Human Diseases

1. Human Diseases Introduction: Chapter 1

2. Definitions • Disease • Disorder or cessation of body functions, systems or organs having at least 2 of the following: • Recognized etiology • Identifiable group of symptoms and signs • Consistent anatomic alteration

3. Definitions • Illness • Condition of the patient experiencing the disease • Syndrome • Group of signs & symptoms associated with any disease that together constitute a picture of that disease

4. Definitions • Symptom • Complaints of the patient • Subjective • Abdominal pain, shortness of breath, etc. • Sign • Physical findings • Objective • Labored respirations, pallor, etc.

5. Disease Categories • According to etiology (cause) • Infectious, traumatic, hereditary, etc • According to body system involved • Cardiac, respiratory, dermatologic, etc

6. Disease Categories • Acute vs. chronic • Multiple system vs. single system • Focal vs. diffuse • Organic vs. psychological • Age group (pediatric vs. geriatric)

7. How a diagnosis is made • SOAP format • S = subjective = symptoms • Patient complaints and observations • O = objective = signs • Physical exam, tests by examiner • A = assessment (suspected diagnosis) • Differential diagnoses • P = plan (further tests & treatment)

8. Etiology • The cause of the disease • Many diseases are multifactorial • More than one causal factor • Adult onset diabetes, addictions • Predisposing factors: • Condition making a person more susceptible to developing a disease • Hypertension, diabetes, colon polyps, etc

9. Hereditary Diseases • Due to abnormalities of DNA or chromosomes • Not the same as congenital disease • Recognizable at birth • May affect any or multiple organ systems, various severities • May not be apparent at birth

10. Terminology: Genetics • Chromosome • 23 pairs, counting 2 sex chromosomes • Homozygous • Heterozygous • Genotype • Phenotype • Mutation

11. Hereditary Diseases: Categories • Mendelian alterations • One gene involved • Chromosomal alterations • Part or all of a chromosome involved • Multiple genes involved • Multifactorial errors

12. Mendelian Disorders • Mutation in a single gene • Subcategories: • Recessive • Dominant • Sex-linked • Autosomal

13. Mendelian Disorders • Autosomal disorders • Two identical copies of a gene exist • Recessive disease • Will not manifest if there is at least one normal copy of the gene • Dominant disease • Will manifest if there is even one abnormal copy of the gene

14. Autosomal Disorders: Examples • Autosomal Recessive • Cystic fibrosis, Tay-Sachs disease, PKU, cretinism, sickle cell anemia • Autosomal Dominant • Diabetes insipidus, retinoblastoma

15. Other Mendelian Disorders • Sex-linked or X-linked • Hemophilia • Duchenne’s Muscular Dystrophy

16. Hereditary Diseases: Chromosomal • Abnormalities in chromosome number or chromosome structure • Mechanisms of these alterations: • Additions • Deletions • Translocations

17. Chromosomal Diseases: Examples Trisomy 21 (Down Syndrome) Klinefelter’s Syndrome (XXY) Turner’s Syndrome (missing X)

18. Disease Category: Inflammatory • Inflammation • Cascade of numerous chemical reactions • Increase local WBC and edema • Acute or chronic • Response to many stimuli • Physical agents, toxins, infections, trauma, allergens, chemicals

19. Inflammatory Diseases • Signs and Symptoms • Edema • Erythema • Pain/tenderness • Warmth • Variable loss of function

20. Disease Category: Infectious • Infection: • Invasion and multiplication of pathogenic organisms in the body • Bacteria, viruses, rickettsiae, fungi, protozoa, parasites • Vs. non-pathogenic organisms • Overgrowth = pathological

21. Infectious Agents • Bacteria (bacterium) • Single celled organism capable of reproduction, DNA, RNA, & protein synthesis. • Gram negative or gram positive in color • Cocci, bacilli, or spiral in shape • May be pathogenic or nonpathogenic

22. Infectious Agents • Rickettsiae (rickettsia) • A genus of bacteria (Rickettsiales) • Obligate intracellular parasites • Arthropod vectors usually • Typhus, Rocky Mtn. Spotted Fever, etc

23. Infectious Agents • Protozoa • Unicellular animal-like microorganisms • Phylum Protista • Saprophytes often • Live on dead tissue • Fecal-oral route, food or water contaminated with cysts/spores, insect bite • Malaria, giardia, sleeping sickness

24. Infectious Agents • Virus • Smallest microorganisms • A nucleic acid inside a protein shell • Reproduces only after infecting host cell • Classified by • DNA vs. RNA • Reproductive method (retrovirus) • Mode of transmission (enterovirus) • Etc.

25. Infectious Agents • Fungi (fungus) • Yeast, mold, or mushroom • Belongs to the kingdom Fungi • Candidiasis, Valley Fever, aspergillosis

26. Disease Category: Trauma • Physical, chemical, radiation injury • Usually physical mechanism • Effects of external force applied to the body • Categories: • Blunt or penetrating • According to body part affected • Physical, chemical, radiation

27. Trauma • May cause shock • Shock • Hypoperfusion state • Classical signs and symptoms • Tachycardia • Hypotension • Pallor • Altered mental status/consciousness

28. Head Trauma • Skull fractures • Often “protective”, less force transmitted to brain • Categories: open, closed, basilar • Cerebral contusions • Contusion of brain • Concussion • Alteration in function of brain without visible damage to brain

29. Head Trauma • Intracranial hemorrhages • Intracerebral- inoperable • Subarachnoid-nuchal rigidity • Epidural-lucid period • Subdural-most common ICB

30. Chest Trauma • Rib fractures • flail • Pneumothorax • “collapsed lung”, abnormal air collection in between the pleura • Hemothorax • Injury to heart, esophagus, lungs, major vessels

31. Abdominopelvic Trauma • Blunt • Liver and spleen most commonly injured • Penetrating • Small intestine most commonly injured Major considerations: Hemorrhage and infection (spillage of GI contents and nonpathogenic bacteria)

32. Spinal Trauma • Cervical spine trauma commonly associated with head trauma • Typical signs and symptoms: • Paresis or paralysis below injury level • Loss/alteration in sensation below injury level • Some autonomic (ANS) loss also

33. Extremity Trauma • May be fractures, dislocations, soft tissue or skin injury • May be associated with major disability • May be associated with nerve or blood vessel disruption

34. Environmental Diseases • Conditions caused by the effects of various components of the environment • Heat or cold • Radiation • Chemicals • Bariatric (atmospheric pressure) • Electrical injury • Chemicals • Animals, insects, marine life • Submersion or drowning

35. Environmental Diseases • Heat-related diseases • Prickly heat-rash, blockage of sweat pores • Heat edema • Heat syncope • Heat cramps • Heat tetany • Heat exhaustion-temp nl to 104 • Heat stroke- temp over 105, altered mental status

36. Environmental Diseases • Cold-related diseases • Hypothermia-temp less than 95 degrees • Chilblains-damp, nonfreezing exposure • Trench foot-nonfreezing, water exposure • Frostbite-freezing, ice crystals in tissues • Frostnip-superficial injury, no ice crystals

37. Bariatric Diseases • Low Pressure • Altitude diseases • Hypoxia, pulmonary HTN, Acute Mountain Sickness, HAPE, HACE • High Pressure • Air embolism, nitrogen narcosis • Decompression sickness • Nitrogen bubbles in blood & tissues • The “bends” = musculoskeletal form

38. Electrical Injuries • Electric shock • May be due to natural (lightning strike) or man-made sources • Major effects: • Internal and external burns • Cardiac dysrhythmias • Local injuries/path of electrical current

39. Toxicology/Poisoning • Purposeful exposure • Suicide attempts • industrial exposure • Accidental exposure • Childhood ingestions • Theraputic medication errors • Occupational/industrial exposure

40. Toxicology • Bimodal peaks of overdoses according to age • Toddler age group • adolescence • Supportive care usually the key to treatment and survival • Antidotes are rare.

41. Drowning • Hypoxemia caused by obstruction of airway by laryngospasm and fluid while patient is submerged. • Fresh vs. salt vs. chlorinated water • Often associated with hypothermia. • Other complications, e.g. aspiration pneumonia • Higher survival rates in children. • Association with diving accidents. • Spinal trauma and other injuries

42. Bites and Stings • Most commonly fatal sting in US: • Hymenoptera (bee sting) • Allergic etiology • Black Widow Spider • Local muscle cramping generalizes • Abdominal findings, severe pain • HTN in 10-30%, some with coma, shock, & respiratory failure

43. Bites and Stings • Brown Recluse Spider • Local effects: erythema, blisters, spreading necrosis • Varies with amount of envenomation

44. Asphyxiation • Cessation of oxygenation • Also carbon dioxide accumulation • Variable etiologies • Drowning • Airway obstruction • Hypoventilation • Toxic inhalational injuries

45. Burns • Categorized by depth • Percentage of TBA (total body surface area) • Rule of Nines (modified for pediatrics) • Prognosis • Varies with depth and TBSA involved

46. Immune-Related Diseases • Basic categories of immune diseases • Immune deficiency • Deficient protection against invading organisms • May be iatrogenic • Allergy/anaphylaxis • Activation of inflammatory/histamine reactions • Autoimmunity • Immune system reacts against the patient as if he/she is an invading organism

47. Immune System ConceptsReview • Congenital or acquired • Humoral • Immunoglobulins (Ig’s) • Circulating proteins, rapid response • Cellular • T-cells, B cells & others • Tissue response mostly • Often delayed (takes days)

48. Immune System Review • Vocabulary • Phagocytosis • Antibody • Antigen • Macrophages • anaphylaxis

49. Allergic Symptoms • Skin • Urticaria, wheals • Erythema, pruritis • Respiratory • Airway edema, obstruction, stridor • Wheezing, asthma, dyspnea • Life-threatening • Anaphylactic shock

50. Autoimmune Diseases • Can affect any body system • Often affect multiple systems • Often unpredictable course • Exacerbating and remitting • Examples: • Ulcerative colitis, primary biliary cirrhosis, hemolytic anemia, ITP, Hashimoto’s thyroiditis, etc