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week 46 > Carbs, Proteins, Minerals and Vitamins > Flashcards

Carbs, Proteins, Minerals and Vitamins Flashcards

1
Q

Absorptive Cells

A
  • Transport nutrients and ions
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2
Q

Capillaries

A

Transport most Absorbed nutrients

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3
Q

Intestinal epithelium

A
  • intestinal epithelial cells
    • joined by tight junctions
    • microvilli on apical surface (lumen facing)
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4
Q

Carbohydrate Digestion

A
  • Involves:
    • salivary amylase
    • pancreatic amylase
    • enzymes on intestinal brush border:
      • disaccharides
        • sucrase
        • maltase
        • isomaltase
        • lactase
      • glucomylase
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5
Q

Amylose vs Amylopectin

A
  • Amylose
    • straight polygllucose chain
    • a-1,4 glycosidic linkages
  • Amylopectin
    • Branched polyglucose chain
    • a-1,4 & a-1,6
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6
Q

Cellulose

A

Insoluble to humans

B-1,4 Glycosidic linkage

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7
Q

What are the brushborder membrane bound enzymes

A
  • Disaccharides
    • maltose
    • sucrose
    • Lactose
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8
Q
A
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9
Q

Maltose, Sucrose, and Lactose are broken down into

A
  • Maltose–> 2 glucose
  • Sucrose–>1 glucose + 1 Fructose
  • Lactose–> 1 glucose + 1 galactose
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10
Q

What are examples of glucose polymers?

A
  • Starch
  • Glycogen
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11
Q

What are Glucose polymers are broken down into and by what enzyme?

A
  • Starch/Glycogen–>Disaccharides
    • Salivary/Pancreatic Amylase
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12
Q

Lactose Intolerance

A
  • Lactase decreases after childhood
    • except northern european decent
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13
Q

Artificial Sweetener

A
  • Splenda
  • Sugar substitute
  • Non-digestable derivative of sucrose
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14
Q

Absorption of Monosaccharides

A
  • Glucose, Fructose, Galactose, and amino acids are absorbed in the small intestine
    • duodenum and jejunum
  • SGLT1 symporter
    • transport Glucose/Galactose mainly w/Na+
      • and xylose=not digested
  • Fructose enters via GLUT5 and exits via GLUT2
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15
Q

Protein Digestion: Proteases and Peptidases in what parts of GI tract and what enzymes

A
  • Stomach/Gastric lumen
    • Pepsin
    • HCl
  • Intestinal Lumen
    • Trypsin
    • Chymotrypsin
    • Carboxypeptidases A & B
    • Elastase
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16
Q

Pancreatic Juice: Conversion from inactive proenzymes to active

A
  • Trypsinogen–> Trypsin
    • via enteropeptidase (aka enterokinase)
  • Trypsin activates all proenzymes
    • Chymotrypsinogen–>Chymotrypsin
    • Procarboxypeptidase–>Carboxypeptidase
    • Procolipase–> Colipase
    • Prophospholipase–> Phospholipase
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17
Q

Digestion of Proteins into amino acids and small peptides

A
  • Stomach:
    • Acid Hydrolysis
    • Gastric Pepsin (endopeptidase-digests internal peptide bond)
  • Pancreas
    • secrete peptidases
      • exopeptidase-digest terminal peptide bonds to release amino acids
      • Aminopeptidase
      • Carboxypeptidase
    • Trypsin
      • activated by enteropeptidase (enterokinase)
    • Trypsin (endopeptidase) activates pancreatic proteases
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18
Q

Amino Acid/peptide absorption

A
  • Amino Acids
    • Na+-coupled transport
      • Na+ and aa in
    • basolateral transport=facilitated diffusion
  • Di/Tripeptides
    • H+-coupled Transport
    • proton gradient created by NHE
  • Small Peptides
    • PepT1 symporter
      • H+-coupled transport
      • also absorbs antibiotics, chemotherapeutics, other peptidomimemetic drugs
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19
Q

What cells are CCK released from

A

I cells of duodenum

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20
Q

Mechanism for controling the release of CCK

A
  • During digestion, CCK-RP and pancreatic monitor peptide stimulates release of CCK
  • After absorbing amino acids: CCK-RP, monitor peptide, and luminal digestive enzymes are removed from lumen
    • reduces CCK release and pancreatic enzymes
21
Q

Regulate Enzyme release

A
  • Cephalic Phase
    • vagal release of HCL and digestive enzymes
  • Gastric phase
    • Food in stomach
    • Gastrin stimulates HCL
      • HCL converts pepsinogen to pepsin
  • Intestinal phase
    • Fats and proteins in duodenum
    • CCK, Secretin stimulate pancrease
22
Q

Regulate Enzyme Activity

A
  • Pepsin requires acidic pH
    • don’t have to remove pepsin
  • Pancreatic proteases
    • secreted as zymogens
    • Trypsin activated by enteropeptidase (enterokinase)
23
Q

Where is enteropeptidase is located?

A
  • ONLY duodenal epithelial cells
24
Q

Regulate enzyme degradation

A
  • Proteases autodigest when no proteins are present
  • Monitor peptide
    • Pancrease secreted in intestine lumen
    • stimulates CCK release until protein digestion is complete
    • last proteins to be digested
25
Q

NaCl Reabsorption in the small intestine and colon

A
  • Small intestine or Colon epithelial cells absorb Na+ using 3 membranep proteins:
    • apical Na+ channels
    • Na+-Cl- symporter
    • NHE Na+-H exchanger
      • Also in Small intestine=Na+-depedent trasnporters coupled to sugars and aminoa acids
  • Chloride uptake
    • apical side:
      • Cl-HCO3- exchanger
    • Basolateral side
      • Cl- channel
  • K+ uptake:
    • passive diffusion via paracellular pathway
  • Water absorption:
    • osmotic gradient
26
Q

Where does most water absorption take place?

A
  • Mainly in SI
  • Little in colon
27
Q

Water and chloride absorption in colon are driven by:

A
  • Cl-
    • Electrical gradient
  • H2O
    • osmotic gradient
28
Q

Uptake of SCFA in colon

A
  • uptake by SMCT1=Na+-monocarboxalate transporter-1
    • Na+ SCFA cotransporter
29
Q

Examples of SCFA

A

Acetate

proprionate

butyrate

30
Q

Nucleic acids

A

digested into nitrogenous bases and monosaccharides

31
Q

What does the intestine absorb?

A
  • Vitamins and minerals
    • Fat-soluble vitamins absorbed with fats
      • but not in olestra diet
    • Water soluble-transport
      • Vit B12 + IF=ileum
      • Mineral by activae transport
32
Q

What does Vitamin B12 deficiency lead to?

A

Pernicious anemia

33
Q

Mechanisms of Vitamin Absorption in Intestine

A
  • Simple Passive absorption
    • Vitamin C (ascorbic acid)
    • Biotin*, pantothenic acid, pyridoxine (B6)
    • Fat solube (A,D,E)
  • Facilitated passive absorption
    • Fat soluble: K
    • Folic Acid*, Niacin*
    • Riboflavin (B2)
  • Active Absorption
    • Vit B12
    • Folic acid*, Thiamine*(B1)

*=Vitamins absorbed by more than one mechanism

Vit K and BIotin synthesized by gut microflora

34
Q

Intrinsic Factor

A
  • secreted from stomach
  • binds to Vit B12 and allows absorption in ileum into bloodstream
35
Q

Vitamin B12

A
  • Bound to dietary protein when enterin stomach
  • acid and pepsin digest and release B12
  • B12 binds to haptocorrin (R-Protein)in stomach
  • Forms B12-R-protein complex
    • resistant to acid and pepsin digestion in the stomach
  • Duodenum
    • R-protein digested in duodenum, releases B12 and binds to IF
  • Ileum
    • B12 absorbed by endocytosis/pinocytosis
36
Q

Ca2+ absorption

A
  • Absorbed in small intestine via Calcium Binding protein
  • Active transport
    • pumped out by Ca2+-ATPase/Na+-Ca+ antiport
37
Q

Iron Absorption

A
  • Ferric (Fe+3) reduced to ferrous (Fe2+) in duodenum
    • by Ferrireductase
    • on brush border membrane
  • Fe2+ binds to ferrin binding protein (DMT1)
  • Inside cell, Fe2+ is bout to ferritin
  • Ferroportin
    • Fe2+ exits basolateral membrane
    • oxidized to Fe3+ via hephaestin
    • Fe3+ binds to transferrin and circulates
38
Q

Trivalent ion absorption

A
  • Trivalent ions–> Divalent ions before absorption
    • via DMT1
    • Copper, Zn
    • Phosphorus absored as Pi via Na+-coupled transporter
39
Q

Colonic Microflora

A
  • Microorganisms not flora
    • 700-1000 species
  • Make up 60% of the feces dry weight
  • Symbiotic relationship:
    • produces Vit K and B (Ex: biotin, B7)
    • Ferment starches into fatty acids
    • stimulate development of immune system
40
Q

Intestinal Gas

A
  • ~1L odorless gas/day
  • Produced by intestinal bacteria
    • fermentation of nutrient in colon
    • Polysaccharids (Benas, lentils) not digested in small intestine
  • Composition;
    • Nitrogen:
    • Co2:
    • Methane:
    • Hydrogen:
    • Butyric acid, hydrogen sulfide, carbonyl sulfide
41
Q

Risks of Intestinal Gas

A
  • Explosive
    • electrocautery
  • High altitude flatus expulsion
    • airplane depressurization
  • Social Stigma
42
Q

What happens b/w meals in GI system after gastric/intestinal emptying?

A
  • Salivary production-low rate
  • Secondary peristalsis in esophagus
  • slow wave
    • gastric-intensity diminishes
    • intestinal-do not reach threshold
  • Motilin stimulates MMC
  • Water and electrolytes absorbed in gallbladder and cecum
43
Q

Diarrhea

A
  • Secretory
    • enhanced secretion/impaired absorption of ions
  • Osmotic
    • maldigestion
    • magnesium ingestion
  • Motility:
    • inadequate time for water absorption
  • inflammatory
    • damage to mucosal lining
44
Q

Vomoting

A
  • Protective reflex
  • aka Emesis
45
Q

Vomiting: stimuli

A
  • CNS
    • chemical trigger zone
    • opiates
  • Labyrinthine receptors
    • motion
    • balance
  • Throat Touch receptors
  • Visceral Mechanoreceptors
  • Stomach/duodenal chemoreceptors
    • ipecac
  • Genitourinary pain receptors
46
Q

Vomiting: Integration

A
  • Medullary Vomiting Center
  • Medullary Retching Center
    • Retching before vomiting
47
Q

Vomiting: Effectors

A
  • Smooth Muscle-reverse peristalsis (upper GI)
    • intestinal smooth muscle
    • stomach
  • Sphincters (Backflow)
    • Pylorus
    • Esophageal sphincters
  • Abominal Muscles
  • Respiratory muscles
48
Q

Vomiting: Sequence

A
  • Sympathetic Activation
    • sweat
    • pale
  • Retching center activated
    • reverse peristalsis
      • small intestine & stomach
    • Inspiration against a closed glottis
      • negative thoracic pressure
      • LES open
      • Gastric contents forced into esophagus
  • Upper Esophageal sphincter= closed
  • Vomiting Center activated
    • Reverse Peristalsis (SI and stomach)
    • inspiration agsint closed glottis
      • negative thoracic pressure
      • LES opens
      • Gastric contents forced into esophagus
      • abdominal muscles contract
      • diaphragm contracts
  • UES opens
    *

week 46 (9 decks)

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