The following table shows the concentration of various solutes in the blood plasma entering the kidney, glomerular filtrate, and urine of a man. Solute Concentration of solute (g/ 1000 cm3) Blood plasma entering the kidney Glomerular filtrate Urine excreted by the kidney Urea 0.25 0.25 20.00 Glucose 1.00 1.00 0.00 Protein 70.00 0.20 0.00 Na+ ion 3.00 3.00 3.00 Cl- ion 3.50 3.50 6.00 SO42- ion 1.00 1.00 1.00 Name the process by which dissolved nutrients in blood plasma enter the Bowman's capsule. (1 mark) i. Explain why very little protein is found in the glomerular filtrate. (2 marks) ii. Explain why glucose is not found in the urine excreted. (1 mark) Explain briefly two ways by which urine is concentrated during its formation in the kidney. (4 marks) What is the immediate effect on urine formation if the man drinks one liter of seawater? (2 marks)
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Step 1: The process by which dissolved nutrients in blood plasma enter the Bowman's capsule is called filtration. Show more…
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Epithelial cells in the kidney reabsorb glucose from urine and return it to the bloodstream in a manner very similar to what happens in the intestine during absorption of food nutrients. It is known that the reabsorption of glucose into the epithelial cell from the urine is dependent on sodium reabsorption, but passage of glucose out of the epithelial cell and into the blood is not. The direction of glucose reabsorption and relevant concentrations of glucose (Glc) and sodium (Na+) are shown in the diagram at right. What is the molecular composition and structure of a typical cellular membrane? Briefly explain how the biochemical structure and properties of the membrane components allow membranes to carry out their function(s). Define passive and active transport and explain specifically how they differ. Based on what you've learned in the course, propose a mechanism by which glucose reabsorption occurs in these epithelial cells in a sodium dependent manner. Be as detailed as possible and include the source of energy, if necessary. Based on what you've learned in the course, propose a mechanism by which glucose moves from the kidney epithelium to the blood (kidney capillaries). Be as detailed as possible and include the source of energy, if necessary.
Sri K.
Excretion Assignment Name: Date: 1. The chart below gives the concentration of various dissolved substances in the blood plasma, filtrate, and urine. The arterial blood is the blood coming into the glomerulus, the postglomerular blood is the blood leaving the glomerulus and entering the capillary network. The venous blood is the blood leaving the capillaries. The filtrate is the fluid produced by the filtering of the blood plasma in the glomerulus and collected in Bowman’s capsule. Urine is the filtrate after all the nutrients are reabsorbed back in the capillary network surrounding the nephron. Concentration of Dissolved Substances (mg/100mL of fluid) Dissolved Substances | Arterial Blood | Postglomerular Blood | Filtrate | Urine | Venous Blood Urea | 30 | 0 | 30 | 1800 | 15 Uric acid | 4 | 0 | 4 | 50 | 3.6 Glucose | 100 | 0 | 100 | 0 | 98 Salts | 900 | 0 | 900 | 2300 | 850 proteins | 8000 | 9000 | 0 | 0 | 8020 c. Offer an explanation why you do not find proteins in the filtrate. d. Offer an explanation why the levels of urea, uric acid and salts in the urine are higher in concentration compared to the filtrate. e. Offer an explanation for the difference in concentration of glucose between the filtrate and urine. f. Offer an explanation for the difference in concentration of glucose between the filtrate and the venous blood. g. Give the name of the chemical the nephron is most effective in removing from the blood and the rationale for your answer.
Adi S.
2. Hemodialysis is a process by which a machine is used to filter urea and other waste products from a patient's blood if the kidneys fail. The amount of urea within a patient during dialysis is sometimes modeled by supposing there are two compartments within the patient: the blood, which is directly filtered by the dialysis machine, and another com- partment that cannot be directly filtered but that is con- nected to the blood. A system of two differential equations describing this is $$\frac{d c}{d t}=-\frac{K}{V} c+a p-b c \quad \frac{d p}{d t}=-a p+b c$$ where $c$ and $p$ are the urea concentrations in the blood and the inaccessible pool (in $\mathrm{mg} / \mathrm{mL} )$ and all constants are positive (see also Exercise 14 in the Review Section of this chapter). Suppose that $K / V=1, a=b=\frac{1}{2},$ and the initial urea concentration is $c(0)=c_{0}$ and $p(0)=c_{0} \mathrm{mg} / \mathrm{mL}$ $$\begin{array}{l}{\text { (a) Classify the equilibrium of this system. }} \\ {\text { (b) Solve this initial-value problem. }}\end{array}$$
Systems of Linear Differential Equations
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