1. CHAPTER 10 RESPIRATORY SYSTEM: EXCHANGE OF GASES
PowerPoint® Lecture Slide Presentation by Robert J. Sullivan, Marist College
Human Biology
CHAPTER 10 RESPIRATORY SYSTEM: EXCHANGE OF GASES
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings.

2. The Need for Oxygen:
O2 is vital to life! Humans can survive for only a few minutes without oxygen (3-4 minutes is enough to cause some brain damage). Needed in most chemical reactions in our body (cellular respiration)
Air is 78% nitrogen, 21% oxygen, and 1% other gases including carbon dioxide
We take between and breaths everyday. It happens subconsciously and we can stop breathing momentarily, but it resumes automatically regardless of how hard you try

3. Function:
The two main functions of the respiratory system is to provide O2 from the ambient (outside) air to the blood and to pick up waste gas, CO2 from the blood and transport it out of the body
CO2 O2

4. Other Functions: Other functions of respiratory system
include protecting body from microorganisms:
-cells of trachea secrete mucous that can trap foreign objects that were not stopped in nasal cavity
-microscopic cilia then work to “sweep” out trapped substances back to the pharynx
-once in pharynx these substances can be swallowed or expelled
Respiratory system also provides sound by vocal cords (in larynx) – these cords vibrate as air is forced past them, producing sound

5. Aerobic Cellular Respiration
Aerobic cellular respiration: the series of chemical reactions that occur in the cell that provide energy and consume oxygen
C6H12O6 + 6O2  6CO2 + 6H2O + energy
Glucose + oxygen  carbon dioxide + water + energy
About 64% of our energy is released as thermal energy created during respiration, the rest is stored as ATP (adenosine triphosphate). 36 ATP are made for every glucose molecule

6. Making ATP
ATP is formed when energy from the breakdown of glucose is used to attach a phosphate group (Pi) to adenosine diphoshate ADP
Called phosphorylation
Cells use ATP to power most all energy requiring reactions like active transport and building new molecules
When ATP is converted back to ADP energy is released and is able to do work
C6H12O6 + 6O ADP + 36 Pi  6CO2 + 6H2O + 36 ATP + thermal energy

8. Gas Exchange:
The process by which oxygen diffuses into the body cells and carbon dioxide diffuses out of the cells
External respiration (lungs and environment)
Oxygen diffuses from the air into the blood stream
Internal respiration (blood and cells)
Oxygen diffuses from the blood stream into the cells through interstitial fluid (fluid surrounding all cells)
Carbon dioxide follows the reverse
Ventilation (breathing): the process of moving oxygen-rich air into the lungs and carbon dioxide rich air out of the lungs

9. Human Respiratory System
Alveoli
R lung
L lung

10. Components of the Upper Respiratory Tract
Figure 10.2

11. Requirements for Function:
1. A thin permeable membrane through which diffusion can occur
Alveoli have a membrane that is 1 cell thick
2. A large surface area for gas exchange
There are 150 million alveoli per lung
3. A breathing system for bringing in oxygen-rich air to the respiratory membrane
Lungs assisted by diaphragm and intercostal muscles
4. Large blood supply
capillaries surround alveoli

12. Structure:
Passage:
Nasal cavity or mouth, to the pharynx, to the trachea and moves down the trachea into lungs. Within the lungs the air moves into the bronchi, which branch into bronchioles and into alveoli.
Air is warmed and moistened in the nose and mouth before entering the lungs so as to prevent damage to the thin delicate tissue. Cilia and mucus in nose filter dust, bacteria and other air borne particles

13. Structure:
Trachea: a semi-rigid tube of soft tissue, wrapped around c-shaped bands of cartilage that leads from the mouth towards the lungs. Lined with cells that have cilia and produce mucus.
Cilia: tiny hair-like structures that are found on some cells ( ex. Trachea, lungs and nose)
wavelike motions of the cilia sweep the trapped material upward through the trachea where it is swallowed or expelled through coughing or sneezing

14. Lungs:
Enclosed in the thoracic (chest) cavity and are protected by the ribs
Provide respiratory membranes, large surface area and have a good supply of blood

15. Components of the Lower Respiratory Tract
Figure 10.3

16. Structure:
Bronchi: the trachea branches into two bronchi (singular: bronchus)
Bronchioles: the bronchi repeatedly branch into smaller and smaller tubes called bronchioles
Alveoli: airway end in clusters of tiny sacs called alveoli that form the respiratory membrane. Each cluster is surrounded by a network of capillaries. Each alveolus is tiny measuring (0.1 to 0.2 micrometers in diameter). There are approximately 150million in each lung
If the entire surface area of our lungs was flattened out it would cover a tennis court

17. Gas Exchange Between the Blood and Alveoli
Respiratory
membrane
is 1 cell thick
Air is at 37C.
Moist air is critical as diffusion cannot occur until gas is dissolved in a liquid
Figure 10.8A

18. Mechanism of ventilation: breathing…..
Based on the principle of NEGATIVE PRESSURE
When lungs have a lower pressure than atmospheric pressure, air is forced in
When air pressure is higher in the lungs air is forced out
Diaphragm: large dome shaped sheet of muscle beneath the lungs that facilitates breathing.
INHALATION: diaphragm contracts (negative pressure)
EXHALATION: diaphragm relaxes (positive pressure)

19. External Intercostal muscles: during inhalation these muscles between each rib, pull the ribs outward and upward. This INCREASES volume and DECREASES pressure
Internal intercostal muscles: are a second set of muscles that start to contract and relax during strenuous exercise

20. Ventilation:

21. Pleural membranes: a thin layer of connective tissue that covers the outer surface of the lungs and lines the thoracic cavity. Prevents friction between lungs and thoracic cavity
Pleural cavity: the space between the pleural membranes. Filled with fluid to prevent the membranes from separating, but still slide past one another (like 2 wet slides).
Pneumothorax: a collapsed lung caused by the introduction of air between the pleural membranes

22. Respiratory Cycle
Figure 10.9

23. Lung Capacity: with a spirometer
Total lung capacity: the maximum volume of air that can be inhaled during a single breath
Tidal volume: the volume of air inhaled or exhaled during a normal, involuntary breath
Inspiratory reserve volume: the volume of air that can be forcibly inhaled after normal inhalation
Expiratory reserve volume: the volume of air that can be forcibly exhaled after normal exhalation
Residual volume: the volume of air remaining in the lungs after forced exhalation
Vital capacity: the maximum amount of air that can be inhaled or exhaled

25. Factors Affecting Lung Capacity
Larger volumes
Smaller volumes
males
females
taller people
shorter people
non-smokers
heavy smokers
professional athletes
non-athletes
people living at high altitudes
people living at low altitudes
Figure 10.10A

26. Oxygen usage:
physical activity depends on the energy released during aerobic cellular respiration and this depends on the supply of oxygen
A high maximum rate of oxygen usage(the rate at which oxygen can be used in cellular respiration) indicates an efficient respiratory system
VO2 : an estimated or measured value representing the rate at which oxygen is used in the body. (ml/kg/min)
VO2max: the maximum rate at which oxygen can be used in an individual (ml/kg/min); during exercise

27. Spirometer:measuring oxygen usage efficiency and lung capacity
efficiency depends
on gender, age
and fitness