Lauren Young
8th Block
3/22/13
Bone: 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.
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- 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.
Things 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.
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.
Skeleton
By the time a human
reaches adulthood, he/she
will have about 206 bones.
-Bones are connected to one
another by ligaments.
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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-toside, 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)
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.
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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.
Muscles: a tissue composed of cells or fibers, the contraction of which
produces movement in the body.
Somatic: dealing with movement of bone or cartilage
Visceral: 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.
Smooth: 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.
Muscles 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.
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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
AMNIOTE
Farabee, 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
Unknown
http://www.cfbstaff.cfbisd.edu
http://www.morgancc.edu