Glomerular Filtration Rate, GFR, is the amount of plasma that is filtered in a minute; this filtration occurs because of the pressures in the afferent and efferent arterioles of the glomerulus. GFR can be affected by the net filtration pressure (NFP); furthermore, GFR can be affected by the sympathetic nervous system. NFP is the pressure that drives filtrate through the glomerulus; it is calculated by taking the difference of outward and inward pressures. If the pressure is increased and more filtrate is going through the glomerulus, GFR increases thus increasing urine output. If NFP decreases, less filtrate is going through the glomerulus, so GFR and urine output is decreased.
In the event that fluid is lost (dehydration, blood loss etc.),
The blood circulates around the body. The heart contract and relax, this mechanism of heart makes the blood to flow in the arteries to the body from heart and come back from body to heart through veins. The arteries carry oxygenated blood or oxygen rich blood and the veins carry deoxygenated blood or oxygen poor blood. This flow creates the pressure on the arterial wall and the pressure that is exerted on the arterial wall is known as blood pressure. Blood pressure is expressed by the
Shearing forces acting on the vascular endothelium generated by blood flow causes a release of calcium and subsequent cNOS (cyclic nitric oxide synthase) activation. Therefore, increases in blood flow stimulate NO formation (flow-dependent NO formation). Nitric oxide then causes independent vasodilation by inhibiting vasoconstrictor influences of phenylephrine and alters its potency and contractile effect. (Richard E. Klabunde. 2010)
It collects excess fluid and particulate matter. It deposits them in the blood stream through the
d. Describe the collecting duct role relative to urine concentration. Depending on the body fluid
It is calculated that the total change in mass in the normal cell is 2.1 whereas the change in mass for the cystic fibrosis cell is 3.5. The greater change in mass is indicated in the cystic fibrosis cell and not the normal cell. The normal cell remained stable, whereas the cystic fibrosis cell fluctuated at a greater rate. Below shows the data table for mass in grams of dialysis bags containing NaCl solution with respective time.
17. When the one-way valve between the collecting duct and the urinary bladder was closed, what happened to the filtrate pressure in Bowman's capsule (was not directly measured) and the GFR? The filtrate pressure and GFR increased.
If George was in the second stage of chronic renal failure, what percent of his nephrons have been lost? What changes will be seen in the GFR; urination; and percent of nephrons lost when George reaches end-stage renal failure?
2. How could you adjust the afferent or efferent radius to compensate for the effect of the reduced pressure on glomerular filtration rate and urine volume? Use the simulation to determine your answer.
Two mechanisms act by changing the resistance or diameter of afferent arterioles. When the afferent arteriole tighten, within the glomerular capillaries, the pressure decreases. Myogenic regulation is the first of the intrinsic mechanisms that are arteriole-related. Arteriole constriction is when there is an increase in stretch, as observed if pressure increases. To maintain GFR, constriction tends to limit the change in pressure all throughout the glomerular capillaries. The second arteriole-related intrinsic mechanisms, called tubuloglomerular feedback, involve the juxtaglomerular apparatus, where the afferent and efferent arterioles come in contact
The main purpose of this lab was to study the capillary pressure (Pc) in eight sandstone core samples in order to obtain saturation values and the height above the free water contact in the reservoir rocks. In general, capillary pressure can be defined as the difference in pressure between two immiscible fluid phases (usually oil and water) that occupy the same pores. It is basically generated by the interfacial tension between two different phases. It is considered to be one of the important factors that control fluid distribution in reservoir rocks. Moreover, capillary pressure can be the key to determine the relationship between important rock properties such as porosity, permeability, and water saturation above oil-water contact in reservoirs.
There are two hormones in the body that contribute to the control of urine volume of composition: aldosterone and vasopressin. Vasopressin, also known as antidiuretic hormone, acts on principal cells to promote water reuptake back into the body. This results in concentrated urine because most of the water is reabsorbed back into the blood. Fluid deprived subjects stimulated more vasopressin in order to retain as much water as possible in order to prevent dehydration as much as possible. As the blood volume in the fluid deprived subjects decreased, ADH was stimulated to increase water reabsorption by the principal cells into the blood stream to decrease the urine flow rate. Since ADH results in concentrated urine, there will be more ions present
As aging progresses, the kidneys begin to lose anatomical structures and physiological functions. Only 3% of the elderly have normal kidney structure and function (Mareib and Hoehn, 2012). This is most commonly observed by the loss of renal mass; this can start in early adulthood and 50-90g can be lost. At 90 years old the kidneys weigh 20-40% less than that at 30 years (Saladin, 2010). This loss starts from ages 30-59, and is most considerable from ages 60-70 (Čukuranović and Vlajković, 2005). The loss in renal mass can be primarily attributed to the cortex area and the decline in renal blood flow (Čukuranović and Vlajković, 2005). The changes in renal blood flow will be discussed later. The cortex mass loss is due to the loss of 30-40% the amount of functional nephrons. After the kidney length peak at ages 20-30, there is a subtle shrinking until age 60 and then the decrease accelerates (Čukuranović and Vlajković, 2005).
Capsular hydrostatic pressure (CHP): hydrostatic pressure exerted by fluid within the capsular space of the glomerular capsule, and blood colloid osmotic pressure (BCOP): osmotic pressure resulting from plasma proteins, oppose the GBHP and create the net filtration pressure (NFP) of 10mmHg under normal conditions. This pressure promotes filtration of water and solutes (Jenkins, Kemnitz and Tortora, 2010). However with the drop of GBHP, the NFP will drop and even the small supply of blood that had not bypassed and entered the capillaries will not be filtered. Change in pressure and levels of solutes will affect other levels such as concentration gradients of solutes and osmotic pressure within the peritubular capillaries, interstitial fluid and renal tubules, which are vital during tubular reabsorption and secretion. As a result, nephron function will
The functional unit of the kidney is the nephron. It consists of a renal corpuscle where fluid can be filtered and a renal tubule where the filtered fluid flows through. Nephrons perform three basic functions, Glomerular filtration, tubular reabsorption, and tubular secretion. Glomerular filtration occurs as pressure (glomerular blood hydrostatic pressure) forces water and dissolved blood components through the endothelial pores of the capillaries, basement membrane, and on through the filtration slits of the adjoining visceral wall of the glomerular capsule. The resulting fluid is called the filtrate. Most substances in blood plasma are filtered by the renal corpuscle. However, blood cells and most proteins are not filtered. Filtration of blood depends on the force of glomerular blood hydrostatic pressure. Filtration fraction is the percentage of
If the solution contains only sucrose then the osmotic pressure will increase substantially. This would represent a hypotonic solution because more water molecules are entering the cell meaning the solution contains no invertase. If the osmotic pressure has a slight increase than the solution contains sucrose and invertase due to the rate of the sucrose being broken down, however the cell will overtime begin to shrink. If the osmotic pressure remains close to the same than the solution contains no sucrose, containing only water and invertase. We predicted that because the height of the fluid in the osmometer tubing was increasing only a little bit our blue solution was hypertonic and contained invertase and sucrose. The invertase was able to break down sucrose into glucose and fructose which were small enough to be able to leave the cell membrane. This would reflect a hypertonic solution. We predicted this would cause the cell to shrink in size and the height of the fluid would never increase.