Disease & Disease-Producing Organisms

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

2. 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

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

4. 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

5. 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

6. 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

7. Nutritional Excesses

8. 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.

9. 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)

10. 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

11. 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

12. 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.

13. 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.

14. 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

15. 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

16. 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

17. Example of Endemic Disease: The Goiter Belt in the US

18. 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

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

20. 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

22. 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

24. 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

25. 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

26. 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

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

28. 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

29. 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

30. 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

31. 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

32. 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

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

34. 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

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

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

38. 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

39. 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

40. 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

41. 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)

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

43. Viruses

44. 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

45. 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

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

47. 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

48. 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

49. Protozoa Movement

50. 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