Bone

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Questions and Answers

What is a common cause of Rickets in children?

Lack of vitamin D (correct)

Lack of calcium

Infection of the bones

Excessive protein intake

Which condition involves abnormal growth or swelling of bone?

Acromegaly

Osteoporosis

Fibrous dysplasia (correct)

Osteomyelitis

What condition results from the deposition of calcium in soft tissues and can lead to complications in the bones?

Multiple myeloma

Paget's disease (correct)

Osteitis

Bone cancer

Which of the following is not considered a primary bone cancer?

Metastatic cancer Signup and view all the answers

What is the primary infection associated with Osteomyelitis?

Staphylococcus aureus Signup and view all the answers

In which age group is acromegaly most typically diagnosed?

Young adults Signup and view all the answers

What is the most common reason for bone fractures in children?

High-impact sports Signup and view all the answers

How are most primary bone cancers typically discovered?

Radiology imaging due to pain or swelling Signup and view all the answers

What is the main structural unit of compact bone called?

Haversian system Signup and view all the answers

What distinguishes short bones from long bones?

Short bones are cube-shaped. Signup and view all the answers

Which type of bone is primarily responsible for movement and support?

Long bones Signup and view all the answers

What is the role of osteoclasts in bone tissue?

Bone resorption Signup and view all the answers

What term describes the embedding of bones within tendons?

Sesamoid bones Signup and view all the answers

During which stage of bone healing is the primary callus formed?

Formation phase Signup and view all the answers

Which factor can significantly delay bone healing?

Increased mobility at the fracture site Signup and view all the answers

Which tissue type is primarily found in spongy bone?

Red bone marrow Signup and view all the answers

What is the primary component of the organic matrix in bone?

Collagen Signup and view all the answers

What function does the periosteum serve for bone?

Nourishment and muscle attachment Signup and view all the answers

Which type of bone has a largely irregular lattice structure?

Cancellous bone Signup and view all the answers

What is a common characteristic of all types of bone tissue?

Presence of osteocytes Signup and view all the answers

What is the primary mineral component that provides strength to bone?

Calcium phosphate Signup and view all the answers

What age is bone development generally complete?

25 years Signup and view all the answers

Study Notes

Bone

Bones work with muscles and joints to form the musculoskeletal system.
The skeleton helps to hold the body together and enables movement.
Bones can come in five different types: long bones, short bones, flat bones, irregular bones, and sesamoid bones.

Bone Structure

Bone is one of the hardest tissues in the body when fully developed.
Bone consists of:
- Organic material (40-50%): mainly collagen
- Inorganic material (30-40%): mineral salts, such as calcium and phosphate
- Water (~20%)
Bone is a vascular tissue with a large capacity for growth in the first two decades of life and the ability to regenerate throughout life.
There are three key types of bone cells:
- Osteoblasts: Single-nucleus, immature bone cells that form bone.
- Osteocytes: Mature bone cells that originate from osteoblasts that become trapped in lacunae.
- Osteoclasts: Multi-nucleated bone resorption cells that help maintain bone shape by breaking down bone tissue.

Bone Development

Bone development starts before birth and completes around age 25.
It involves two main types of ossification:
- Intramembranous ossification: Bone develops directly from mesenchymal tissue.
- Endochondral ossification: Bone develops from cartilage models.

Types of Bone Tissue

There are two main types of bone tissue:
- Compact bone: appears solid and contains numerous Haversian systems.
- Cancellous bone: also known as spongy bone, appears spongy with red bone marrow and trabeculae.

Bone Structure: Osteon

The basic structural and functional unit of bone is the osteon, also known as the Haversian system.
Each osteon contains a central Haversian canal running longitudinally through the system, which houses blood vessels, lymph, and nerves.
The Haversian canals are surrounded by concentric rings of bone known as lamellae.
Between the lamellae are spaces called lacunae, which contain lymph and osteocytes.
Canaliculi link the lacunae to the lymph vessels, providing nourishment to osteocytes.

Bone Structure: Periosteum

The surface of bone is covered by the periosteum, a vascular fibrous membrane.
The periosteum functions to:
- Provide nourishment through blood vessels to the bone.
- Provide attachment points for muscle tendons.
- Assist in bone formation and repair.

Bone Healing

Bone healing involves several stages:
- Formation of fibrocartilaginous callus: During the first months after injury, a fibrocartilaginous primary callus forms. The dead bone is resorbed, and spongy bone appears. The size of the callus is affected by the immobility of the fracture site; the smaller the movement, the smaller the callus.
- Replacement with lamellar bone: Spongy bone is gradually replaced by lamellar bone, uniting the fracture with a bony secondary callus.
- Remodeling: The final phase restores the shape of the bone to normal and can take several years.

Factors Affecting Bone Healing

Factors that can delay bone healing include:
- Infection
- Tissue fragments between the ends of the bone
- Deficient blood supply
- Old age
- Medications such as steroids
Factors that can improve bone healing include:
- Limited movement/resting of the broken bone
- Pain relief
- Good nutrition
- Appropriate movements under guidance
- Younger age

Bone Conditions

Common bone conditions include:
- Fractures: Broken bones of various types.
- Osteoporosis: Loss of bone density and strength.
- Osteomyelitis: Infection of the bone.
- Bone cancer: Primary bone cancers include osteosarcomas and chondrosarcomas, but most cancers found in bone spread from other organs.
- Osteitis: Bone inflammation, e.g., Paget's disease of the bone.
- Acromegaly: Overgrowth of bones in the face, hands, and feet.
- Fibrous dysplasia: Abnormal growth or swelling of bone.
- Rickets: Growing bones fail to develop due to a lack of vitamin D.
- Multiple myeloma: Cancer of the plasma cells in bone marrow.