Physiology, Drugs and Disease

Lecture 2The skeleton

FDSc FISM year 2 Janis Leach

Understand the main functions of bone Define the four classifications of bones and

features of a long bone. Identify the microscopic structures of compact

bone. Describe the process of bone growth. Define the different types of fractures and

describe the healing process. Define osteoporosis and identify risk factors. Research arthritis and bone disease

Objectives

Assessment ICA Group presentation lasting 15 minutes in Week 20.

The content of the presentation will link factors involved in physiology, disease and drugs. The module title lends itself to opportunities for an even distribution of group work and allows students to experience the coordination of group work and individual research that contributes to the group presentation. The nature of the course makes communication of information to an audience a vital element in the practitioner’s skills. The ability to work as part of a team in a professional context is also implied. ICA 30% Group Presentation.

Assessment ECA A written examination in Week 30. This

paper will consist of 6 essays covering key aspects of the module, specifically function of the body systems, common drugs in sport and exercise and relevant common diseases. END 70% Written exam.

Introduction

Bone despite its appearance is a dynamic living tissue. Without bone and associated soft tissue such as cartilage, ligaments and tendons we would be immobile lumps of tissue.

Introduction

Think about the functions of the skeleton

Discuss them with a partner

Write them down to explain to the rest of the group.

Function

Support Bones provide a rigid internal framework for support

and anchorage of soft tissues

Protection Bones protect soft organs of the body e.g. the bones of

the skull protect the brain, the vertebrae protect the spinal cord, and the ribs and sternum protect the vital organs of the thorax

Movement Attached to the bones by tendons, skeletal muscles use

the bones as levers to move the body and its parts. Without this contribution to movement we would be immobile lumps of tissue.

Function

Storage Bone serves as a storehouse for minerals (calcium and

phosphorous, potassium, sulphur, sodium, magnesium and copper) which can be mobilised to other parts of the body as required. Fat is also stored in bone in the marrow cavity.

Red blood cell formation Formation of red blood cells occurs in the bone

marrow of certain bones

Classification The adult skeleton is comprised of 206 bones, with many

shapes and sizes. Classification reflects the shape not the size of bones. The unique shape of each bone has evolved so it fulfils a particular function.

Bones are classified by shape into five groups: Long - longer than they are wide Short - more-or-less cube shaped Flat - thin, flattened and usually curved Irregular - bones that do not fit into the above categories Sesamoid - bones embedded in tendon (floating)

Structure of a typical long bone

With a few general exceptions, all long bones have the same general structure:

The diaphysis or shaft The epiphyses (bone ends)

with articular cartilage Medullary cavity or

marrow cavity containing fat in adults

epiphysis

diaphysis

epiphysis

articularcartilage

Compact bone Structural unit is called

an osteon. Functionally osteons are similar to tiny weight bearing pillars.

An osteon consists of hollow tubes of bone matrix called lamellae.

Central canals run through each osteon. The canals contain small blood vessels and nerves.

lamellae osteonblood vessel

spongy bone

Compact bone

Compact bone

Spider shaped osteocytes (mature bone cells) occupy small cavities called lacunae.

Although the bone matrix is hard, small canals called canaliculi allow bone cells to be well nourished.

The canaliculi connect all osteocytes in an osteon together.

Central canal

canaliculi lacuna

osteocyte

Cancellous bone (spongy) Cancellous bone consists of trabeculae (meshwork) that are

aligned along lines of stress. Although the arrangement of trabeculae appears haphazard,

the structure of the bone enables it absorb considerable stress.

spongy bone

compact bone

Bone Growth In early foetal life the skeleton is primarily made of

hyaline cartilage. By birth or shortly after, most cartilage has ossified except

for two regions - the articular cartilage and the epiphyseal (growth) plates.

The growth plate between the diaphysis (shaft) and epiphysis (ends of the bones) are sites of growth in the length of long bones - this allows growth to proceed without interfering with the shape of joints.

At the end of the growth period, the cartilaginous plates ossify (end of teenage years). Some growth continues into the early twenties - widening of the shoulder and pelvic girdles.

Fractures There are many different types of fractures. Below,

identify the three types of fractures in the diagram

A. What type of fracture is this?

B. What type of fracture is this?

C. What type of fracture is this?

Fracture repair The figures below illustrates the four major events of the

repair of bones:Blood vessels are ruptured when the bone breaks. As a result, a mass of clotted blood called a____________

Within 2-3 days new capillaries grow into the hematoma and phagocytes clean up the debris. Over time connective tissue cells form a mass of repair tissue called the ___________________

forms. Bones cells deprived of nutrition die.

hematoma

fibrocartilaginous callus,which splints the broken ends of the bone

Fracture repair

Osteoblasts invade the area and the fibrocartilage is transformed into a __________

This process continues until the bone is united completely a few months later. The bone is gradually remodelled to resemble the original shape and alignment.

bony callus within 3-4 weeks.

Healedfracture

Pathology Osteoporosis is a deficiency of bone resulting

from an imbalance in the rate of remodelling, where osteoclast activity is higher than osteoblast activity.

Consequently, compact bone and spongy bone becomes thinner and more porous - the density of the bone reduces.

The bone becomes fragile and can increase the risk of fractures occurring, especially in weight bearing structures such as the fractured heads and the vertebrae. GroupsGroups

at high at high riskrisk

Risk Risk factorsfactors

Exercise/biomechanicalExercise/biomechanical stressstressNutritioNutritionnSteroidSteroid useuse

Woman of all ages?Woman of all ages?

Osteoporosis

Arthritis

Osteoarthritis

Osteoarthritis Most common type in UK Estimated 8.5 million people affected Any joint can be affected Causes cartilage damage – therefore affects

smooth joint movement Research risk factors

Rheumatoid arthritis Rheumatoid Arthritis (RA) is a chronic,

progressive and disabling auto-immune disease which affects approximately 8% of the UK adult population (NRAS, 2008)

Systemic disease – can affect the whole body Unknown causes

Genetic? Environmental

Independent study TASK

In groups of 3, you will research a given topic on bone disorders. Include the following in your research Genetic aspects Steroid use and bone disease Environment Repetitive strain.