nutrition/ digestion! (or: where your food goes after swallow)

Nutrition/ DIGESTION!(or: where your food goes after swallow)

Nutrition/ DIGESTION!Rugae - wrinkly parts in stomach

Parietal -part of the wall, on the sideparietal cells, parietal lobe

Duodenum -from arabic 12 fingers

Jejunum L empty – part after the Duodenum

Ileum Gr twisted – last part of the small intestine

Acinus L berry

Isla island, e.g. islets of Langerhans, insulin, insular,

Essential minerals

Essential fatty acids

Essential amino acids

Vegetarians

Essential amino acids

Essential vitamins and minerals Korsakoff’s

Hypervitaminosis-Vitamin A -liver damage, hair loss, skin peeling, birth defects

Vitamin D -Constipation, vomiting, weakness

Vitamin E - excessive bleeding – “iatrogenic hemophilia”

Vitamin B6 -motor neuropathy

Tube within a Tube!Chew/amylase

swallow

Acidifies/ cleaves protein

Goes to duodenum

Liver/panc.Put in lipasesand proteases

Monomers absorbed in small intestine

Water/salts absorbed in large intestine

Lots of bacteria Poop (30% bacteria)

As usual, we focus on the molecular stuff


swallow


Goes to duodenum





Stomach

Duodenum

Small Intestine

Stomach: secretion of stuff and digestion

Stomach

Special cells:

G cells - secrete gastrin in response to stretching

Parietal cell – secretes HCl in response to gastrin

Chief cell – secretes pepsinogen->pepsin, which cuts proteins

Mucus cells – secrete mucus

Question #45In terms of the stomach: who does what to whom?

a) Secretin cleaves pepsin to form pepsinogenb) HCl cleaves gastrinogen to form gastrinc) G cells secrete pepsinogen in response to stressd) Chief cells secret gastrin in response to HCle) Gastrin cleaves itself via positive feedbackf) None of the above

Parietal cells up close

To note: H+ is pumped via H+/K+ cotransporter“H+/K+ ATPase”

Cl- follows due to charge

K+ leak channels

CO2+H20H2CO3 provides more H+

HCO3- (bicarbonate) gets exchanged for more Cl- from blood

Question #46“Proton pump inhibitors”, like prilosec are available over the counter for stomach problems. What would you expect to be the consequences of such medication?

a) Increased transport of chloride ions from the blood into parietal cellsb) Higher levels of CO2 in parietal cellsc) Decreased levels of gastrin in the blood streamd) Higher ratios of pepsinogen/pepsin in the lumen of the

stomache) More than one of the above


swallow


Goes to duodenum





Stomach

Duodenum

Small Intestine

Duodenum! (start of small intestine)

Duodenum! (start of small intestine)

-Secretes Cholecystekinin in response to fats in chyme

-Secretes Secretin in response to acidity in chyme

-starts absorbing nutrients

-gets lots of helpful stuff from pancreas, gall bladder, and liver

Secretin and Cholecystekinin

Question 47

For dinner last night, I had vegetarian tacos, and my girlfriend ate a ½ lb hamburger, and a couple of “TUMS®”. Which of the following statements is true?(Note: TUMS = sucrose + CaCO3, a base) a) I should have higher levels of blood pepsin, and she should have lower levels of blood secretinb) She should have higher levels of blood pepsin, and I should have higher levels of blood cholecystekininc) She should have higher levels of blood cholecystekinin, and I should have higher levels of blood secretin d) I should have lower levels of blood secretin, and she should have higher levels of chyme cholecystekinine) She should have eaten the tacos, and I should have eaten the hamburger. (None of the above)

Accessories!

Gall Bladder dumps bile salts(in response to CCK)

Pancreas dumps HCO3- (in response to secretin)

Pancreas dumps lots of pre- enzymese.g. trypsinogen(in response to CCK)

-> oligomers

Question 48Below is a plot of enzyme efficiency as a function of pH. Match the enzyme with the plot

a) Green could be amylase, and red could be pepsinb) Green could be gastrin, and red could be trypsinc) Green could be trypsin, and red could be renind) Green could be gastrin, and red could be amylasee) More than one of the above f) None of the above

2 9

Absorption

Carbohydrate Absorption

Peptide Absorption

Brush Border

Question 49Some glucose enters microvilli epithelial cells via the SGLUT1 symporter, located on the apical surface, which allows Na+ flowing down its concentration gradient to pull glucose along with it via secondary active transport. The correct cytoplasmic Na+ concentration is maintained by Na+/K+ pumps on the basolateral membrane, pumping ions into/out of the blood. If the Na+/K+ pumps stopped working, you would expect:a) An increase in cytoplasmic glucoseb) A decrease in cytoplasmic sodiumc) An increase the transport of glucosed) An increase in cytoplasmic sodiume) More than one of the above

Question 50While the SGLUT1 symporter is responsible for only a small portion of the glucose absorbed across the brush border, it is responsible for most of the sodium absorbed in the jejunum. In case of prolonged diarrhea (which causes loss of both water and sodium), it’s better to drink Gatorade than just water, or salt water. Why?

a) It’s the Thirst Quencherb) The artificial dyes helpc) Drinking pure water could lead to a dangerous state of

hyponatremiad) The presence of glucose will allow more sodium to be

absorbede) More than one of the above.

Cholera Question In the epithelial cells of the small intestine , there are “CFTR” transmembrane proteins, which, when activated, pump Cl- into the intestinal lumen, dragging Na+ along. Cholera (a bacteria), upon establishing itself in the small intestine, causes a cascade of events which eventually hyperactivates the CFTR pumps. An expected sign of cholera infection would probably be:

a) High blood pressureb) Dehydrationc) Decreased release of renin by the macula

densad) decreased blood glucose levelse) None of the above

Fats!Gall Bladder dumps bile salts(in response to CCK)

Pancreas dumps lots of pre- enzymes(in response to CCK)Including lipases

Fats!

micelles

Bile Salts

Bile Salts

Bile Salts

Bile Salts

Bile Salts1<pKa<4

5<pKa<6.5

Bile Salts

Bile Salts1<pKa<4

5<pKa<6.5

Fully dissociated in pH~7 duodenum-> ionic functional groups

-amphiphilic

->Micelles

Chylomicrons

->Lacteals -> lymph

Question 51

In the 70s, Procter and Gamble invented the food additive Olestra, which consists of sucrose with 8 ester linkages to fatty acids. While Olestra has a similar taste and “mouth feel” to normal triglycerides, it was found to have zero calories, making it seem like a very promising product! Why did Olestra have zero calories?a) It couldn’t be used in the TCA, since the TCA enzymes

could not break it down into acetyl groups to add to coAb) It couldn’t be stored in adipocytes, without the correct

carrier proteinc) It couldn’t be absorbed into the intestinal endothelial cellsd) It was insoluble in the lactealse) It couldn’t form chylomicrons.

Question 51

In the 70s, Procter and Gamble invented the food additive Olestra, which consists of sucrose with 8 ester linkages to fatty acids. While Olestra has a similar taste and “mouth feel” to normal triglycerides, it was found to have zero calories, making it seem like a very promising product! Why did Olestra have zero calories?a) It couldn’t be used in the TCA, since the TCA enzymes

could not break it down into acetyl groups to add to coAb) It couldn’t be stored in adipocytes, without the correct

carrier proteinc) It couldn’t be absorbed into the intestinal endothelial cellsd) It was insoluble in the lactealse) It couldn’t form chylomicrons.

Also:

-since it doesn’t get absorbed – it lubricates the intestines and causes diarrhea -and chelates fat soluble vitamins

Where does all this absorbed stuff go?

More Pancreas!

Acinar cells secrete pancreatic juice (exocrine)-HCO3-, pre-enzymes

Islet cells are endocrine (secrete hormones)-alpha cells – glucagon-beta cells - insulin

More Pancreas! (hormone feedback loops)

Question 52

Shortly after eating a chocolate cake, we would expect the levels of _______ to decrease and _____ to increase in my blood.

a) Insulin, glucagonb) insulin, cholecystekininc) glucagon, insulind) Glucagon, pancreatic lipasee) More than one of the above is correct

Question 53

Suppose I have an autoimmune disorder which causes my immune system to attack and kill the beta cells in my pancreas. How would my response to the cake be different?

a) No glucagon would be released into my bloodstreamb) Less glucose would be absorbed by my muscle cellsc) Less water would be reabsorbed in the collecting duct of

my nephrond) More glucagon would be released into my bloodstreame) More than one of the above is correct.

Question 53

Suppose I have an autoimmune disorder which causes my immune system to attack and kill the beta cells in my pancreas. How would my response to the cake be different?

a) No glucagon would be released into my bloodstreamb) Less glucose would be absorbed by my muscle cellsc) Less water would be reabsorbed in the collecting duct of

my nephrond) More glucagon would be released into my bloodstreame) More than one of the above is correct.

Type 1 Diabetes Mellitus (Juvenile)-must take insulin shot with food

Type 2 is when cells don’t respond to insulin as much

Question 54

Suppose I take my insulin injection before breakfast, but then realize I’m late for 900am bio recitation, and run out the door without eating. What will happen?

a) The extra glucose stored in my muscle cells will give me extra energy, so I’ll arrive on time.

b) My blood glucagon levels will increasec) The extra glucose in my blood will cause me to have to

go to the bathroom in the middle of recitation.d) My brain will be starved for glucose, and I’ll get confused

and mess up all my example questionse) More than one of the above.

Question 54

Suppose I take my insulin injection before breakfast, but then realize I’m late for 900am bio recitation, and run out the door without eating. What will happen?

a) The extra glucose stored in my muscle cells will give me extra energy, so I’ll arrive on time.

b) My blood glucagon levels will increasec) The extra glucose in my blood will cause me to have to

go to the bathroom in the middle of recitation.d) My brain will be starved for glucose, and I’ll get confused

and mess up all my example questionse) More than one of the above.

-hypoglycemia

Question 55

Suppose I’m scared of needles, so instead of injecting my insulin with a syringe, I start squirting it into my bowl of Lucky Charms and eating it instead. What will happen?

a) The insulin will get to my blood stream faster than if injected, and I’ll have no problem

b) The insulin will react with the glucose in my cereal bowl, and I thus won’t be able to absorb it by the time it gets to my small intestine

c) The insulin will get to my blood stream slower than if I had just injected it, so I’ll be hypoglycemic for a little while

d) The glucose in the Lucky Charms will overwhelm the insulin, and I’ll be in trouble.

e) None of the above

Question 55






e) None of the above, but what will eventually happen?

Question 55






e) None of the above, but what will eventually happen?

-hyperglycemia, muscle weakness…

Question 56 In all animal cells, there are Na+/K+ pumps, which pump out 3 Na+ ions and pump in 2 K+ ions. Most cells also have potassium leak channels, which let the K+ ions gradually go back out. In Beta cells, the leak channels are special, and are actually inhibited (closed) by high levels of ATP. Other channels, called L-type Voltage-gated Ca2+ channels, when opened, allow Ca2+ to rush into the cell, which in turn causes insulin-filled vesicles to exocytose into the blood stream.What triggers the Calcium channels to open?a) More (-) voltage: when glucose levels are low, the beta cells

should excrete insulinb) More (+) voltage: when glucose levels are high, the beta cells

should excrete insulinc) More (-) voltage: when glucose levels are high, the beta cells

should excrete insulind) More (+) voltage: when glucose levels are low, the beta cells

should excrete insuline) All of the above are false






Beta cells secrete insulin when blood glucose is high







High Glucose-> high ATP

->calcium rushes in-> vesicles get exocytosed, and glucagon is released







High Glucose-> high ATP->K+ channels close








High Glucose-> high ATP->K+ channels close

->K+/Na+ pump keeps working - > voltage becomes more (+)…


Calcium influx causes regulated exocytosis

Calcium influx causes regulated exocytosis

Extremely important in the brain!!!(chapters 37 and 38)

Question 57 A skeletal muscle cell is shown in the picture on the right. One of the effects of Cortisol (from the adrenal cortex) is to prevent the translocation of glucose transporters to the cell membrane. How would we expect cortisol injections to compare to insulin?

a) Both cortisol and insulin will decrease blood glucose levelsb) Both cortisol and insulin will increase gluconeogenesisc) Cortisol will decrease the amount of insulin secreted from the

pancreasd) Cortisol will increase blood glucose levels, while insulin will

decrease fatty acid synthesis.e) None of the above

Question 58 Cortisol inhibits inflammation and decreases immune response, and thus cortisol analogs (e.g. prednisone) are often prescribed to treat various autoimmune problems. What side effect would you expect to see in patients taking such medication?

a) Increased glucagon and glucose levels in the bloodb) Blood insulin and glucose levels similar to those in an

untreated type 1 diabeticc) Hypoglycemia, confusion, cold sweats, shaky handsd) Blood insulin and glucose levels similar to those in an

untreated type 2 diabetice) More than one of the above

Question 58 Cortisol inhibits inflammation and decreases immune response, and thus cortisol analogs (e.g. prednisone) are often prescribed to treat various autoimmune problems. What side effect would you expect to see in patients taking such medication?

a) Increased glucagon and glucose levels in the bloodb) Blood insulin and glucose levels similar to those in an

untreated type 1 diabeticc) Hypoglycemia, confusion, cold sweats, shaky handsd) Blood insulin and glucose levels similar to those in an

untreated type 2 diabetice) More than one of the above

“steroid induced diabetes”

Question 59 Eskimos traditionally lived their entire lives above the arctic circle, where there was no vegetation, and consequently had extremely lowcarb diets. Most of their food was whale or seal blubber (fat). In such conditions, we would expect for:

a) Oxidative phosphorylation and the TCA cycle to stop, and for pyruvate to be reduced in fermentation.

b) Blood insulin levels to be elevatedc) Fatty acids and proteins to be cleaved and sent directly to the

electron transport chain for oxidative phosphorylationd) Blood glucose levels to be elevatede) Fatty acids and amino acids to be cleaved and sent to the TCA

cycle.

Question Eskimos traditionally lived their entire lives above the arctic circle, where there was no vegetation, and consequently had extremely lowcarb diets. Most of their food was whale or seal blubber (fat). In such conditions, we would expect for:

a) Oxidative phosphorylation and the TCA cycle to stop, and for pyruvate to be reduced in fermentation.

b) Blood insulin levels to be elevatedc) Fatty acids and proteins to be cleaved and sent directly to the

electron transport chain for oxidative phosphorylationd) Blood glucose levels to be elevatede) Fatty acids and amino acids to be cleaved and sent to the TCA

cycle.

Beta-Oxidation (for Fun)

Fatty acid

Beta position

Acetyl CoA(Goes to TCA)

Shorter Fatty acid

Question 60 The product of “beta oxidation” of fatty acids are “ketone bodies”, which enter the blood stream, and can be used by other cells in the TCA for cellular respiration. However, such molecules are quite acidic, and can decrease blood pH (“acidosis”).Other than in eskimos, when would we expect to find such “metabolic acidosis”? (we will talk about respiratory acidosis in chapter 34)

a) In someone whose alpha-cells had been destroyed by diseaseb) In someone who just ate a whole box of Oreosc) In someone with Addison’s disease (adrenal cortex destroyed

by autoimmune disease => no cortisol)d) In a type 1 diabetic who ran out of insuline) In a type 2 diabetic who just took a shot of insulin

Question 60 The product of “beta oxidation” of fatty acids are “ketone bodies”, which enter the blood stream, and can be used by other cells in the TCA for cellular respiration. However, such molecules are quite acidic, and can decrease blood pH (“acidosis”).Other than in eskimos, when would we expect to find such “metabolic acidosis”? (we will talk about respiratory acidosis in chapter 34)

a) In someone whose alpha-cells had been destroyed by diseaseb) In someone who just ate a whole box of Oreosc) In someone with Addison’s disease (adrenal cortex destroyed

by autoimmune disease => no cortisol)d) In a type 1 diabetic who ran out of insulin (Diabetic KetoAcidosis)

e) In a type 2 diabetic who just took a shot of insulin

Question 61 Alpha cells (which secrete glucagon) have the same type of ATP-inactivated potassium channels as beta cells, but they have calcium channels of a different kind (called “T-type calcium channels”). We expect them to open in response to what type of stimulus?

a) High ATP concentrationb) High potassium concentrationc) More (+) voltaged) More (-) voltagee) More than one of the above



Alpha cells secrete Glucagon when glucose is low




Low Glucose->

-> vesicles get exocytosed, and glucagon is released




Low Glucose-> low ATP->K+ open (K+ flows out)






->voltage becomes more (-)…


Question 61 Alpha cells (which secrete glucagon) have the same type of ATP-inactivated potassium channels as beta cells, but they have calcium channels of a different kind (called “T-type calcium channels”. We expect them to open in response to what type of stimulus?




->voltage becomes more (-)…




“pulsatile secretion”



“pulsatile secretion”

“Delayed Rectifier Potassium channel”(opens when membrane potential isPositive -> allows K+ to flow out, returningMembrane potential to normal level)

Question 62…Voltage gated sodium channels, common in endocrine and brain cells, open when the membrane potential is more positive. How would we expect the structure of such a protein to look like?

a) It could have a domain of amino acids with anionic side chains, which, when moved towards the exterior of the cell, cause the channel to open.

b) It could have a domain of amino acids with anionic side chains, which, when moved towards the interior of the cell, cause the channel to open.

c) It could have a domain of amino acids with cationic side chains, which, when moved towards the exterior of the cell, cause the channel to open.

d) It could have a domain of amino acids with cationic side chains, which, when moved towards the interior of the cell, cause the channel to open.

e) None of the abovef) More than one of the above

Question 62…Voltage gated sodium channels, common in endocrine and brain cells, open when the membrane potential is more positive. How would we expect the structure of such a protein to look like?

a) It could have a domain of amino acids with anionic side chains, which, when moved towards the exterior of the cell, cause the channel to open.

b) It could have a domain of amino acids with anionic side chains, which, when moved towards the interior of the cell, cause the channel to open.

c) It could have a domain of amino acids with cationic side chains, which, when moved towards the exterior of the cell, cause the channel to open.

d) It could have a domain of amino acids with cationic side chains, which, when moved towards the interior of the cell, cause the channel to open.

e) None of the abovef) More than one of the above

If membrane potential is positive -> cytoplasm is positive and extracellular fluid is negative-> cations will move towards exterior-> anions will move towards interior

nutrition/ digestion! (or: where your food goes after swallow)

Documents

blood slide

digestion slide

swallow slide

mucus slide

stomach parietal

stomach special cells

gastrin cg cells

minerals korsakoffs