BIO 104 5/10/96

These notes not reviewed by Dr Barstow

There will be a help session Sunday at 5:00 pm in room 1501 Plant Sciences.

Respiratory System:

respiration is the delivering of oxygen to the tissues.
we need oxygen for the formation of ATP
Glucose goes through a long series of reactions resulting in CO₂ and water
this process gives you energy which takes ADP and potassium to make ATP

Atmospheric pressure: this is the measure of pressure in the atmosphere, it is measured in mm. The atmospheric pressure moves mercury up a column and at sea level the measure is 760 mm Hg

O₂ 21% of the atmosphere and has a partial pressure of 159. This is just 760 x 21%.
N₂ 77% 593
CO₂ .03% .23
Argon .97% 7.6

Partial pressure is the measure of how much the element plays in the overall pressure.

In fresh water you can dissolve oxygen at the following rates and temperatures:

0 C 10ml O₂/l
15 C 7ml O₂/l
37 C 5ml O₂/l

in hotter water you can dissolve less oxygen
gases are 20% less soluble in salt water than in fresh water.

To get oxygen to the tissues:

diffusion: must occur across a thin, moist membrane
need a large respiratory surface for diffusion (gills or lungs)
need a way to ventilate the system. (See figure 39.5 below)

Countercurrent Flow. Figure 39.5

flowing in different directions
constant diffusion, unlike noncounter-current flow

Characteristics of respiratory surface area:

Evaginations (out pockets)
1. gills
2. book lungs
Invaginations (in pockets)
1. trachea (insects)
2. lungs
- amphibians get their air through gills and the skin
- mammals ventilate through our lungs, we breath out.

Site of exchange of oxygen and carbon dioxide is the Alveoli

surrounded by capillary bed
looks like grapes to increase the surface area
As the blood enters the partial pressure is not equal to the pressure of the alveolar gas, and as the blood goes through the lungs it acquires more O₂ to increase the partial pressure and as a result the pressure is even when it enters the pulmonary vein.
Oxygen is picked up by the blood and packaged in hemoglobins (Hb)
there are 280 million molecules per 1 red blood cell
The oxygen and hemoglobins join to form oxy- hemoglobin, and when the HbO₂ reaches the tissue the O₂ and Hb are converted back to their original forms.

External Respiration:

Oxygen is picked up by red blood cells; then the O₂ diffuses from the red blood cells to the tissue cells.
At the same time CO₂ is picked up by the plasma and red blood cells and becomes a bicarbonate, and this is how it is transferred to the lungs. Once in the lungs it changes back to CO₂.

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