Intro To Pathology Flashcards
What is pathology?
The study of diseases: causes, diagnosis, effects on the body
What is “disease?”
Any harmful deviation from the normal structural or functional state of an organism, generally associated with certain signs and symptoms and differing in nature from physical injury
Simple definition: occurs when there is a disruption of loss of “normal”
Types of pathology
Anatomical: study disease by looking at tissues and organs (think necropsies, biopsies)
Clinical: assess disease by study body fluids (blood, urine, joint fluids)
Microbiologist
Study infectious organisms( bacteria, virus, fungus)
Parasitologist
Study parasites
Immunologist
Study antibodies and antigens (proteins on the surface of organisms)
Toxicologist
Study toxins/poisons
Hematologist
Study blood
Veterinary nurse responsibilities
Must be familiar with:
-Types of analytic instruments available
-Testing procedures used (in house vs send out testing)
-Proper sample collection, handling, and sometimes interpretation of
-The need for and the knowledge of “normal”
Etiology
The study of the cause of disease
Pathogenesis
Formation of beginning of a disease
Pathogen
An infectious agent capable of causing a disease
Knowledge of etiology remains the basis of:
-Diagnosis of disease
-understanding the nature of disease
- treatment of the disease
Etiology agents
Factors capable of causing disease or tissue damage
Internal etiologic factors
Genetic: defects, mutations
Immune response: abnormal response
Aging: natural or premature
External etiologic factors
Physical: trauma
Chemical: toxins
Infectious: bacteria, parasites
Environment: nutrition, temperature, husbandry, radiation
Cause of disease; Pathogens VS Nonpathogens
Pathogens: infectious organisms that have the potential to cause a disease (bacteria, viruses, fungi, parasites)
Non-pathogens: Disease caused by trauma (mechanical, sonic, thermal, electrical, temperature radiation, would or injury.)
Classifications of diseases
-Acquired
-Congenital
-Idiopathic
Classifications of disease: Acquired
Develop as a result of the effects of one or more etiologic agents.
(pneumonia, dermatitis)
Classifications of disease: congenital
The animal is born with-
•Etiological agent acts on the developing embryo or fetus, on the uterus or placenta, or on the mother (before or during pregnancy)
•Clinical signs may not be seen at birth
•Developmental abnormalities – heart defects, orthopedic defects
Classifications of disease: Idiopathic
Diseases of which we do not (yet) know the cause
Factors that influence the course of the disease
Age
Immune system
Drugs
Genetics
Environment
Secondary diseases
Cellular injury: response to harmful stimuli
Degeneration
Necrosis
Changes
Degeneration
Pathological condition that causes cells to change in structure and function. Injury is mainly the cytoplasm of the cell, these lesions of reversible when the pathological stimuli are reduced or eliminated
Necrosis
Cellular death irreversible
Changes
Cell growth, size +/- numbers
Reversible
Irreversible
Types of cellular degeneration
-Accumulation of cellular component;
As cells age, old and non-functional organelles may shrivel up or
be broken down
Their constituents remain in the cytoplasm
-Hydropic change;
Damage to cell membranes cells swell with fluid
-Fatty change;
Lipids accumulate in cells because of increased or long-term fat
breakdown in the body
Or because the ability of cells to metabolize normal amounts of fat
is decreased by cell damage
Cellular death: necrosis
Death of cels or tissues in a living animals
Common causes: decreased blood supply,
Pressure, burns, trauma, poisons and toxins, infectious agents
Types of necrosis
Coagulative
Liquefactive
Caseation
Fat
Gangrene
Types of necrosis: coagulative
MOST COMMON
●Occurs due to loss of blood supply to an area
●Occurs in “solid” organs (e.g. kidney, heart)
●Dead cells retain their outline but are pale and ghost-like (look cooked)
●After a period of time, inflammatory cells move in to remove the dead cells
Types of necrosis: Liquefactive
Areas of necrosis become liquified by powerful enzymes which degrade dead cells and surrounding tissues
●Characteristic to the brain
Interruption of the blood supply or bacterial infection (meningitis)
Types of necrosis: Caseation
●Dead tissue is converted to a cheesy texture
●Usually associated with chronic bacterial infections (tuberculosis)
Types of necrosis: Fat
Occurs after inflammation in/around fatty tissue, due to enzymes which degrade fat cells
●The fat becomes hard and nodular
●Seen after pancreatitis, when pancreatic enzymes leak into the abdomen
Types of necrosis: Gangrene
Bacteria usually involved, affected part is cold to the touch
4 Types
1. Dry- No bacteria (cold, shriveled, discolored)
2. Gas- gas producing bacteria (crepitus)
3. Moist- pus producing bacteria (rotten, foul smelling)
4. Wet- bacteria w/inflammation of surrounding tissue (cellulitis
Body’s response to infection or injury
Fever
Inflammation
Fever
Pyrexia- the bodies response to pyrogens; activates phagocytes and causes iron to be removed from the blood
Inflammation
5 signs-
Heat
Swelling
Pain
Redness
Loss of function
Tissue repair: regeneration
replacement of cells by the same type of
Tissue repair: organization
Replacement by fibrovascular connective tissue (scar tissue)
Tissue healing: first intention
Edges of wounds close together
No scaring
Bandages, Sutures, skin tape
Tissue healing: second intention
Greater tissue damage
Granulation tissues (connective tissues)
Fibrosis/scar tissue- contracts long process
