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 Sign Syndrome
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 cause or set of causes of 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
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
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 is 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
Not always accurate or appropriate
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 Incidence
The number of persons who have the disease at any given time
Incidence
The number of new cases per year

12. Mortality versus Morbidity
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 Secondary Tertiary
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