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51 Cards in this Set

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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?
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.
- 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.
- 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.
malabsorption of lipids
(T/F) Pancreatic juices require a less acidic environment than do stomach enzymes.
(T/F) Proteins and carbohydrates are paritally digested before they reach the small intestine.
(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.
(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
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
A sustained (increase/decrease) in plasma osmolarity triggers ADH secretion.
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?
- 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?
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?
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?
- 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.
Determine the effect when proteins are lost from the blood.
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.
An increase in capillary hydrostatic pressure or an increase in interstitial oncotic pressure will lead to ______
capillary filtration