Question

Identify one specific example each of mass and momentum transport in a mammalian system. Briefly describe each example and identify the driving force and the resistance. In each example, identify a parameter that can change in value, how that parameter is likely to change, and the effects of that change on mass or momentum transfer in your example.

Answer 1

Surface to volume ration is an important theme in biological system. Smaller organism has higher surface to volume ratio while complex organism such as mammalian has lower surface to volume ratio. Substances needed by a large organism could not be supplied through its exposed external surface. Oxygen passing through an external surface would be rapidly used up before reaching the many layers of underlying cells. Similarly waste substances would not be excreted quickly enough. To solve this problem we need transport system.

• Example of mass transport- molecular diffusion (mass transfer) such as ion diffusion.
• Example of momentum transfer- fluid flow (momentum transfer) such as blood flow.

Blood flow in mammalian is one of the example of momentum transport system. Arteries carry blood away from the heart. Capillaries are the site of the exchange of materials between the blood and tissues. Veins take blood back into the heart. Viscosity of fluid such as blood create resistance. Complex structure of such system also create resistance in the way of mass trasport. Pressure difference is driving force for momentum transport system. Pressure difference can be treated as parameter. If presssure difference is higher then blood flow is quick from higher to lower pressure in capillary.

Molecular diffusion such as ions flow in mammalian is one of the example of mass transport system. Sodium and potassium pump can serve as a mass transport system. Concentration differnce and potential difference are driving force for mass transport system. Inhibitor such as serotonin can generate resistance by blocking the sodium channel. such as Concentration difference can be treated as parameter. If concentration difference is higher then ions diffusion is quicker from higher to lower concentration in system. ATP is the source of energy for this system.

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