PLTW Medical Interventions - EoC Study Guide

Medical Interventions

Any measure or action taken to improve health, prevent or treat disease, or alter the course of a medical condition.

Preventive Interventions

Measures taken to prevent disease, including vaccinations and public health efforts.

Vaccinations

Introduce antigens to elicit an immune response.

Public health efforts

Sanitation, hygiene education, quarantine measures.

Diagnostic Interventions

Measures used to diagnose diseases, including lab tests and imaging.

Lab tests

Tests such as ELISA, PCR, and blood cultures used for diagnosis.

Imaging

Techniques like X-rays, MRIs, and CT scans used to visualize internal structures.

Therapeutic Interventions

Measures taken to treat diseases, including antibiotics and surgical procedures.

Antibiotics

Medications used to treat bacterial infections.

Surgical procedures

Operations such as removal of tumors and organ transplants.

Gene therapy

Inserting corrected genes to treat disorders.

Rehabilitative Interventions

Measures aimed at recovery, including physical therapy and prosthetic limbs.

Pharmaceutical Interventions

Medications such as antivirals, antifungals, and chemotherapy.

Genetic Interventions

Techniques like CRISPR, RNA interference, and Preimplantation Genetic Diagnosis (PGD).

Technological Interventions

Assistive devices like cochlear implants and wheelchairs.

Outbreak Investigation

Identifying the source and path of transmission of infectious diseases.

Contact Map

A graphical tool that illustrates how infected individuals interacted with others.

Index case

First documented patient (Patient Zero) in an outbreak.

Epidemiological Triangle

Model consisting of agent (pathogen), host (human), and environment (conditions favoring spread).

DNA Sequencing

Determines the exact nucleotide sequence (A, T, C, G) in a DNA sample.

BLAST

Basic Local Alignment Search Tool that identifies species causing illness from DNA sequences.

Serial Dilutions

Used to quantify concentration of a solution by stepwise dilution.

ELISA

Enzyme-Linked Immunosorbent Assay that detects presence and amount of a specific antigen or antibody.

Bacterial Cell Structures

Components of bacteria, including capsule and cell wall.

Capsule

Structure that prevents desiccation and helps evade immune response.

Cell wall

Structure that provides support and protection to bacterial cells.

Gram-positive

Bacteria with a thick peptidoglycan layer that stains purple.

Gram-negative

Thin peptidoglycan + outer membrane (lipopolysaccharides), stains pink.

Plasma membrane

Controls what enters/leaves.

Plasmid

Small circular DNA; often contains resistance genes.

Ribosomes (70S)

Protein synthesis.

Flagella

Motility.

Pili

Attachment and genetic transfer (conjugation).

β-Lactams

Inhibit cell wall synthesis; effective mostly against Gram-positive bacteria.

Tetracyclines

Block tRNA from binding ribosome → inhibits protein synthesis; broad spectrum.

Fluoroquinolones

Inhibit DNA gyrase → block DNA replication; especially effective for UTIs, respiratory infections.

Sulfonamides

Competitive inhibitors of PABA → disrupt folic acid synthesis (essential for DNA synthesis).

Aseptic Technique

Prevents contamination during lab procedures; includes sterilizing surfaces, using gloves, flaming instruments, proper waste disposal.

Enzymatic Degradation

β-lactamase enzymes destroy β-lactam antibiotics.

Efflux Pumps

Actively pump antibiotics out of the cell.

Target Modification

Mutation in ribosome or enzyme binding site prevents antibiotic from attaching.

Biofilm Formation

Bacteria in biofilms are harder to penetrate and more resistant.

Conjugation

Plasmid transferred via pilus from donor to recipient; often carries resistance genes.

Transformation

Uptake of free DNA fragments from environment.

Transduction

Transfer of DNA via bacteriophage (virus infecting bacteria).

Antibiotic Regime

A prescribed plan for dosage and duration.

Stages of Bacterial Death

1. Highly sensitive bacteria: Killed quickly. 2. Intermediate bacteria: Take longer to die. 3. Resistant bacteria: Survive if antibiotics are stopped too early.

Pinna (Auricle)

Captures sound waves.

Auditory Canal

Funnels sound to tympanic membrane.

Tympanic Membrane (Eardrum)

Vibrates from sound waves.

Ossicles

Smallest bones: Malleus (hammer), Incus (anvil), Stapes (stirrup); amplify and transmit vibrations to the oval window.

Cochlea

Snail-shaped, fluid-filled organ; vibrations cause fluid movement → stimulates hair cells (mechanoreceptors).

Auditory Nerve (CN VIII)

Sends impulses to temporal lobe of brain.

Types of Hearing Loss

Conductive: Problem with outer/middle ear. Sensorineural: Problem in inner ear or nerve. Mixed: Combination of both.

Rinne Test

Compares air conduction (AC) to bone conduction (BC); normal: AC > BC.

Weber Test

Tuning fork placed mid-forehead; sound lateralizes toward affected ear = conductive loss, toward unaffected ear = sensorineural loss.

Pure-Tone Audiometry

Measures threshold (softest sound detected); frequencies tested: 250 Hz - 8000 Hz.

Audiogram

Graph of hearing ability; normal: 0-20 dB, mild loss: 20-40 dB, moderate: 40-60 dB, severe: 60-80 dB, profound: 80+ dB.

Hearing Aids

Amplify sound.

Cochlear Implants

Convert sound → electrical signals sent to cochlea.

Bone-Anchored Hearing Aid (BAHA)

For conductive/mixed loss.

Tympanoplasty

Eardrum repair.

Ossiculoplasty

Replacing ossicles.

Vaccination

Introduces an antigen to stimulate an immune response.

Primary Response

First exposure; slower, weaker response.

Secondary Response

Faster, stronger due to memory B-cells.

Active Immunity

Natural (infection) or Artificial (vaccine).

Passive Immunity

Natural (maternal antibodies) or Artificial (antibody injection).

Live Attenuated Vaccine

Weakened pathogen; long-lasting immunity; risky for immunocompromised patients.

Inactivated (Killed) Vaccine

Pathogen is killed; safer but may need boosters.

Toxoid Vaccine

Inactivated bacterial toxins; used for diseases like tetanus.

Subunit/Conjugate Vaccine

Parts of pathogen (proteins, sugars); low risk of side effects.

mRNA Vaccines

Use messenger RNA to encode antigens (e.g., COVID-19 vaccines).

Recombinant DNA Technology

Combine DNA from multiple sources and insert gene of interest into a plasmid vector.

Attack Rate Calculation

\text{Attack Rate} = \left(\frac{\text{Number of new cases}}{\text{Number of people at risk}}\right) \times 100

Cohort Study

Follows exposed vs. unexposed groups over time; prospective.

Case-Control Study

Starts with people who already have the disease; looks backward to assess exposure; retrospective.

Single-Gene Disorders

Include Dominant (Huntington's), Recessive (Cystic fibrosis), X-linked (Hemophilia).

Multifactorial Disorders

Result from multiple genes + environment (e.g., Heart disease, diabetes).

Chromosomal Disorders

Whole/partial chromosomes affected (e.g., Down syndrome = Trisomy 21).

Mitochondrial Disorders

Passed from mother (e.g., Leber's hereditary optic neuropathy).

Polymerase Chain Reaction (PCR)

Purpose: Amplify DNA.

PCR Steps

1. Denaturation (95°C): DNA strands separate. 2. Annealing (50-65°C): Primers bind. 3. Extension (72°C): Taq polymerase adds nucleotides.

SNP

Single base pair variation; can alter enzyme recognition site.

Restriction Enzymes

Cut DNA at specific sequences; cut or no-cut reveals allele present.

Gel Electrophoresis

DNA migrates through agarose gel; smaller fragments travel further; visualize bands with dye.

Prenatal Genetic Testing

Screenings: Non-invasive; Maternal serum analysis, nuchal translucency (ultrasound). Diagnostics: Amniocentesis and Chorionic Villus Sampling (CVS).

Gene Therapy

Altering genes to treat or cure disease.

CRISPR-Cas9

Cas9 = enzyme that cuts DNA; Guide RNA = matches target sequence; enables precise gene editing.

PGD (Preimplantation Genetic Diagnosis)

Performed during IVF; screen embryos for genetic abnormalities before implantation.

Blastomere biopsy

Use blastomere biopsy at 8-cell stage to avoid implantation of affected embryos.

Risk Factor

A risk factor is any attribute, characteristic, or exposure that increases the likelihood of developing a disease.

Types of Risk Factors

Risk factors are categorized into Behavioral, Environmental, Biological/Genetic, Infectious, Modifiable, and Non-modifiable.

Behavioral Risk Factors

Includes smoking, alcohol use, UV exposure, and diet.

Environmental Risk Factors

Includes radiation, pollutants, and workplace exposure.

Biological/Genetic Risk Factors

Includes family history and inherited mutations (e.g., BRCA1).

Infectious Risk Factors

Includes HPV, Hepatitis B and C.

Modifiable Risk Factors

Changeable factors such as diet and lifestyle.

Non-modifiable Risk Factors

Factors that cannot be changed, such as age and genetics.

X-Ray

Best for bone fractures and some tumors; passes radiation through body; dense tissues absorb more, appearing white.