The Skeletal System

Health Science 20

S. Lewchuk

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Stolen / Adapted from content developed by Richard Bowes

Skeletal System

• The infant body contains 300 plus bones

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• The human adult body contains 206 bones

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• After birth bones start to fuse together in the infant body to become larger and stronger bones.

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Functions of the Skeletal System

• 1. Support

Your bones provide the framework for your body.

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• 2. Protection

Many of the body’s internal organs are protected by your bones.

Example: your brain is protected by your skull and heart by your rib cage.

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• 3. Movement

Muscles are attached to bone and therefore bones aid in movement of the body.

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Functions of the Skeletal System

• 4. Blood Cell Production

Red bone marrow produces red blood cells and white blood cells.

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• 5. Storage

Bones store minerals (calcium and phosphate) and fats. Yellow bone marrow stores the fats, which is found in long bones

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Types of Bones

• 1. Long Bones

have a greater length than width. Usually curved for strength.

Examples include femur, tibia, fibula, humerus, ulna and radius

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• 2. Short Bones

approximately equal length and width. Found in ankles and wrists

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• 3. Flat Bones

thin in structure. Provide considerable protection, and large surfaces for muscle attachment.

Examples include cranial bones, sternum/ribs, and scapulae (shoulder blades)

Types of Bones

• 4. Irregular bones

have a complicated shape that is based on the function of the bone. An example is the vertebrae, where the function is support and protection of the spine.

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• 5. Sesamoid bones

develop in areas of tension and stress, but can vary person to person. Example: patella bone (knee cap).

Skeletal System

• The skeletal system is composed of two types of skeletons:

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Axial Skeleton:

made up of bones found in the trunk and the head of your body

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Appendicular Skeleton:

made up of limbs that extend from your trunk. This includes arms, legs, hands and feet.

Skeletal System

• Bone Structure:

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Compact Bone

Forms the outer layer of the bone. This is a very hard and solid layer of bone.

Spongy Bone

Tissue located beneath the compact bone. It is a porous tissue and has a meshy appearance and contains many spaces that hold the bone marrow.

Cartilage

Flexible connective tissue. Found between bones. Cartilage cushions your bones, and allows for smooth movements. Cartilage is typically found on the end of bones and in the rib cage.

Bone Marrow

• Red = hematopoietic tissue
• Bone cell forming tissue
• Everywhere in infant

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• Yellow = fatty tissue
• Young to middle age develop in shafts
• Does NOT produce blood

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How Do Bones Form and Grow?

• As infants, our bodies are mostly cartilage. Over time this flexible cartilage is turned to hardened bone.

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• Cartilage is hardened when a mixture of collagen and calcium phosphate combine. This process is called calcification.

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• Bones continue to grow through childhood, growing longer, wider and thicker. Growth occurs from the inside/center outwards.

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How Do Bones Form and Grow?

• During puberty, sex hormones allow bones to become more dense.
• Bones are the strongest between ages 18 and 30, but after that calcium is lost to other areas of the body.
• Bone growth and health is directly related to exercise and diet, especially in your childhood and teenage years.

Process of Bone Growth

• Ossification

The process by which bone is formed.

• Osteoblasts

Cells that secrete collagen and calcium phosphate to build bones

• Collagen

fibrous connective tissue

• Calcium phosphate

mineral that hardens collagen

• Osteoclasts

responsible for breaking down bone

Bone Joints

Joint

The place where bones meet.

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• Joints allow various amounts of movement
• Some joints are held together for no movement, some have a wide range of motion
• Try moving these joints: knee joint, vertebrae joints (bending side to side)

Types of Joints

• 1. Gliding Joints

Allow flat surfaces of bone to slide over each other. These joints are found in the ankle and wrist, which allow flexibility

• 2. Pivot Joints

Two bones rotate on each other. An example is the two top vertebrae that support the head. These joints pivot allowing you to turn your head

• 3. Ball and Socket Joints

A ball-like end of a bone fits into a cup like socket of another bone. An example is the femur bone fitting into the socket of the hip bone

Types of Joints

• 4. Saddle Joints

Allows movement front and back, left and right. Example is the thumb joint.

• 5. Hinge Joint

Allows movement of bone in one direction. Think of a swinging door. The knee joint is a hinge joint.

Types of Joints

Skeletal Disorders

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• Osteomalacia
• Soft Bones
• Lacking minerals (Calcium, Vitamin D)
• Rickets
• Child form of Osteomalacia
• More Detrimental since bones are still growing
• Signs: bowed legs; deformities of pelvis, ribs and skull
• Osteomyelitis
• Bone Marrow Inflammation
• Caused by pus-forming bacteria that enters via wound or nearby infection.

Skeletal Disorders

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• Osteoporosis
• Bone degradation occurs faster than bone can be deposited
• Decrease in bone mass
• Fractures in the vertebrate and femur are common
• Most common post menopause: rapid decline in estrogen (stimulates osteoclasts and inhibits osteoblasts).
• Giantism
• Childhood hypersecretion of Growth Hormone
• Excessive growth

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Skeletal Disorders

• Acromegaly
• Adult hypersecretion of Growth Hormone
• Overgrowth of face, feet, hands
• Pituitary Dwarfism
• Childhood deficiency of Growth Hormone
• Short long bones; max height is 1.20 metres
• Paget’s Neoplasms
• Bone remodeling process disturbed
• Bones are abnormal, enlarged, not as dense, brittle, and prone to fracture
• Affects older adults

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Types of Fractures

• Simple

The bone is broken, but the skin is not lacerated.

• Compound

Skin is pierced by the bone or by a blow that breaks the skin at the time of the fracture

• Greenstick

Fracture on one side of the bone, causing a bend on the other side of the bone.

• Spiral

Fracture wraps around bone in spiral manner

• Comminuted

Results in three or more bone fragments.

• Transverse

The fracture is at right angles to the long axis of the bone

• Compression

Occurs in the vertebrate

• Lisfranc

One or all of the metatarsal bones are displaced from he tarsus.

Types of Fractures

Types of Fractures

(Fracture

Hematoma)

Bony

The Bodies Response to Fractures