Cellular Adaptation Lecture Notes PDF

 CELL INJURY AND CELLULAR ADAPTATIONS Cellular responses to stress & injurious Normal stimuli cell (homeostasis) Altered physiologic stimuli Injurious stimuli like reduced and non lethal in...

 CELL INJURY AND CELLULAR ADAPTATIONS Cellular responses to stress & injurious Normal stimuli cell (homeostasis) Altered physiologic stimuli Injurious stimuli like reduced and non lethal injurious oxygen supply, chemical injury stimuli and microbial infection CELL INJURY CELL ADAPTATIONS Acute and Progressive and HYPERPLASIA transient severe IRREVERSIBLE CELL HYPERTROPHY REVERSIBLE CELL INJURY ATROPHY INJURY CELL DEATH METAPLASIA DYSPLASIA Necrosis and apoptosis Causes of cell injury Oxygen Deprivation (Hypoxia) Physical Agents (e.g. temperature, trauma, pressure) Chemical Agents and Drugs. Infectious Agents. Immunologic Reactions (e.g. Autoimmune diseases Genetic Derangements (e.g. Chromosomal abnormalities) Nutritional Imbalances (decreased or increased )  Adaptation of the cells It is a state lies intermediate between the normal cell and the injured cell. Adaptations are reversible changes in the cell which can be physiologic (normal stimulation by hormones or mediators) or pathological (stress changes structure & function). It includes: - Hyperplasia. - Hypertrophy. - Atrophy. - Metaplasia. - Dysplasia. Hyperplasia: In Greek “ Huper” means – “Over” and “Plasia” means – “Formation Hyperplasia is an increase in the number of cells but there is no change in the size of tissue. Hyperplasia takes place in cells, which are capable of synthesizing DNA. Hyperplasia can be: a) Physiologic- 2 types 1-Hormonal- Examples are- female breast at puberty, pregnancy and pregnant uterus. 2-Compensatory- E. g.- regeneration of liver. b) Pathological- Endometrial hyperplasia, wound healing. Hypertrophy In Greek “Huper” means – “Excess” and “Trophy” means – “Nourishment”. Hypertrophy is an increase in the size of cells resulting in increase in the size of the organ. There is no change in the number of cells. Hypertrophy can be of two types: Physiologic Enlarged size of uterus in pregnancy, breast tissue in puberty & pregnancy is an example of hypertrophy as well as hyperplasia. Pathological Tissues showing hypertrophy in cardiac muscles, smooth muscle, skeletal muscle. NOTE: 1- hypertrophy and hyperplasia can occur together, e.g.  Uterus during pregnancy  Benign prostatic hyperplasia Physiologic hypertrophy reflects an increase in workload that is not caused by disease —for example, the increase in muscle size caused by hard physical labor or weight training. Atrophy:- “A” means – “Absence” , “Trophy” means - “Nourishment” Atrophy: Decrease in size of a cell or tissue Mechanism of atrophy consists of combination of decreased protein synthesis & increased protein degradation ‫تدهور البروتين‬ Pathological atrophy such as:  Atherosclerosis can cause ischemic atrophy  Nutritional deficiency  loss of innervation ‫التغذيه‬ ‫العصبيه‬ Metaplasia:- In Greek “Change in form” Metaplasia is the reversible replacement of one differentiated cell type with another mature differentiated cell type. Dysplasia Dysplasia is disordered cellular development. It affects only epithelial cells. Cellular pleomorphism – variation in size and shape of cells and their nuclei. Dysplasia:- derangement of cell growth that leads to tissues with cells of varying size, shape and appearance. It is characterized by – - increased cell proliferation (more mitosis) - presence of atypical morphology (abnormally large nuclei) - decrease differentiation (cellular immaturity) Dysplasia is a premalignant condition. It may occur in tissue that has coincident ‫ متزامن‬metaplasia. Most common examples are uterine cervix and respiratory tract Neoplasia Neoplasia:- Definition: Is an abnormal mass of tissue, the growth of which is uncoordinated with that of normal tissues. Classification of Neoplasia:- 1) Benign 2) Malignant Benign tumors : Will remain localized. Cannot spread to distant sites. Generally can be locally excised. Patient generally survives. Malignant neoplasms: Can invade and destroy adjacent structure. Can spread to distant sites. Cause death (if not treated).  Benign tumors: Type of cell + (-oma) Malignant tumors – use embryonic origin of tissue - Carcinomas this cancer begins in the skin or in tissues that line or cover internal organs... - Sarcomas this cancer occur in connective tissue, muscle, nerve and endothelial tissues. this cancer begins in the connective or supportive tissues such as bone, cartilage, fat, muscle or blood vessels Malignant tumors (cancers) ① Carcinoma: Malignant tumors of epithelial cell origin. The name of organ and derived tissue/ cell + carcinoma e. g. adenocarcinoma of thyroid. ② Sarcoma: malignant tumors arising in mesenchymal tissue or its derivatives The name of organ and derived tissue/ cell + sarcoma  Benign tumors different names depending on where they develop: Adenoma: This is a benign tumor on or in a gland or organ (such as the pituitary gland, colon or liver). Chondroma: A chondroma is a benign neoplasm that forms in cartilage Hemangioma: These types of benign neoplasms grow from blood vessels. Lipoma: This benign fatty tumor grows just below your skin. It’s the most common type of benign tumor. Lymphangioma: This type in your lymphatic system Myoma: in smooth muscle. (often grow in the uterus) Osteoma: This noncancerous tumor forms from bone.  NOMENCLATURE Tissue Benign Malignant Surface epithelium Papilloma Carcinoma Glandular epithelium Adenoma Adenomacarcinoma Adipose Lipoma Liposarcoma Fibrous Fibroma Fibrosarcoma Cartilage Chondroma Chondrosarcoma Bone Osteoma Osteosarcoma Smooth muscle Leiomyoma Leiomyosarcoma Striated muscle Rhabdomyoma Rhabdomyosarcoma Nerve Neurofibroma Neurofibrosarcoma Nerve sheath Neurolemmoma Neurolemmosarcoma Glial cells Glioma Malignant glioma  Comparison between Benign & Malignant tumors BENIGN MALIGNANT Slow growth Rapid growth (expands by invasion, infiltration) Encapsulated. No Capsule Local spread. Spread by metastasis Low mitotic figure. High mitotic figure Good prognosis (No death) Bad prognosis ( result in death) Easily surgically removed & no Difficult to treat and can reoccurs recurrence No atypia. Shows atypia Structural differentiation retained Structural differentiation shows wide range of changes Nuclear variation in size and shape Nuclear variation in size and shape minimal minimal to marked Functional differentiation usually Functional differentiation often lost  Characteristics of benign and malignant neoplasms Differentiation and anaplasia Rate of growth Local invasion Metastasis Metastasis : Definition : the development of secondary implants discontinuous with the primary tumor. 3 pathways – 1. Lymphatic spread : 2. Hematogenous spread : 3. Seeding of the body cavities: pleural, peritoneal cavities and cerebral ventricles.  Lymphatic spread : favored by carcinomas Breast carcinoma  axillary lymph nodes Lung carcinomas  bronchial lymph nodes Hematogenous spread : - favored by sarcomas - Also used by carcinomas - The liver and lungs are the most frequently involved secondary sites. Genetic Basis of cancer Several cellular control pathways must be altered to produce cancer )Abnormal proliferation(. The main alterations causing cancer includes –  Activation of oncogenes (gene that has the potential to cause cancer)  Inhibition of tumor suppressor genes. 29 Environmental factors causing cancer Tobacco use Diet Alcohol use Sexual and reproductive behavior Air pollution UV radiation and other radiation Hormones Viruses. 30  Cancer Treatment Chemotherapy Surgery - can remove entire tumor, adjuvant chemotherapy or radiation Radiation - targets DNA Immunotherapy - Nonspecific enhancement of the immune system, protect against recurrence, eliminates cancer cells only Targeted Therapies - Drugs that target the processes of cancer cells specifically. 31