BIO107 A&P I: Bone Remodeling, Fracture Repair, and Disorders (Chapter 6.6–6.8) (Lecture 9)

What is bone remodeling?

The process of replacing bone tissue every 10 years.

What are the two main processes involved in bone remodeling?

Bone resorption and bone deposit.

What is the role of osteoclasts in bone remodeling?

Osteoclasts resorb bone by secreting H+ and digestive enzymes.

How do osteoblasts contribute to bone remodeling?

Osteoblasts deposit new bone by secreting osteoid and enzymes that remove phosphates.

What is Wolff's Law?

The extent of bone remodeling depends on the mechanical demands placed on the bone.

What hormone is primarily involved in maintaining blood calcium homeostasis?

Parathyroid hormone.

What are the consequences of hypocalcemia?

Neurons become hyperexcitable, leading to arrhythmias and muscle cramps.

What are the consequences of hypercalcemia?

Neurons and muscles become non-responsive, leading to kidney stones and calcium deposits.

How are bone fractures classified by position?

Nondisplaced and displaced fractures.

What are the two types of complete fractures?

Complete and incomplete fractures.

What distinguishes a simple fracture from a compound fracture?

A simple (closed) fracture does not penetrate the skin, while a compound (open) fracture does.

What is the first stage of bone fracture repair?

Hematoma formation.

What occurs during fibrocartilaginous callus formation?

New blood vessels grow into the hematoma, and fibroblasts and chondrocytes create a soft callus.

What is the role of osteoblasts during bony callus formation?

Osteoblasts invade and direct the formation of spongy bone within the fibrocartilaginous callus.

How long does it typically take for a simple fracture to remodel?

About 6-8 weeks.

What causes osteomalacia?

Vitamin D deficiency in adults, leading to poor bone mineralization.

What is rickets?

A condition in children caused by vitamin D deficiency, resulting in severe skeletal abnormalities.

What characterizes osteoporosis?

Bone resorption outpaces bone deposit, leading to porous and brittle bones.

What are common risk factors for osteoporosis?

Insufficient exercise, poor diet in calcium or vitamin D, chronic tobacco and alcohol use.

What is Paget's disease?

A condition characterized by haphazard bone deposit and resorption, leading to irregular bone structure.

What is the significance of the medullary cavity in long bones?

It does not reduce the ability of long bones to withstand compression and tension.

What are the steps in the repair of a simple bone fracture?

1. Hematoma formation 2. Fibrocartilaginous callus formation 3. Bony callus formation 4. Bone remodeling.

Why is it important for reduction to occur soon after a fracture?

To ensure proper alignment and healing of the bone.

How does Paget's disease differ from other bone diseases?

It involves irregular bone deposits and reduced osteoclast activity, leading to abnormal bone structure.