Respiration Independent Study Unit
Part 1- Breathing and Cellular Respiration
1.a) breathing- the complex exchange of gases
b) Another term to describe breathing is respiration.
2. Three things that are essential to this process are the diffusion of the oxygen and carbon dioxide between lungs
between the blood in the transport system, the transportation of oxygen and carbon dioxide by the blood to the body
cells and the diffusion of the oxygen and carbon dioxide between the blood and body cells.
3. (Figure 21.1)

4. The difference between breathing and cellular respiration is that cellular respiration is the reactions that occur in
the mitochondria, which release chemical energy from food materials, and breathing is just a complex exchange of
gases in the system.
5. Physical factors that affect gas exchange systems are the area of the cell membrane, the greater the area, the more
exchange will take place. The second one is the concentration difference. The greater the concentration in the air,
lungs and blood, the more rapid the diffusion. The third factor is diffusion distance. The rate of diffusion is in
inverse geometric ratio to the square of the distance.
6. Page 520 #5,6,7.
5. If it takes 2 seconds for an oxygen molecule to diffuse through a cell, it would take 6 seconds to pass through
three cells.
6. Drowning suffocates a person because humans cannot absorb the oxygen through water like fish; they absorb it
through air. After a while with no exchange of gases, the human stops breathing and eventually dies.
7. The surface of the lungs must be kept moist so the oxygen molecules can be transferred through it. The moisture
makes the lung a permeable membrane to the oxygen molecules.
7.a) The difference between invaginated and in envaginated respiratory systems is that invagination occurs in lungs
when the tissue folds over and envagination occurs in gills when the tissue folds out wards. An example of this is a
fish and a human.
b) A third type of respiratory surface is skin. An example of this is the frog exchanging gases through it's skin.

Part 2- Structure and Function of the Human Gas Exchange System
1. Labeled diagram.
Structure Function Chart of the Human Gas Exchange System
Structure Function
Nasal Cavity Allows oxygen to enter
Mucous Coats nasal passages
Cilia Tiny hair like projections which trap dust, bacteria and
foreign objects
Pharynx Tube connecting to mouth and gut
In invertebrates, it is where the mouth and nasal cavity meet
Trachea Where air passes through after connecting with the pharynx
Conducts air to the lungs
Esophagus Conducts food to the stomach
In absence of food, the esophagus is partially collapsed
Epiglottis A flap of tissue which prevents food from entering the trachea
Rings of Cartilage Holds up the trachea walls
Larynx Most of the air breathed in enters the larynx
It is the enlarged upper portion of the trachea
Glottis A split which can open and close depending on varying degrees
Vocal Cords Strong tissue in the larynx which vibrate to produce sound
Bronchioles A small tube which branches off from the bronchus
Alveoli A sac found at the end of a bronchiole which is surrounded by
a capillary net to allow gas exchange to take place
Pulmonary Capillaries A very small blood vessel which surrounds an alveolus and
allows gas exchange to occur
Pleura A double membrane which surrounds each lung
Diaphragm A thin layer of tissue separating the thoracic cavity from the
abdominal cavity which is involved in breathing

3. Before the incoming air reaches the respiratory surface, it is conditioned since the muscles between the rib
contracts, pulling the ribs up and out. The diaphragm contracts and pulls down. Both of these activities increase the
volume of the chest cavity. As the volume increases, air pressure in the lung decreases and atmospheric pressure in
the lungs pushes air into the lungs.
4. The path a molecule of oxygen travels from the outside atmosphere until it reaches the bloodstream is first when it
enters the human, the molecule would strike the moist coating of the alveolar wall and dissolve in this liquid. By
diffusion, it then moves through this liquid coating to the alveolar cells, to the cells of the capillaries, to the blood
plasma and then across the cell membranes of the red blood cells.
5. The structure