Physiology-membrane Channels-cell Vol Reg

A glucose symporter is a type of cotransporter that transports glucose across the cell membrane along with another molecule or ion. In this case, the appropriate cation associated with a glucose symporter would be Na+ (sodium ion). This is because glucose symporters often work in conjunction with sodium ions to transport glucose into the cell. Sodium ions create a concentration gradient by actively pumping out of the cell, and glucose is transported along with the sodium ions, utilizing the energy from the sodium gradient.

An increase in membrane thickness will decrease the rate of simple diffusion on a non-polar substance. This is because a thicker membrane creates a longer distance for the non-polar substance to travel through, resulting in slower diffusion. The diffusion rate is directly proportional to the surface area available for diffusion and inversely proportional to the distance the substance needs to travel. Therefore, an increase in membrane thickness will hinder the movement of the non-polar substance, leading to a decrease in the rate of diffusion.

Diagram B shows a dotted line that represents the change in fluid volume that will occur as a result of an isotonic saline infusion. The dotted line starts at the initial fluid volume and remains flat, indicating that there is no change in fluid volume after the saline infusion. This is characteristic of an isotonic solution, where the fluid volume remains the same.

The movement of water across a membrane by osmosis is determined by the concentration of water on each side of the membrane. Osmosis is the process by which water moves from an area of lower solute concentration to an area of higher solute concentration. Therefore, the concentration of water, rather than the permeability of the membrane to solutes or the presence of ion channels or transporters, is the primary determinant for the movement of water across a membrane by osmosis.

The correct answer is A because when the RBC is placed in an isotonic NaCl solution, there is no net movement of water into or out of the cell, so the volume remains unchanged. At point 1, the RBC is transferred to a solution with a lower osmolarity (225 mOsm/L), causing water to enter the cell by osmosis, leading to an increase in volume. At point 2, more NaCl is added to the solution, increasing its osmolarity to 375 mOsm/L. This higher osmolarity causes water to leave the cell by osmosis, resulting in a decrease in volume. Therefore, the correct graph should show an initial constant volume, followed by an increase in volume at point 1, and then a decrease in volume at point 2.

The number of binding sites for either one of the transported substances is the most important factor that determines the maximal rate of transport for substances via a cotransport carrier-mediated transport. This is because the binding sites on the carrier protein determine the capacity of the carrier to bind and transport the substances. The more binding sites available, the greater the capacity for transport, leading to a higher maximal rate of transport. The concentration gradient for Cl-, the transmembrane electrical gradient, and the electrical gradient for glucose are also important factors, but the number of binding sites has the greatest impact on the transport rate.

If there is a loss of hypo-osmotic fluid from the extracellular space, it means that there is a higher concentration of solute inside the cell compared to outside. As a result, water will move from the extracellular space into the intracellular space to balance out the concentrations. This influx of water will cause an increase in the intracellular osmolarity, leading to an increase in the concentration of solute inside the cell. Therefore, the correct answer is an increase in intracellular osmolarity.

Loss of isotonic body fluid due to hemorrhage, urine, diarrhea, or vomiting will result in a loss of extracellular fluid volume. This means that the overall amount of fluid in the extracellular space will decrease. However, since the loss is isotonic, the concentration of solutes in the extracellular fluid will remain the same. Therefore, there will be no change in extracellular osmolarity.

The patient's interstitial fluid volume is 15 L. This can be determined by calculating the total amount of mannitol and Evans blue dye that was given to the patient (1.0 L + 0.5 L = 1.5 L) and comparing it to the plasma concentration of these substances two hours later (0.1 g/L). Since there was no loss of indicator in the urine, it can be assumed that the entire amount of mannitol and Evans blue dye remained in the plasma. Therefore, the patient's interstitial fluid volume must be equal to the volume of fluid given (1.5 L) minus the plasma volume (0.1 g/L x 1.5 L = 0.15 L), which equals 15 L.

The extracellular fluid volume is determined by the concentration of the indicators in the plasma and the amount of indicator given to the patient. Since the concentration of inulin and antipyrine in the plasma is 1 g/L after two hours, it means that the indicators have equilibrated throughout the patient's extracellular fluid. Given that 1 L of 12 g/L inulin and 100 ml of 10 g/L antipyrine were given, it indicates that the initial amount of indicators distributed in the extracellular fluid was 12 g of inulin and 1 g of antipyrine. Therefore, the patient's extracellular fluid volume is 12.0 L.

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The patient's blood volume can be calculated using the indicator dilution method. In this method, the amount of indicator in the plasma is divided by the concentration of the indicator in the injected solution, and then multiplied by the volume of the injected solution. Since the concentration of both Evans blue dye and antipyrine in the plasma is 1 g/L, it means that the patient's blood volume is equal to the volume of the injected solution, which is 5.0 L.

To calculate the plasma volume, we can use the formula: Plasma Volume = (Amount of dye in plasma / Concentration of dye in plasma) * 100.
Given that there is 0.4 mg of dye per 100 ml of plasma, and the woman's plasma volume is being asked, we can substitute these values into the formula.
Plasma Volume = (0.4 mg / 0.4 mg per 100 ml) * 100 = 100 ml.
Since 1 L = 1000 ml, the plasma volume is 100 ml / 1000 = 0.1 L or 0.1 L.
To calculate the whole blood volume, we can use the formula: Whole Blood Volume = Plasma Volume / (1 - Hematocrit ratio).
Given that the hematocrit ratio is 45%, we can substitute these values into the formula.
Whole Blood Volume = 0.1 L / (1 - 0.45) = 0.1 L / 0.55 = 0.18 L or 0.18 L.
Therefore, the woman's plasma volume is 0.1 L and her whole blood volume is 0.18 L.

In the urea solution, the cells will swell. This is because urea has an osmotic coefficient of 0, meaning it does not contribute to the osmotic pressure. Therefore, water will move into the cells to equalize the osmotic pressure, causing them to swell.

In the NaCl solution, the cells will not change in size. This is because NaCl has an osmotic coefficient of 1, meaning it fully dissociates into ions and contributes to the osmotic pressure. The osmotic pressure inside and outside the cells will be equal, so there will be no net movement of water and no change in cell size.