscle appears in all muscle cells. The pattern observed in tail somites is very close to that seen in the whole body of a fish. Scientists also found a thin layer of distinct cells similar to that seen in amniotes. The cells express the pax3 protein, which plays a critical role in the development of tissues and organs during embryonic development. The Xenopus also displays the sonic hedgehog gene, which has a crucial role in assuring that all organs and limbs are in the proper place.

These similarities imply that muscle development in the common ancestor of teleosts and tetrapods occurred in a manner similar to that observed in Xenopus tail.

Xenopus & AmnioteXENOPUS AMNIOTE

ReferencesFarabee, M.J. (18 May 2010) . Muscular and Skeletal Systems. Retrieved from

http://www.estrellamountain.edu

Fernandes, Jorge M.O. (1 Sept. 2004). Evolution of Muscles to Cope with Trunk Four Legs. Retrieved from http://www.jeb.biologists.org

Johanson, Donald (May 2001). Origins of Modern Humans: Multiregional or Out of Africa? Retrieved from http://www.actionbioscience.org

Kanis, JA, A. Oden (20 Sept. 2001). Bone Cells. Retrieved from http://www.depts.washington.edu

Perman, Anna (26 Oct. 2011). Sonic Hedgehog Gene. Retrieved from http://www.guardian.co.uk

Unknown (Aug. 2012). Pax3 gene. Retrieved from http://ghr.nlm.nih.gov Unknownhttp://www.cfbstaff.cfbisd.edu

http://www.morgancc.edu