Scientific Concepts: Infection Control, Anatomy, and Chemistry
What this domain covers
Three subjects appear as separate question clusters: infection control, anatomy and physiology, and chemistry.
Infection control. Know the chain of infection (pathogen, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host) and the shapes of bacteria: cocci (round), bacilli (rod), spirilla (spiral). Viruses cause hepatitis and HIV; fungi cause tinea; parasites include pediculosis. Learn the three levels of decontamination. Cleaning uses soap and water to remove debris. Disinfection uses chemicals to kill most microorganisms on nonporous surfaces. Sterilization destroys all microbial life, including spores, through an autoclave, dry heat, or a chemical sterilant. EPA-registered hospital disinfectants carry labels such as bactericidal, fungicidal, virucidal, and pseudomonacidal; the tuberculocidal claim matters for blood and body-fluid cleanup. Standard Precautions means treating every client's blood and body fluids as infectious.
Anatomy. Review the layers of the skin (epidermis, dermis, subcutaneous), the bones of the cranium and face, and the major muscles of the head and neck (frontalis, temporalis, masseter, occipitalis, sternocleidomastoid, trapezius). For nerves, the trifacial (trigeminal) is the chief sensory nerve of the face and the facial nerve is the chief motor nerve.
Chemistry. The pH scale runs 0 to 14 with 7 neutral and is logarithmic. Distinguish solutions, suspensions, and emulsions by how particles are dispersed. Oxidation-reduction reactions drive haircolor and neutralizers.
Traps and a rule of thumb
Questions swap disinfection for sterilization, trigeminal for facial nerve, and bacilli for cocci. Rule of thumb: porous plus blood equals discard - if an item cannot be fully contacted by disinfectant, it cannot be disinfected. Example: 10-volume developer is about 3% hydrogen peroxide and 20 volume is about 6%; the numbers scale the peroxide concentration, not a guaranteed amount of lift.