Pathology scientific study of disease; scientific study of molecular, cellular, tissue, or organ system response to injuries agents.

General pathology concerned with the basic reactions of cells and tissues to abnormal stimuli that underlie all diseases.

Pathology serves as bridge or link between the preclinical sciences (anatomy, physiology etc) and the courses in clinical medicine.

Techniques used by pathology1.Human pathology (autopsy, biopsy, cytology)2.Experimental (animal experiment, tissue)

Pathogenic agents mechanisms cellular stress cellular response (growth, alterations, cell damage and cell death) reactions of tissues (inflammatory process)

Pathogenic Agents: -intrinsic (arise in the body)-extrinsic

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Diseasesa)developmental (genetic, congenital)b)acquired (inflammatory, neoplastic (tumours), degenerative (ageing), metabolic, iatrogenic (drug induced)

Etiology- study of causes of a specific event; search for factors playing role in origins of the diseases and relationship between them

Endogenous and exogenous causes

Causes of disease1.Environmental agents (physical, chemical, nutritional, infections)2.Immunological (psychological)3.Genetic factors (age, genes)4.Multifactorial: diabetes, cancer, hypertension

Etiological agent- factor (virus np) responsible for lesions or disease

Pathology by physical agents1.Transfer of energy (radiation, electric, thermic, mechanic)2.Sound waves3.Atmospheric pressure

Radiation:a)corpuscular energy in form of kinetic energy possessed by elementary particles of the atom (protons, neutrons, alfa, bet particles )b)electromagnetic energy transferred without mass (x-rays, infrared, UV, visible light, gamma)

Radiation:1.Ionizing -higher energy electromagnetic waves (gamma) or heavy particles (beta-cause light damage, alpha-cause heavy damage)- high enough energy to pull electron from orbit)

2. Non-ionizing-lower energy electromagnetic waves-not enough energy to pull electron from orbit, but can excite the electron Potential radio waves effects: -heating of the body (thermal effect)-cataracts-some studies show effects of teratogenicity and carcinogenicity.

Radiation from natural sources: cosmic rays, earth, radon, human body, building materialRadiation from mandmade sources: medical fallout from past experiments, consumer products (laptops),nuclear power

Ionizing radiation at cellular level:-causes break in one or both DNA strands-causes free radicals formation

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Critical organs to radiation: lymphocytes, bone marrow, gastrointestinal gonads and other fast growing cells; CNS is relatively resistant.

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Effects of exciting radiations-thermal (radiations absorbed by dark bodies and melanin) /infra red/-photochemical reactions /light radiations/

UV effects-bacteria inactivation (sterilization by UV lamps)-inhibition of cellular division-mutations-dell death-tumour

Acute tissue changes (inflammatory rather), then is either regeneration or replacement of the cells Chronic tissue changes (manifest after healing process)- hair loss np.