LAB 5 BIO

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Brock University *

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2P97

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Biology

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Dec 6, 2023

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docx

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Lab 5 The Renal System Investigating Cell Osmolarity, Tonicity and Conducting Urinalysis 1. The data presented in the table represents the spectrophotometric analysis of red blood cells lysis. Hemolysis is the process through which the membranes of red blood cells or erythrocytes get ruptured and cause the release of Hemoglobin. A spectrophotometer determines how much a substance absorbs light at a particular wavelength, by measuring

the light intensity as it passes through the sample. The absorbance at 540 nm indicates absorbance of hemoglobin or the amount of hemoglobin while 640 nm indicates the intact red blood, which when dissolved in solution will form a cloudy mixture that will absorb light. Decrease in absorbance at 540 nm indicates hemolysis. At 640 nm, light dispersion of RBC suspension was measured. Decrease in absorbance at 640 nm indicates decrease in light dispersion. At 5% NaCl, the absorbance was 0.723, which is the second highest. The highest was 2% NaCl and was 1.3% at 540 nm. This is so because when the surrounding solution is concentrated, the water by osmosis leaves the cell and it leads to crenation and has a higher absorbance since there is less or no absorbance of hemoglobin. At 640 nm, 2% NaCl, the absorbance is highest 0.620, which shows most of the red blood cells are intact. the Moreover, in the solution with a concentration of 0.9% NaCl, the absorbance at 540 nm was low, 0.048, which can be due to some error since the normal osmolarity of the blood is around 275 to 295 milliosmole/kg and that is equivalent to 0.9%. At this osmolarity the red blood cells stay intact to give an opaque solution. At 0.2 % NaCl, the absorbance is lowest indicating that there is lysis of red blood cells at 0.028. During lysis, the solution has a pretty low osmolarity, causing the red blood cells to take up water and burst, releasing all of the intracellular contents. 0.1% Tween 20, 0.5 M glucose, 0.2% NaCl, 0.4% NaCl and 0.6% NaCl are hypo- osmotic compared to red blood cells. Hypo-osmotic solution causes an increase in red blood cell volume as water enters the red blood cell, thereafter the cell swells and eventually ruptures. 0.9% NaCl is iso-osmotic to red blood cells. 2% NaCl and 5 % NaCl are hyper-osmotic compared to red blood cells. Hyperosmotic solutions cause decrease in

red blood cell volume as water moves out from cell to solution. The cells get crenated. 20% Tween 20 is generally used as a positive control to induce red blood cell lysis. 2. The urine composition of a healthy individual normally consists of 95% water, along with urea, uric acid, creatinine, and other ions and molecules. These include sodium, potassium, sulphate, ammonium, phosphate etc. The pH of normal urine is about 4.5-8 while the range of specific gravity is 1.002–1.030 g/ml . There should be no traces of glucose, blood and molecules like ketones, urobilinogen and proteins are in very little amount. In the urinalysis performed in the lab, the composition of urine differed between the control and four other groups. The individuals with Glomerulonephritis had kidneys with inflammation filters, glomeruli. This means the glomeruli cannot filter substances and blood and proteins are found in the urine as shown by table 2, moderate amount of blood and 300(++) of protein, which leads to foamy urine. Next urine sample tested was Type 2 Diabetes Mellitus. In this type of diabetes, the pancreas does not make enough insulin, a hormone that regulates blood glucose levels and so instead of being taken up by cells, glucose builds up in the bloodstream and is also excreted with urine. Glucose is not usually found in urine, but a normal range can be up to 0 to 15 mg/dL but as shown in table the amount of glucose was really high, 1000 mg/dL or 60 mml/L. People with diabetes also have high levels of ketones because the body doesn't make enough insulin and as shown by table 2, the ketone levels are large. The Leukocytes count was also recorded as Large, which is a sign of infection somewhere in the urinary tract. Moreover, in a condition called Nephrotic Syndrome, the glomeruli are inflamed causing too much

protein to be passed down in urine but in table 2, the results are negative, which might be due to some error. The ketones levels, however, were large. Lastly, in the dehydrated individual urine sample, the level of ketones, nitrites were high and the pH was alkaline, 8.5. Loss of water leads to loss of minerals and electrolytes and increases blood pH. High levels of nitrite can indicate UTD infection. The hormone that is secreted in response to dehydration is called ADH or vasopressin. The role of vasopressin is to maximize water reabsorption and to maintain the osmolarity. It is produced by the hypothalamus and is transported to the posterior pituitary. ADH is released in response to increased osmolarity of plasma and decreased arterial blood volume. It stimulates the addition of aquaporins into the membrane of kidney tubules. These channels transport solute free water through tubules and eventually back into blood, leading to increase in osmolarity of urine. The volume of urine is also reduced and it results in the increase in Glomerular Filtrate rate. 3. The Glomerulus is a cluster of capillaries, known as tuft, located between two resistance vessels (Pollak et al., 2014). These capillaries are embedded in the Bowman’s capsule and are the only capillaries in the body not surrounded by interstitial tissue. The Bowman's capsule is a cup-like structure of the nephrons in the kidneys. It is connected to the tubular part of the nephrons. The glomerulus is inside this capsule. The blood is filtered in the Bowman's capsule as it passes through the glomerular capillaries. The factors affecting renal filtration are the hydrostatic pressure in the glomerulus , which pushes filtrate out of the capillaries and into the nephron. Increased blood volume and blood pressure will increase glomerular filtration rate. Vasodilation in the afferent arteriole and vasoconstriction in the efferent arteriole will increase blood flow

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