Henle: A Case Study

In this lab experiment, half our group observed and measured osmosis using dialysis tubes that were represented as the semipermeable membrane. It is permeable to water and other small molecules but is impermeable to larger molecules such as the sucrose solution used in each of the four beakers and tubing. The other half of our group observed the tonicity of sheep blood to determine whether the blood was isotonic, hypotonic, or hypertonic. The 85 g/dL of NaCl solution was the ideal isotonic number in relation to the sheep blood cells as well as a reference to the other observations of the solutions.

We hypothesize that as the solute concentration increases, more water will diffuse into the dialysis tubing (shown by a greater percent increase in mass).

Consequently, the efferent arteriole, which filters blood away from the glomerulus, is tinier in diameter than the afferent arteriole, which carries blood into each glomerulus. This puts blood under high pressure in the glomerulus; thus it forces tiny molecules and liquid out of the capillary and into the Bowman’s capsule. Soon afterwards, the tiny and liquid molecules cross the epithelium of the Bowman’s capsule, the basement membrane and capillary wall in order to get into the Bowman’s capsule and to arrive in the nephron tubules. The consequence of this is that the filtrate (the tiny and liquid molecules) pass along the remainder of the nephron and helpful substances are reabsorbed along the route. Last of all, “the filtrate flows through the collecting duct and passes out of the kidney along the ureter” as mentioned by (Parson’s, R: p128).

The difference is that along with large molecules, living cells prevent molecules with positive charges and solubility. This is not representing in dialysis tubing, and is only found in living cells because the tubing is only based on molecular size (98). When referring the rate of diffusion, the concentration gradient influences the diffusion rate, based on the factors of temperature. The ability for molecules diffuse from high to low concentrations primarily depends on the concentration gradient between the two areas.(96-99). My hypothesis for the study is that in the hypotonic, hypertonic, and isotonic solutions, the direction and rate of osmosis will determine based on the concentration inside the dialysis tubing. My prediction is that if the solution is hypotonic the results will decrease, if the solution is hypertonic the results will increase and if the solution is isotonic the solution will vary and or remain constant.

The purpose of this experiment is to observe the natural process of osmosis using drops of sheep’s blood in various saline solutions. Since the cell membrane is a selective membrane, the water goes in and out freely but a solute such as NaCl it cannot freely move in or out. Osmosis is a passive process that doesn’t require the input of energy to transport water molecules across a membrane. The channels that allow water to enter or leave a cell are known as aquaporin. Using aquaporin, water moves from a solution with a low solute concentration to a solution with a higher solute concentration. This process continues until equilibrium in solute concentration is established between a cell and its environment.

We filled bags of dialysis tubing with 20 ml of sucrose, NaCl, ovalbumin, and glucose and weighted them. After soaking them in distilled water for 10 minutes we measured them again. All of the bags gained water. Our hypothesis was that water will diffuse into the cells with ovalbumin, NaCl, glucose, and sucrose, but not the bag with distilled water. The independent variables were the different solutes in the dialysis tubing. The dependent variable was if the water would diffuse into the

Secondly, osmosis was to be observed to gain a proper understanding of how the principal of dialysis functions.

this, this urine that leaves the distal tubule is dilute. If the osmolality of the urine is

Pills that cause your body to send more water through the kidneys are designed to help people who retain water due to poor body function. The most common reasons doctors prescribe diuretics is due to high blood pressure or heart problems. These disease and other factors cause fluid to build up in places like feet ankles, legs, and sometimes even the belly.

If the concentration of sodium is low, the osmoreceptors activate the mechanisms to increase blood volume by decreasing the amount of Antidiuretic hormone ,which causes sodium to be retained , less urine is produced.

Water reabsorption is regulated by vasopressin since its release increases the water permeability of distal tubule and collecting duct cells in the kidney. After stimulation by vasopressin, aquaporin-2 (AQP2) accumulates in the plasma membrane of these target cells on the apical side. Aquaporin-2 is a water channel that allows water to be reabsorbed from the filtrate (urine), returned to the bloodstream and consequently concentrating urine.

In Kidney failure cases urea, creatine, uric acids and electrolytes move from the blood to the dialysate with the net effect of lowering their concentration in the blood. RBC s WBC s and plasma proteins are too large to diffuse through the pores of the membrane. Hemodialysis patient are exposed to 120 to 130 L of water during each dialysis treatment. Small molecular weight substances can pass from the dialysate in to patient’s blood. So the purity of water used for dialysis is monitored and controlled.

Diuretics are drugs that that increases the amount of urine output. Diuretics work by promoting the kidney to excrete salt and water out. This action reduces the volume of the blood an also reduce the amount work the heart has to do. The way that Lasix promotes the kidney to excrete salt and water is that since sodium, chloride and water that is filtered out of the blood is usually reabsorbed into the blood by the peritubular capillaries and the rest is eliminated from the body through urine. Furosemide works by blocking the absorption of sodium, chloride, and water from the peritubular capillaries in the kidney which causes an increase in the urine

In this experiment, renal regulation of osmolarity will be demonstrated through the use of urinalysis.

Osmoregulation is the process in which an organism balances the uptake and loss of water and solutes, on a cellular level, in an attempt to maintain homeostasis (Campbell and Reece, 2009). In osmoregulation, the regulation of osmotic pressure is the way in which organisms prevent their fluid from becoming to concentrated or diluted. The osmotic pressure, generated by the net movement of water across a selectively permeable membrane, driven by differences in solute concentrations on each side of the membrane, is critical in the maintenance of homeostasis. During osmosis, water flows from the solution with the lower concentration of solute to the higher concentration of solute. If the solution outside the cell has a higher solute concentration than inside the cell, it is a hypertonic solution and water will leave the cell. A hypotonic solution occurs when the cell has a higher solute concentration than out side the cell, and water will enter the cell. If the concentrations on both sides of the membrane are equal to each other, then the solution is known to be isotonic which results in no net flow of water.