What is the Respiratory System?
The respiratory system is the group of organs — nose, pharynx, larynx, trachea, bronchi and lungs — that move air in and out of the body and exchange oxygen for carbon dioxide. It also helps regulate blood pH and enables speech.
The respiratory system brings air through the airway pathway into the alveoli of the lungs, where oxygen diffuses into the blood and carbon dioxide diffuses out, driven by pressure changes from the diaphragm and intercostal muscles.
- 1↓Nose / mouthAir is warmed, humidified and filtered as it enters.
- 2↓Pharynx & larynxShared passage for air and food; the larynx houses the vocal cords.
- 3↓TracheaCartilage-ringed windpipe carrying air to the lungs.
- 4↓Bronchi & bronchiolesBranching airway tree distributing air throughout each lung.
- 5AlveoliTiny air sacs where O₂ and CO₂ are exchanged with the blood.
Try it: interactive calculator
Step-by-step worked examples
A resting adult has a tidal volume of 500 mL and breathes 12 times per minute. Find the minute ventilation.
VE = TV × RR VE = 500 mL × 12 breaths/min VE = 6000 mL/min = 6 L/min
During exercise, tidal volume rises to 800 mL and respiratory rate to 25 breaths/min. Find the new minute ventilation.
VE = TV × RR VE = 800 × 25 VE = 20,000 mL/min = 20 L/min
A patient's minute ventilation is measured at 9000 mL/min with a respiratory rate of 18 breaths/min. Find the tidal volume.
VE = TV × RR → TV = VE / RR TV = 9000 / 18 TV = 500 mL
Flashcards
Quick quiz
Q1.Where does oxygen diffuse into the bloodstream?
Q2.What is the formula for minute ventilation?
Q3.Which muscle contracts and flattens to increase chest volume during inhalation?
Q4.Which respiratory tract structures are considered 'upper' airway?
The full card deck, worked steps and AI-tutor support for “What is the Respiratory System?” are in Notek — study by hand before your exam.
Common mistakes
Thinking gas exchange happens in the trachea or bronchi. — Correct: Those are just conducting airways; gas exchange only occurs in the alveoli.
Believing the lungs actively pump air like a muscle. — Correct: Lungs are passive; the diaphragm and intercostal muscles create the pressure changes that move air.
Assuming a higher respiratory rate always means healthier breathing. — Correct: Minute ventilation depends on both rate AND tidal volume — shallow fast breaths can under-ventilate.
Confusing tidal volume with total lung capacity. — Correct: Tidal volume is air moved in one normal breath (~500 mL); total lung capacity is much larger (~6 L).
FAQ
What is the respiratory system?
It is the organ system — airway plus lungs — responsible for moving air and exchanging oxygen and carbon dioxide with the blood.
What is the minute ventilation formula?
VE = TV × RR: tidal volume multiplied by respiratory rate, giving air volume moved per minute.
What are examples of the respiratory pathway?
Air travels: nose/mouth → pharynx → larynx → trachea → bronchi → bronchioles → alveoli.
How do you calculate minute ventilation?
Multiply tidal volume (mL per breath) by respiratory rate (breaths per minute), e.g. 500 mL × 12 = 6000 mL/min.