T1_General Concept of Disease.pdf

BIOL 2006SEF CELLS IN HEALTH AND DISEASE TOPIC 1: GENERAL CONCEPT OF DISEASE Heidi Wong [email protected] Outline  Characteristics of Disease  Classifications of Disease  Health and Disease  Screening Tests  Diagnostic Tests and Procedures Characteristics of Disease Disorder : An illne...

BIOL 2006SEF CELLS IN HEALTH AND DISEASE TOPIC 1: GENERAL CONCEPT OF DISEASE Heidi Wong [email protected] Outline  Characteristics of Disease  Classifications of Disease  Health and Disease  Screening Tests  Diagnostic Tests and Procedures Characteristics of Disease Disorder : An illness that disrupts normal physical or mental functions Disease: a pathological condition resulting from the disruption of normal bodily functions, leading to specific symptoms or signs indicating an abnormal state of health Lesions: well-defined, characteristic structural changes in organs and tissues as a result of disease Organic disease  Associated with structural changes  Gross examination  Histologic examination Functional disease  No morphological abnormalities but body functions are profoundly disturbed  Pathology: study of the structural and functional changes in the body caused by disease  Pathologist: physician who specializes in diagnosing and classifying diseases by studying the morphology of cells and tissues  Clinician: physician/ health care professional that cares for patients Symptoms: subjective manifestations such as pain or dizziness Signs: physical findings or objective manifestations such as swelling or redness  Symptomatic disease: with symptoms and/or signs Asymptomatic disease: no signs or symptoms  Distinction between asymptomatic and symptomatic depends on extent  Early stages of disease, usually asymptomatic  If not treated, progresses to symptomatic Syndrome: a group of symptoms/ changes which consistently occur together e.g Down’s syndrome Etiology: cause of disease Etiologic agent: agent responsible for causing disease Pathogenesis: process of development of disease Pathogen: disease-causing bacterium or other harmful organism Classifications of Disease Congenital and hereditary diseases  Developmental disturbances  Causes: genetic abnormalities; abnormalities in chromosome number or distribution; intrauterine injury; interaction of genetic and environmental factors  Congenital rubella syndrome induced by the German measles virus infection via maternal-fetal transmission and develops birth defects  Hemophilia (hereditary)  Inflammatory disease  body reacts to injury through an inflammatory process  Bacteria or microbiologic agents: sore throat  Allergic reaction: hay fever  Autoimmune diseases: Systemic Lupus Erythematosus (SLE), diabetes type 1  Unknown etiology Degenerative diseases  Tissue or organ degeneration as a result of aging or breakdown  Arthritis, arteriosclerosis Metabolic diseases  Disturbance in metabolic process in body  Diabetes, hyper- or hypothyroidism, fluid and electrolyte imbalance  Sequence of events in an inflammatory reaction Inflammation is a response of vascularized tissues to infections and tissue damage that brings cells and molecules of host defense from the circulation to the sites where they are needed, to eliminate the offending agents. The offending agent, which is located in extravascular tissues, is recognized by host cells and molecules. Leukocytes and plasma proteins are recruited from the circulation to the site where the offending agent is located. The leukocytes and proteins are activated and work together to destroy and eliminate the offending substance. The reaction is controlled and terminated. The damaged tissue is repaired. Vinay Kumar, Abul K. Abbas, Jon C. Aster, Andrea T. Deyrup. (2022). Robbins & Kumar Basic Pathology (11th ed.). Elsevier.  Neoplastic diseases: Abnormal cell growth leading to the formation of various types of benign and malignant tumors  Benign: lipoma  Malignant: Lung cancer Basis of classification 1. Similarity of lesions (morphology) 2. Similarity of pathogenesis 3. Similarity of molecular abnormalities Diseases with similarities may not necessarily be closely related. Health and Disease  WHO (1948) – wellness is the complete state of physical, mental and social well-being and not simply the absence of disease and infirmity  Good health: more than the absence of disease  Condition in which body and mind function efficiently and harmoniously as a integrated unit Traditional medicine: goal is to cure or ameliorate disease Modern medicine: advances relieve suffering and advance human welfare but do not guarantee good health Continuum of Health and Disease Good Serious Health Illness Everyone is somewhere between the midpoint and good health Good health requires active participation, assuming responsibility for one’s health  Eat properly, exercise, avoid harmful excesses such as overeating , smoking, heavy drinking, or using drugs  Use one’s mind constructively, express emotions appropriately, nurture a positive mental attitude Principles of Diagnosis Diagnosis: A diagnosis is the identification of a disease, condition, or injury from its signs and symptoms  Clinical history  Physical examination  Differential diagnosis Prognosis: A prognosis is the prediction your healthcare team makes for the expected development of a disease.  eventual outcome of disease  the chance of recovery or recurrence Treatment  Special treatment – directed at underlying cause  Symptomatic treatment – relieve symptoms but does not influence course of disease Clinical History 1. History of current illness Severity, time of onset, and character of patient’s symptoms 2. Medical history Details of general health and previous illnesses that may shed light on current problems 3. Family history Health of patient’s parents and family members; diseases that run in families 4. Social history Patient’s occupation, habits, alcohol and tobacco consumption, general health, current problems 5. Review of symptoms Symptoms other than disclosed in history of present illness, suggesting other parts of the body affected by disease Physical Examination Physical examination  Systematic examination of patient, with emphasis on parts of body affected by illness  Abnormalities noted correlated with clinical history Differential diagnosis  Consideration of various diseases or conditions that may also explain patient’s symptoms and signs  Diagnostic possibilities narrowed by selected laboratory tests or other diagnostic procedures  Opinion of medical consultant may be sought Screening Tests Screening tests for detection of disease  Detect early asymptomatic diseases amenable to treatment to prevent or minimize late-stage organ damage Screening for some genetic diseases  To screen for carriers of some genetic diseases transmitted from parent to child as either dominant or recessive trait  Identifying carriers allows affected persons to make decisions on future childbearing or management of current pregnancy  Example: recessive gene for sickle cell anemia in 8% of Black population Requirements for Effective Screening A significant number of persons must be at risk for the disease in the group being screened A relatively inexpensive noninvasive test must be available to screen for the disease that does not yield a high number of false-positive or false- negative results Early identification and treatment of the disease will favorably influence course of disease Good screening test:  the test must be inexpensive and easy to administer, with minimal discomfort and morbidity to the participant  the results must be reproducible, valid, and able to detect the disease before its critical point Examples of Screening Tests Purified Protein Derivative (PPD) for tuberculosis (TB)  A standardized solution made with PPD, which is derived from tuberculin, is injected under the skin, PPD produces a T-cell mediated delayed-type hypersensitivity reaction if the person has been infected with TB bacteria Prostate Specific Antigen (PSA) for Prostate Cancer  a blood test that measures the level of PSA in a sample of your blood. PSA is a protein made by your prostate. It's normal to have a low level of PSA in your blood. Alpha Fetoprotein (AFP) – screening to detect certain fetal abnormalities  An AFP blood test is used during pregnancy to check the baby's risk of birth defects and genetic disorders, such as neural tube defects or Down syndrome.  An AFP tumor marker test is a blood test that measures the level of AFP in a sample of your blood. It's usually used to help diagnose certain types of cancer and to check how well treatment is working. High levels of AFP can be a sign of cancer of the liver, ovaries or testicles.  Mammogram to detect Breast Cancer  X-ray images of the breasts designed to detect cancers and other changes in breast tissue  A screening mammogram is used to detect breast changes that could be cancerous in people who have no signs or symptoms. Pap Smear for Cervical Cancer  A procedure in which a small brush is used to gently remove cells from the surface of the cervix and the area around it so they can be checked under a microscope for cervical cancer or cell changes that may lead to cervical cancer. Colonoscopy for Colon Cancer  During a colonoscopy exam, a long, flexible tube (colonoscope) is inserted into the rectum. A tiny video camera at the tip of the tube allows the doctor to detect changes or abnormalities inside the entire colon.  Colonoscopy is one of the most sensitive tests currently available for colon cancer screening. The doctor can view your entire colon and rectum.  Abnormal tissue, such as polyps, and tissue samples (biopsies) can be removed through the scope during the exam.  Blood Sugar test for diabetes  A blood glucose test measures the level of glucose (sugar) in your blood.  The test can involve a finger prick or a blood draw from your vein.  most commonly use blood glucose tests to screen for Type 2 diabetes Blood Pressure test for Hypertension  A blood pressure test measures the pressure in the arteries as the heart pumps.  A blood pressure test may be done as a part of a routine health checkup or as a screening for high blood pressure, also called hypertension.  Some people use home monitors to check their blood pressure at home.  In general, hypertension is a blood pressure reading of 130/80 millimeters of mercury (mm Hg) or higher.  if blood pressure rises and stays elevated over time, a number of serious health problems may appear, including stroke, coronary heart disease and heart failure, chronic kidney disease, and even early death. Diagnostic Tests and Procedures Clinical laboratory tests  Purpose: to determine concentration of substances in blood or urine frequently altered by disease  Uses: Determine concentration or activity of enzymes in the blood Evaluate function of organs Monitor response of certain cancers to treatment Detect disease-producing organisms in urine, blood, feces Determine response to antibiotics  Tests of electrical activity: to measure electrical impulses associated with bodily functions and activities  Electrocardiogram (ECG): measures serial changes in electrical activity of the heart in various phases of the cardiac cycle Identify disturbances in heart rate, rhythm, abnormal impulses Recognize heart muscle injury from ECG abnormalities  Electroencephalogram (EEG): measures electrical activity of brain; brain waves  Electromyography (EMG): measures electrical activity of skeletal muscle during contraction and at rest  Radioisotope (radionuclide) studies: evaluate organ function by determining rate of uptake and excretion of substances labeled with a radioisotope Uses:  Anemia: radioisotope-labeled vitamin B12  Hyperthyroidism: radioactive iodine  Pulmonary blood flow: albumin; to detect presence of blood clots  Cancer spread: phosphorus; to determine presence of tumor deposits in bone or spine  Heart muscle damage: evaluate blood flow  Endoscopy  To examine interior of body using rigid or flexible tubular instruments equipped with lens and light source  To perform surgery formerly done through large abdominal incisions Bronchoscope: trachea and major bronchi Cystoscope: bladder Laparoscope: abdomen Ultrasound  Mapping echoes produced by high-frequency sound waves transmitted into body; echoes reflect change in tissue density, producing images  X-ray  Principle: use of high-energy radiation waves at lower doses to produce images to help diagnose disease  Can penetrate through tissues at varying degrees depending on tissue density  Act on a photographic film or plate (roentgenogram) as the rays leaves the body Radiopaque: appears white on film; high-density tissues such as bone absorb most of the rays Radiolucent: appears dark on film; low-density tissues allow rays to pass through  X-ray can include use of contrast media to outline structures not otherwise visualized on standard films - Barium sulfate: intestinal tract - Radiopaque oil: bronchogram - Intravenous dye: intravenous pyelogram; urinary tract - Radiopaque tablets: visualize gallstones - Arteriogram: visualize blood flow, identify narrowing or obstruction - Cardiac catherization: blood flow through heart, detect abnormal communications between chambers  Computed tomographic (CT) scans - Principle: radiation detectors record amount of X-rays or ionizing radiation absorbed by body and feed data into a computer that reconstructs the data into an image - Radiopaque and radiolucent tissues appear white and dark as in a conventional x-ray - Individual organs sharply demarcated by planes of fat that appear dark because of its low density - Delivers higher dose of ionizing radiation than x-ray Uses of computed tomographic (CT) scans - Cancer screening asymptomatic individuals - Detect abnormalities in internal organs that cannot otherwise be identified by standard x- ray  Magnetic resonance imaging (MRI) - Principle: computer-constructed images of body based on response of hydrogen protons in water molecules when placed in a strong magnetic field  Protons align in the direction of the magnetic field  Protons are temporarily dislodged and wobble when radiofrequency waves are directed at them  Protons emit a measurable signal (resonance) that can be used to construct images  Intensity of resonance depends on water content of tissues, strength and duration of radiofrequency pulse MRI: advantages over CT scan - Does not use ionizing radiation - Can detect abnormalities in tissues surrounded by bone, such as spinal cord, orbit, skull - Bone interferes with scanning because of its density but does not produce an image in MRI because of its low water content Uses - Multiple sclerosis - Superior to mammography in detecting breast cancer  Positron emission tomography (PET) - Principle: Measures metabolism of biochemical compounds that are labeled with positron- emitting isotopes to measure organ function, example glucose - Disadvantages  Very expensive and not widely available  Requires facilities for incorporating the isotopes into the biochemical compound Uses of PET - Detect atypical metabolism of the tracer in diseases before the disease shows up in other imaging tests - Detection of primary, metastatic recurrence cancers - Heart diseases with decrease in blood flow - Brain disorders – Alzheimer’s disease  Cytologic and histologic examinations - Cytology studies the characteristics of individual cells or small groups of cells that are either shed or sampled from body organs - Papanicolau (Pap) smear: identifies abnormal cells in fluids or secretions; for recognizing early changes that may be associated with cervical and other cancers - Histology examines the structure of organs and the tissues and groups of cells of which they are composed. The pathologist uses histopathology to recognize changes in tissue that are indicative of disease. - Biopsy: tissue samples obtained for histologic examination to determine abnormal structural and cellular patterns accompanying disease  Liver, kidney, lung, etc References 1. Vinay Kumar, Abul K. Abbas, Jon C. Aster, Andrea T. Deyrup. (2022). Robbins & Kumar Basic Pathology (11th ed.). Elsevier. 2. Emily Reisner, Howard Reisner. (2016). Crowley’s An Introduction to Human Disease: Pathology and Pathophysiology Correlations (10th ed.). Jones & Bartlett Learning.