The Nature of Disease

1. The Nature of Disease

2. Definitions • Physiology • Function of the Body in the healthy state • Pathology = From the Greek for Pathos meaning Disease • Deals with the study of the structural and functional changes in cells, tissues and organs of the body that cause or are caused by disease • Pathophysiology • Focuses on the mechanisms of the underlying disease and provides the background for preventive as well as therapeutic health care measures and practices

3. The Nature of Disease • Disease = an unhealthy state caused by the effect of injury • Acute Disease = arises rapidly, lasts a short time • Chronic Disease = usually begins slowly • Has signs and symptoms • Persists for a long time • Can’t be cured by medication

4. Sign versus Symptom • Symptom • A subjective complaint that is noted by the person with a disorder • Sign • A manifestation that is noted by an observer • Syndrome • A collection of clinical signs, symptoms and data

5. Etiology • The causeor set of causesof a disease or condition.

6. Etiologic Factors • Biological Agents • Bacteria, viruses • Physical Forces • Trauma, burns, radiation • Chemical Agents • Poisons, alcohol • Nutritional Excesses of Deficits • Most diseases are multi-factorial in origins • Risk Factors • For example, heart disease or cancer

7. Idiopathic versus Iatrogenic • Idiopathic • If etiology is unknown the disease is said to be idiopathic • Iatrogenic • If the disease is a byproduct of medical diagnosis or treatment • Iatros = for physician

8. Diagnosis versus Differential • Diagnosis • The designation as the the nature or cause of a health problem • Requires history and physical examination • Differential Diagnosis • A systematic method used to identify unknowns. This method, essentially a process of elimination

9. Diagnosis • Normality • An important factor when interpreting diagnostic test results is the determination of whether they are normal or abnormal • Within normal Range • Reliability • The extent to which an observation is repeatable • Validity • The extent to which a measurement tool measures what is intended to measure

10. Diagnosis • Sensitivity • The proportion of people with a disease who are positive for that disease on a given test or observation (e.g.,Patient is 99% positive for the disease) • Specificity • The proportion of people without the disease who are negative on a given test or observation • 95% accurate v. 100%

11. Prevalence on Tests • Prevalence • The number of persons who have the disease at any given time • Incidence • The number of new cases per year

12. Mortality versus Morbidity • Mortality • Death statistics • Morbidity • The effects of an illness has on a person’s life • Concerned not only with the occurrence and incidence of the diseases but also the long-term impact of the disease

13. Prognosis Prognosis is the probable outcome and prospect of recovery from a disease

14. Levels of Prevention • Primary • Keeping disease from occurring by removing risk factors • Secondary • Detect disease early when it is still asymptomatic • Pap smears • Tertiary • Clinical interventions that prevent further deterioration or reduces the complication of a disease once it is diagnosed