Functions Of The Digestive And Kidney Systems Of The Body Essay, Research Paper

1. You eat a hot dog, leave the bun, describe the physiological response to the increased food in your stomach.

Food inters the stomach and it increases the pH and H+ decreases thus the stomach get more basic. The stomach walls are also stretched. Chemoreceptors and stretch receptors detect the change in pH and the stretch on the walls. Nerve impulses travel to the submucosal plexus this stimulates parasympathetic fiber. Waves of peristalsis occur and the flow of gastric juice and from parietal cells begins. This causes secretion of the hormone of gastrin to occur. The release of gastrin causes the release of acid and pepsinogen into the stomach. These chemicals stimulate more stomach mobility. This mobility starts to break up the hot-dog (chyme) in order to give it more surface area so that it can better mix with the acid and pepsinogen. Gastrin also relaxes the pyloric sphincter. Chyme is then passes into the small intestine for main absorption and digestion. The pH in the stomach returns to normal and the stretch receptor stop getting stimulated.

#2 You are having severe stomach cramps, the doctor says that you secretin receptors have been blocked. How has this affected your digestive process and what two hormones might be able to alleviate one of the affects.

Secretion inhibits stomach movement, emptying, slows secretion of gastric juices and causes bicarbonate to be dumped in from the pancreas and liver to the small intestine. This neutralizes the acid that is coming in. Since this process does not occur there is an increase of emptying of chyme into the small intestine. The small intestine fills and gastric juices keep flowing. The acidity will continue to increase (pH falls). The acid is does not get fully neutralized. Two hormones that can elevate the affects are GIP and CCK. These hormones signal the stomach to slow down and decrease stomach emptying. Substances such as fats stimulate the release of GIP and CCK. So if you eat some lard you may help slow stomach movement and slow secretion of gastric juices that are probably causing the discomfort because the acid is being pushed into the small intestine and it does not get neutralized.

Describe the path through which the hot-dog you ate earlier goes once it has made it past the ileocecal valve. (What is your hot-dog called now?) Be sure to include all embarrassing potential side effects of your less than healthily lunch and their causes.

The hard to resemble hot-dog is now called feces after it turn the corner around past the ileocecal value into the large intestine. The large intestine absorbs H20 and salts and Vitamins K and B. K and B vitamins are made from bacteria found in the intestine. If the body feels that the hot-dog you ate earlier may have toxins or microbes that irritate gastro intestinal mucosa you will get diarrhea. This causes the feces to pass quickly because the large intestine stops of absorption of water, salt and vitamins. The rapid loss of this material is inconveinent but necessary since it could be detrimental if the large intestine would absorb toxins in the process of absorbing the water and salts. If you ate your hot-dog to fast you will probably ingest some air. This will cause embarrassing (or high five’s depending on your company) flatus. Flatus isn’t just air you swallowed it is also Co2, methane, hydrogen sulfide, and hydrogen.

Once the water and salts are absorbed toward the end of the large intestine (sigmoid colon) the feces is ready for defecation as soon it inters the rectum. The presents of the feces in the rectum cause stretch receptors to feel the stretch on the walls of the rectum. A message is then sent to the spinal cord this intern increases peristalsis (shorting of the rectum) and a relaxation of the internal sphincter (smooth, involuntary muscle). Now you are in control for a while to find an appropriate time to relax the external sphincter (smooth, voluntary muscle).

#4 Describe the complete process of fat digestion from small intestine to the liver to cells.

Pancreatic lipase is secreted with pancreatic juices into the small intestine. Free fatty acids are transported into the cells of the intestinal wall by simple diffusion while glycerol is transported by active transport. Free fatty acids and glycerol are packaged and recombined to form triglycerides and proteins. They are put into globules along with phosopholipids and cholesterol and become coated with proteins. These packages are called chylomicrons. These chylomicrons leave the cell by way of exocytosis and are picked up by the lymph capillaries. These lymph capillaries send the packages into the blood. Within ten minutes of absorption, the chylomicrons are absorbed in the liver and in adipose tissue. The liver breaks down these packages with lipase and recombines the lipids and proteins to form lipoproteins known as VLDL and LDL. HDL formed in the liver is eventually converted to bile only to rid the body of cholesterol. VLDL and LDL are then sent to the cells. LDL delivers cholesterol to cells while VLDL delivers tryglicerides to cells

5. If you were suddenly suffering from a complete loss of pancreatic function, what steps of the digestive process would be effected? How would it be effected?

Without pancreatic function, no HCO3- secretion would occur to the small intestine. This would cause a fall in pH and the acidity would go up. Since pancreatic function is not occurring properly, the enteroendocrine cells would not be able to stimulate parietal cells to secrete HCO3- and papsinogen. Secretin in the body will keep increaseing causeing a decrease in gastric acid in the stomach therefore raising the pH, and inhibits stomach movement. Secretion will keep increasing because the pancreas cannot secret COH3-. The liver will pick up some of the slack and try to neutralize the acid.

6. You are chosen by the N.I.H to be the first person shrunken and ejected into the kidney. As you move from the blood vessel to the nephron, describe how things are moving in and out.

You’re traveling in the blood from the afferent artery traveling to the glomerulus. You are then filtrated. The filtration occurs because of increased blood pressure in the artery and decreased blood pressure in the glomerulus. This filtration is due to hydrostatic pressure. The membrane of the capillary is very thin and porous and as you enter the glomerulus, you notice there is a lot of surface area. You are so small you are able to pass into the next room and you notice that some substance stay behind that are too large to fit through the holes. When you exit the glomerulus and enter the renal tubule, you notice the reabsorption of NaCl, H2O, glucose, amino acids, and plasma back into the paritubular capillaries. Meanwhile, you notice you are swimming in an abundance of extra penicillin and acid secreted from the efferent artery. As you travel down the nephron tubule, you find yourself in a large chamber called the bladder. Soon after, you are excreted and peed out.

7. What is the function of the Loop of Henle and why is it important?

The Loop of Henle absorbs salt to create a very hypertonic region at the tip of the Loop of Henle. This hypotonic region is needed because when you want to retain water from the collecting ducts, the large concentration gradient causes the water to flow out when the aquorins are open thus retaining water into the interstitial fluid. This causes salt to be left in the interstitial fluid. Tubule fluid continues to pass through the Loop of Henle and enters the distal convoluted tubule. This fluid will be hypotonic. The fact that the loop of Henle left a hypertonic solution around the tubule with in the interstitial fluid this will cause the neighboring distal convoluted tubule to release water from the collecting duct because the distal convoluted tubule is hypotonic and the region outside of it is hypertonic.

8. Compare the proximal convoluted tubule to the distal convoluted tubule. What is absorbed?

The proximal convoluted tubule always absorbs a constant two thirds of NaCl and H2O. Na is absorbed first and creates a concentration and charged gradient so this causes H2O and Cl- to follow Na+ passively. The proximal convoluted tubule also reabsorbs 100 percent of glucose and amino acids. This only occurs with the use of transporters. In the case of diabetes mellitus, sugar and amino acids remain in urine because the proximal convoluted tubule’s transporters are completely saturated. The PCT has no control of how much is absorbed. Its only concern is to absorb two thirds of the NaCl and the H2O. The distal convoluted tubule fine-tunes Na reabsorption. The DCT is sensitive to aldosterone. Aldosterone synthesizes sodium transporters, which increases sodium reabsorption. The distal convoluted tubule then transports tubule fluid to the collecting ducts. The DCT does not absorb amino acids and glucose like the PCT.

9. You are about to weigh in for your inaugural WWF performance but you did not stick to your strict diet. So your are counting on the fact that you have purposely dehydrated yourself in effort to shrink osmotic receptors and lose a few pounds. Starting with the response of the hypothalamus, describe your body’s general response and the effect on urine concentration and total body water.

After you become dehydrated, the osmotic receptors shrink and your hypothalamus sends information to your posterior pituitary to release ADH into the blood stream. The release of ADH causes more aquorins to be active and allow water out into the hypertonic interstitial fluid created by the Loop of Henle. This causes an increased reabsorption of H2O which contributes to increase the total body water. The urine is going to be more concentrated because it had less water content and more solutes. This process is called antidiuresis.

10. Referring to the salty hot dog eaten earlier, describe the body’s response to sudden Na increase.

Sodium in the extracellular fluid will increase causing the blood volume to increase thus increasing the main arterial pressure. This increased arterial pressure will activate baroreceptors, which will send information to the CV center, and the CV center will send the information to the adrenal cortex to decrease the release of aldosterone. The distal convoluted tubules do not receive any aldosterone. This will cause no sodium to be reabsorbed lowering the interstitial concentration of sodium.

Increased sodium in the interstitial fluid also causes Na delivery to the J-G apparatus. This causes J-G cells to decrease the release of renin. ADH in turn also decreases but is compensated by the osmoreceptors.

Increased sodium in the interstitial fluid also causes the release of ADH, which causes collecting ducts to retain H2O. Arteriolar constriction will occur along with a strong desire to drink water.