B1- Exchange Substances Flashcards
What is the primary function of the lungs?
To transfer oxygen to the blood and remove waste carbon dioxide from it
What are the tiny air sacs in the lungs where gas exchange occurs called?
Alveoli
List the four adaptations of alveoli that maximize gas diffusion.
- An enormous surface area (about 75 m² in humans)
- A moist lining for dissolving gases
- Very thin walls
- A good blood supply
What is the role of villi in the small intestine?
To increase the surface area for quicker absorption of digested food into the blood
What type of cells cover the surface of the villi?
A single layer of surface cells
True or False: Villi have a poor blood supply to assist in absorption.
False
How does digested food move into the blood?
By diffusion and by active transport
What are the two types of muscle present in the small intestine?
- Circular muscle
- Longitudinal muscle
Fill in the blank: The lungs contain millions of little air sacs called _______.
alveoli
What is the approximate surface area of alveoli in humans?
About 75 m²
What is the significance of the moist lining in alveoli?
It helps in dissolving gases
What is the main purpose of the good blood supply in alveoli and villi?
To assist quick absorption
Which gases are exchanged in the alveoli?
- Oxygen
- Carbon dioxide
What is the primary function of the villi in the small intestine?
To increase absorption efficiency of digested food
