1. The Respiratory System

2. Why Do We Need Oxygen?
Respiration a series of chemical reactions to release energy when breaking down compounds
Aerobic Respiration use of oxygen to break down compounds
C6H12O6 + 6O2  6CO2 + 6H2O + Energy
Anaerobic Respiration not using oxygen to break down chemicals
C6H12O6 C2H5OH + 2CO2 +Energy
(alcohol)
C6H12O6 2C3H6O3 + Energy
(lactic acid)

3. Why Do We Need Oxygen? What do we do that requires energy?
Muscle contraction
Digestion
Cell division
Absorbing nutrition
ENZYMES!!
Homeostasis healthy point for a living organism
What is the energy unit of a cell?
ATP
Where is ATP made?
Mitochondria

4. Gas Exchange in the Lungs
Lungs organ where gas exchange occurs
Air moves through nose/mouth then…
1) Larynx “voice box”; muscles in throat that produce sounds
2) Trachea “windpipe”; tube connecting throat to lungs
Protected by C-shaped cartilage
3) Bronchi split in of trachea into left and right lung
4) Bronchioles smaller division of bronchi through out lungs
5) Alveoli “air sacs”; where gas exchanges happens with blood

5. Separating Food and Air
Food has to pass by the trachea (entrance to the lungs) so a small cartilage cover (epiglottis) blocks the opening
Eating too fast can send food “Down the Wrong Pipe”

6. The Chest Lungs organ for breathing
Ribs and Sternum protect lungs and heart
Intercostal muscles muscle the fill space between ribs
Pleural membranes wet soft area to prevent the lungs from rubbing against the ribs
Diaphragm muscle across bottom of ribs that controls breathing
Contracts to expand chest and allow lungs to fill with air

7. Breathing Lungs cannot be controlled! Only muscles!
Inspiration Breathing In
Intercostal muscles and diaphragm contract
Chest volume increases, so pressure on lungs decreases
Lungs expand, air is sucked in to fill space
Boyles’ Law if the volume goes up, the pressure goes down (inversely proportional)

8. Breathing (Part 2) Expiration Breathing Out Keep it Clean!
Internal intercostal muscles contract while outer intercostal muscles and diaphragm relax
Chest decreases in volume, so pressure on lungs increases
Lungs shrink so air is forced out
Keep it Clean!
Cilia move a stream of mucus through the throat and nose
Mucus catches bacteria and dust
Enter digestion system when you swallow

9. What is Air? 21% 0.04% 78% < 1%; varies 78% 4% 16% Saturated
What is the composition of the air you breath in?
Oxygen?
CO2 ?
Nitrogen?
Water Vapor?
What is the composition of the air you breath out?
CO2 ?
Water vapor?
21%
0.04%
78%
< 1%; varies
78% 4%
16%
Saturated

10. Gas Exchange 16% O2 exhaled comes from:
Need of oxygen in body
Dead air space; air that never makes it to alveoli
How do O2 and CO2 enter and leave the blood?
Diffusion
What factors limit diffusion rate?
Concentration Gradients
Surface Area
Distance
Material

11. In The Alveolus 0.04% 21% 4% 16% Concentration gradients: Surface Area
O2 21% vs. 16%
CO2 0.04% vs. 4%
Surface Area
Small, numerous alveoli make lots of membrane space
Distance
Walls of alveoli and capillaries are only 1 cell thick
Material
Watery surface is easier for gasses to dissolve into alveoli
0.04%
21% 4%
16%

12. Respiratory Rate Relaxed 12-16 breaths /min
Exercise increases dramatically; varies with person
Muscles need more O2 and make more CO2
Breath faster and deeper
Relaxed 0.5 L / breath
Exercise 4.5L/ breath
Vital Capacity max of 5 L
After exercise, O2 is still too low and CO2 is still too high, so heart rate and breath rate stay high till normal

13. Controlling Respiratory Rate
Which causes you to breath faster during exercise; Low O2 or High CO2?
High CO2
What will raised CO2 do to your blood?
Lower the pH; make is acidic
Brain scans blood, if pH is too low, send signals to breath faster
What is your brain trying to maintain?
Homeostasis!

14. Fermentation
In the absence of oxygen，cells can still produce ATP through fermentation (anaerobic respiration)
There are two major types of fermentation:
Alcoholic fermentation
Lactic Acid fermentation

15. Alcohol Fermentation C6H12O6 C2H5OH + 2CO2 +Energy
Used by man to make various products:
CO2 released causes bread and cakes to expand
Ethanol used to make beer and wine

16. Lactic Acid Fermentation
C6H12O6 2C3H6O3 + Energy
Helps energy supply during hard exercise
Lactic acid can not be broken down in the muscles cells; must be sent to the liver
Oxygen debt O2 needed to removed lactic acid before homeostasis is reached
Lactic acid builds up too fast and changes the pH of muscle cells
Change in pH slows
performance and
weakens the muscle
cells; sore

17. Oxygen is Key
P 235