Week 5

Question 1

What does GI system include and what is its function?

Answer 1

• Includes:
  - GI Tract: mouth, esophagus, stomach, small intestine, large intestins
  - Accessory glands: salivary glands, liver, gallbladder, pancreas
• Function: assimilation of nutrients and excretion of waste product

Question 2

Major events for assimilation of nutrients:

Answer 2

• chewing makes food into bolus; allows for saliva to lubricate food and provides enzymes for digestion; 10 sec
• stomach mixes and grinds food to make them into smaller pieces, gastric acid dissolves and denatures components of food; 1-4 hrs
• food in small intestine is accompanied with exocrine secretions from pancreas and gallbladder. Pancreas also secretes HCO3 to neutralize acid from stomach.
• food moves through intestine where the nutrients is broken down by enzymes and absorbed; takes 7-10 hours
• food goes through large intestine where water and electrolytes are taken out, unprocessed carbs are fermented, and fecal matter is stored. The fecal matter will be released in 1-3 days.

Question 3

Tissue layers that comprise the GI tract

Answer 3

• Mucosa
-epithelium; single cell layer
-highly folded
-contains cells that release enzymes to break down food
-Contains membrane transporters to bring in broken down substances
-Contains lamina propria on basal side for microvasculature and nerves
• Submucosa:
-contains blood and lymph vessels
-contains nerves
• Muscularis externa:
-two smooth muscle layers responsible for mixing and moving food along GI tract
-mesenteric plexus lies between two muscles
• Serosa
-peritoneum
-Includes blood vessels, extrinsic (muscle) nerves, ducts of large accessory glands

Question 4

Gastroparesis:

Answer 4

• caused by diabetes
  
  • consists of slow stomach emptying
  • causes early satiety and sporadic emptying making it hard to control blood sugar

Question 5

Celiac Spruce:

Answer 5

• malabsorption due to hypersensitivity to gluten

- causes immune system to destruct villi in small intestine

Question 6

Sarcoidosis:

Answer 6

-granulomas secrete vitamin D-like substance which causes increased Ca2+ absorption and hypercalcemia

Question 7

Hemochromatosis

Answer 7

• automsomal recessive; mutation of HFE

- HFE no longer able to regulate iron absorption and causes toxic iron overload

Question 8

Lactase deficiency

Answer 8

• milk intolerance

- causes osmotic diarrhea and bloating

Question 9

Three functions of small intestinal motilityduring the fed state are

Answer 9

1. Mixingof foodstuffs with digestive secretions and enzymes.
2. Distributionof the luminal contents around the mucosa for absorption.
3. Propulsionof the luminal contents in the aboral direction (away from the mouth)

Question 10

Types of motility

Answer 10

1. Segmentationcontractions produce a string of segments that constantly form and reform.The main function of segmentation contractions is mixing of the luminal contents.
2. Peristalsisconsists of a wave of contractions that moves a bolus aborally.The function of peristalsis is propulsion of luminal material. Peristalsis is a reflex, and the main stimulus is moderate distension of the gut wall. The circular muscle contracts in the upstream contracting segment, forcing the bolus forward;receptive relaxationof the circular muscle in the downstream segment reduces the force needed to move the bolus aborally.

Question 11

Carb absorption

Answer 11

• Amylase breaks down starch into oligosaccharides
• Glucoamylase and isomaltase break down oligo into di (lactose, maltose, sucrose)
• disacch are broken down by lactase, sucrase, maltase into monomers L (gluc, galac), S (gluc and fruc), M (fruc, galac)
• SGLT1: picks up Na and glucose/galactose and brings into enterocyte, exit enterocyte through GLUT2
• Drives fluid absorption into enterocyte through use of Ca2
• Fructose is taken up by GLUT5, exit enterocyte through GLUT2

Question 12

Protein absorption

Answer 12

• Protein is put into enterocyte by pepsin
• Endopeptidases break into oligopeptides
• Ectopepdiase break into individual AA
• AA transported into enterocyte with cotransporter of Na
• Dipeptides/Tripeptides transported into enterocyte with H linke cotransporter

Question 13

Fat digestion

Answer 13

• involves a mechanical phase and a chemical phase.
• mechanical: chewing and peristalisis; creates emulsion
• Lipase removes fatty acids from triglycerides
• Medium fatty chains diffuse from lumen into blood
• Long fatty chains diffuse in micelles, the micelles travel to the unstirred layer above enterocyte and are destabilized which allows for long FA to escape into the membrane, the FA’s are put back into triglycerides in the enterocyte smooth ER, apoproteins are added to triglyceride in golgi and vessicle (chylomicron) takes lipoprotein across basolateral cell wall into lymph, lymph reaches systemic blood when it enters into vein and triglyceride is freed from chylomicron by endothelial lipoprotein lipase, the triglyceride goes to fat storage in adipose tissue or muscle and chylomicron travels to liver

Question 14

Fat soluble viatmins

Answer 14

A, D, E, and K

Question 15

Function of Vitamin B

Answer 15

B1(thiamine): Coenzyme in pyruvate and α-ketoacid metabolism
B2(riboflavin):Coenzyme in mitochondrial oxidative metabolism
B3(niacin):Coenzyme in mitochondrial oxidative metabolism
Pantothenic acid:Coenzyme A: needed for metabolism of carbohydrate and fat via acetyl-coenzyme A and amino acid synthesis

Question 16

Energy Densities

Answer 16

fat (9 kcal/g),
carbohydrate (4 kcal/g),
protein (4 kcal/g),
alcohol (ethanol) provides energy (7 kcal/g).

Question 17

Marasumus

Answer 17

• caused by starvation or chronic illness
• all energy sources are affected
• starved appearance, serum albumin normal
• poor wound healing,

Question 18

Kwashikor

Answer 18

• caused by acute illness
• only protein digestion
• Normal BMI, edema, low serum albumin,
• easily infected

Question 19

Hepatic portal circulation

Answer 19

blood is drained from the digestive organs (and the spleen, gall bladder, and pancreas) and the then delivered to the liver to be processed before returning back to venous system to be brought back to heart

Question 20

How do all energy sources feed into TCA?

Answer 20

All are converted into acetyl-CoA during their breakdown

Question 21

Aerobic vs. Anaerobic ATP production

Answer 21

32 vs 2

Question 22

PFK-1

Answer 22

• controls when G6-P is made into F6P
• has 4 sites for regulation: ATP inhibition (build up of ATP will stop glycolysis and start storage), AMP activation (build up of AMP will start glycolysis to produce ATP), Citrate inhibition (allows for glycolysis to participate with other pathways), F2-6 BP activation (build up of F26 BP will continue to activate glycolysis)

Question 23

BMR

Answer 23

amnt of energy cells would spend for normal sustenance

- measured when resting-not after eating because we would be breaking down food - factors: age (eat less), body mass (lean vs fatty), sex (males have more lean muscle), thyroid (increases/decreases metabolism)

Question 24

DEE:

Answer 24

amnt of energy cells need with BMR and activity

-can lead to weight loss with increased activity

Question 25

RBC glycolysis

Answer 25

does not have mito so they do not put glucose into TCA and instead only break down glucose into pyruvate which produces 2 ATP

Question 26

Neurons and glycolysis

Answer 26

- glucose is main fuel oxidized by neurons because cannot oxidize fat due to not having two enzymes - in absence of glucose would use ketones (during starvation)

Question 27

Allosteric regulation

Answer 27

- will bind to site other then active catalytic site; can cause conformational change - positive: increase activity of enzyme - negative: decrease activity of enzyme

Question 28

Vmax

Answer 28

enzyme is saturated with substrate and can no longer bind any more

Question 29

Km

Answer 29

concentration where you have 1/2 max velocity | -increase substrate = increase velocity

Question 30

Pesticides and glycolysis

Answer 30

Produces f-acetyl-SCoA which is competitive inhibitor of enzyme that changes fluorocitrate into cisaconitate in TCA; therefore stopping TCA

Question 31

Complex of ETC

Answer 31

Complex 1: uses NADH | Complex 2: uses FADH2

Question 32

Rotenone

Answer 32

blocks complex 1; will be increase in NADH leading to acidosis and low ATP

Question 33

Diet medications causing uncoupled ETC from ox phos

Answer 33

- pokes holes into mito membrane - allows for electrons to pass from intermembrane space into inner cytoplasm of mito without going through ATP synthase which means electrons are not being used to create ATP and - Since electrons not being used to make ATP the cell will start to rely on anaerobic glycolysis which will deplete glycogen storage and cause fat to be used to produce energy

Question 34

Active transport

Answer 34

Primary: occurs via membrane proteins that directly couple ATP hydrolysis to solute movement. Secondary: energy is used to develop a favorable electrochemical driving force for one solute, which is then used to power the transport of other solutes

Question 35

Passive transport

Answer 35

does not require ATP hydrolysis or coupling to another solute

Question 36

Na electrochemical gradient and glucose

Answer 36

Na/K pump (primary) on basolateral side of eneterocyte is used to pump Na out of eneterocyte into submucosa. On apical side Na is then coupled to glucose and flows down its gradient to transport glucose into the enterocyte (secondary). Water is also moved from lumen into enterocyte because it is coupled to Ca which follows Na.

Question 37

steatorrhea

Answer 37

fat in stool caused by inability to break down fat due to decrease in enzymes released from pancreas

Question 38

zero order absorption

Answer 38

Absorption is independent; drug is saturating very quickly

Question 39

first order absorption

Answer 39

- Absorption is dependent; has half life; most drugs. - Following absorption across the gut, the portal vein system delivers the drug to the liver prior to entry into the systemic circulation

Question 40

First pass metabolism decreases

Answer 40

drug bioavailability

Question 41

Principal organ of drug metabolism

Answer 41

Liver

Question 42

Other tissues that display considerable drug metabolism

Answer 42

gastrointestinal tract, the lungs, the skin, the kidneys, and the brain. 

Question 43

Phase I reactions

Answer 43

- convert the parent drug to a more polar metabolite by introducing or unmasking a functional group - Phase I: Acetylation, Reduction, Deamination, Hydrolyses, Oxidation

Question 44

Phase II reactions

Answer 44

- link or conjugate polar functional groups of phase I metabolites with molecules containing hydrophilic functional groups. - Phase II: Glucuronidation, glycine conjugation, methylation, glutathion conjugation, sulfation

Question 45

CYP

Answer 45

2C9, 2D6, 34A account for 75% of CYPs. Inducers can be other drugs or natural remedies. Inhibitors are drug-drug interactions

Question 46

What is energy made out of? (2)

Answer 46

Resting Energy + Physical activity

Question 47

How do you calculate estimated energy requirement?

Answer 47

``` (Resting Energy) (Physical activity) RE: males- 900+10(kg) females-700+7(kg) PE: sedentary: 1.2 moderately active: 1.4 very active: 1.8 ```