RespirationGases in, Gases OutPage 447-451

Gas ExchangeThe alveoli exchange gases with the blood as the gases move from ___________concentration

The Air We BreatheAir has relatively:

◦High O2

◦Low CO2

The Air We BreatheConcentrations of gases are usually described in terms of __________◦The more gas there is, the more _______ it exerts on surrounding environment

The air at sea level has an atmospheric pressure of 101.3 kPa

The Air We BreathePartial Pressure: the pressure of an

_______________ in a sample◦The sum of the partial pressures in a sample will equal the _____________

◦As O2 makes up 20.9% of the air, it has a partial pressure of 21.2kPa (20.9% of 101.3 kPa)

◦Carbon dioxide has a partial pressure of 0.0397kPa

Gas ExchangeGases move from _____ partial pressure to _____ partial pressure

Gas ExchangeExplain this:

Gas ExchangeOxygen in the alveoli is 13.3 kPa while it is about 5.3 kPa in the blood

Oxygen diffuses until blood oxygen is 13.3 kPa

Using this mechanism, 1L of blood will carry 3 mL of O2

HemoglobinProtein in the blood that binds to _______

Hemoglobin

Made up of four subunits

Each subunit surrounds a _______ group

HemoglobinHeme group

HemoglobinHeme group

◦Circular, ring structure with an ___ ion in the middle

◦The ___ ion is capable of binding to O2

HemoglobinWorks by binding to oxygen that has become

dissolved in the blood

Oxyhemoglobin gives blood a bright red color

Allows the blood to carry much more oxygen than it normally could◦Blood with hemoglobin can carry 200mL of oxygen per 1L of blood

◦An increase of 70x

Gas ExchangeOxygenated blood travels to the cells of the body where

it diffuses into the cells◦The partial pressure in the blood is 13.3 kPa while it only 5.33 kPa in the cells

◦As pressure in the blood decreases, hemoglobin releases it’s oxygen

Carbon dioxide also diffuses out of the cell into the blood◦Partial pressure is 5.6 kPa in the cell and 5.33 kPa in the blood

Carbon dioxide in the bloodUndergoes a serious of steps:

CO2 + H2O H2CO3

H2CO3 H+ + HCO3-

The H+ causes the blood to be _______

Carbon dioxide in the bloodThe hemoglobin that is no longer carrying oxygen is able to bind to these H+ ions

◦This reduces the _______ of the blood

Carbon dioxide in the bloodBack in the lungs, the hemoglobin releases the H+

as it would much rather bind to the ________◦The released H+ undergoes this reaction:

H+ + HCO3- CO2 + H2O

Carbon dioxide diffuses out of blood into the alveoli◦Partial pressure of CO2 in blood is 5.6 kPa and only 5.33 kPa in alveoli

Thought questions for homeworkWhy is it important for the partial pressures of O2 and CO2 to be different in the alveoli than it is in the surrounding air we breathe?

How does altitude affect our breathing?