Term
|
Definition
| is the only means to exchange these gases. |
|
|
Term
|
Definition
Q = DA (P1 - P2/L)
Q is the rate at which a substance diffuses between two locations.
D is the diffusion coefficient. It depends on the size and shape of the diffusing substance, the medium, and temperature.
A is the cross-sectional area over which the substance is diffusing.
P1 and P2 are the partial pressures of the gas at two locations (or concentrations of the substance).
L is the distance between these locations. |
|
|
Term
| Adaptations for maximizing respiratory gas exchange |
|
Definition
Increase the surface area for exchange (A)
Maximize the partial pressure gradient across that surface area (P1 – P2)/L
1. Proper ventilation of the respiratory medium on the outside of the respiratory surface.
2. Proper blood flow on the inside of the respiratory surface
3. Decrease L |
|
|
Term
|
Definition
| There is a decrease in oxygen, lower partial pressure. |
|
|
Term
|
Definition
| oxygen diffuses much less easily in water than in air.so fish work harder to get oxygen. |
|
|
Term
| Temperature;s effect on water breathers |
|
Definition
As temperatures rise, so does the animal’s metabolism and the need for more O2.
However, warm water holds less dissolved O2 than cold water.
These two combine to produce problems for water breathers
Therefore, more energy must be expended to get a decreasing O2 supply. |
|
|
Term
|
Definition
| are branched and folded thin membranes on the body surface that provide a larger diffusion area. |
|
|
Term
|
Definition
| are similar to external gills but are protected from damage by their location inside body cavities. |
|
|
Term
|
Definition
| Insects' a unique system for gas exchange, which are branched tubules. The tracheae penetrate through fine terminal branches to tissues and cells, presenting an enormous surface area for gas exchange. It begin at openings on the outside of the body called spiracles, which admit air. |
|
|
Term
|
Definition
| brings fresh air or water with high PO2 and low PCO2 into contact with the respiratory surface. |
|
|
Term
|
Definition
| by the circulatory system helps maintain the low PO2 and the high PCO2 on the inside of exchange surfaces. |
|
|
Term
|
Definition
ever-finer branches of air tubes in trachea, O2 is delivered to air capillaries not more than a few micrometers away from cell mitochondria.
Since O2 diffuses at a higher rate in air than in water, this system ensures an abundant supply for high metabolism.
However, small diameter and total length of these dead-end airways limits body size. |
|
|
Term
| double pump system for ventilation |
|
Definition
Water passes into the mouth, over the gills and out the opercular flaps.
This produces a constant, one-way water flow over the gills that maximizes the PO2 on the external gill surfaces.
Blood flow on the internal side minimizes the PO2 by sweeping O2 away rapidly. |
|
|
Term
|
Definition
maximize the surface area for gas exchange (A). SA may be 10x > than rest of body surface.
Each gill has hundreds of subunits called gill filaments supported by the gill arches; each filament is covered with lamellae, the gas exchange surfaces.
The structure (thin and high surface area) of the lamellae minimizes the path length for diffusion (L). |
|
|
Term
|
Definition
| airways in which gas exchange cannot occur. Fluid in the lungs, resulting from conditions such as em |
|
|
Term
|
Definition
the incoming air mixes with the stale air remaining in the lung, which severely limits the PO2 gradient. PO2 in alveoli ~ 100mm Hg.
The volume of this stale air is the sum of the residual volume and the expiratory reserve volume.
Tidal breathing also reduces gas exchange efficiency by not permitting countercurrent gas exchange between air and blood.
To offset the inefficiencies of tidal breathing, mammalian lungs have an enormous surface area and a very short path length for diffusion. |
|
|
Term
|
Definition
are thin-walled air sacs and are the sites of gas exchange. Human lungs have ~300 million alveoli, with a surface area of 70-90 m2. Capillary blood vessels closely surround the alveoli, resulting in a diffusion path of less than 2 mm, which is less than the diameter of a red blood cell.
Deep breaths increase PO2 in the alveoli. |
|
|
Term
|
Definition
| captures dirt from air and uses cilia to move mucus to swallow. |
|
|
Term
|
Definition
is a chemical substance that reduces the surface tension of a liquid.
The aqueous lining of the lung has surface tension that must be overcome to permit inflation and inhibit deflation of the alveoli.
Cells in the alveoli produce surfactant molecules (lipoproteins) when they are stretched. Premature babies may develop respiratory stress syndrome if they are born before cells in the alveoli are producing surfactant. |
|
|
Term
| External intercostal muscles |
|
Definition
| expand the thoracic cavity and increase the volume of air inhaled. |
|
|
Term
| Internal intercostal muscles |
|
Definition
| decrease the volume of the thoracic cavity and increase the amount of air exhaled. |
|
|
