HYPS Bio
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- What happens during the gastic phase of digestion?
- Food in the stomach, particularly the presence of amino acids and peptides, causes G cells to secrete gastrin which in turn stimulates parietal cells.
- What does gastrin stimulate?
- parietal cells
- What inhibits gastrin secretion?
- once acidic chyme, with a pH less than 3, reaches the duodenum.
- What do parietal cells secrete?
- HCl
- Determine the role of HCl in the stomach.
- In the stomach, HCl is necessary for the proper function of pepsin b/c the proper pH for pepsin is btw 1 and 3.
- Once cyme reaches a certain acidity (pH <3) and moves into the small intestine, what happens?
- gastrin secretion is inhibited and therefore HCl secretion is decreased.
- Examine what occurs when acidic chyme reaches the small intestine.
-
- Once the chyme moves into the small intestine, hte pH needs to be increased in order to reach the optimal pH (>5) for pancreatic proteases and lipases.
- Gastrin release is inhibited and the pancreas is stimulated to secrete bicarbonate in order to neutralize the acid.
- The pancreas also releases hydrolytic enzymes such as amylase, trypsinogen, chymotrypsinogen, and pancreatic lipases. - What does the pancreas release?
-
- it is stimulated to secrete bicarbonate in order to neutralize the acid.
- Hydrolytic enzymes such as amylase, trypsinogen, chymotrypsinogen, and pancreatic lipases. - Examine teh effect of a gastrin-secreting tumor.
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- A gastrin-secreting tumor will secrete gastrin at all time and will not be inhibited by normal feedback mechanisms such as the presence of chyme in the small intestine.
- Excess of acid will move with the chyme into the small intestine.
- Normal amounts of bicarbonate will be released; however this is not enough to effectively neutralize such an excess of HCl. - Determine the effects of an acidic environment in the small intestine.
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- Pancreatic juices require a less acidic environment than do stomach enzymes.
- If environment in small intestine is too acidic, then pancreatic secretions will be unable to function normally.
- While proteins and carbohydrates are paritally digested before they reach the small intestine, fats don't begin digestion until they reach the duodenum.
- If pancreatic lipases are unable to function due to an excessively acidic environment, they will not be able to digest lipids.
- This hypersecretion of gastrin will lower the pH of the duodenum so that the lipases are inactivity.
- This will result in the malabsorption of lipids, also known as steatorrhea. - Steatorrhea
- malabsorption of lipids
- (T/F) Pancreatic juices require a less acidic environment than do stomach enzymes.
- True
- (T/F) Proteins and carbohydrates are paritally digested before they reach the small intestine.
- True
- (T/F) Fats begin digestion before they reach the duodenum.
- False, they do not begin digestion before they reach the duodenum.
- (T/F) The pH levels of the stomach and the small intestine don't affect the ability of enzymes to function properly.
- FALSE
- (T/F) An acidic duodenal pH will affect the functioning ability of all of the pancreatic enzymes but protein absorption can still occur b/c proteins are digested in the stomach
- True
- Carbohydrate digestion relys on pancreatic secretions.
- False, carbohydrate digestion doesn't relies on pancreatic secretions.
- Where does carbohydrate digestion begin?
- mouth and continue to be borken down by maltase and sucrase in the intestinal brush border.
- What would most likely happen to the rate of ATP consumption (based on Na/K pump) if a cell were moved to a hypertonic environment?
-
- B/c the cell was moved to a hypertonic solution, water will most likely move out of the cell and the cell's volume will decrease.
- Na/K pump pumps in 2K ions for every 3Na out. Therefore, there is a net loss of one ion.
- To counter this effect, ATP consumption will decrease to maintain cell volume. - What does caffeine inhibit?
- ADH activity, thus decreasing water reabsorption activity from the collectin duct.
- What should you think first when there is excessive urine output?
- problem at the reabsorption level ==> failure to reabsorb water from the nephron.
- What does renal failure relating to filtration usually result in?
- irregular plasma osmolarity (ie. the urea concentration is too high or the albumin concentration is too low)
- What critical role does secretion play?
- maintains blood pH, K+ concentration in blood, and nitrogenous waste concentration in the filtrate.
- Reabsorption affects...?
- filtrate concentration as essential substances such as glucose, salts,a nd blood are returned to the blood.
- (T/F) ADH works directly on the collecting duct by increasing its permeability to water
- True.
- A sustained (increase/decrease) in plasma osmolarity triggers ADH secretion.
- Increase
- If the solution is hypertonic to the blood plasma, what happens?
-
- osmolarity increases momentarily, but water from the interstitial fluid will move in to stem the increase.
- NOTE: end result leads to an increase in arterial pressure. - What happens when a large volume of soda is ingested?
- it increases arterial pressure, leading to a decrease in renin and aldosterone, and therefore a decrease in water reabsorption.
- What does aldosterone do?
-
- increases sodium reabsorption;
- water will follow sodium on its way out of the tubules of the nephron so it also increases water reabsorption. - What regulates aldosterone?
- renine, which is secreted when blood pressure is low.
- What is the role of filtrate osmolarity.
- An abnormally high filtrate osmolarity will decrease the osmotic gradient between the tubule and the instituial fluid, causing a drop in water reabsorption levels.
- Nutrasweet: can it be reabsorbed back into the blood from the nephron?
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- No. Therefore, there is less water reabsorption, and ultimately the excretion of urine with nutrasweet.
- The same is true with diabetes milletus where not all the glucose can be reabsorbed. - Function of the kidney
- to produce urine hypertonic to the blood however diuretics and alcohol will more likely produce urin that is hypotonic to the blood.
- Patients who excrete protein in their urine (filtration failure) have low levels of blood osmolarity and a result there is (high/low) level of water reabsorption.
- Low. Therfore, the urine produced will still be hypertonic to the blood.
- (T/F) Do glomerular cappilaries normally allow the passage of plasma proteins or red blood cells?
- - No.
- What happens when the glomerular capillaries are damaged so that they become permeable to plasma proteins?
- Plasma proteins enter the renal tubule; these proteins will be lost b/c they cannot be reabsorbed along the tubule.
- What is the major force that keeps fluid from leaving the capillaries?
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Osmotic pressure;
- oncotic pressure of the plasma proteins. - What is major force in capillary filtration?
- capillary hydrostatic pressure (blood pressure)
- Interstitial fluid has what kind of pressure and what does it opppose?
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hydrostatic pressure, which opposes filtration out of the capillary.
- the proteins of the interstitial fluid exert oncotic pressure and tend to favor filtration out of the capillary. - What does blood pressure in the capillary do?
- it tries to force fluid out of the capillary
- What do proteins in the interstitial space try to do?
- to suck fluid out of the capillary
- What do proteins in the blood ty to do?
- to hold the fluid in the capillary.
- WHen blood enters the arterial end of a capillary, the Pc pressure acts to force fluids to (enter/leave) the capillary and enter the interstitial space. What is the effect of this?
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- leave.
- Increases the concentraiton of solute, or proteins, in the blood due to loss of fluid...
- this increase in oncotic pressure "pulls" fluid back into the capillary at the venous end. - Any fluid that is not returned to the capillary is generally picked up by the ____ system.
- lymphatic
- Determine the effect when proteins are lost from the blood.
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Loss of plasma proteins will cause a drop in oncotic pressure in the blood ==> water that leaves the arteriole end of the capillary will not be reabsorbed at the venule end.
- Fluid in large quantities can't be picked up by the lymphatic system, so this fluid will remain in the interstitial space and back up in the extremedities ==> condition known as edema. - What happens when there is a failure of fluid to be reabsorbed from the institial space?
- leads to a large drop in blood volume and therefore blood pressure.
- capillary filtration and reabsorption are favored at which ends?
- filtration at the arteriole end; and reabsorption at the venule end.
- What happens when the tissue (interstitial) hydrostatic pressure increases?
- the hydrostatic gradient across the capillary thereby limiting filtration.
- What happens when capillary filtration is increased?
- it decreases interstitial protein concentration and reduces the oncotic pressure.
- The more permeable the capillary barrier is to proteins, the higher the ______ oncotic pressure.
- interstitial
- An increase in capillary hydrostatic pressure or an increase in interstitial oncotic pressure will lead to ______
- capillary filtration