Pathology & micro biology intro

It is the study of nature & cause of disease which involves changes in structure and function
The aspects of a disease process that form the core of pathology include:
its cause, the pathogenesis that is the sequence of events which give rise to the manifestations of the disease), and
the morphologic changes (structural alterations induced in cells & tissues by the disease

1. INTRODUCTION PATHOLOGY It is the study of nature & cause of disease which involves changes in structure and function The aspects of a disease process that form the core of pathology include: its cause, the pathogenesis that is the sequence of events which give rise to the manifestations of the disease), and t he morphologic changes (structural alterations induced in cells & tissues by the disease

2. What is Pathology? Pathology is the study of patterns, causes, mechanisms and effects of illness (disease) To interpret symptoms and signs it is important to know the range of abnormalities possible in an organ system Basis of differential diagnosis

3. Pathology clinical disciplines Histopathology Haematology Clinical chemistry Immunology Microbiology Genetics

4. Pathology - diagnostic tools Structural examination Fluid and tissue cytology Biopsy Autopsy

5. Pathology encompasses all aspects of disease Genetic function Physiological/ biochemical function Structural abnormalities Cells Tissues Organs

6. Aetiology The root cause of a disease process Genetic Environmental agent Immune Infective Neoplastic Primary inflammatory Vascular Iatrogenic

7. Pathogenesis The molecular, physiological and cellular mechanisms that occur after the first injury and which lead to the expression of a disease Understanding pathogenesis is important in choosing, or developing, an appropriate therapy

8. Natural history The course of a disease process Untreated Modified by therapy Prognosis* Disability Disease-free survival Survival * With its prefix  pro- , meaning "before",  prognosis  means basically "knowledge beforehand" of how a situation is likely to turn out.  Prognosis  was originally a strictly medical term, but it soon broadened to include predictions made by experts of all kinds. Thus, for example, economists are constantly offering prognoses (notice the irregular plural form) about where the economy is going, and climate scientists regularly  prognosticate  about how quickly the earth's atmosphere is warming. Diagnosis: the process of determining by examination the nature and circumstances of a diseased condition i.e. the decision reached from such examination. Abbreviation:  Dx .

9. Sequelae The clinical and pathological consequences of a disease process ( A  sequela  (UK: /sᵻˈ kwiːlə /, US: /sᵻˈ kwɛlə /; usually used in the plural,  sequelae ) is a pathological condition resulting from a disease, injury, therapy, or other trauma. Typically, a  sequela  is a chronic condition that is a complication which follows a more acute condition )

10. Studying Pathology This is a GOOD thing… Pathology enters all disciplines of medicine Pathology is the bedrock of good clinical medicine General Pathology Systems Pathology

11. Pathological Manifestations Adaptation of cells to environmental changes What happens to cells when they cannot adapt and how they die Disorders due to abnormal cell growth, for example cancer Tissue responses to injury and how tissues heal

12. Atheroma * and disease of blood vessels Thrombosis and infarction Tumour pathology Classification and nomenclature Behaviour and diagnosis Causation and cell biology Revision genetics * Atheroma :degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue, and leading to restriction of the circulation and a risk of thrombosis . As well, the fatty material which forms deposits in the arteries.

13. Systems pathology continues through the whole of the clinical course Pathology tutorial system with guided reading Probably 40% of the content of all examinations in clinical course consist of Pathology

14. It is defined as a variety of stresses a cell encounters as a result of change in its internal and external environment

15. Flow chart (last page) depicts apoptotic and necrotic beta cell death cascades along with possible modes of intervention. Causes/agents of beta cell death are indicated in red while agents/strategies for prevention of beta cell damage are indicated in blue. Red arrows stand for possible sites of intervention. IL-11 : Interleukin 11, IKK : Inhibitor of kappa kinase , iNOS : inducible nitric oxide synthase , NO , Nitric oxide, STZ : Streptozotocin , ROS : Reactive oxygen species, PARP : Poly (ADP-Ribose) Polymerase, CAT : Catalase : SOD , superoxide dismutase; GSH : glutathione peroxidase , NF- kB : Nuclear Factor kappa B. Mechanisms of (islet) cell death .

16. Definition: If the limits of adaptive responses are exceeded or if cells are exposed to injurious agents or stress, deprived of essential nutrients, or become compromised by mutations that affect essential cellular constituents, a sequence of events follows that is termed  cell injury . Cell injury

17. Overview of Cell Injury • Cells actively control the composition of their immediate environment and intracellular milieu within a narrow range of physiological parameters (“homeostasis ”) • Under physiological stresses or pathological stimuli (“injury”), cells can undergo adaptation to achieve a new steady state that would be compatible with their viability in the new environment. • If the injury is too severe (“irreversible injury”), the affected cells die.

18. Causes of Cell Injury Hypoxia and ischemia Chemical” agents “Physical” agents Infections Immunological reactions Genetic defects Nutritional defects Aging

19. Apoptosis A natural process of self- destruction by  degradative  enzymes in certain cells, such as  epithelial cells and erythrocytes, that are  genetically  programmed to have a limited lifespan or  are damaged, as by irradiation or toxic drugs.  Also called programmed cell death .

20. Necrosis Pathologic death of one or more cells, or of a portion of tissue or  organ, resulting from irreversible damage; earliest irreversible  changes are mitochondrial, consisting of swelling and granular  calcium deposits seen by electron microscopy; most frequent  visible alterations are nuclear:  pyknosis , shrunken and abnormally  dark basophilic staining; karyolysis , swollen and abnormally pale  basophilic staining; or  karyorrhexis , rupture, and fragmentation of  the nucleus. After such changes, the outlines of individual cells are indistinct &  affected cells may merge, sometimes forming focus of  coarsely granular, amorphous, or hyaline material.

21. Necrosis – phenomenon continued ( referred as Death of some or all cells in an organ or tissue).  The process involves swelling of the nucleus ( pyknosis ),  fragmentation of nucleus ( karyorrhexis ) and complete dissolution of the  nuclear chromatin ( karyolysis ). Necrosis is caused by disease,  Trauma*  or interference with blood supply. There are many  sequelae  to ocular necrosis (e.g. inflammation, reduction in aqueous  humour  production following  ciliary   epithelium necrosis, corneal opacity following necrosis of corneal epithelial cells, and visual loss and floaters following  retinal necrosis). *Trauma  is often the result of an overwhelming amount of stress that exceeds one's ability to cope, or integrate the emotions involved with that experience.

22. Types Of Necrosis There are six types of Necrosis : Coagulative necrosis Liquefactive necrosis Caseous necrosis Fat necrosis Fibroid necrosis Gangrenous necrosis The type of necrosis can often be categorized based on how the cells look after death. Sometimes the entire cell loses its structure, and sometimes the outer architecture remains the same and only the inside is affected. 

23. More Common Types Aseptic necrosis necrosis  without infection or inflammation. Caseous  necrosis  in which the tissue is soft, dry and cheesy, occurring typically in tuberculosis. Central necrosis  affecting the central portion of an affected bone, cell or lobule of the liver. cheesy necrosis  in which the tissue resembles cottage cheese; most often seen in tuberculosis. coagulation  necros isdeath  of cells, the  protoplasm  of the cells becoming fixed and opaque by coagulation of the protein elements, the cellular outline persisting for a long time. colliquative  necrosis see  liquefactive  necrosis (below). liquefactive  necrosis  when necrotic material becomes softened and liquefied. moist necrosis here the dead tissue is wet and soft. Zenker's  necrosis wherein occurs the hyaline degeneration and necrosis of striated muscle; also called  Zenker's   degeneration.

24. Apoptosis & Necrosis In General, there are two steps that occur when a cell dies: Proteins inside the cell break down The body releases enzymes that digest these dead cells The apoptosis process is a natural part of the cell's life cycle, and the body is ready to carry the dead cell materials away. In necrosis, however, the body isn't prepared to remove the dead cells, and as a result, causes an inflammatory response. Cells need blood to live, and any interruption to blood flow results in necrosis. Injury, infection, disease, toxins, and many other factors can block blood from getting to a cell and cause unnatural death. Sometimes a dead cell releases chemicals that can affect the nearby cells, spreading necrosis to wide areas in a condition called  gangrene , which occurs when tissues in certain areas, usually the hands and feet, die. Again, a dead cell can't turn back into a living one, so the only cure for gangrene is to amputate the area. Sub cellular Responses: Autophagy is a common phenomenon involved in the removal of damaged organelles during cell  injury  and the cellular remodeling of differentiation, and it is particularly pronounced in cells undergoing atrophy induced by nutrient deprivation or hormonal involution.