Medical Physics Chapter 3: Physics of the Skeleton

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Questions and Answers

What is the primary function of the vertebral column?

To protect the spinal cord (correct)

To store chemicals

To protect the internal reproductive organs

To provide a framework for the body

What is the process of producing blood cells in the red bone marrow?

Bone resorption

Osteoporosis

Hematopoiesis (correct)

Bone remodeling

What is the function of bones in locomotion?

To store chemicals

To act as levers to convert muscular contraction to movement (correct)

To provide a framework for the body

To serve as a point of attachment for ligaments and tendons

What is the function of the ossicles in the middle ear?

To transmit sound vibrations to the inner ear Signup and view all the answers

What is the frequency of replacing the entire skeleton?

Every 7 years Signup and view all the answers

What is the function of bones in supporting soft tissue?

To support soft tissue Signup and view all the answers

What is the role of bones in storing chemicals?

To release calcium when needed Signup and view all the answers

What percentage of the skeleton is recycled every week?

5-7% Signup and view all the answers

What is the function of the pelvic bones?

To protect the internal reproductive organs Signup and view all the answers

What is the main function of Osteoblasts?

Specialized in bone building Signup and view all the answers

What happens to the amount of Osteoblasts and Osteoclasts with age?

Osteoblasts decrease and Osteoclasts increase Signup and view all the answers

What is the percentage of collagen in the volume of solid bone?

40% Signup and view all the answers

What is Bone Mineral composed of?

Calcium hydroxyapatite Signup and view all the answers

What is the main component of compact bone by weight?

Bone Mineral Signup and view all the answers

What is the surface area of Bone Mineral?

4×10^5 m2 Signup and view all the answers

What is the name of the condition characterized by weak bones and spontaneous fractures?

Osteoporosis Signup and view all the answers

What percentage of calcium is present in bones?

2.22% Signup and view all the answers

What is the primary function of trabecular bone?

To absorb compressive forces in the spine and joints Signup and view all the answers

How many bones are there in the human body?

206 Signup and view all the answers

What is the advantage of trabecular bone over compact bone?

It is more flexible and can absorb more energy Signup and view all the answers

What is the primary component of compact bone?

Solid bone tissue Signup and view all the answers

What is the main reason X-rays show bones so well?

Because bones have a higher concentration of calcium Signup and view all the answers

What is the primary function of bones in the body?

To provide support and structure Signup and view all the answers

How are bones categorized according to their shape?

Into flat, long, cylindrical, irregular, and ribs Signup and view all the answers

What is the approximate density of bone in grams per cubic centimeter?

1.9 g/cm3 Signup and view all the answers

What is the strength of bone in compression compared to granite?

As strong as granite Signup and view all the answers

What happens to the density of bone as it becomes more porous with age?

It remains constant Signup and view all the answers

What is the ratio of stress to strain in the initial linear portion of bone deformation?

Young's modulus Y Signup and view all the answers

What is the approximate stress at which bone breaks?

120 N/mm2 Signup and view all the answers

What is the change in length of bone proportional to when it is placed under tension or compression?

The stress applied Signup and view all the answers

What is the purpose of the instrument used to measure the elongation of bone under tension?

To measure the strain of bone Signup and view all the answers

What is the unit of measurement for the cross-sectional area of the bone shaft in the example?

square centimeters Signup and view all the answers

Study Notes

Importance of Bones

Bones are crucial for the proper functioning of the body, which is why many medical specialists, such as dentists, orthopedic surgeons, rheumatologists, and radiologists, focus on this area.

Functions of Bones

Provide a framework for the body
Support soft tissue
Serve as a point of attachment for ligaments, tendons, fascia, and muscles
Enable locomotion by serving as levers to convert muscular contraction to movement
Protect vital organs such as the brain, eyes, ears, spinal cord, heart, and lungs
Act as a chemical "bank" for storing elements for future use by the body
Release calcium when it is needed
Facilitate nourishment through teeth
Enable sound transmission through ossicles in the middle ear
Produce blood cells through hematopoiesis in the red bone marrow

Bone Remodeling

A continuous process of destroying old bone and building new bone
The equivalent of a new skeleton is formed every 7 years
5-7% of the skeleton is recycled every week
Involves two types of cells: osteoblasts (bone building) and osteoclasts (bone destroying)
Osteoblasts predominate in young people, while osteoclasts predominate in older people, leading to a decrease in bone mass and an increased risk of osteoporosis

Composition of Bones

Consist of two main materials: collagen and bone mineral
Collagen is the major organic fraction, making up 40% of the weight and 60% of the volume of solid bone
Bone mineral is made up of calcium hydroxyapatite (Ca10(PO4)6(OH)2) and accounts for 60% of the weight and 40% of the volume of solid bone

Types of Bones

Classified into five categories based on shape: flat, long, cylindrical, irregular, and rib-like bones
Composed of one or a combination of different types of bones, including compact and cancellous bone
Cancellous bone is made up of thin thread-like trabecular bone

Mechanical Properties of Bone

Density: constant throughout life at about 1.9 g/cm3
Length: changes under tension or compression, with a stress limit of about 120 N/mm2
Young's modulus (Y) is the ratio of stress to strain in the initial linear portion of the stress-strain curve

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Description

This quiz covers the importance of bones, functions of bones, bone remodeling, types of bones, and mechanical properties of bone. It's a part of chapter three in Medical Physics course.