10 Questions
What is the primary function of gas exchange in humans?
To provide oxygen needed for cellular respiration and to remove waste gas
What is the term for the exchange of gases between an animal and its environment?
Bulk gas exchange
What is the site of gas exchange in the lungs?
Alveoli
What is the role of hemoglobin in the transport of oxygen?
To transport oxygen from the lungs to the body's tissues
What is the term for the pathway that air follows as it enters the respiratory system?
Pathway of air
What happens to the chest cavity volume during inhalation?
It increases
What is the function of the medulla oblongata in controlling breathing?
To monitor the pH of the cerebrospinal fluid
How many molecules of O2 can each hemoglobin molecule carry?
4
What happens to the diaphragm during exhalation?
It relaxes
What happens to the air pressure inside the lungs during inhalation?
It decreases
Study Notes
Gas Exchange in Humans
- Gas exchange involves breathing, transport of gases, and exchange with body cells to provide oxygen for cellular respiration and remove waste CO2.
- The process involves inhalation, transport, and exchange of gases between the environment and body cells.
Pathway of Air
- Air enters the respiratory system through the nostrils, where it is filtered, warmed, and humidified in the nasal cavity.
- Air then passes through the pharynx, a common passageway for air and food, and into the larynx, which contains vocal cords.
- The trachea, a tube with cartilage rings, leads to the bronchi, which branch into smaller bronchioles that eventually dead-end into alveoli, tiny grape-like clusters of air sacs.
Gas Exchange in Alveoli
- Alveoli are surrounded by blood capillaries, where gas exchange occurs through diffusion.
- Oxygen diffuses into the blood and carbon dioxide diffuses out of the blood into the alveoli.
Ventilation by Negative Pressure Breathing
- Ventilation occurs through negative pressure breathing, which creates a pressure gradient by changing the volume of the lungs.
- During inhalation, the diaphragm contracts, the rib cage expands, and air moves in due to the decrease in air pressure inside the lungs.
- During exhalation, the diaphragm relaxes, the rib cage gets smaller, and air pressure increases, pushing air out of the lungs.
Control of Breathing
- Breathing is controlled by involuntary mechanisms, with the medulla oblongata in the brain regulating breathing rhythm.
- Sensors in the medulla monitor the pH of cerebrospinal fluid, responding to changes in CO2 levels.
- When CO2 levels rise, the medulla increases breathing rate and depth to eliminate excess CO2 and maintain homeostasis.
Hemoglobin and Gas Transport
- Hemoglobin, an iron-containing pigment in red blood cells, carries oxygen and helps transport carbon dioxide.
- Each hemoglobin molecule can bind to four oxygen molecules, which bind to the four iron atoms.
- Hemoglobin also helps buffer the blood by binding to excess hydrogen ions.
Learn about the respiratory system, including gas exchange, breathing, and transport of oxygen and carbon dioxide in the human body.
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