Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Breathing is a physical process that involves two steps: Inhalation (taking in air rich in ) and Exhalation (giving out air rich in ).
The respiratory system in humans includes the nostrils, nasal cavity, windpipe (trachea), and lungs, which are situated in the chest cavity.
The chest cavity is surrounded by ribs on the sides, and a large, muscular sheet called the diaphragm forms the floor of the chest cavity.
During inhalation, the ribs move up and outwards, while the diaphragm moves down. This increases the volume of the chest cavity and decreases air pressure, causing air to rush into the lungs.
During exhalation, the ribs move down and inwards, while the diaphragm moves up to its relaxed position. This decreases the volume of the chest cavity and increases air pressure, pushing air out of the lungs.
The inhaled air contains approximately and , while exhaled air contains approximately and .
Sneezing occurs when we inhale dust or foreign particles; the body expels these particles to ensure only clean air enters the lungs.
📐Formulae
💡Examples
Problem 1:
Calculate the breathing rate of an individual who is found to take breaths over a duration of minutes.
Solution:
Explanation:
The breathing rate is defined as the number of times a person breathes in one minute. By dividing the total breaths by the total time, we get the rate per minute.
Problem 2:
Compare the percentage of in inhaled air versus exhaled air.
Solution:
Inhaled air contains , while exhaled air contains .
Explanation:
During cellular respiration, oxygen is used to break down glucose, resulting in the production of carbon dioxide. Therefore, the air we breathe out has a much higher concentration of than the air we breathe in.
Problem 3:
What physical changes occur in the chest cavity to facilitate the movement of air out of the lungs?
Solution:
The ribs move down and inwards, and the diaphragm moves up to its original position.
Explanation:
These movements reduce the space in the chest cavity, which increases the air pressure inside the lungs relative to the outside atmosphere, forcing the air out.