Review of Normal Histology PDF

Review of Normal Histology Prepared by: Princess Red Rose G. Rodriguez 1 Disciplines of Histo-pathology Histology (microscopic anatomy) involves all aspect of tissue biology , with the focus on how cells’ structure and arrangement optimize functions...

Review of Normal Histology Prepared by: Princess Red Rose G. Rodriguez 1 Disciplines of Histo-pathology Histology (microscopic anatomy) involves all aspect of tissue biology , with the focus on how cells’ structure and arrangement optimize functions specific to each organ Pathology study of the changes in the structure and functions in cells, tissues and organs during the disease process 2 Disciplines of Histo-pathology Histopathology combination of histology and pathology. Branch of pathology which deals with the study of disease in tissue section Histochemistry is the branch of science concerned with the identification and distribution of the chemical constituents of tissues by means of stains, indicators and microscopy Cytology science that deals with the study of the cell 3 Review of Normal Histology “I praise you because I am fearfully and wonderfully made; your works are wonderful, I know that full well.” Psalm 139:14 4 Normal Cell Structure 5  Powerhouse of the cell? Responsible for the maintenance of the shape of the cell and for the movement of the organelles and inclusions within the cell? Part of the cell that is involved in phagocytosis and pinocytosis? Involved in the synthesis, intracellular transport, and release of proteins? The center of all activities of the cell? Involved in the production of H2O2 or the destruction of H2O2 to water. Plays a major role in the synthesis of glycoproteins, “packaging” of secretory materials, transport and release of these secretory vessels into the cell? 6  The living substance that surrounds the nucleus? Also known as “suicide bags”. They are membrane-bound, dense- appearing structures that contain hydrolytic enzymes? They are active in the process of cell division and in the formation of cilia? Involved in the synthesis of ribosomes? 7 Epithelial Tissues 9 10 11 12 13 14 15 Connective Tissues 17 18 19 20 21 22 23 24 Muscle Tissues 25 26 27 28 Nervous tissue 30 Cellular Properties Respiration- taking in of oxygen and using this for oxidation of food substances with the resulting liberation of energy Excretion- the ability to eliminate waste materials Absorption & assimilation- the ability to absorb food and other substances and utilize them Secretion- the ability to synthesize useful substances from those that they absorb abd give off these secretory products 31 Cellular Properties Irritability- the property that enables a cell to respond to a stimulus Conductivity- the ability of a cell to transmit a wave of excitation throughout the substance of the cell Contractility- the ability of a cell, on being stimulated, to shorten and return to its original length when the stimulus is removed Cell division- the ability of a cell to grow to a limited extent and produce other cells 32 Cellular Adaptations Is a state which lies intermediate between the normal, unstressed cell and the overstressed, injured cell, which allows the cell to maintain an equilibrium between the environment and its metabolic activity Tissues and organs may appear smaller or larger than normal Four most important adaptive changes: Atrophy Hypertrophy Hyperplasia Metaplasia 33 Cellular Adaptations I. Retrogressive changes A. Developmental defects B. Atrophy II. Progressive Changes A. Hypertrophy B. Hyperplasia III. Degenerative Changes A. Metaplasia B. Dysplasia C. Anaplasia D. Neoplasia 34 I. Retrogressive changes Organs or tissues are small than normal which may be due to: A. Developmental defects- originating in the embryo and fetus that is, in the prenatal period B. Atrophy- acquired decrease in size of a body part, cell, organ, or other tissue 35 Retrogressive changes A. Developmental Defects 1. Aplasia (a= not/without; Gr. plassein/ plasia =form or development)- incomplete or defective development of a tissue or organ Ex: Acquired pure red cell aplasia, Aplasia cutis congenita, Radial aplasia, Germ cell aplasia, Thymic aplasia, Aplasia of the lung 2. Agenesia/Agenesis (a= not/without; genesis=origin/beggining)- complete non- appearance of an organ. Ex: Turner syndrome 3. Hypoplasia (hypo= under; Gr. plassein/ plasia =form or development)- failure of an organ to reach or achieve its full mature adult size due to incomplete development 4. Atresia (a= not/without; tresis= perforation/hole) (Clausura)- failure of an organ to form an opening 36 Retrogressive changes B. Atrophy a decrease in the size of a tissue or organ due to cellular shrinkage which decreases the cell size or reduction of number of cells Causes of atrophy: Decreased workload Loss of innervation Diminished blood supply Inadequate nutrition Loss of endocrine stimulation *stromal fatty infiltration- composed of connective and adipose tissues which replaced dead atrophic cells 37 Types of Atrophy 1. Physiologic atrophy Occurs as a natural consequence of maturation (e.g. atrophy of thymus and lymphoid tissues during puberty) Senile atrophy- occurs in old age 38 Types of Atrophy 2. Pathologic atrophy- refers to the decrease in the size of tissue or organs, outside the range of normal variability, usually as a consequence of disease a. Vascular atrophy (Due to lack of nutrition) occurs if the blood supply of an organ or tissue becomes reduced below critical level, commonly encountered in kidney and brain Example: Progressive ateriosclerosis b. Pressure atrophy Persistent pressure on the organ or tissue may directly injure the cells or may secondarily promote diminution of blood supply leading to vascular atrophy Examples: amyloids deposited on an organ, expanding benign tumor, pressure of a localized dilatation of an artery c. Starvation/ hunger atrophy Produces a general wasting of tissue due to lack of nutritional supply necessary for normal growth 39 Types of Atrophy 2. Pathologic atrophy d. Atrophy of disuse Inactivity or diminished function of a tissue or organ may lead to narrowing of the blood vessels with loss of nutrition and consequent atrophic changes e. Exhaustion atrophy Prolonged overwork, especially of an endocrine organ may produce initial enlargement with ultimate slow progressive loss of parenchymal elements due to excessive formation of acid metabolites with subsequent increase in catabolic enzymes f. Endocrine atrophy Diminished or absent endocrine stimulation may produce functional atrophy of organs which are mainly dependent on their endocrine supply for maintenance of their normal structure 40 II. Progressive Change Organs or tissues are larger than normal and may be due to: A. Hypertrophy- increase in size of tissues or organs due to an increase in size of the individual cells Hypertrophied organs have no new cells, just larger cells B. Hyperplasia- increase in the size of an organ or tissue due to an increase in the number of cells resulting from growth of new cells Not all adult cell types have the same capacity for hyperplastic growth such as nerve cells and skeletal muscle cells 41 A. Hypertrophy 1. True Hypertrophy Usually observed in the skeletal muscle, heart, kidneys, endocrine organs (breast, uterus) and smooth muscle of holly viscera (e.g., intestinal tract) due to increased workload and endocrine stimulation (e.g., during exercise and pregnancy) 2. False Hypertrophy Due to edema fluid and connective tissue proliferation (e.g., in cirrhosis and chronic hypertrophic salpingitis or appendicitis) 3. Compensatory Hypertrophy Involves one of paired organs when the other opposite organ has been removed or suffered from functional insufficiency 42 B. Hyperplasia 1. Physiologic hyperplasia a. Hormonal hyperplasia Best exemplified by the enlargement of the glandular epithelium of the female breast at puberty and during pregnancy and the physiologic hyperplasia of the pregnant uterus b. Compensatory hyperplasia Exemplified by the hyperplasia that occurs when a portion of the liver is removed (partial hepatectomy). A similar sequence occurs in the epidermis following skin abrasion, in which the cells of the basal layer undergo increased mitosis that results in regeneration of the superficial layers and restoration of the original skin 43 B. Hyperplasia 2. Pathologic hyperplasia Brought about by disease as observed in hyperplasia of lymphoid follicles and Payer’s patches of the intestines in typhoid fever 44 III. Degenerative Changes due to Aberration of Cellular Growth Patterns A. Metaplasia B. Dysplasia C. Anaplasia D. Neoplasia 45 A. Metaplasia Reversible change in which one adult cell type (epithelia or mesenchymal) is replaced by another adult cell type Example: squamous metaplasia which occurs in the respiratory tract in response to chronic irritation such as those seen in habitual cigarette smoker 46 B. Dysplasia Regressive alteration in adult cells manifested by variation in size, shape and orientation, associated with chronic inflammation and protracted irritation; usually applied to epithelial cells Removal of inflammation or irritation causes the reversion to the epithelium of normal flora Difference in metaplasia Metaplasia- the adult cell type changes towards another adult cell type Dysplasia- changes in structural component of the cell Both are still reversible 47 C. Anaplasia Dedifferentiation Regressive change in adult cells towards more primitive or embryonic cell types Usually utilized as a criterion toward malignancy *Anaplastic cells generally have hyperchromatic nuclei, prominent nucleoli, and a nucleus to cytoplasm size ratio that approaches 1:1- a characteristic of an embryonic or primitive cell type 48 D. Neoplasia Tumor The continuous abnormal proliferation of cells without control, serving no useful purpose or function Usually accompanied by increase in size and pigmentation, mitosis, number, metaplastic and anaplastic changes of the cells Pathologic overgrowth of the tissue 49 50