Skeletal System

Bone. is a type of connective tissue that is hard and inflexible.

Functions of bone:

Serves as attachment points for muscles.

Gives the body shape and supports the body structures.

They protect the body's delicate organs.

They serve as storage places for minerals, such as calcium and phosphorus.

They are hemopoetic (produce blood cells).

Composition of bone:

Bone is made up of living cells called osteocytes. If bone tissue were not alive, broken bones would not be able to heal after an injury. These bone cells are surrounded by a nonliving matrix of material made up of a protein called collagen and inorganic salts made of calcium and phosphorus. The arrangement of the bone cells forms a target pattern. A layer of cells followed by a layer of nonliving material, etc.

The center of these target-like structures is hole filled with blood vessels called Haversian canals. Bone cells are nourished from the material transported by the blood through these canals.


The bone is covered with a thin membrane called the periosteum. The main job of the periosteum is to make new bone for growth and repair.

There are two types of bone: compact and spongy bone. The main difference between the tissues is the density of each. The center of most bone is hollow. A material called marrow fills this space.

Red marrow produces red and white blood cells and platelets.

Yellow marrow contain a large amount of fat. Red marrow is found in the flat and long bones of the skeleton, while yellow marrow is found in the long bones.

Cartilage is a type of connective tissue much like bone, except in the number and type of cells, and the lack of minerals in the matrix. Its major function lies in its flexibility. The early human skeleton contains large amounts of cartilage. As the baby develops the cartilage is replaced by bone. This process is called ossification. Cartilage also functions as a cushion ,preventing bones from rubbing together.

 

 


The Human Skeleton.

The adult human skeleton contains 206 bones. It is an internal skeleton or endoskeleton. This type of skeleton allows the organism to grow without having to molt like organisms containing an exoskeleton.

The skeleton has 2 main parts. The axial skeleton, containing the cranium, spinal column, sternum, and ribs.

The appendicular skeleton, is made up of arm and leg bones and the pelvic and pectoral girdles.

The bones of the skeleton are held together by connective tissue called ligaments.

 

Bones of the Skeleton

Arm
Legs
humerus
femur
radius
fibula
ulna
tibia
carpals (wrist)
tarsals (ankle)
metacarpals (palm of hand)
metatarsals (arch of foot)
phlanges (fingers)
phlanges (toes)

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Skull
Vertebrae
frontal
cervical (7)
mandible
thoracic (12)
occipital
lumbar (5)
temporal
sacrum
zygomatic
coccyx

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Pelvic Girdle
Pectoral Girdle
ischium
clacicle
ilium
scapula
pubic
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Joints:

A joint is the area where two or more bones come together. There are 5 types of joint found in the human body.

Immovable- joints of the skull

Hinge- elbow and knee

Pivot- joint below the skull

Ball-and- socket-shoulder and hip

Gliding- wrist and vertebrae