PATHOPHYSIOLOGY

PATHOPHYSIOLOGY w DEFINED Involves the study of function that results from disease processes.

PATHOPHYSIOLOGY w What is pathology?

PATHOPHYSIOLOGY w Pathology is the branch of medical sciences that treats the essential nature of disease, especially the changes of structure and function in tissues and organs of the body that cause or are caused by disease.

PATHOPHYSIOLOGY w Why is pathophysiology studied?

PATHOPHYSIOLOGY w In the clinical setting, pathologists, histotechnologists, and cytotechnologist study tissues and cells to establish the cause of a disease. w Physicians use that information to form a treatment plan.

PATHOPHYSIOLOGY w What is a pathologist?

PATHOPHYSIOLOGY w A pathologist is a physician who is specifically trained and experienced in anatomical and physiological pathology.

PATHOPHYSIOLOGY w What is a histologic technician or histotechnologist?

PATHOPHYSIOLOGY w Histologic technicians and Histotechnologists prepare slides of body tissue for microscopic examination. w Career opportunities for both are excellent in hospitals, research institutions, industrial labs, and government agencies w A technician requires a 12-month, hospital-based on-the-job training program or an AAS degree. w A histotechnologist requires a BS degree and one year of additional laboratory experience.

PATHOPHYSIOLOGY w What type of studies are performed in the clinical pathology laboratory?

PATHOPHYSIOLOGY w Tissue of all types are sent to the histology department for studies into the disease process. Any exam done by a microscope is called a microscopic exam.

PATHOPHYSIOLOGY w The pathologist studies the tissue by doing a gross examination. Any exam done with the naked eye is a called a gross examination.

PATHOPHYSIOLOGY w Tissues are looked at closely and all observations are recorded.

PATHOPHYSIOLOGY w The tissue is then prepared for microscopic studies by placing it in a tissue cassette.

PATHOPHYSIOLOGY w The histotechnologist prepares the tissue for microscopic examination. This is done by using the embedding center. The tissue is placed in paraffin wax in order to cut thin slices of the tissue.

PATHOPHYSIOLOGY w The embedding center instrument

PATHOPHYSIOLOGY w The histotechnologist pours paraffin wax over a tissue specimen.

PATHOPHYSIOLOGY w Once the tissue is embedded in paraffin, the block of wax is cooled. The histotechnologist then cuts ribbon-like sections for placement on slides. The instrument used is called a microtome.

PATHOPHYSIOLOGY w A water bath is used for spreading the paraffin ribbons and sections are placed on microscope slides to be stained.

PATHOPHYSIOLOGY w Tissues are stained at the staining center. The basic stain for all tissues is the Hemotoxylin and Eosin (counterstain) stain. Blue Pink

PATHOPHYSIOLOGY w Special stains are used for particular details. They include: AFB-Acid Fast Bacilli Stain PAS-Periodic Acid Schiff Stain Trichrome Stain Iron Stain

Acid Fast Bacilli Stain (AFB) w Type of bacteria that resists decolorizing by acids during staining Ex: -Mycobacteria, tuberculosis, leprae, some parasites

Periodic Acid Schiff Stain (PAS) w Used to identify glycogen in tissue; oxidizes the glucose residues and creates aldehydes that react with schiff reagant and creates a purple color For glucose storage diseases: Pagets disease Paget's disease is a chronic condition of bone characterized by disorder of the normal bone remodeling process.

Trichrome Stain w 3 color staining process used to distinguish cells from connective tissues Red= keratin and muscle fibers Blue/green= collagen and bone Light red or pink= cytoplasm Dark brown to black= cell nuclei

Trichrome stained liver showing fibrous tissue. The fibrous tissue is stained blue while the cytoplasm of hepatocytes are stained red. The nuclei can be seen as dark red to black structures within cells; Collagen is the fibrous tissue are stained Blue (with aniline blue) or very light green (by aniline light green).

Trichrome stain showing cirrhotic liver. As it is evident, the normal architecture of the liver is destroyed in this disease and the liver shows nodules surrounded by fibrous bands. 

PATHOPHYSIOLOGY w The pathologist then studies the slide to determine pathological states within the tissues. A written report is then given to physician to aid him/her in the diagnosis and treatment of the patient.

PATHOPHYSIOLOGY w Pathologists also perform frozen sections for patient’s in surgery on the Cryostat.

PATHOPHYSIOLOGY w Exciting opportunities await students who want to explore the physiology of the tissues and cells under the microscope!