11.2: The Human Respiratory System
1. Add the missing labels to the diagram below. [k/u]
The movement of air into the Lungs:
1. Air enters the respiratory system through the nostrils or the mouth.
2. Inside the nasal passage air is warmed and moistened. Cilia cleanse it of dust.
3. The warm, moist air passes through the pharynx into the glottis and the larynx.
The epiglottis closes when you swallow to keep food from entering the glottis.
4. Air passing through the larynx produces sound as you exhale – your voice.
5. The flexible trachea is strengthened and held open with rings of cartilage.
6. Two bronchi carry air from the trachea to the lungs.
7. Air travels through microscopic bronchioles to 50 million tiny sacs called
alveoli in the lungs, where gas exchange occurs. Each alveolus is surrounded
by network of capillaries. The walls of the alveolus and of the capillaries are
only one cell thick, and gases can diffuse easily between them.
Label the diagram:
11.2: Gas Exchange & Transport
During external respiration, oxygen and carbon dioxide diffuse between the air in
the alveoli and the blood in the capillaries that surround the alveoli.
Blood which enters the alveoli is deoxygenate (low in oxygen) by high in carbon
dioxide. Carbon diffuses into the alveoli from the capillary and oxygen diffuses
from the alveolus into blood in the capillary. The blood is now oxygenated (high
in oxygen).
Blood contains red blood cells which contain a large concentration of hemoglobin
molecules. Hemoglobin increases the ability of blood to carry oxygen.
Blood then transports oxygen to the all the tissues and cells that make up the body.
1. Imagine a person enters an environment where the concentration of oxygen is
very low. How might that affect their respiratory process? [App]
2. Think back to chapter 10. What essential nutrient can help ensure that our
cells get oxygen they need? How does this nutrient help? [App]