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9 multiple-choice questions and 5 flashcards on Respiratory System, about 6% of the HS Anatomy & Physiology bank. Every one carries a written rationale.
Respiratory System is one of 13 chapters in CoStudy's HS Anatomy & Physiology bank, and it holds 9 of the bank's 150 multiple-choice questions — roughly 6% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.
Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.
5 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.
Blood components include:
Answer: E — Plasma (~55%, water + proteins + electrolytes), red blood cells (RBCs, carry O₂ via hemoglobin), white blood cells (WBCs, immunity), platelets (clotting)
Blood: liquid connective tissue. Plasma (water, proteins like albumin, fibrinogen, antibodies, hormones, nutrients). Formed elements: RBCs (~99%, hemoglobin, ~120 day lifespan), WBCs (various types: neutrophils, lymphocytes, etc.), platelets (clotting). Total ~5L in adult.
The primary site of gas exchange in the lungs is the:
Answer: C — Alveolus — thin-walled sacs where O₂ and CO₂ diffuse with capillary blood
C) ~300 million alveoli provide the diffusion surface. A/B/D) Conducting airways, not the exchange surface.
The heart has how many chambers?
Answer: B — Four — right atrium, right ventricle, left atrium, left ventricle (two atria receive, two ventricles pump)
Four chambers: blood enters atria, fills ventricles, ventricles pump out. Right side: deoxygenated blood to pulmonary circulation. Left side: oxygenated to systemic. Septum prevents mixing. Valves prevent backflow (tricuspid, mitral, pulmonary, aortic).
During inhalation, the diaphragm:
Answer: B — Contracts and flattens (moves down), increasing chest volume so air flows in
B) Active contraction → larger thoracic volume → lower pressure → air in. A) Reverses the cycle (this is exhalation). C/D) Physiologically incorrect.
Which respiratory structure is the actual site of gas exchange between air and blood?
Answer: D — Alveoli
D) Alveoli are thin-walled sacs surrounded by capillaries — site of O₂/CO₂ exchange. A–C) Are conducting airways only.
3 cards from the 5 in this chapter.
Adrenal glands?
On top of kidneys. Cortisol (stress, metabolism), aldosterone (Na/K balance), epinephrine (fight-or-flight).
Interactive respiratory system — hover any structure.
The respiratory system moves air in and out of the body for gas exchange (O2 in, CO2 out). Upper airway: nasal cavity, oral cavity, pharynx, larynx. Lower airway: trachea → 2 primary bronchi → 5 secondary bronchi → bronchioles → ~300 million alveoli per lung. Gas exchange happens across the thin (~0.5 μm) alveolar-capillary membrane. The diaphragm contracts (flattens) during inhalation, expanding thoracic volume so air rushes in (Boyle's law).
Pituitary gland?
"Master gland." Releases hormones controlling other endocrine glands. Hangs from hypothalamus.
These are a sample. The full Respiratory System chapter runs 14 items with per-chapter progress tracking, on the web and in the iOS app.
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