Alveoli Flashcards
Lesson 6
What is diffusion?
Diffusion is the net movement of molecules from a place of higher concentration to a place with lower concentration down a concentration gradient as a result of random movement.
Difference in gas exchange in unicellular and multicellular organisms
Unicellular organisms rely on diffusion alone.
Multicellular organisms require a gas exchange system where gas exchange takes place in the alveoli.
What is an alveoli?
Alveoli are the small balloon shaped air sacs at the end of the bronchioles. They are where the lungs and blood exchange oxygen and carbon dioxide through the process of inhalation and exhalation
Adaptations of alveoli for efficient gas exchange
Thin Walls
Shorter diffusion path
Moist Lining
More efficient transporting because gases dissolve in moisture.
A rich blood supply
To absorb and carry dissolved food molecules.
Millions of Alveoli
There so as much gas exchange as possible can happen.
Large Surface Area
More surface area for absorption
Process of gas exchange in the aveoli?
A - Deoxygenated blood flows to the alveoli after delivering oxygen to the body. The blood is low on oxygen and high in concentration of carbon dioxide.
B - Carbon dioxide moves by diffusion from high concentration in the blood to low concentration in the alveoli
C - Air is exhaled.
D - Air is inhaled.
E - The blood is oxygenated by diffusion, from high concentration in the alveoli to low concentration in the blood.
F - Oxygenated blood leaves the alveoli.
How does the body keep the air clean?
Air is warmed and moistened by evaporation of water from the lining of the nose.
The hair inside the nose filters air and removes particles and pathogens.
Trachea, bronchi and bronchioles are lined with ciliated epithelial cells and mucus secreting cells so dust particles and pathogens get trapped in the slimy mucus.
Cilia beat to carry mucus up the nose and throat to remove unwanted particles.
There’s a watery salin layer that allows cilia to push mucus towards the pharynx.
