1. The Respiratory System

2. Think, Pair, & Share 2 minutes
What is the respiratory system?
What are its functions? / Why is it important?
What organs does it comprise?

3. FUNCTIONS OF THE RESPIRATORY SYSTEM
Transport air into and out of lungs
Protect organism against inhaled particles
Promote gas exchange: inhale oxygen, exhale carbon dioxide

4. oxygen Human life cannot be sustained without oxygen:
Cells of the human body need oxygen in order to undergo oxidation:
a chemical reaction that breaks down organic compounds (like glucose) to produce energy (ATP)
reaction that constitutes cellular respiration

5. oxygen Oxygen is the second-most abundant gas of Earth’s atmosphere
Accounts for 21% of its composition
Nitrogen is the most abundant gas
Accounts for 78% of its composition
Argon 1%, carbon dioxide 0.04%

6. respiration Refers to all the processes used to:
Supply oxygen to lungs and to the tissues of the body
Remove carbon dioxide from lungs and tissues of the body

7. respiration Four types of respiration:
Breathing: the process by which air enters and leaves the lungs
External respiration: the exchange of O2 and CO2 between external air and blood
Internal respiration: the exchange of O2 and CO2 between blood and tissues of the body
Cellular respiration: series of reactions within cells, in which oxygen and glucose react to produce energy (ATP) and carbon dioxide

8. Cellular respiration
Oxygen + Glucose  Carbon dioxide + Water + Energy (ATP)
6 O2 + C6H12O6  6 CO2 + 6 H2O + Energy

9. respiration
The ultimate goal is cellular respiration.

10. Make connections!  1-2 minutes
What is the opposite of cellular respiration?
Hint: You just saw this in a recent unit!
PHOTOSYNTHESIS
What is its formula?
Carbon dioxide + Water + Energy  Oxygen + Glucose
6 CO2 + 6 H2O + Energy  6 O2 + C6H12O6

11. The challenge of getting oxygen
Animals have adaptations that enable the “capturing” of oxygen:
Increased surface area for gas exchange
E.g. Earthworms use skin as respiratory membrane
Skin must always be kept moist to allow for gas diffusion

12. The challenge of getting oxygen

13. The challenge of getting oxygen
E.g. Fish, salamanders, clams, starfish and crayfish use gills
Increases surface area, ensures constant diffusion of oxygen from water to blood
Remember lecture on blood vessels!

14. The challenge of getting oxygen

15. The challenge of getting oxygen
Given their need to be kept moist at all times, gills would not be an efficient adaptation for land animals.
Exposing gills to air would cause too much evaporation, drying out the gills, impeding gases from diffusing through
So land animals use other adaptations
E.g. Insects use tracheal system—a series of branching respiratory tubes that connect cells to the external environment through “spiracles” on exoskeleton

16. The challenge of getting oxygen

17. The challenge of getting oxygen
But for larger land animals, the tracheal system is not enough to provide sufficient oxygen.
Hence the trachea branches out into lungs.
E.g.: Frogs

18. The challenge of getting oxygen
Frogs
Balloon-like lungs that enable gas exchange between air and blood
Increase surface area so more oxygen can be absorbed
Can still absorb oxygen through skin as respiratory membrane
Internal location of lungs prevents excessive evaporation and drying out of membrane

19. THE MAMMALIAN RESPIRATORY SYSTEM: VIDEO

20. What did you learn? Discuss with your elbow partner:
Why might the left lung be slightly smaller than the right lung?
Why is the trachea enclosed by cartilage rings that are not fully closed (i.e. c-shaped rings)?

22. The mammalian respiratory system
Air enters in one of two ways:
1. through the two nasal cavities, or
II. through the mouth

23. The nasal cavities The nasal cavities
Hairs that trap foreign particles
Warm and moisten incoming air
Mucus that traps particles and keep cavities warm

24. Pharynx and trachea
The nasal cavities open into the pharynx, an air-filled channel in the mouth
The pharynx gives rise to the trachea and the esophagus
The esophagus moves food down into stomach
The trachea contains mucus-producing cells
The mucus traps particles not trapped by nasal cavity
The trachea also contains cilia, tiny hair-like proteins that sweep foreign particles back up into the pharynx

25. Pharynx and trachea

26. Trachea and epiglottis
One of the open cartilage rings on the trachea supports the epiglottis
What is the epiglottis? Think back to the digestive system.
A “flap” that covers the glottis (the opening of the trachea) when swallowing, to prevent food from entering the respiratory tract
Food in trachea: cilia push it back into pharynx, and we develop a “violent cough”

27. Trachea and epiglottis

28. larynx Above trachea. Called the voice box: contains the vocal chords.
Vocal chords vibrate with air sent from lungs
Protected by “Adam’s Apple,” a thick band of cartilage
Growth of Adam’s Apple increases larynx (voice box) lowering the pitch of the voice
Pitch irregularities in voice of teenage males

29. Bronchi & Bronchioles
Bronchi: Air travels from trachea into the two bronchi, the passageways that lead to the lungs
Like trachea, contain cartilage rings
Bronchioles: Before turning into lungs, air travels from bronchi to bronchioles, small branched passageways
No cartilage rings
Smooth muscle  can decrease diameter  resistance of air flow  wheezing sound

30. Bronchi and bronchioles

31. Alveoli (SINGULAR: ALVEOLUS)
From bronchioles, air travels into alveoli, sacs found at the end of the bronchioles
where the exchange of gases between the atmosphere and the blood in the lungs occurs
Recall: What did we say this type of respiration is called? (External? Internal? Cellular)
External

32. Alveoli (SINGULAR: ALVEOLUS)
Gas exchange: Oxygen and carbon dioxide diffuse down their concentration gradient… meaning?
Meaning that each gas moves from an area where it has a higher concentration to an area where it has a lower concentration
Like the gradient diffusion in the gills of a fish!
This causes oxygen to move from air with lungs into alveoli… and carbon dioxide from alveoli to air inside the lungs.

33. Alveoli (SINGULAR: ALVEOLUS)
Each alveolus:
diameter: micrometers
surrounded by capillaries
single-cell layer: rapid gas exchange
Each lung: 150 million alveoli

34. Alveoli

35. Pleural membranes
Thin membrane covering surface of lungs and inner wall of chest cavity
Space between the two membranes is filled with fluids  reduces friction between lungs and chest cavity during inhalation

36. Gas exchange: alveolus and capillaries

37. O2 O2 O2 O2 O2 O2 O2 O2 O2 O2
O2 O2 O2 O2 O2 O2 O2 O2 O2 O2 O2 O2
CO2 CO2 CO2
CO2 CO2 CO2 CO2 CO2 CO2 CO2 CO2

39. Gas exchange: capillaries and systemic body tissues

42. Breathing movements
Air moves into and out of the lungs due to a difference in gas pressure between the atmosphere (external air) and the chest (thoracic cavity).
While atmospheric gas pressure remains relatively constant, the pressure inside the chest cavity may vary.

43. Breathing movements
While gases move from an area of high concentration to an area of low concentration, gases also move from an area of high pressure to an area of low pressure!

44. Breathing movements
Inspiration occurs when the pressure inside the chest cavity is lower than the pressure in the atmosphere.
 We breathe in (inspire) to increase the pressure in our chest cavity.

45. Breathing movements
Expiration occurs when the pressure inside the chest cavity is higher than the pressure in the atmosphere.
 We breathe out (expire) to decrease the pressure in our chest cavity.

46. The diaphragm
A dome-shaped sheet of a muscle that separates the chest cavity from the abdominal cavity.
Regulates the pressure in the chest cavity.

47. diaphragm

48.  which reduces pressure in the chest
The diaphragm
During inspiration
Rib cage rises
Diaphragm contracts and is pulled downward
As such, chest expands
 which reduces pressure in the chest
 which forces air to enter lungs

49. The diaphragm
The increased pressure in the chest forces us to breathe out, or undergo expiration.

50. Chest volume decreases
The diaphragm
During expiration
the diaphragm relaxes as it is pushed back upward (by abdominal muscles) to its resting, dome-shaped position
Chest volume decreases
 increasing pressure of chest to the point that it is greater than in atmosphere
 causing air to exit the lungs

51. The diaphragm

52. The intercostal muscles
Set of muscles between the ribs
Aid the movement of the diaphragm by causing the ribs to move
Two sets: external intercostal muscles, internal intercostal muscles

53. The intercostal muscles

54. External intercostal muscles
When they contract, the they pull the ribs upward and outward (so as to increase volume of chest cavity and thereby force air into it)
When they are are relaxed, they allow the rib cage to fall back down (so as to decrease volume of chest cavity and thereby force air out of it)

55. internal intercostal muscles
Pull the rib cage downward during times of extreme exercise or forced exhalation, such as blowing out a candle
Are not employed during normal breathing

56. Breathing movements
Breathing Movements Summary: Video

57. Punctured pleural cavity
A puncture in the pleural cavity leads to a collapsed lung. This is because the diaphragm can still contract and the rib cage can still rise, but much less air will flow in… because the air will escape through the puncture.
Puncture needs to be sealed for lung to regain function.

58. Collapsed lung