Animal Physiology: Respiration

Why is it so cool for birds to have unidirectional flow in respiration?

Cross-current exchange rather than tidal exchange (more efficient)

Alveoli

Very fine airways designed to increase surface area and increase rate of diffusion

Why does hemoglobin exist?

O2 isn’t very soluble, so hemoglobin binds it to help it integrate into the bloodstream

What metal does hemoglobin have in it?

Iron

Oxyhemoglobin

Hemoglobin bound to O2

Deoxyhemoglobin

Hemoglobin not bound to O2

Methemoglobin

Hemoglobin with Fe³⁺ iron, which will not bind O2

Carboxyhemoglobin

Hemoglobin bound to CO

Why is CO so dangerous?

Hemoglobin is 200x more attracted to CO than to O2

How many O2 molecules does one molecule of hemoglobin bind?

4

The Bohr Effect

Affinity for O2 to disconnect from Hb decreases as pH decreases or as CO2 partial pressure increases

Where is partial pressure of O2 highest?

In the lungs

Impact of high temperatures on blood O2

Gives O2 less ability to dissociate from hemoglobin and go to tissues

2,3-DPG

Intracellular metabolite that helps organisms acclimatize to higher altitudes (high concentrations promote release of O2 to important tissues)

The Root Effect

As pH increases, O2 doesn’t want to go to tissues (not that important in mammals)

Bicarbonate (HCO₃^-)

Primary pH buffer in living organisms

CO2 transport in the blood

Almost always converted to bicarbonate or carbamino compounds

The Haldane Effect

Deoxygenation promotes CO2 uptake, oxygenation promotes CO2 unloading

Carbonic Anhydrase (CA)

Enzyme that catalyzes conversion of CO2 and H2O into Bicarbonate (and an H+ ion)

Why does Chloride enter the red blood cell at the same time as bicarbonate leaves?

We don’t know 🙂 it’s like a big mystery

Where does bicarbonate go once it has been made in the red blood cell?

Out into the plasma

Normal plasma pH

7.4

At what pH ranges are you dead?

>7.7, <6.8

How is ventilation controlled?

Through the brain stem, and it can be voluntary or involuntary (your breathing has now been set to manual)