1. The Respiratory System
Biology 11
A. Allen
Cow lungs 

2. Activate your prior knowledge!
What is ‘respiration’?
What organs/structures make up the respiratory system?
Draw a sketch of a human respiratory system.
What are the lungs for?
How does air get in and out your lungs?

3. Interesting facts
There are 150 million alveoli in each lung. Total surface area in both lung = 40 m2 (1/2 tennis court). diameter of alveoli = 0.1 – 0.2 mm.
Laryngitis is the swelling of the vocal cords in the larynx (voice box). Can cause your voice to sound hoarse. Some smokers have permanent hoarseness from chronic inflammation.
You automatically cough when food heads down your trachea. Coughing brings the food back up to the mouth.
Your epiglottis closes off the trachea as you swallow. Why?
Tuberculosis (TB) is caused by bacteria that destroys the air sacs in the lungs.
An estimated 1.7 million people died from TB in The highest number of deaths was in Africa.

4. …Interesting facts
you lose about ½ litre of water a day through breathing
The stuff that comes out of your mouth when you cough travels at about 160 km/hr.
One acre of trees produces enough oxygen to keep 18 people alive for one year.
Cigarettes and cigarette smoke contain over 4,000 chemicals, including 43 known to cause cancer. 
Every cigarette shortens your life by ~14 minutes.
Lizards can’t breathe when they are running. Their breathing depends on the muscles between their ribs. These muscles must be used during running.  
Some animals such as certain frogs can breathe through their skin.

5. Importance of Gas Exchange
Composition of Atmosphere
 78% Nitrogen
 21% Oxygen
 0.03% Carbon Dioxide
Cells obtain energy by breaking down sugars. O2 is the required.
Humans need oxygen to survive (250 mL/min)
Humans may live several days without water, weeks without food, only minutes without oxygen.

6. Human Respiratory System

7. Components of the Upper Respiratory Tract
Passageway for respiration
Receptors for smell
Nose lined with mucus, cilia and long hairs to filter incoming air.
Moistens and warms incoming air
Resonating chambers for voice

8. Components of the Lower Respiratory Tract
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
Bronchioles: small branches that lead to alveoli fr bronchi
Lungs: transport air to alveoli for gas exchange
Diaphragm: essential for breathing…
contraction   chest volume 
 pressure  inspiration!

9. Summary of Air Movement
air from environment…
into nasal cavity/mouth (hair and mucus filter particles - boogers!)…air get moistened and warmed.
into pharynx…
pharynx branches into trachea (mucus and cilia –sweeping hair-like structures- filter air in trachea ..debris goes to pharnyx…swallow it!
pharynx branches into 2 bronchi (one in each lung)…
bronchi branch off into bronchioles (smaller)…
bronchioles end in air sacs, made of alveoli, the site of gas exchange between blood and air!
Respiration

10. THE RESPIRATORY SYSTEM
Like the nasal passages, the trachea is lined with a cilia & a mucous membrane for trapping foreign particles. The cilia constantly move to sweep debris up towards the pharynx…spit it out or swallow!
The smoke from one cigarette will paralyze the cilia for 20 minutes and increase the production of mucus in the air passages resulting in “smoker’s cough”.
The trachea is about 12 centimeters long and about 2.5 centimeters wide and is lined by rings of cartilage which help maintain its shape and prevent it from collapsing when air is exhaled.

11. Boogers!
When dust, dirt, germs, and pollen get stuck inside the nose, the mucus surrounds it and tiny hairs inside the nose called cilia help move the mucus and the trapped stuff toward the front of the nose or the back of the throat. When the mucus, dirt and other debris dry and clump together, you're left with a booger!

12. THE RESPIRATORY SYSTEM
As with the blood vessels, as the air passages subdivide into more branches, their diameter decreases.
As the bronchial tubes divide and subdivide, their diameter decreases, their walls become thinner and they eventually lose their cartilage rings.
Finally, they form a network of tiny tubes called BRONCHIOLES.

13. THE RESPIRATORY SYSTEM
The bronchioles end in little air sacs called ALVEOLI.
Alveoli are surrounded by capillaries and are the site of gas exchange (oxygen and carbon dioxide) with the circulatory system.
Inhaled oxygen diffuses into the blood and binds with hemoglobin - carbon dioxide diffuses from the blood into the alveoli and is exhaled.

14. Oxygen Transport Oxygen enters the blood stream from the lungs.
Oxygen itself is not very soluble. There is only 0.3 mL of oxygen/100 mL of blood.
After 0.3 mL of oxygen enters 100 mL of blood, no more oxygen will diffuse into the blood.
Hemoglobin acts to ‘disguise’ the oxygen.
Hemoglobin and oxygen bond together to form oxyhemoglobin.
When this happens, more oxygen can come into the blood.
(When oxygen is formed as oxyhemoglobin, it does not count towards the 0.3mL.)
When oxygen is ‘disguised’ as hemoglobin, blood can transfer 20 mL of oxygen for every 100 mL of blood.
Oxygen does not split from hemoglobin until partial pressure drops to 5.3kPa. This happens in the capillaries next to the body tissues.
hmcgraw-hill.movement_of oxygen_and_carbon_dioxide
alveolar_pressure_changes_McGraw Hill

15. Carbon Dioxide Transport
Carbon Dioxide is 20 X more stable than Oxygen.
In the blood:
9% is in the plasma (liquid portion of blood).
27% is combined with hemoglobin to form carbaminohemoglobin.
64% combines with water from plasma to form carbonic acid. (H2CO3)
The enzyme carbonic anhydrase causes this reaction to increase by 250x.
When carbon dioxide is in the form of carbonic acid it is in ‘disguise’.
This saves room for more carbon dioxide to enter the blood.
Remember: carbon dioxide travels from areas of greater partial pressure to areas of lesser partial pressure .
If it seems like there is less carbon dioxide in the blood, more will leave the tissues.
If some of the carbon dioxide is ‘in disguise’ in the blood stream, then more carbon dioxide will leave the tissues.

16. Mechanics of Breathing
Inspiration (breathing in)
requires chest cavity to increase in volume to create low pressure.
Accomplished when:
diaphragm contracts and moves down (abdominal breathing)
External intercostal muscles contract (only during forced inspiration)

17. …Mechanics of Breathing
Expiration (breathing out)
requires chest cavity to decrease in volume to create high pressure.
Accomplished when:
diaphragm relaxes and moves up (abdominal organs help with this…they were squished during inspiration)
Internal intercostal muscles contract (only during forced expiration)
Diaphragm youtube
3D breathing youtube
Gas exchange youtube

18. …Mechanics of Breathing
When the external intercostals contract, the ribs swing up and out like bucket handles. This increases the chest volume to create the low pressure required for air to enter the lungs.

19. Measurement of Lung Function
Tidal volume: volume of air inhaled and exhaled in a single breath
Residual Volume: the air that remains in the airways and does not participate in gas exchange
Vital capacity: the maximal volume that can be exhaled after maximal inhalation
Inspiratory reserve volume: the amount of air that can be inhaled beyond the tidal volume
Expiratory reserve volume: the amount of air that can be forcibly exhaled beyond the tidal volume
Residual volume: the amount of air remaining in the lungs, even after a forceful maximal expiration

20. Regulation of Breathing
Figure 10.13

21. Breathing rate is monitored by:
Blood CO2 levels - increase as more CO2 is produced as a waste product
Blood O2 levels - decrease as O2 is used up in respiration to produce ATP
Rate is more sensitive to changes in CO2 levels. In the blood, carbon dioxide dissolves into hydrogen and bicarbonate ions (HCO3-)
CO2 + H2O ↔ H+ + HCO3-
Fall of CO2
Equation shifts to the left
More CO2 is produced by removing hydrogen ions
This increases blood pH (more alkaline)
Excess CO2 (exercise)
Equation shifts to the right
More CO2 dissolves in blood to produce more hydrogen ions
This reduces blood pH (more acidic)
Chemoreceptors
Located in the aorta (aortic bodies) and common carotid arteries (carotid bodies)
Monitor pH and CO2 levels
Send impulses to the medulla
Aortic bodies monitor CO2 and O2 levels, and BP but NOT pH!
Carotid bodies monitors CO2 and O2 levels, and pH
Exercise
Increases CO2 / blood becomes more acidic
Chemoreceptors detect low pH and stimulate respiratory centres in the medulla oblongata.
Respiratory centres send more impulses to diaphragm and intercostals muscles
Increases breathing rate and depth

22. Disorders of Respiratory System
Reduced air flow: asthma, emphysema, bronchitis
Infections: pneumonia, tuberculosis, botulism
Lung cancer
Congestive heart failure
Cystic fibrosis

23. 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

24. Regulation of Breathing: Nervous System Involvement
Respiratory center in the medulla oblongata: establishes basic breathing pattern
Chemical receptors: monitor carbon dioxide, hydrogen ions, and oxygen levels
Medulla: sensitive to hydrogen ions in cerebrospinal fluid resulting from carbon dioxide in blood