PathologyConcepts of Health and Disease

Health and Society Prehistoric Times

◦ Angry god or evil spirits caused illness◦ The gods needed to be pacified to obtain a cure◦ Evil spirits driven out

Communities helped to secure health of its members◦ Health practices were based on belief systems

Modern Western Thinking◦ Originating with the Greeks

No supernatural powers affecting health

Health and Society Western Beliefs

◦ Everything that can be known can be found through studying and observing science

◦ Cortez conquering the Aztecs changed a culture’s belief in polytheism to monotheism

Diseases were thought to have been caused by emotional turmoil or grief (nervous condition)◦ Certain illnesses had a stigma attached

Leprosy, AIDS

Hippocrates◦460-377BC◦The foundation of cl inical principles and ethics for modern medicine

◦Four Humors Blood (red) from the heart = sanguine

Yel low bi le from the l iver = choleric Black bi le from the spleen = melanchol ic

Phlegm from the brain = phlegmatic

Early Scholars

384-322BC Dissection of small

animals Heart was the most

important organ◦ Center of the body ◦ Seat of emotions

Aristotle

Galen 129-199AD Physician to the Emperor of Rome

Continued to do more dissections

Started experimentations on live animals◦ Severed a pig’s spinal cord to cause paralysis

The body carried 3 kinds of blood

◦ Natural spirit from the liver◦ Vital spirit from the lungs◦ Animal spirit from the nerves

His work was considered infallible for 1400 years

Professor of Anatomy from Padua, Italy

1514-1564 Dissection of

Humans (considered horrible!)

Made much more accurate drawings and diagrams

Andreas Vesalius

1578-1657 English physician

and physiologist Established blood

circulates in a closed system impelled by a pump-like heart

William Harvey

Anton van Leeuwenhoek

1632-1723Refined the microscope lens

Robert Hooke Published Micrographia

◦ Described the plant cells in cork◦ First to describe what a cell was

Antoine Lavoisier

1743-1794 Was actually a lawyer but devoted his life to

scientific pursuits He studied Chemistry

◦ Came up with new ideas that allowed for the beginning of Biochemistry

He was beheaded during the French Revolution.

Edward Jenner

1749-1823 Conducted the first vaccination of

cowpox on a jerseymaid◦ Saved a child’s life with smallpox

1827-1912Concluded that

microbes caused wound infections

Used Carbolic acid on wounds to kill microbes

Listerine

Joseph Lister

1820-1910 Leading proponent of

sanitation Crimean War with

Napoleon◦ Had 38 nurses with her to

treat 2000 wounded and sick soldiers

◦ She and her nurses cleaned up the hospital tents

◦ Used hygiene on the soldiers and

◦ Slashed the death rate of soldiers from from 40% to 2%!!!!!!

Florence Nightingale

1822-1895 First real

Bacteriologist Studied fermentation

processes◦ Learned how to prevent

the souring of wine◦ “Pasteurization”

Dispelled the idea the “Miasma” or fumes was the cause of diseases

Louis Pasteur

Robert Koch

1843-1910 Claimed microorganisms are the cause of illnesses

Identified the organism for tuberculosis◦Discovered TB skin testing method

1845-1923 Discovered X rays

Wilhelm Rontgen

1845-1915 Bacteriologist

◦ “magic bullets” could attack diseases and leave the rest of the body undamaged

He used arsenic compound (Salvarsan) as a weapon again syphilis

Paul Ehrlich

Sir Alexander Fleming

1881-1955 In 1928 he studied the relationship between

bacteria and the mold Penicillium ◦ Penicillium had the ability to kill Staphylocci

Not until 1940 were researchers able to use the microorganism as an antibiotic Penicillin

Sir Frederick Banting and Charles Best

1921 Discovered Insulin

◦ Isolated insulin from the pancreas of a dog 1922

◦ Successfully treated a little boy with diabetes

1914-1995 Vaccine for

Poliomyelitis ◦Used inactivated

virus vs the vaccine already in use with activated virus

Jonas Salk

Watson and Crick DNA structure

DNA Molecule

Pathophysology 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

Physiology◦ Function of the Body in the healthy state

Pathophysiology◦ Focuses on the mechanisms of the underlying

disease and provides the background for preventive as well as therapeutic health care measures and practices

Disease Any deviation from or interruption of the

normal structure or function of a part, organ, or system of the body that is manifested by a characteristic set of symptoms or signs

Etiology The causes of disease = etiologic factors

◦ Biological Agents Bacteria, viruses

◦ Physical Forces Trauma, burns, radiation

◦ Chemical Agents Poisons, alcohol

◦ Nutritional Excesses of Deficits Most diseases are multifactorial in origins

◦ Risk Factors For example, heart disease or cancer

Pathogenesis The sequence of cellular and tissue events

that takes place from the time of initial contact with an etiologic agent until the ultimate expression of a disease.

Morphology Fundamental structure or form of cells or

tissues◦ Histology

Clinical Manifestations Signs v. Symptoms

Symptom◦ A subjective complaint that is noted by the person

with a disorder Sign

◦ A manifestation that is noted by an observer

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

Diagnosis

Normality◦ An important factor when interpreting diagnostic test results is the

determination of whether they are normal or abnormal

Reliability◦ The extent to which an observation is repeatable

Validity◦ The extent to which a measurement tool measures what is intended to

measure

Sensitivity◦ The proportion of people with a disease who are positive for that disease

on a given test or observation

Specificity◦ The proportion of people without the disease who are negative on a

given test or observation 95% accurate v. 100%

Morbidity and Mortality 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

Risk Factors

Conditions suspected of contributing to the development of a disease

Studies to determine risk factors◦ Cross-sectional studies

Simultaneous collection of information for classification of exposure and outcome

◦ Case-control studies Compares persons known to have the outcome of

interest and those known not to have the outcome of interest

◦ Cohort studies Group of persons who were born at approximately the

same time or share some characteristics of interest◦ Longitudinal studies

A cohort is studies over a period of time

Framingham Study Framingham Massachusetts

◦ In 1948, the Framingham Heart Study embarked on an ambitious project in health research to identify the common factors that contribute to cardiovascular disease by following its development over a long period of time in a large group of participants.

5000 people between 30 and 59 years of age

Followed for 20 years Looking at coronary artery disease

Prognosis Probable outcome and prospect of recovery

from a disease

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