Disease & Disease-Producing Organisms Chapter 5 Anatomy & Physiology I

Disease Any abnormality of the structure or function of a part, organ or system Diseases fall into 7 different, but often overlapping categories 7 Predisposing factors increase the probability of a person becoming ill The study of disease

Categories of Disease Infection: Degenerative diseases Nutritional disorders Metabolic disorders Immune disorders Neoplasms Psychiatric Disorders

Infection Believed to play a part in at least 50% of all human illnesses Cause: Many diseases are caused by infectious organisms Example cold, AIDS, tuberculosis etc

Degenerative Diseases Involve degeneration (breaking down) of tissues in any system of the body Causes Hereditary Wear and tear Infection No known causes Example: Alzheimer, osteoporosis, and arthritis

Nutritional Disorders Caused by: dietary lack (deficiency) of essential vitamins, minerals, proteins, or other substances Excess alcohol, caloric intake Example Scurvy – lack of Vitamin C Rickets – lack of Calcium Beriberi- lack of thiamine Kwashiorkor- lack of protein Goiter: lack of iodine

Nutritional Excesses

Metabolic Disorders A disturbance in the buildup, breakdown, or excretion of substances Causes Disruption in the reactions of cellular metabolism Hormone imbalance regulate many metabolic activities Hereditary errors of metabolism Examples diabetes, gout (a disorder of the joints), >> uric acid digestive disorders, and hereditary dysfunctions.

Immune Disorders Caused by Immune deficiencies: The decreased ability of the body to fight infection and disease. Caused by genetic or infection Example: AIDS Hypersensitivity – overactive immune system Allergies Animals, pollen, medicine, nuts etc Autoimmune disorders Example: rheumatoid arthritis, multiple sclerosis (MS), and systemic lupus erythematosus (SLE)

Neoplasms The word neoplasm means “new growth” and refers to cancer and other types of tumors. An abnormal and uncontrolled growth of tissues Benign Metastatic

Psychiatric Disorders A health condition that changes a person’s thinking, feelings, or behavior (or all three) and that causes the person distress and difficulty in functioning

Predisposing Factors May not cause a disease, but does increase the probability of a person becoming ill Age: measles is more common in children, Alzheimer in elders Gender: heart disease to men, diabets to women Heredity: diabetes, allergies, and certain forms of cancer. Living conditions & habits: sleep, exercise, diet, drugs, alcohol, and tobacco Emotional disturbance: stress, anxiety, anger, sensitivity Physical & chemical damage – Injuries & chemical exposure Preexisting illness: high blood pressure or diabetes, increases one's chances of contracting another disease.

The Study of Disease Pathophysiology: Is the study of close relationship of each disease's pathologic and physiologic aspects and the understanding of these fundamentals in treatment.

Disease Terminology Etiology – study of the cause of disease Epidemiology: the study of diseases in populations. Epidemiology statistics include: Incidence – The number of new disease cases, occurence and tendency to affect certain groups of individuals more than other groups Morbidity – the proportion of a population with a specific disease Mortality – the proportion of a population that dies from a given disease

Disease Terminology Cont. Diseases are classified based on severity and duration as: Acute – relatively severe but last a short time Chronic – may be less severe but likely to be continuing or recurring Subacute – between acute and chronic diseases

Disease Terminology Cont. Based on origin: Idiopathic – disease without known cause Iatrogenic – disease caused by adverse effects from medical treatment Communicable – disease that can be transmitted from one person to another Epidemic – many people from a certain region acquire a certain disease at the same time Endemic – a disease found to a lesser extent, but continuously in a particular region Pandemic – a disease prevalent throughout the world

Example of Endemic Disease: The Goiter Belt in the US

Treatment and Prevention of Disease Medical process History, including signs and symptoms Sign – objective evidence (observed by physician or other healthcare professional Symptoms – subjective evidence (conditions noted by the patient). For example: imaging studies, blood tests, and study of tissues removed in biopsy. Syndrome – a characteristic set of signs and symptoms that accompany a disease; PMS, AIDS Diagnosis – a conclusion as to the nature of the illness Prognosis – prediction of probable outcome of disease Therapy – course of treatment

Treatment: Complementary and Alternative Medicine Methods of disease prevention or treatment that can be used along with or instead of traditional modern medical practices

Alternative Medicine Naturopathy: healthy life style Chiropractic: correcting misalignment for treatment of musculoskeletal disorder Acupuncture: insert needle to relief pain Biofeedback: electronic devices monitor changes and feed info back to a person Herbal medicine

Disease Prevention Modern medicine’s major focus is on treating patients who currently have a disease Wellness movement focuses on preventing the occurrence of disease by promoting health Health – an optimal physical, mental and emotional state of being, not merely the absence of disease Health-promoting practices Massage Diet Exercise Stress management

Infectious Disease Invasion of the body by disease-producing microorganisms Microorganisms – Aka microbes, germs A tiny living thing too small to be seen by the naked eye Most are harmless, many are beneficial, a few cause illness (are pathogenic) Parasite – a living organism that lives on or in a living host at the host’s expense Pathogen – disease-producing organism

Types of Infection Infection – pathological state resulting from the invasion of the body by pathogenic microorganisms Local – infection restricted to a small area Systemic – infection throughout the whole body Opportunistic infection – an infection that takes hold because the body has been weakened by disease or injury

Modes of Transmission Direct Contact Indirect Contact Touching Sexual activity Indirect Contact Touched objects Vector – an insect or animal that transmits a pathogen from one host to another (mosquito) Atmosphere

Portals of Entry & Exit Skin Respiratory tract Digestive system Urinary system Reproductive system

The Common Cold 1 billion Americans “catch” a cold every year Leading cause of doctor visits & missed days of work & school Caused by over 200 different types of viruses One sneeze can send hundreds of thousands of particles several feet, where they live for 3-6 hours To prevent Avoid close contact Wash hands Do not touch your face Clean surfaces frequently

Microbiology Microorganisms- simple, microscopic, usually single-cell, forms of life. The group includes bacteria, viruses, fungi, protozoa, and algae. Book: table 5.1 Microbiology – The study of these microscopic organisms Bacteria – single-celled organisms which grow in many environments Viruses- composed of nucleic acids & protein; can only multiply inside of living cells Fungi – plantlike organisms Single celled – yeasts Filamentous - molds Protozoa – single-celled animals Aka parasites Includes worms

Microorganisms Most are harmless to humans and are essential to all of life on earth Normal flora – population of microorganisms that normally grow on or within our bodies Beneficial If normal flora are destroyed it can cause overgrowth of normally harmless bacteria, rendering them pathogenic

Bacteria Single celled organisms One of the most primitive forms of life on earth Their genetic material is not enclosed by membrane Do not have a true nucleus Lack most organelles

Bacteria Cont. Classification Aerobic – require oxygen to grow Anaerobic – grow in the absence of oxygen Facultative anaerobes – use oxygen if present but are also able to grow without oxygen – e. coli Endospores – resistant forms of bacteria that can tolerate long periods of dryness or other adverse conditions. Endospores can be become airborne Resistant to ordinary methods of disinfection Particularly dangerous – tetanus, botulism, anthrax

Bacteria Movement Flagella: helps them to swim rapidily Pili – short “hairs” that help bacteria to glide across solid surfaces & anchor it to surfaces

Bacteria Cont. Largest group of pathogens to humans Can divide every 20 minutes or every 24 hours Cause damage to humans in 2 ways Produce toxins Growing in human tissues

Human defence mechanism Physical barriers – skin, mucus membranes Immune system

Shape & Arrangement of Bacteria Three groups of bacteria based on their shape Cocci Diplococci Streptococci Staphylococci Bacilli Curved rods Vibrios Spirilla spirochetes

Cocci & Bacilli Cocci – round Bacilli – straight rods Diplococci – in pairs – causes gonorrhea, and meningitis Streptococci – in strings – strep throat Staphylococci – in clusters - pneumonia and fever. Bacilli – straight rods All endospore-forming bacteria are bacilli TB, typhoid fever, Legionnaire’s disease

Curved Rods Vibrios – short curved rods, like a comma cholera Spirilla – resemble a corkscrew Spirochetes – similar to spirilla but capable of waving & twisting motions. Casues syphilis

Obligate Intracellular Parasites Bacteria that are much smaller than normal Also include viruses, which are not bacteria They only grow within the cells of their hosts Chlamydia Ricksettia Transmitted through insect bites Rocky Mountain spotted fever, typhus

Viruses Extremely small in comparison to bacteria: seen by electron microscope Have some characteristics of living matter but not all Contain genetic material & are able to reproduce Contain only DNA OR RNA Generally made of genetic material surrounded by a protein coat Are not cellular Do not have enzyme systems Can only grow within a host’s cell (obligate)

Virus size comparison. A chlamydia and a staphylococcus are shown for reference

Viruses

Classifying and naming Viruses Classified according to: type of nucleic acid they have: DNA or RNA whether that nucleic acid is single stranded (ss) or double stranded (ds). The diseases they cause: common cold, hepatitis, measles where they were isolated : West Nile the symptoms they cause: yellow fever the host : Chickenpox, HIV, Swine influenza

Other Agents Smaller than Viruses Prions (proteinaceous infectious )-made solely of proteins Slow growing and hard to destroy Mad cow disease Viroids Composed solely of RNA with no protein coat So far have only been discovered to cause plant diseases

Fungi Types Simple plant-like organisms Very few cause diseases Yeast – single celled Molds – long & filamentous Simple plant-like organisms Do not contain chlorophyll Grow in dark, damp places Very few cause diseases

Mycotic (Fungal) Infections Diseases caused by fungi are called mycotic Can affect skin Ringworm – tinea corporis or capitis Athlete’s Foot Can affect those with compromised immune systems Candidiasis

Protozoa Single-celled animal-like organisms Amebas – a “blob” that can move Ciliates – tiny hairs propel this organism Flagellates – a tail propels this organism Sporozoa – cannot propel themselves Obligate parasites, unable to grow outside host Carried by mosquitos malaria

Protozoa Movement

Parasitic Worms (Helminths) Roundworms Ascaris – intestinal; hard to control & eliminate Pinworm – intestinal; hard to control & eliminate Hookworms – intestinal; suck blood & cause anemia; larvae enter body through foot Trichinea – live in muscles of animals & people; enter body through undercooked meat Filaria – live in lymphatic system

Hookworm

Roundworms Ascaris & Filaria

Filaria Infection

Parasitic Worms (Helminths) Cont. Flatworms Tapeworms – can be 50 feet long in intestines, spread through undercooked meat Flukes – can infect many body parts

Tapeworm

Microbial Control Infectious diseases are increasing Increased population, travel, food processing Public health measures help control microbes Sewage/garbage disposal Water purification Prevention of food contamination Milk pasteurization

Aseptic Techniques & Methods Sterilization – kills EVERY living microorganism on an object Disinfection – kills all pathogens (except spores) but does not necessarily kill harmless microbes Antisepsis – pathogens not necessarily killed but prevented from multiplying

Universal Precautions to Control Infection Healthcare workers MUST use barriers for any contact with moist substances, non-intact skin, & mucous membranes –REGARDLESS of whether or not blood is visible & REGARDLESS of a patient’s diagnosis Soiled linen and trash are treated as contaminated Needles are not recapped after blood draws Handwashing – goal of 100% compliance

Handwashing The single most important measure to prevent the spread of infection in ALL settings Gloves are not a substitute for handwashing

Areas Missed During Handwashing

Antimicrobial Agents Antibiotics Penicillin Danger of opportunistic infections developing due to loss of normal bacteria Danger of resistant strains of pathogens developing Antiviral agents – very few and they have a limited range of effectiveness Viruses mutate rapidly to become resistant Antiviral agents are often used in combinations

Antibiotics