Bones and Bone Tissue

Skeletal System

Includes the bones, joints, and other supporting tissue

Bones

Main organs of the system; Adults typically have 206 bones

Each bone includes:

Bone (Osseous) Tissue

Dense regular collagenous tissue

Dense irregular connective tissue

A tissue called Bone Marrow

Functions of the Skeletal System

protection, mineral storage and acid base homeostasis, blood cell formation, fat storage, movement, support

Protection

Bones such as the skull, sternum, and ribs protect underlying organs

Mineral Storage and Acid Base Homeostasis

Bone stores minerals including calcium, phosphorus, and magnesium salts

These minerals are electrolytes, acids, and bases in the blood, and are critical for electrolyte and acid-base maintenance

Blood Cell Formation

Red Bone Marrow in bones is the site of Hematopoiesis, or formation of blood cells

Fat Storage

Yellow Bone Marrow in bones contains adipocytes with stored triglyceride

Movement

Bones are the sites of attachment for most skeletal muscles

When muscles contract, they pull the bones which generates movement around a joint

Support

The skeleton supports the weight of the body and provides its structural framework

Classification of Bone by Shape

long bones, short bones, flat bones, irregular bones, sesamoid bones,

Long Bones

Longer than wide

ex. bones of the limbs; Some long bones are very small

Short Bones

About as long as wide or roughly cube- shaped

ex. the wrist and ankle bones

Flat Bones

Thin and broad

ex. most of the skull bones and bones of the pelvis

Irregular Bones

Irregular shapes

ex. the vertebrae

Sesamoid Bones

Small, flat, oval-shaped bones located within tendons

ex. the kneecap