Human Diseases

Introduction: Chapter 1

DefinitionsDisease

Disorder or cessation of body functions, systems or organs having at least 2 of the following:

Recognized etiologyIdentifiable group of symptoms and signsConsistent anatomic alteration

DefinitionsIllness

Condition of the patient experiencing the disease

SyndromeGroup of signs & symptoms associated with any disease that together constitute a picture of that disease

DefinitionsSymptom

Complaints of the patientSubjectiveAbdominal pain, shortness of breath, etc.

SignPhysical findingsObjectiveLabored respirations, pallor, etc.

Disease CategoriesAccording to etiology (cause)

Infectious, traumatic, hereditary, etc

According to body system involvedCardiac, respiratory, dermatologic, etc

Disease CategoriesAcute vs. chronicMultiple system vs. single systemFocal vs. diffuseOrganic vs. psychologicalAge group (pediatric vs. geriatric)

How a diagnosis is madeSOAP formatS = subjective = symptoms

Patient complaints and observations

O = objective = signsPhysical exam, tests by examiner

A = assessment (suspected diagnosis)

Differential diagnoses

P = plan (further tests & treatment)

EtiologyThe cause of the diseaseMany diseases are multifactorial

More than one causal factorAdult onset diabetes, addictions

Predisposing factors:Condition making a person more susceptible to developing a diseaseHypertension, diabetes, colon polyps, etc

Hereditary DiseasesDue to abnormalities of DNA or chromosomesNot the same as congenital disease

Recognizable at birth

May affect any or multiple organ systems, various severitiesMay not be apparent at birth

Terminology: GeneticsChromosome

23 pairs, counting 2 sex chromosomes

HomozygousHeterozygousGenotypePhenotypeMutation

Hereditary Diseases: Categories

Mendelian alterationsOne gene involved

Chromosomal alterationsPart or all of a chromosome involvedMultiple genes involved

Multifactorial errors

Mendelian DisordersMutation in a single geneSubcategories:

RecessiveDominantSex-linkedAutosomal

Mendelian DisordersAutosomal disorders

Two identical copies of a gene existRecessive disease

Will not manifest if there is at least one normal copy of the gene

Dominant diseaseWill manifest if there is even one abnormal copy of the gene

Autosomal Disorders: Examples

Autosomal RecessiveCystic fibrosis, Tay-Sachs disease, PKU, cretinism, sickle cell anemia

Autosomal DominantDiabetes insipidus, retinoblastoma

Other Mendelian DisordersSex-linked or X-linkedHemophiliaDuchenne’s Muscular Dystrophy

Hereditary Diseases: Chromosomal

Abnormalities in chromosome number or chromosome structureMechanisms of these alterations:

AdditionsDeletionsTranslocations

Chromosomal Diseases: Examples

Trisomy 21 (Down Syndrome)Klinefelter’s Syndrome (XXY)Turner’s Syndrome (missing X)

Disease Category: Inflammatory

InflammationCascade of numerous chemical reactionsIncrease local WBC and edema

Acute or chronicResponse to many stimuli

Physical agents, toxins, infections, trauma, allergens, chemicals

Inflammatory DiseasesSigns and Symptoms

EdemaErythemaPain/tendernessWarmthVariable loss of function

Disease Category: Infectious

Infection:Invasion and multiplication of pathogenic organisms in the body

Bacteria, viruses, rickettsiae, fungi, protozoa, parasites

Vs. non-pathogenic organismsOvergrowth = pathological

Infectious AgentsBacteria (bacterium)

Single celled organism capable of reproduction, DNA, RNA, & protein synthesis.Gram negative or gram positive in colorCocci, bacilli, or spiral in shapeMay be pathogenic or nonpathogenic

Infectious AgentsRickettsiae (rickettsia)

A genus of bacteria (Rickettsiales)Obligate intracellular parasitesArthropod vectors usuallyTyphus, Rocky Mtn. Spotted Fever, etc

Infectious AgentsProtozoa

Unicellular animal-like microorganismsPhylum ProtistaSaprophytes often

Live on dead tissue

Fecal-oral route, food or water contaminated with cysts/spores, insect biteMalaria, giardia, sleeping sickness

Infectious AgentsVirus

Smallest microorganismsA nucleic acid inside a protein shellReproduces only after infecting host cellClassified by

DNA vs. RNAReproductive method (retrovirus)Mode of transmission (enterovirus)Etc.

Infectious AgentsFungi (fungus)

Yeast, mold, or mushroomBelongs to the kingdom FungiCandidiasis, Valley Fever, aspergillosis

Disease Category: Trauma

Physical, chemical, radiation injuryUsually physical mechanism

Effects of external force applied to the bodyCategories:

Blunt or penetratingAccording to body part affectedPhysical, chemical, radiation

TraumaMay cause shockShock

Hypoperfusion stateClassical signs and symptoms

TachycardiaHypotensionPallorAltered mental status/consciousness

Head TraumaSkull fractures

Often “protective”, less force transmitted to brainCategories: open, closed, basilar

Cerebral contusionsContusion of brain

ConcussionAlteration in function of brain without visible damage to brain

Head TraumaIntracranial hemorrhages

Intracerebral- inoperableSubarachnoid-nuchal rigidityEpidural-lucid period Subdural-most common ICB

Chest TraumaRib fractures

flail

Pneumothorax“collapsed lung”, abnormal air collection in between the pleura

HemothoraxInjury to heart, esophagus, lungs, major vessels

Abdominopelvic TraumaBlunt

Liver and spleen most commonly injured

PenetratingSmall intestine most commonly injured

Major considerations:Hemorrhage and infection (spillage of GI contents and nonpathogenic bacteria)

Spinal TraumaCervical spine trauma commonly associated with head traumaTypical signs and symptoms:

Paresis or paralysis below injury levelLoss/alteration in sensation below injury levelSome autonomic (ANS) loss also

Extremity TraumaMay be fractures, dislocations, soft tissue or skin injuryMay be associated with major disability May be associated with nerve or blood vessel disruption

Environmental DiseasesConditions caused by the effects of various components of the environment

Heat or coldRadiationChemicalsBariatric (atmospheric pressure)Electrical injuryChemicals Animals, insects, marine lifeSubmersion or drowning

Environmental DiseasesHeat-related diseases

Prickly heat-rash, blockage of sweat poresHeat edemaHeat syncopeHeat crampsHeat tetanyHeat exhaustion-temp nl to 104Heat stroke- temp over 105, altered mental status

Environmental DiseasesCold-related diseases

Hypothermia-temp less than 95 degreesChilblains-damp, nonfreezing exposureTrench foot-nonfreezing, water exposureFrostbite-freezing, ice crystals in tissuesFrostnip-superficial injury, no ice crystals

Bariatric DiseasesLow Pressure

Altitude diseasesHypoxia, pulmonary HTN, Acute Mountain Sickness, HAPE, HACE

High PressureAir embolism, nitrogen narcosisDecompression sickness

Nitrogen bubbles in blood & tissuesThe “bends” = musculoskeletal form

Electrical InjuriesElectric shockMay be due to natural (lightning strike) or man-made sourcesMajor effects:

Internal and external burnsCardiac dysrhythmiasLocal injuries/path of electrical current

Toxicology/PoisoningPurposeful exposure

Suicide attemptsindustrial exposure

Accidental exposureChildhood ingestionsTheraputic medication errorsOccupational/industrial exposure

ToxicologyBimodal peaks of overdoses according to age

Toddler age groupadolescence

Supportive care usually the key to treatment and survivalAntidotes are rare.

DrowningHypoxemia 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

Bites and StingsMost commonly fatal sting in US:

Hymenoptera (bee sting)Allergic etiology

Black Widow SpiderLocal muscle cramping generalizesAbdominal findings, severe painHTN in 10-30%, some with coma, shock, & respiratory failure

Bites and StingsBrown Recluse Spider

Local effects: erythema, blisters, spreading necrosisVaries with amount of envenomation

AsphyxiationCessation of oxygenationAlso carbon dioxide accumulationVariable etiologies

DrowningAirway obstructionHypoventilationToxic inhalational injuries

BurnsCategorized by depthPercentage of TBA (total body surface area)

Rule of Nines (modified for pediatrics)

PrognosisVaries with depth and TBSA involved

Immune-Related DiseasesBasic categories of immune diseases

Immune deficiencyDeficient protection against invading organismsMay be iatrogenic

Allergy/anaphylaxisActivation of inflammatory/histamine reactions

AutoimmunityImmune system reacts against the patient as if he/she is an invading organism

Immune System ConceptsReview

Congenital or acquiredHumoral

Immunoglobulins (Ig’s)Circulating proteins, rapid response

CellularT-cells, B cells & othersTissue response mostlyOften delayed (takes days)

Immune System ReviewVocabulary

PhagocytosisAntibodyAntigenMacrophagesanaphylaxis

Allergic SymptomsSkin

Urticaria, whealsErythema, pruritis

RespiratoryAirway edema, obstruction, stridorWheezing, asthma, dyspnea

Life-threateningAnaphylactic shock

Autoimmune DiseasesCan affect any body systemOften affect multiple systemsOften unpredictable course

Exacerbating and remitting

Examples:Ulcerative colitis, primary biliary cirrhosis, hemolytic anemia, ITP, Hashimoto’s thyroiditis, etc

Immunodeficiency Diseases

Involve impaired resistance to infectionOften have recurrent or opportunistic infectionsExamples:

AIDS, Hodgkin’s lymphoma

Nutritional DiseasesDeficiencies of some elements of diet

Vitamins, protein, minerals, etc

Excesses of some elements of dietSame as above

MalnutritionObesity

MalnutritionCondition in which body is not getting enough nutrientsVaries from mild to life-threateningVariety of etiologies:

Improper quality & quantity of foodMalabsorption, anorexia, loss of taste or smell senses, drug-food interactionsIncreased metabolism or need for fuel (certain disease states e.g. trauma, burns, cancers)

Types of MalnutritionKwashiorkor

Protein-calorie malnutrition, poor protein intake compared to calories, S/S: protuberant abdomen

MarasmusSevere malnutrition in children, mostly calorie deficiency, first year of life, disease or parasitic infestation = usual cause

StarvationLack of all/most nutrients needed to preserve life

Vitamin DeficiencyScurvy = vitamin C deficiency

Fatigue, weakness, aches, gum bleeding

Rickets = Vitamin D deficiencyBone pain & weakening, deformities

Beriberi = thiamin (B1) deficiencyDiets with polished riceNerve & cardiac damage, lassitude, anorexia

ObesityAccumulation of excess fat rather than excess weight aloneBMI (body mass index) over 30

Measure of weight relative to height

Over 50% adults and 20% children in US are overweight, 33% are obese2nd leading cause of preventable death in US (tobacco is #1)

Other categories:Idiopathic

Of unknown etiology

IatrogenicCaused by medical treatment

Vitamin DeficiencyPellegra = niacin (vit B3) deficiency

Also protein deficiency (tryptophan is an essential AA)Diet often relies on cornThe Four D’s

DiarrheaDermatitisDementiadeath