Introduction To Pathology

The study of pathology is fundamental in any good anatomy and physiology course but sadly many anatomy and physiology courses do not cover the subject in sufficient detail. A good therapist or exercise teacher needs to understand when it is and when it isn't safe to work with the public and their myriad of pathologies.

The body has many lines of defence:

The skin and mucous membranes and the various associated secretions
White blood cells – phagocytes and macrophages
Immune system esp. antibody production
Liver detoxification of pathogenic material

The body can respond to acute disease in several ways

• Inflammation
• Fever / Sweating
• Diarrhoea / Vomiting / Sneezing / Coughing
• Pain

INFLAMMATION

Reaction of a healthy body to tissue damage characterised by:

• Redness
• Swelling
• Heat
• Pain

If prolonged can lead to permanent tissue or organ changes

Sequence of events:

Entry of irritant stimulus
Release of histamine and other chemicals
Dilation of local blood vessels with consequently greatly increased blood flow
Increased permeability of the capillaries in the area allowing fluid to leak into the tissues
Migration of leucocytes (& later macrophages) through the leaky capillary walls into the tissues

FEVER

The body’s temperature is controlled by a “thermostat” located within the hypothalamus
Fever is an increase in the normal body temperature and nearly always follows a generalised infection of the blood stream

Sequence of events:

Invasion by pathogenic organism
Pathogenic organism produces pyrogens that affect the temp. control mechanism causing the “thermostat” to be set higher
This stimulates heat generating and heat conserving mechanisms of the body such as:

Shivering
Reduction of blood to surface

Rise in body temperature causes more blood flow through tissues and increase in phagocytic activity.  Body’s defences are mobilised
Temperature then reaches that set by hypothalamus and symptoms of chill recede
Thermostat setting returns to normal
Which stimulates body’s heat losing mechanisms such as:

Sweating
Flushed skin

REPAIR

Length of time for tissue damage to heal depends on several factors eg.

• Size of wound
• Innate repair mechanisms of that tissue
• Blood supply to / from the area
• Supply of certain nutrients
• Absence of localised infection

Sequence of events

Macrophages invade inflamed area and break down damaged/diseased tissue
Damaged arteries / capillaries are repaired
Fibroblasts lay down new tissue leading to scar tissue formation
Scar tissue fibres shorten leading to scar contraction

BLUEPRINT FOR DEVELOPMENT OF CHRONIC DISEASE

Causal factors

                  Includes:    Hereditary disposition

                                    Environmental hazards

                                    Physical/chemical damage

                                    Nutritional deficiencies

                                    Psychological stress

Leads to:

Secondary damage

                  (eg. to cell/liver/gut/endocrine/immune/excretory systems)

Disease environment and lowered resistance

Leads to:

Development of disease processes and pathology

Leads to:

Disease symptoms

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