Gas Exchange in Animals

Question 1

What is diffusion?

Answer 1

The movement of particles down a concentration gradient. Particles move passively until gradient is zero.

Question 2

What does it mean to move DOWN the concentration gradient?

Answer 2

to move from a high to low concentration

Question 3

Organisms exchange gases, nutrients, and waste with the environment. Which life processes are each of these for?

Answer 3

gases - respiration/photosynthesis
nutrients - metabolism/growth
waste - excretion

Question 4

Describe the properties of exchange surfaces/

Answer 4

1. Thin: usually one cell thick for rapid diffusion
2. Moist: materials dissolve in water when diffusing.
3. Large Surface Area: increase potential diffusion.
4. Concentration gradient: maintained so that passive diffusion can continue.

Question 5

After being inhaled, where does air travel (and in what order) before it arrives at the alveoli?

Answer 5

It is directed down the trachea, and into the bronchi and bronchioles

Question 6

Where do gases diffuse between in the lungs?

Answer 6

the alveoli and blood capillaries.

Question 7

What gases are diffused in the human respiratory system?

Answer 7

oxygen from the air and carbon dioxide from the blood.

Question 8

What stages does ventilation consist of?

Answer 8

inspiration and expiration.

Question 9

Describe the process of inspiration.

Answer 9

1. intercostal muscles move ribcage upwards and outwards causing the chest to expand
2. diaphragm contracts and flattens, increasing the lungs’ volume and decreasing their air pressure.
3. Air flows from the atmosphere (higher pressure) to the lungs (lower pressure).

Question 10

Describe the process of expiration

Answer 10

1. the intercostal muscles move the ribcage downwards and inwards causing the chest to contract.
2. the diaphragm relaxes and moves upwards, decreasing the volume of the lungs and increasing the air pressure inside the lungs.
3. air flows from the lungs (higher pressure) to the atmosphere (lower pressure).