Question

Describe a physiological role for each of the following gradients in the human body. Use ANY of the organ systems discuss how the gradient is necessary to our survival.

a. Concentration Gradient b. Pressure (or partial pressure) Gradient c. Osmotic Gradient

Answer 1

concentration gradient- the concentration gradient is the difference in concentration of substance across a membrane. For example, in the blood vessels near alveoli, the concentration of carbon dioxide is higher in blood than the alveoli. This creates a gradient across the respiratory membrane. This concentration gradient cause movement of carbon dioxide from blood to alveoli which is required in process of respiration.

pressure gradient.

this can be understood using the example of respiratory system. During inspiration, our chest expands. Due to expansion the intrathoracic volume increase and intrathoracic pressure decreases. This creates a pressure gradient between atmosphere and inside of the lung which cause movement of air into the lungs. Thus a pressure gradient is required for movement of gases in respiration.

osmotic gradient.

this can be understood using example of filtration occurring in kidneys. As the Bowman's capsule filter the blood, the filtrate is formed and it then moves forward along the renal tubules. In the DCT and collecting tubules, the concentration of electrolytes are higher as compared to that in extracellular fluid. This creates a osmotic gradient which cause movement of water from the renal tubules into the interstitium. This movement of water across the concentration gradient is useful in conservative of water and making urine concentrated.