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Chapter 11 – Respiration Worksheet Assignment KEY
TOTAL MARKS = 20
(0.5 each, unless otherwise stated)
1. Inspiration and expiration are involved in the process of _breathing_.
2. During inspiration, the rib cage moves up and _out_; the diaphragm moves _down_.
3. The primary stimulus for breathing is the amount of _carbon dioxide and Hydrogen ion
(CO2 & H+)_in the blood.
4. Oxygen moves from the alveoli to the capillaries by means of _diffusion_.
5. Carbon dioxide is carried in the plasma as the _bicarbonate_ion.
6. Hemoglobin readily takes up oxygen in the lungs, where the pH is _lower_and the
temperature is _cooler_.
7.
At the tissues, _oxygen (O2)_diffuses out of the blood and _carbon dioxide
(CO2)_diffuses into the blood.
8. In which structures does gas exchange actually occur? _capillaries_
9. When food is swallowed, the respiratory passage is closed off. How are the nasal
passages closed off?(1 mark) __by movement of the soft palate up to close off the
nasopharynx and subsequently the nasal cavity_
10. How is the trachea (larynx) closed off? (1 mark) __during swallowing, the epiglottis is
pushed down to cover the glottis which prevents food from entering the trachea_
11. Indicate whether the following phrases describe INSPIRATION or EXPIRATION:
i) lungs expanded
_ INSPIRATION _
ii) muscles (diaphragm and ribs) relaxed
_ EXPIRATION _
iii) diaphragm dome-shaped
_ EXPIRATION __
iv) chest enlarged
__ INSPIRATION __
v) less air pressure in lungs than environment
_ INSPIRATION _
13. Put these statements in the proper sequence:
Event
a Respiratory center stops sending messages to diaphragm and rib
muscles
b Respiratory center sends excitatory message to diaphragm and rib
muscles
c Diaphragm becomes dome-shaped and rib muscles relax
d Chest expands as diaphragm goes down and rib cage goes out.
e Air goes rushing out as lungs recoil.
f
Air comes rushing in as lungs expand
g Expanded lungs send message to respiratory system
Correct sequence: _b  d  f  g  a  c  e_ (1 mark)
14. Where does oxygen enter the blood? _at alveoli and pulmonary capillaries_. Where
does oxygen leave the blood? _at tissue cells and systemic capillaries_
15. Where does carbon dioxide enter the blood? _ at tissue cells and systemic capillaries
_Where does it exit from the blood? _ at alveoli and pulmonary capillaries _
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18.
A person was brought to the emergency room unconscious. Breathing was shallow
and irregular. A blood sample showed the blood pH to be 7.18 (normal = 7.4). A
mechanical respirator, which increased breathing rate, was inserted and sodium
bicarbonate was administered intravenously. (1 mark each = 3 marks)
a) Explain why the lowered breath rate lowers the blood pH
due to a build up of CO2 in the blood which results in an increase in H+ as CO2 is converted
to HCO3- in the blood. The increased H+ results in a lowered blood pH.
b) How does the respirator help return the blood pH to normal?
By increasing respirations, the excess CO2 is removed from the blood as it is exhaled using
the respirator. This pushes the reaction backwards where HCO3- and H+ combine to form
CO2. As a result, the less H+ there is in the blood the higher the pH will go until it can be
brought back to normals.
c) What was the reason for administering the sodium bicarbonate?
Since NaHCO3- can dissociate and produce HCO3- in the blood, this can also help to buffer
the blood by combining with the H+ and helping to increase the pH back to normal.
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