1. Respiration
Cambridge Biology

2. Let’s watch a video! But first…
What is “respiration”?
NOT “breathing”!
This is the action of your lungs inhaling and exhaling air; “ventilation.”
Respiration = the process of breaking down glucose to use for ENERGY
If glucose were gasoline, then respiration would be the engine running in your car.
(you can’t go anywhere if the engine’s not running!)

3. One more thing before video:
Aerobic Respiration
Anaerobic Respiration
Using O2 to break down glucose
“with air” ~ “with oxygen”
NOT using O2
“without air”

4. Aerobic Respiration
Using O2 to break down Glucose to release Energy for cells.
Glucose + Oxygen  Carbon Dioxide + Water + Energy
C6H12O6 + 6O2  6CO2 + 6H20 + Energy

5. But where did the Glucose come from?
You ate it!
Food breaks down into glucose molecules in the stomach (Digestion).
These glucose molecules enter your blood in the small intestine (Absorption).
Blood carries the glucose molecules to individual cells (Circulation).

6. But where did the Oxygen come from?
You inhaled it (breathing).
In your lungs, your blood takes in O2 and lets out CO2.
This is called Gas Exchange.
(you’re exchanging one gas for another)
You need LOTS of surface area to exchange gasses quickly enough.
Lungs have about 70 square meters of S.A.
(about the size of a tennis court!)

7. How do you get so much Surface Area in the Lungs?
Alveoli: very tiny sacs about 0.25 mm across
Alveoli are where Gas Exchange occurs
Gas can only exchange through a small distance
Blood capillary is right next to alveolus
Gas moves through capillary wall and alveolus wall
Distance of mm

8. Alveolar Gas Exchange

9. Alveolar Gas Exchange

10. Alveolar Gas Exchange

11. Alveolar Gas Exchange

12. Pathway of Inhaled Air Mouth/nose Trachea R + L Bronchi Bronchioles
Alveoli

13. Pathway of Oxygen Alveoli Pulmonary (Lung) Capillaries Pulmonary Vein
The blood in this Vein is Oxygenated (!!)
It is moving AWAY from the Lungs, but TOWARD the Heart.
Heart  Aorta  Arteries  Arterioles  Capillaries  Body Cells
Respiration (conversion to Energy) happens in the Cell
Now the Cell has plenty of Energy!

14. Pathway of Oxygen

15. Pathway of Oxygen

16. Pathway of Oxygen

17. Question Time!
Where does the blood in Pulmonary Vein come from? (Hint: it is Oxygenated)
The Lungs
Where is it going?
The Heart
Where does the blood in the Pulmonary Artery come from? (Hint: it is Deoxygenated)
The Lung

18. Oxygen Content of Air Inspired Air Expired Air Oxygen 21.00 % 16.00 %
Carbon Dioxide
00.04 %
04.00 %
Nitrogen
78.00 %
Moisture Content
Variable
High
Temperature

19. How do we Breathe? Ventilation:
Moving fresh air into lungs
Moving “used” air out of lungs
Ventilation happens because of changes in pressure that our body creates by contracting and relaxing muscles:
Diaphragm
Intercostals (“between ribs”)
Pleural membranes keep everything airtight.

20. Pleural Cavity and Breathing Muscles

21. Lungs & Diaphragm

22. Inhalation Diaphragm contracts Intercostal muscles contract
It moves DOWN because of its unique shape
Intercostal muscles contract
Making the ribs move UP
Volume increases inside pleural cavity.
Pressure decreases; creates a vacuum!
Air from outside flows into the Lungs.

23. Diaphragm

24. Inspiration

25. Inspiration

26. Exhalation Diaphragm relaxes Intercostals also relax Volume DECREASES
Now it moves back UP
Intercostals also relax
Ribs can move back DOWN
Volume DECREASES
Pressure INCREASES – like a full balloon!
Air moves back out of the Lungs.

27. Inspiration / Expiration

28. Air Pressure in Model Lung

29. How do Other Animals Breathe?
Diffusion:
Small animals with no ventilation structure
Gills:
Fish
Lungs:
Mammals
Birds
Herpetiles (Reptiles + Amphibians)
Skin:
Amphibians
Tracheae:
Insects

30. Diffusion
O2 and CO2 diffuse in and out of the organism without a specialized organ
Small size
Large surface area

31. Gills Structures on fish that allow gas exchange with water.
Fish “pump” water over and through gills.

32. Gills in Respiration

33. Gills in Respiration

34. Lungs Allow gas exchange with air.
Bird lungs are structured to allow maximum gas exchange
Air moves through the lungs, not in-and-out like in mammals

35. Bird Respiratory System

36. Bird Respiration

37. Lungs + Skin

38. Tracheae Network of branching tubes in insects.
Gas exchange occurs directly between tracheae and respiring cells.
No blood involved!
Insects breathe in and out through spiracles.

39. Insect Anatomy

40. Insect Tracheae

41. Respiration WITHOUT Oxygen
“Anaerobic Respiration”
Many organisms respire anaerobically.
Even humans! (sometimes)
But Aerobic Respiration is more efficient
It yields about 19 times as much energy from one glucose molecule as Anaer. Resp.

42. Anaerobic Respiration in Yeast
Yeast is a single-celled fungus.
Breaks down Glucose into Ethanol and CO2
Can be used to make alcoholic drinks and bread
Ethanol = alcohol
CO2 bubbles = bread rises

43. Yeast: Anaerobic Respiration

44. Anaerobic Respiration in Humans
Only when our muscles run out of O2
During strenuous exercise
We break down glucose into lactic acid to release useable energy.
Lactic acid is toxic!
So, we can’t do this very long.

45. How do your Lungs stay Clean?
The air we inhale contains dust and bacteria.
Lung passages are lined with goblet cells and cilia, which keep unwanted particles from getting to the alveoli.

46. Goblet Cells + Cilia
Goblet cells secrete mucus that traps dust and bacteria.
Cilia are tiny hairs that sweep the mucus up toward the back of your throat.
Then you swallow the mucus, along with everything else!
Bacteria die in your stomach’s acid and enzymes.

47. Goblet Cells and Cilia

48. Cigarette Smoke: Tar Damages DNA in lung cells
This can result in lung cancer
Lung cells divide uncontrollably into a mass called a tumor.
If Tar (or other harmful chemicals) get into the blood, they can be carried to other parts of the body and cause other types of cancer.

49. Cigarette Smoke: Tar Tar can paralyze or destroy Cilia
Now they can’t sweep mucus out of the bronchial tubes!
Tar makes Goblet Cells excrete more mucus
Mucus slides down into lungs, creating a breeding ground for bacteria
Excessive coughing damages lining of tubes
Bronchitis: inflammation of bronchi
Damage to alveolar walls hinders gas exchange
Emphysema: difficulty getting enough O2

50. Cigarette Smoke Also contains Carbon Monoxide (CO)
CO binds to hemoglobin in blood (just like O2)
But it never comes off!
So that means less places in the blood for O2
Smokers often run short of O2 during energetic activity.

51. Air Pollution: Particles
Coarse
1-10 μm across
Filtered out in airways and bronchial tubes
Fine
0.1 to 1 μm across
Not filtered out; can deposit in alveoli
Ultrafine
0 to 0.1 μm across
Can penetrate cell walls, enter bloodstream, and travel to your brain!

52. Particles

53. Air Pollution: Sulfur Dioxide
Gas produced from burning fossil fuels
(industry + automobiles)
Mixes with water and becomes sulfuric acid (acid rain):
SO2 + H2O  H2SO4
SO2 turns to acid when enters your lungs and can damage the lining and alveoli.

54. So… what should you do to protect your Lungs?
Don’t smoke!
Try not to breathe polluted air.