The Respiratory System

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)

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

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 sounds2) 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

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”

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

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)

Breathing (Part 2)• Expiration Breathing Out

– 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

What is Air?• 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?– Nitrogen?– CO2 ?– Oxygen?– Water vapor?

21%0.04%

78%< 1%; varies

78%4%

16%Saturated

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?

1) Concentration Gradients2) Surface Area3) Distance4) Material

In The Alveolus1) Concentration gradients:

– O2 21% vs. 16%

– CO2 0.04% vs. 4%

2) Surface Area– Small, numerous alveoli make

lots of membrane space

3) Distance– Walls of alveoli and capillaries

are only 1 cell thick

4) Material– Watery surface is easier for

gasses to dissolve into alveoli

21%

16%4%

0.04%

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

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!

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

Alcohol Fermentation2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Pyruvate

2 Acetaldehyde2 Ethanol

(b) Alcohol fermentation

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Lactate

(a) Lactic acid fermentation

H

H OH

CH3

C

O –

OC

C O

CH3

H

C O

CH3

O–

C O

C O

CH3O

C O

C OHH

CH3

CO22

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Pyruvate

2 Acetaldehyde2 Ethanol

(b) Alcohol fermentation

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Lactate

(a) Lactic acid fermentation

H

H OH

CH3

C

O –

OC

C O

CH3

H

C O

CH3

O–

C O

C O

CH3O

C O

C OHH

CH3

CO22

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Pyruvate

2 Acetaldehyde2 Ethanol

(b) Alcohol fermentation

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Lactate

(a) Lactic acid fermentation

H

H OH

CH3

C

O –

OC

C O

CH3

H

C O

CH3

O–

C O

C O

CH3O

C O

C OHH

CH3

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Pyruvate

2 Acetaldehyde2 Ethanol

(b) Alcohol fermentation

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Lactate

(a) Lactic acid fermentation

H

H OH

CH3

C

O –

OC

C O

CH3

H

C O

CH3

O–

C O

C O

CH3O

C O

C OHH

CH3

CO22

• 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

Lactic Acid Fermentation

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Pyruvate

2 Acetaldehyde2 Ethanol

(b) Alcohol fermentation

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Lactate

(a) Lactic acid fermentation

H

H OH

CH3

C

O –

OC

C O

CH3

H

C O

CH3

O–

C O

C O

CH3O

C O

C OHH

CH3

CO22

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Pyruvate

2 Acetaldehyde2 Ethanol

(b) Alcohol fermentation

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Lactate

(a) Lactic acid fermentation

H

H OH

CH3

C

O –

OC

C O

CH3

H

C O

CH3

O–

C O

C O

CH3O

C O

C OHH

CH3

CO22

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Pyruvate

2 Acetaldehyde2 Ethanol

(b) Alcohol fermentation

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Lactate

(a) Lactic acid fermentation

H

H OH

CH3

C

O –

OC

C O

CH3

H

C O

CH3

O–

C O

C O

CH3O

C O

C OHH

CH3

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Pyruvate

2 Acetaldehyde2 Ethanol

(b) Alcohol fermentation

2 ADP + 2 P1 2 ATP

GlycolysisGlucose

2 NAD+ 2 NADH

2 Lactate

(a) Lactic acid fermentation

H

H OH

CH3

C

O –

OC

C O

CH3

H

C O

CH3

O–

C O

C O

CH3O

C O

C OHH

CH3

CO22

• 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

Oxygen is Key

P 235