Airway Anatomy
This structure contains the vocal cords.
Larynx
This muscle beneath the lungs contracts during inhalation.
Diaphragm
These tiny air sacs are the specific site of gas exchange in the lungs.
Alveoli
Most oxygen binds to this protein in red blood cells.
Hemoglobin
This part of the nervous system helps control breathing automatically.
Brainstem
This flap helps prevent food from entering the airway during swallowing.
Epiglottis
During inhalation, lung volume increases. Pressure inside the lungs does this.
Decreases
Gases move from higher to lower concentration through this process.
Diffusion
Most carbon dioxide travels through the blood as these ions.
Bicarbonate
As working muscles produce more carbon dioxide, breathing rate does this.
Increases
These rings support the trachea and help keep it open.
Cartilage
During quiet exhalation, the diaphragm does this.
Relaxes
Gas exchange between alveoli and blood is called this.
External respiration
This finger device estimates how saturated hemoglobin is with oxygen.
Pulse oximeter
A blocked main bronchus directly reduces this entering the affected lung.
Airflow
Place these structures in order after the trachea: alveoli, bronchioles, bronchi.
Bronchi → bronchioles → alveoli
Pulling down the bottom membrane of a balloon lung model represents this action of the diaphragm.
Contraction
Oxygen leaving blood and entering a muscle cell is an example of this process.
Internal respiration
The respiratory system exchanges gases, while this body system carries them between lungs and tissues.
Cardiovascular system
After exercise, cellular activity and carbon dioxide production decrease. Breathing rate normally does this.
Decreases
Name two features of alveoli that make gas exchange efficient.
Thin walls and large surface area. (also capillaries or a short diffusion distance)
Explain why air enters the lungs when the diaphragm contracts.
Contraction increases chest/lung volume, lowering pressure below outside air pressure, so air moves inward.
At the lungs, state the direction oxygen moves and the direction carbon dioxide moves.
Oxygen: alveoli → blood. Carbon dioxide: blood → alveoli
A person’s lungs work normally, but they have fewer red blood cells. Explain why exercise may become more tiring.
Fewer red blood cells means less oxygen can be carried to muscles, limiting aerobic ATP production during exercise.
Fluid fills the alveoli during a severe infection. Explain how this can affect ATP production in body cells.
Fluid interferes with gas exchange, so less oxygen reaches body cells for aerobic ATP production.
An oxygen molecule reaches an alveolus normally, but the heart is pumping very little blood. A student claims, “The body cells will still receive enough oxygen because the lungs are working.”
Explain why the student’s claim is incorrect. Include the role of both body systems.
The respiratory system moves oxygen into the blood, but the cardiovascular system must circulate that blood to body tissues. Inadequate blood flow can reduce oxygen delivery even when lung gas exchange works normally.