Micro exam 4

Structure and Function of the Skin:

  • Epidermis:

    • Outermost layer of tightly packed cells.

    • Contains keratinocytes for waterproofing.

  • Dermis:

    • Thick connective tissue with hair follicles and glands.

    • Sebum prevents drying and inhibits microbes.

    • Sweat has salt and lysozyme for microbial defense.

  • Hypodermis:

    • Subcutaneous layer with adipose and connective tissue.

Structure of the Eye:

  • Conjunctiva: Mucous membrane covering the outer eye, washed by tears containing lysozyme.

  • Rashes:

    • Exanthem (widespread, systemic symptoms).

    • Enanthem (mucous membrane involvement).

Types of Rashes:

  1. Macular: Flat, red, <1 cm.

  2. Vesicular: Small blisters.

  3. Papular: Solid, elevated.

  4. Pustular: Filled with pus.

  5. Maculopapular: Reddened papules.

Major Viral Diseases of the Skin:

  1. Measles (Rubeola):

    • Pathogen: Measles virus; highly contagious.

    • Symptoms: Flu-like, high fever, macular rash, Koplik’s spots.

    • Prevention: MMR vaccine.

  2. Chickenpox/Shingles:

    • Pathogen: Varicella-Zoster Virus.

    • Symptoms: Rash; reactivation causes shingles with painful localized rash.

    • Prevention: Vaccines (Chickenpox, Zoster).

  3. Smallpox:

    • Pathogen: Orthopoxvirus (eradicated, potential bioterrorism risk).

    • Symptoms: Rash, severe complications.

  4. Herpes Simplex Virus (HSV):

    • HSV-1: Cold sores; HSV-2: Genital herpes.

    • Symptoms: Blisters; latent infection can affect the eye.

  5. Warts (HPV):

    • Pathogen: Human papillomavirus.

    • Symptoms: Growths; linked to skin and cervical cancers.

Major Bacterial Diseases of the Skin:

  1. Staphylococcus Infections:

    • Common flora; opportunistic.

    • MRSA: Antibiotic-resistant.

    • Diseases: Folliculitis, Impetigo, Scalded Skin Syndrome, TSS.

  2. Necrotizing Fasciitis:

    • Pathogen: Streptococcus pyogenes.

    • Symptoms: Rapid tissue destruction; requires urgent treatment.

  3. Pseudomonas Infections:

    • Pathogen: Pseudomonas aeruginosa.

    • Diseases: Dermatitis, swimmer’s ear, burn infections.

  4. Acne:

    • Pathogen: Cutibacterium acnes.

    • Types: Comedonal, inflammatory, cystic.

Fungal Diseases of the Skin & Nails:

  1. Dermatomycoses (Tinea or Ringworm):

    • Pathogens: Fungi affecting scalp, nails, groin, feet.

  2. Candidiasis:

    • Pathogen: Candida albicans.

    • Diseases: Thrush, vaginitis.

Microbial Diseases of the Eye:

  1. Conjunctivitis (Pinkeye):

    • Pathogens: Haemophilus influenzae, adenoviruses, Pseudomonas spp.

  2. Ophthalmia Neonatorum:

    • Pathogen: Neisseria gonorrhoeae.

    • Prevention: Antibiotics for newborns.

  3. Trachoma:

    • Pathogen: Chlamydia trachomatis.

    • Symptoms: Eyelash turning, corneal scarring.

    • Treatment: Azithromycin.

  4. Parasitic Keratitis:

    • Pathogen: Acanthamoeba.

    • Symptoms: Severe pain, potential vision loss.

Chapter 21

Cardiovascular and Lymphatic Systems:

  • Cardiovascular System:

    • Pulmonary circuit: heart-lungs circulation.

    • Systemic circuit: heart-body circulation.

  • Lymphatic System:

    • Lymph capillaries transport interstitial fluid and immune cells.

    • Collects bacteria and infectious agents for immune response.

Viral Systemic Infections:

  1. Infectious Mononucleosis (Mono):

    • Pathogen: Epstein-Barr Virus (EBV).

    • Symptoms: Fever, sore throat, enlarged spleen, fatigue.

    • Transmission: Saliva ("kissing disease").

    • Complications: Establishes latency in B cells.

  2. Burkitt’s Lymphoma:

    • Linked to EBV and malaria.

    • Symptoms: Tumor of the jaw, airway obstruction.

    • Treatment: Chemotherapy.

  3. Ebola Virus Disease:

    • Pathogen: Ebola virus.

    • Symptoms: Severe fever, muscle pain, bleeding.

    • Transmission: Body fluids; reservoir in fruit bats.

    • Mortality rate: ~50–60%.

  4. Marburg Virus Disease:

    • Pathogen: Marburg virus.

    • Symptoms: Headache, fever, internal bleeding.

    • Transmission: Body fluids, bats, or primates.

Systemic Bacterial Infections:

  1. Sepsis and Septic Shock:

    • Sepsis: Infection-induced systemic inflammation.

    • Septic Shock: Severe hypotension with high mortality.

    • Gram-negative sepsis: Endotoxins (LPS) cause shock.

    • Gram-positive sepsis: Exotoxins or teichoic acid.

  2. Plague (Yersinia pestis):

    • Pathogen: Yersinia pestis.

    • Symptoms: Swollen lymph nodes (buboes), fever, skin discoloration.

    • Types:

      • Bubonic: Lymphatic spread, 50-75% mortality.

      • Septicemic: Bloodstream infection.

      • Pneumonic: Airborne spread, nearly 100% fatal without treatment.

  3. Anthrax (Bacillus anthracis):

    • Pathogen: Bacillus anthracis (spore-forming).

    • Types:

      • Cutaneous: Enters through skin; low mortality.

      • Gastrointestinal: From contaminated food; >50% fatal.

      • Pulmonary: Inhalation of spores; near 100% fatal.

  4. Tularemia (Rabbit Fever):

    • Pathogen: Francisella tularensis.

    • Symptoms: High fever, muscle pain, ulceration.

    • Transmission: From rodents via vectors or aerosols.

  5. Lyme Disease:

    • Pathogen: Borrelia burgdorferi.

    • Transmission: Deer tick bite.

    • Symptoms:

      • Phase 1: Bull’s-eye rash, flu-like symptoms.

      • Phase 2: Joint pain, facial paralysis.

      • Phase 3: Chronic arthritis, encephalitis.

    • Treatment: Antibiotics, harder to treat in late stages.

Systemic Parasitic Infections:

  1. Toxoplasmosis:

    • Pathogen: Toxoplasma gondii.

    • Symptoms: Minimal in healthy individuals, severe in immunocompromised.

    • Transmission: Infected cats shed spores ingested by intermediate hosts.

    • Danger: Transplacental transmission causing stillbirth or neurological damage.

  2. Malaria:

    • Pathogen: Plasmodium spp. (e.g., P. falciparum).

    • Life Cycle:

      • Mosquito bite introduces sporozoites.

      • Liver replication, release of merozoites into the blood.

      • Red blood cell infection and lysis cause symptoms.

    • Symptoms: Fever, chills, headache, vomiting.

Bacterial Infections of the Heart:

  1. Endocarditis:

    • Subacute: Alpha-hemolytic Streptococcus.

    • Acute: Staphylococcus aureus.

    • Symptoms: Impaired valve function, heart damage.

  2. Pericarditis and Myocarditis:

    • Inflammation caused by infections or toxins.

Chapter 22

Digestive System Overview

  • Main Components: Oral cavity, GI tract, salivary glands, liver, gallbladder, pancreas.

  • Defense Mechanisms:

    • Saliva: Contains lysozyme to inactivate pathogens.

    • Mucosa: Produces IgA antibodies.

    • Stomach: Acidity creates a harsh environment.

Oral Diseases

  • Dental Caries:

    • Pathogen: Streptococcus mutans (biofilm producer, Gram-positive).

    • Symptoms: Tooth pain, discoloration, enamel holes.

    • Stages: Bacteria form biofilms → acidic byproducts erode enamel → decay penetrates pulp, causing pain and potential abscesses.

    • Prevention: Brushing, flossing, reducing sugar intake.

Bacterial Diseases of the Digestive System

  • Types of Diarrhea:

    1. Osmotic: Water leaves cells due to higher intestinal osmolarity.

    2. Secretory: Electrolyte imbalance from ion secretion.

    3. Inflammatory: Damage to mucosal cells by cytokines.

    4. Motility-Related: Nutrients bypass absorption (e.g., rotavirus).

  • Common Pathogens:

  • Staphylococcus aureus: Produces enterotoxin causing rapid-onset vomiting/diarrhea.

  • Shigella: Produces Shiga toxin, causes bloody diarrhea.

  • Salmonella enterica: Causes diarrhea, nausea; linked to contaminated poultry.

  • Vibrio cholerae: Causes severe “rice-water” stool diarrhea via cholera toxin.

  • Helicobacter pylori: Survives stomach acid using urease; leads to ulcers.

Viral Diseases

  • Mumps:

    • Symptoms: Fever, swollen salivary glands.

    • Complications: Orchitis, meningitis.

    • Prevention: MMR vaccine.

  • Hepatitis:

    • Caused by Hepatitis viruses A-E.

    • Symptoms: Jaundice, dark urine, liver inflammation.

  • Rotavirus:

    • Causes diarrhea, vomiting in children.

    • Prevention: Vaccination.

Protozoan Diseases

  • Giardiasis:

    • Pathogen: Giardia intestinalis (flagellated protozoan).

    • Symptoms: Greasy stools, bloating, diarrhea.

    • Transmission: Contaminated water.

 

Chapter 23

Urinary Tract Overview

  • Components: Kidneys, ureters, bladder, urethra.

  • Functions: Waste removal, fluid and electrolyte regulation.

  • Defense Mechanisms:

    • Valves prevent backflow.

    • pH (~6-7.5) inhibits pathogens.

    • Mechanical flushing.

Urinary Tract Infections (UTIs)

  1. Cystitis (Bladder Infection):

    • Pathogens: E. coli, Klebsiella, Proteus.

    • Symptoms: Painful urination, frequent urge, inflammation.

    • Complications: Kidney infection, sepsis.

    • Diagnosis: Urinalysis (CFU > 10^5/mL).

  2. Pyelonephritis (Kidney Infection):

    • Symptoms: Fever, back pain, chills, reduced urine production.

    • Complications: Kidney necrosis, septic shock.

Reproductive Tract Overview

  • Female Anatomy: Ovaries, uterine tubes, uterus, vagina, vulva.

  • Male Anatomy: Testes, ducts, urethra, penis.

Sexually Transmitted Infections (STIs)

  1. Gonorrhea (Neisseria gonorrhoeae):

    • Symptoms:

      • Males: Painful urination, pus discharge.

      • Females: Mostly asymptomatic; possible discharge, dyspareunia.

    • Complications: PID (females), epididymitis (males).

    • Transmission: Sexual contact; childbirth (risk of infant blindness).

  2. Syphilis (Treponema pallidum):

    • Stages:

      • Primary: Chancre sores.

      • Secondary: Rash, fatigue, fever.

      • Tertiary: Neurological damage, dementia, tumors.

      • Congenital: Fetal neurological damage.

  3. Chlamydia (Chlamydia trachomatis):

    • Symptoms: Urethral itching, discharge.

    • Complications: PID (females), urethritis (males).

Viral Reproductive Infections

  1. Genital Herpes:

    • Pathogen: HSV-1, HSV-2.

    • Symptoms: Painful genital blisters, recurrent due to latent infection.

    • Complications: Neonatal herpes (60% untreated mortality).

  2. Genital Warts:

    • Pathogen: HPV.

    • Symptoms: Flesh-colored lesions, itchiness.

    • Complications: Cervical, penile, throat cancer.

    • Prevention: HPV vaccine (covers cancer-causing serotypes).

Chapter 24: Infections of the Nervous System

Key Objectives

  1. Learn the structure and function of the nervous system.

  2. Understand how pathogens bypass the blood-brain barrier.

  3. Differentiate infections by bacteria, viruses, prions, fungi, and protozoa.

Nervous System Protection

  • Structures: Brain, spinal cord, meninges, cerebrospinal fluid (CSF).

  • Barriers: Skull, meninges, blood-brain barrier.

  • Challenges: Inflammation compromises barriers, enabling pathogen entry.

Common CNS Infections

  1. Bacterial Meningitis:

    • Pathogens:

      • Haemophilus influenzae (common in children).

      • Neisseria meningitidis (outbreaks in close quarters).

      • Streptococcus pneumoniae (most common).

    • Symptoms: Fever, severe headache, stiff neck.

    • Complications: Brain damage, hearing loss, death.

    • Prevention: Vaccination.

  2. Leprosy (Mycobacterium leprae):

    • Symptoms: Skin patches, nerve damage.

    • Forms: Tuberculoid (mild), Lepromatous (severe).

  3. Tetanus (Clostridium tetani):

    • Symptoms: Muscle spasms, lockjaw.

    • Prevention: Tdap vaccine.

  4. Botulism (Clostridium botulinum):

    • Symptoms: Flaccid paralysis, difficulty breathing.

    • Causes: Contaminated food, improper canning.

Chapter 24

Bacterial Neurotoxins

  1. Tetanus (Clostridium tetani):

    • Pathogen: Gram-positive, anaerobic, endospore-forming.

    • Symptoms: Muscle spasms, lockjaw, respiratory failure.

    • Transmission: Deep puncture wounds.

    • Prevention: Tdap vaccine.

  2. Botulism (Clostridium botulinum):

    • Pathogen: Produces botulinum toxin causing flaccid paralysis.

    • Symptoms: Muscle weakness, difficulty swallowing, respiratory failure.

    • Transmission: Contaminated food, improper canning.

    • Infant Botulism: Associated with raw honey consumption.

    • Prevention: Proper food handling.

Viral Diseases of the CNS

  1. Poliomyelitis (Polio):

    • Pathogen: Poliovirus.

    • Symptoms: Flaccid paralysis, respiratory failure (severe cases).

    • Transmission: Fecal-oral, person-to-person contact.

    • Prevention: Vaccination.

  2. Rabies:

    • Pathogen: Rabies virus (neurotropic).

    • Symptoms:

      • Early: Itching at bite site, fever, nausea.

      • Late: Encephalitis, hallucinations, hydrophobia, paralysis.

    • Transmission: Mammalian bite, saliva contact.

    • Prevention: Postexposure prophylaxis.

  3. Arboviral Encephalitis (e.g., West Nile, EEE):

    • Pathogen: Arthropod-borne viruses.

    • Symptoms: Polio-like paralysis, fatal encephalitis (severe cases).

    • Transmission: Mosquitoes.

    • Complications: High mortality in severe cases (EEE 35%).

  4. Zika Virus:

    • Pathogen: Zika virus.

    • Symptoms: Fever, rash, mild illness (in most cases).

    • Complications: Microcephaly in infants if contracted during pregnancy.

    • Transmission: Mosquito bites, sexual contact.

Fungal CNS Infections

  1. Cryptococcosis (Cryptococcus neoformans):

    • Pathogen: Soil fungus with a thick capsule.

    • Symptoms: CNS invasion in immunocompromised individuals (e.g., AIDS).

    • Transmission: Inhalation of contaminated soil particles.

    • Treatment: Antifungal medications (amphotericin B).

Protozoan Diseases

  1. African Sleeping Sickness (Trypanosoma brucei):

    • Pathogen:

      • T. b. gambiense (human reservoir).

      • T. b. rhodesiense (animal reservoir).

    • Symptoms:

      • Early: Fever, lymph node swelling.

      • Late: CNS involvement, sleep disturbances, coma.

    • Transmission: Tsetse fly bite.

    • Complications: 100% fatal if untreated.

Prion Diseases

  1. Creutzfeldt-Jakob Disease (CJD):

    • Cause: Misfolded proteins (prions).

    • Symptoms:

      • Early: Memory loss, coordination issues.

      • Late: Severe mental deterioration, blindness, coma.

    • Transmission: Contaminated animal products, spontaneous cases.