THE SKELETAL SYSTEM Chapter 14 Lesson 1 part 1

What does the skeletal system do? How do the parts of the skeletal system work together? How does the skeletal system interact with other body systems?

Skeletal System Stats … The human skeleton has about 206 separate bones. Bones account for approximately 1/5 of the body’s weight. Bones in your body are living organs that contain blood vessels, nerves, fat tissues, and blood-cell-forming tissues.

Functions of the skeleton Support Movement Protection Storage Production

Support The skeletal system serves as a framework for the support of the body. Bones provide support that helps you sit up, stand, and move your body.

Movement The skeletal system and the muscular system work together and move your body. Bones serve as levers and with the muscular system produce movement.

Cranium {skull} – brain (eyes, inner ears) ribs - heart and lungs Bones in your skeleton protect soft fragile tissue and internal organs like the spinal cord, heart, and lungs. Cranium {skull} – brain (eyes, inner ears) ribs - heart and lungs vertebrae - spinal cord

Storage calcium phosphorus Fat Minerals: When your body needs calcium, it is released from bones into the blood.

Production of Blood Cells bone marrow is involved in blood cell production

A bone is an organ composed of two types of living tissue: compact and spongy.

Structure of Bones The bone's surface is covered with a layer of dense, white, fibrous tissue called the periosteum. The periosteum is responsible for muscle attachment and for bone growth and repair.

periosteum This thin tissue contains blood vessels and nerves as well as cells that produce new bone tissue. The periosteum nourishes bones and helps them function and grow properly, as well as heal after injury.

Structure of Bones The hard, outer portions of bones are made of a dense web of fibers called compact bone tissue. The small holes in spongy bone tissue make it less dense than a compact bone.

Structure of Bones (cont.) The insides of most bones contain bone marrow. Red bone marrow, found in the spongy ends of long bones and in some flat bones, is the tissue where red blood cells are made. Yellow bone marrow stores fat and is found inside the longest part of long bones.

Red Bone Marrow Red bone marrow - a soft tissue that produces blood cells; located in the marrow cavity of long bones and in the spaces of spongy bone

Red Bone Marrow In young people this cavity is filled mostly with red bone marrow, a soft tissue that produces red blood cells and certain other blood cells. Makes approximately a billion new blood cells everyday.

Yellow Bone Marrow Yellow bone marrow stores fat and is found inside the longest part of long bones. It gradually replaces the red bone marrow as people grow older.

Ligaments & Tendons ligaments - tough, flexible bands of connective tissue that attach bones to other bones at joints (joined to the periosteum)

Ligaments & Tendons tendons - bands of connective tissue that connect muscles to bones (joined to the periosteum)

two main types of tissue make up the skeleton Bone - consists of living bone cells and the non-living material they secrete Cartilage - a flexible supporting tissue blood vessels never pass through cartilage

Cartilage Cartilage is a strong, flexible tissue that covers the ends of bones. Cartilage prevents the surfaces of bones from rubbing against each other and reduces friction.

Osteon (Haversian system) a unit of bone tissue; composed of a central canal which housed a blood vessel, osteocytes (bone cells) and matrix (layers of nonliving material around it)

Osteon

Osteon

Structure of Bones (cont.) The long bones in children and young teens have regions of bone growth, called growth plates, that produce new bone cells.

Growth continues until adulthood, when most of the cartilage has turned to bone.