1. Respiration What is the main purpose of respiration?
In other words why do we breathe?
To provide oxygen to the body
To get rid of carbon dioxide
To burn food
To give energy
C6H12O6 + O H2O + CO2 + ATP
(energy)

2. Respiration External Respiration (lung level)
Respiration occurs on two levels:
External Respiration (lung level)
It is the process by which oxygen is delivered to the blood and carbon dioxide is removed.
Internal Respiration (tissue level)
It is the process by which oxygen is delivered to the cells and carbon dioxide is removed.

3. Respiration Processes
Breathing (ventilation): air into and out of the lungs
External respiration: gas exchange between air and blood
Internal respiration: gas exchange between blood and tissues
Cellular respiration: use oxygen to produce ATP (energy), produce carbon dioxide as waste

4. The Respiratory Cycle
(Mechanism of Breathing)

5. LUNG VOLUMES
Tidal Volume: the normal volume of air you breathe in and out at rest.
2. Inspiratory reserve: the maximum air you can inhale after the tidal volume.
3. Expiratory Reserve: the maximum amount of air you can exhale after exhaling your tidal volume.
4. Vital Capacity: the maximum air you can inhale and exhale (Tidal volume plus inspiratory and expiratory reserves).
5. Residual air: the air in the lungs that cannot be exhaled.

6. Conditioning of Inhaled Air:
Several things happen to the air on its journey into the alveoli. The air is:
1. Cleansed of debris in a 2 part process. The initial cleaning is by the nose hairs and
mucous in the nasal passageways. The second part of the process occurs in the trachea
and bronchi which are both lined with mucous and cilia. Any material other than the
gases of the inhaled air will get caught in the mucous. The cilia (microscopic protein
filaments) are in constant motion, beating the debris-laden mucous up towards the
pharynx. When this material is detected at the back of the mouth, it is swallowed or
coughed up and expectorated (spit out). *Note: cilia do not filter!
2. Adjusted to body temperature (~37 degrees Celsius). The more contact the air has
with moist tissues at 37o C, the closer the temperature of the inhaled air gets to body
temperature. By the time the air arrives at the alveoli there is no difference in its
temperature than that of the surrounding tissues.
3. Adjusted to 100% humidity. The air in the lungs is saturated with water. One of the
things that happens to inhaled air is that as it passes over the mucous passageways, it
becomes saturated with water.

7. Respiration The basic requirements for respiration to take place are:
A respiratory surface that is big enough for the exchange
of oxygen and carbon dioxide to occur at a rate sufficient to
meet the organism’s metabolic needs.
2. A moist environment so that the oxygen and the carbon dioxide
would dissolve.
3. Only 2 cell layers separate air in lungs from the blood

8. Components of the Upper Respiratory Tract

9. Upper Respiratory Tract
Functions:
Passageway for respiration
Receptors for smell
Filters incoming air from large foreign material
Moistens and warms incoming air
Resonating chambers for voice

10. Vocal Cords, Open

11. Vocal cords, closed

12. Components of the Lower Respiratory Tract

15. Lung pleural membranes

17. Lower Respiratory Tract
Functions:
Larynx:
Maintains an open airway, routes food and air appropriately, assists in sound production
Trachea:
Transports air to and from lungs
Bronchi: branch into lungs
Lungs:
Transport air to alveoli for gas exchange

18. Gas Exchange & Transport: A Passive Process
Gases diffuse according to their partial pressures
External respiration: gases exchanged between air and blood
Internal respiration: gases exchanged with tissue fluids
Oxygen transport: bound to hemoglobin in red blood cells or dissolved in blood plasma
Carbon dioxide transport: dissolved in blood plasma, bound to hemoglobin, or in the form of plasma bicarbonate

19. Gas Exchange Between the Blood and Alveoli

20. Gas transport in the blood

22. Partial Pressures

23. Two molecules help the process of gas exchange become more efficient:
Surfactants – these soap-like molecules, consisting of phospholipids and protein, coat the inner surface of the alveoli and reduce surface tension. Without them, the alveolar walls would stick together, making breathing very difficult. [This is one effect that cystic fibrosis sufferers have; they produce too much, very thick mucus.]
B. Haemoglobin – the red oxygen-carrying molecule that fills RBC’s. Each haemoglobin molecule has four oxygen-binding sites. Most of the oxygen in blood - 98 percent – is combined with haemoglobin.

24. Regulation of Breathing: Nervous System Involvement
Respiratory center in the medulla oblongata:
The control of the breathing process is only voluntary to a point. The
medulla oblongata of the brain is sensitive to the concentration of
carbon dioxide and hydrogen ions in the blood. Both of these are
products of cellular metabolism and both need to be excreted. As
CO2 accumulates in the blood, it means that you’re not breathing fast
enough, and therefore, are not getting enough oxygen. When the
concentrations of H+ and CO2 reach a critical level, the breathing
center in the medulla oblongata is stimulated and sends nerve
impulses to the diaphragm and the intercostal muscles (that lie
between the ribs) to initiate their contraction.

25. Carotid and aortic Vessels:
*The aortic arch and carotid arteries also contain chemoreceptors that are sensitive to the oxygen content in the blood. If it is critically low, they will help initiate the inhalation response. Note, however, that this is a secondary mechanism. The primary mechanism that triggers inhalation is still an elevated concentration of carbon dioxide and hydrogen ions.

26. Diseases of the Respiratory System:
• Asthma narrows the airways by causing allergy-induced spasms of surrounding muscles or by clogging the airways with mucus.
• Bronchitis is an inflammatory response that reduces airflow and is caused by long-term exposure to irritants such as cigarette smoke, air pollutants, allergens or infectious agents.
• Cystic fibrosis is a genetic defect that causes excessive mucus production that clogs the airways, also its thick nature tends to keep each alveolus sticking on itself.