The Mechanism of Breathing

• http://teachhealthk-12.uthscsa.edu/curriculum/pulmonary/pulmonary-breathsimulation.asp

(Anatomy of Breathing Flash Animation)

Inhalation

1. The Intercostal muscles contract, sending the rib cage upward and outward

2. The Diaphragm contracts, and moves downward

3. The Volume inside of the chest cavity increases

4. The Pressure inside the chest cavity decreases

5. Air enters the lungs to equalize the pressure

Exhalation

1. The Intercostal muscles relax, sending the rib cage downward and inward

2. The Diaphragm relaxes, and moves upward

3. The Volume inside of the chest cavity decreases

4. The Pressure inside the chest cavity increases

5. Air exits the lungs to equalize the pressure

Another Animation

• http://www.youtube.com/watch?v=43jJGXudePs&safety_mode=true&persist_safety_mode=1&safe=active

Inhaled vs. Exhaled Air  Inhaled Air

 Exhaled Air

Oxygen Concentration 

21 % 16 %

Carbon Dioxide Concentration

0.04 % 5 %

Nitrogen Concentration 

78 % 78 %

Dryness 

Drier Moist

Temperature 

Colder or Warmer than 37 C

Warm (close to 37 C)

Cleanliness 

Dirtier *Cleaner (filtered)

*Exhaled air may contain bacteria or viruses, but is cleaner in terms of dust or pollutants

Turbinate Bones

Increase Surface Area andIncrease the rate of

Filtering Warming and Moistening of air

Breathing versus Respiration

• Breathing: The act of bringing air in and out of lungs; consists of inhalation and exhalation; it is an external mechanical process

• Cellular (Cell) Respiration: When glucose (food) and oxygen combine to produce carbon dioxide, water and ATP energy; occurs in the mitochondria of cells; it is an internal chemical process

Equation: C6H12O6 + O2 CO2 + H2O + ATP

How are Breathing and Cell Respiration Connected?

• In order for cell respiration to occur, oxygen must move into cells, while carbon dioxide must move out of cells.

• The exchange is made in the lungs during breathing

Exchanges made between the lungs and the blood are said to be external exchanges, because the lungs are open to the outside of the body.

Gas Exchange

• Carbon dioxide and oxygen swap places. • The gases move by a process called diffusion.

• In animals, oxygen is moved from the air in the lungs to the blood, and then from the blood to the cells.

• Carbon dioxide moves in the opposite direction

Lungs

Cells

Blood

O2

CO2

http://www.youtube.com/watch?v=HiT621PrrO0&safety_mode=true&persist_safety_mode=1&safe=active

Label and Color the Alveolus Diagram

Use Red for oxygenated blood and Blue for deoxygenated blood

Conditions required for Gas Exchange

1. Thin walls (air sacs and blood vessels) – so that gases can pass through the walls

2. Moist walls – so that gases can dissolve and pass into the blood and cytoplasm of cells (which need materials in liquid, not gaseous form)

3. Concentration gradient – so that gases can move by diffusion; movement of molecules occurs from higher towards lower concentrations

4. Pressure gradient – so that the gases can be pushed in the direction that they need to move into; molecules will move from areas of higher towards areas of lower pressure

High Low

Effect of Altitude on Gas Exchange

At Sea Level, Air Pressure is Higher because there are more air particles on top of you

At high altitudes (like up on a mountain): There are lots of oxygen molecules But oxygen molecules can’t get into the body cells

This is because: There isn’t enough pressure To push the oxygen from the lungs

across the air sacs, blood vessels, and cell membranes into the cells where the oxygen is needed.

    Pressure Gradient

Diffusion Gradient

The Diffusion Gradient is in the right direction but the Pressure Gradient is not

At HIGH altitudes….

Gas Transport

• Oxygen and Carbon dioxide are carried in the blood stream.

• Oxygen is carried from the lungs to cells which then use the oxygen for cell respiration.

• Carbon dioxide is produced by cell respiration and is carried from the cells to the lungs to be exhaled.

Hemoglobin

• A chemical found inside red blood cells. • It has 4 binding spots for gas molecules. • There are many hemoglobin molecules in each

red blood cell. • Hemoglobin can carry

oxygen carbon dioxide hydrogen ions carbon monoxide

• A hemoglobin molecule consists of 4 Globular proteins (polypeptide chains) bound to a central iron (Fe) atom (called a Heme group)….hence the name Hemo Globin.

Fe

Blood Vessel

Red blood cell

Oxygen Transport

• Oxygen travels through the blood stream in 2 ways:• Dissolved in the blood plasma (3%)• Attached to hemoglobin – oxyhemoglobin (97%)

(Hb + O2 HbO2)

• Diagram:

• http://www.youtube.com/watch?v=WXOBJEXxNEo&safety_mode=true&persist_safety_mode=1&safe=active                                                                            (3 min. Pre-load to avoid ad, stop showing at graph)

97%

RBC 3% in plasma

Blood vessel

Carbon Dioxide Transport

• Carbon dioxide travels through the blood stream in 3 ways:

• Dissolved in the blood plasma (9%)• Attached to hemoglobin – carbaminohemoglobin (27%)

(Hb + CO2 HbCO2)• As a combination of bicarbonate ions dissolved in blood

plasma and hydrogen ions attached to hemoglobin - acid hemoglobin (64%)

(Hb + H+ HHb)• Diagram: 64% 

H+

27% CO2

9%  CO2  and 64% HCO3

- in plasma

Blood Vessel

http://www.youtube.com/watch?v=x26TWL3VKMg&NR=1&safety_mode=true&persist_safety_mode=1&safe=active

• If carbonic acid were allow to accumulate in the blood vessels, it would cause respiratory acidosis and could damage blood vessel walls

• The body solves this problem by buffering the blood• Once hydrogen ions are generated they are “hidden

away” inside red blood cells – they attach to hemoglobin to become “acid hemoglobin”

• The bicarbonate ions are benign and can travel through the blood vessels without causing problems

Carbon Monoxide Transport

• Carbon monoxide (CO) binds to hemoglobin 200X more tightly than oxygen

• Even if there is plenty of oxygen present, the hemoglobin will choose CO over oxygen, leading to the death of the person.

• Carbon monoxide is a colorless and odorless gas that is a by-product of combustion reactions – found in smoke.

• It is very important to have a carbon monoxide detector in your home.

Control of Breathing

• Number of breaths per minute taken at rest is about 14-20

• More when exercising• Breathing rate and heart rate are tied together• Breather rate and depth control by the

medulla oblongata and the pons in the brain

Nervous Control of Breathing

• Sensors called chemoreceptors detect CO2 levels in blood

• Higher CO2 levels = faster and deeper breathing

• To speed rate and depth of breathing, the brain sends messages to the diaphragm & intercostal muscles using sympathetic nerves

Nervous Control of Breathing

Muscles contract faster to speed up rate of breathing when CO2 is high

Muscles contract slower to slow rate of breathing when CO2 is low

Brain

Feedback Loops

Exercise Certain drugsHold breath

High CO2

Levels in Blood

Chemo-receptors (medulla &

Pons)

Diaphragm Intercostal muscles

Rate of breathing Increases

High Altitude Athletic Training• Training in places with higher elevations (ex. Colorado) in order to increase

lung capacity and thus performance• At first - breathing & heart rates will be higher than normal

• After a few months of training.... The lungs have stretched Breathing rates return to normal 14-20 breaths/minute More capillaries grew around alveoli to accommodate a faster gas exchange More red blood cells will have been added

to the blood stream for a greater oxygen carrying capacity.

• The athlete then returns to lower altitudes to compete