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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

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disease disease producing organisms

Disease & Disease-Producing Organisms

Chapter 5

Anatomy & Physiology I



  • 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
  • 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
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
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
metabolic disorders
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
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)
  • 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
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
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
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
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 cont1
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

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
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
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
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
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
Modes of Transmission
  • Direct 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
Portals of Entry & Exit
  • Skin
  • Respiratory tract
  • Digestive system
  • Urinary system
  • Reproductive system
the common cold
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


  • 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
  • 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
  • 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
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
Bacteria Movement
  • Flagella: helps them to swim rapidily
  • Pili – short “hairs” that help bacteria to glide across solid surfaces & anchor it to surfaces
bacteria cont1
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 & Bacilli
  • Cocci – round
    • 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
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
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
  • 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)
classifying and naming 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
Other Agents Smaller than Viruses
  • Prions (proteinaceousinfectious )-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
  • Types
    • 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
Mycotic (Fungal) Infections
  • Diseases caused by fungi are called mycotic
  • Can affect skin
    • Ringworm – tineacorporis or capitis
    • Athlete’s Foot
  • Can affect those with compromised immune systems
    • Candidiasis
  • 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
parasitic worms helminths
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
parasitic worms helminths cont
Parasitic Worms (Helminths) Cont.
  • Flatworms
    • Tapeworms – can be 50 feet long in intestines, spread through undercooked meat
    • Flukes – can infect many body parts
microbial control
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
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
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
  • The single most important measure to prevent the spread of infection in ALL settings
  • Gloves are not a substitute for handwashing
antimicrobial agents
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