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Respiratory System Short Answer Review ANSWERS
1. Explain the difference between breathing and respiration.
Breathing is the inhalation and exhalation of air while respiration involves breathing as
well as the transport of gases for internal respiration, external respiration and cellular
respiration.
2. Know the pathway of air going in and out of the lungs
INTO LUNGS: Nostril / mouth ènasal cavity / oral cavity è pharynx èepiglottis
èglottisèlarynxè trachea è bronchi è bronchioles è alveoli
OUT OF LUNGS: reverse order from above
3. Know the respiratory diagram. Be able to explain the structure and function of each part.
4. Why do we breathe?
We breathe so we can get oxygen for our cells to make ATP and so that CO2 can be
removed from our body
5. What happens to the air that we breathe in when it passes through the nasal cavities?
It is warmed, filtered and moistened
6. What are pleural membranes? Why are they important?
Two membranes that surround the lungs – the outer membrane is attached to the
thoracic cavity and the inner membrane is attached to the lung. The membranes are
filled with fluid. These serve to reduce friction and abrasion of the lungs
7. What is the thoracic cavity?
An airtight space surrounded by the ribcage – upper part of the body.
8. How are the lungs kept clean?
Mucous in the respiratory tract traps dust, pollen and debris while the cilia sweep the
mucous with the debris out of the lungs to the pharynx where it can be swallowed and
removed from the body.
9. What is meant by negative pressure breathing?
This is where the pressure inside the lungs decreases (due to the lungs being pulled
open and the thoracic cavity made larger) so that it is less than the atmospheric
pressure outside of the body. The air is then forced into the lungs.
10. What are the steps of inhalation / inspiration?
• The diaphragm & the intercostal muscles contract.
• This causes the diaphragm to flatten and the ribcage to move up & out
• This pulls open the lungs and expands the thoracic cavity
• The pressure inside the lungs & thoracic cavity decreases so they are less than
the atmospheric pressure
• Air is forced into the lungs.
11. What are the steps of exhalation / expiration?
• The diaphragm & intercostal muscles relax
• This causes the diaphragm to return to its dome shape and the ribcage to move
down & in
• This results in the lungs recoiling to their original size and the thoracic cavity
returning to it original size.
• The pressure inside the lungs & thoracic cavity increases so they are greater than
the atmospheric pressure
• Air is then forced out of the lungs.
12. What are vital capacity, reserve volume, and dead air space?
• Vital capacity= the maximum volume of air that can be moved in and out of the
lungs in one breath
• Reserve volume= the amount of air that can be forced into or out of the lungs in
addition to your normal breath
• Dead air space= air in the respiratory system that is not involved in gas
exchange.
13. How is breathing controlled?
• Inhalation= chemoreceptors in the medulla oblongata, carotid bodies, & aortic
bodies which detect high concentrations of CO2 & H+ molecules. When the [CO2]
& [H+] reach the critical level, the medulla oblongata causes the contraction of the
diaphragm & intercostal muscles so that inhalation occurs
• Exhalation= stretch receptors in the alveoli send a message to the medulla
oblongata to stop the contraction of the diaphragm & intercostal muscles. These
muscles then relax so that exhalation occurs.
14. Explain the process of external respiration. Where does it occur and know the associated
equations?
• This is where gas exchange occurs between the pulmonary capillaries and the
alveoli
• O2 diffuses into the pulmonary capillaries from the alveoli and CO2 diffuses into
the alveoli from the pulmonary capillaries.
• The temperature is lower at the lungs, the pH is higher and the pressure is low.
These conditions cause the hemoglobin to accept oxygen & release carbon
dioxide and hydrogen ions.
• The equations are:
o HHb → H+ + Hb
o Hb + O2 → HbO2
o HbCO2 → Hb + CO2
o H+ + HCO3- → H2CO3 → CO2 + H2O
15. Explain the process of internal respiration. Where does it occur and know the associated
equations?
• This is where gas exchange occurs between the blood capillaries of the systemic
system and the systemic tissues of the body
• O2 diffuses from the blood capillary into the surrounding tissue/ ECF and CO2
diffuses from the ECF into the blood capillary
• The temperature is higher at the tissues, the pH is lower (7.3) and the pressure is
high. These conditions cause the hemoglobin to accept carbon dioxide and
hydrogen ions & release oxygen.
• The equations are:
o H+ + Hb → HHb
o HbO2 → O2 + Hb
o Hb + CO2 → HbCO2
o CO2 + H2O → H2CO3→ H+ + HCO3-
16. What is the function of carbonic anhydrase?
It is an enzyme present in the red blood cells that catalyzes / speeds up the formation of
carbonic acid from either: water and carbon dioxide or hydrogen ions and bicarbonate
ions.