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Sem3: PHYS30240 GI and Renal Physiology > L8: DIgestion and Absorption > Flashcards

L8: DIgestion and Absorption Flashcards

1
Q

Absorption in the Duodenum?

A

Iron

Calcium

Fat

Sugars

Amino Acids

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2
Q

Absorption in the Jejunum?

A

Sugars

Amino Acids

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3
Q

Absorption in the Ileum?

A

Bile Salts

Vitamin B12

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4
Q

Absorption in the Colon?

A

Water

Electrolytes

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5
Q

Anemia and osteoporosis are symptoms of ______________________due to poor iron and mineral absorption as a consequence of ________________

A

Anemia and osteoporosis are symptoms of coeliac disease due to poor iron and mineral absorption as a consequence of villous atrophy

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6
Q

Carbohydrate digestion occurs via ______________, _________ and ____________enzymes

Different bond types acted on by different enzymes:

  • Straight chain (1:4 alpha) acted on by __________________
  • __________________ breaks down 1:6a bond
A

Carbohydrate digestion occurs via Salivary, Pancreatic and Brush border enzymes

Different bond types acted on by different enzymes:

  • Straight chain (1:4 alpha) acted on by glucoamylase
  • Alpha Limit Dextranase breaks down 1:6a bond
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7
Q

Only _________________ can cross the epithelial barrier so carbohydrates must be digested to their simplest form

A

Only mono-saccharides can cross the epithelial barrier carbohydrates must be digested to their simplest form

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8
Q

Dimer of Glucose and Fructose?

A

Sucrose

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9
Q

Dimer of Galactose and Glucose?

A

Lactose

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10
Q

Dimer of Glucose with 1:4 Alpha Linkages?

A

Maltose (Not absorbed by small intestine)

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11
Q

_______________________:
Deficiency in Lactase at the brush border
>50% of adults globally

A

Lactose Malabsorption Syndrome:
Deficiency in Lactase at brush border
>50% of adults globally

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12
Q

____________________________:
Rare congenital disorder associated with inability to digest Lactose
Also affects infants

A

Congenital Lactose Intolerance
Rare congenital disorder associated with inability to digest Lactose
Also affects infants

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13
Q

___________________________:
Inherited digestion disorder (Greenland Inuit)
Treated w/ low sucrose diet

A

Sucrase-Isomaltose deficiency
Inherited disorder (Greenland Inuit)
Treated w/ low sucrose diet

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14
Q

Absorption of Carbohydrates in Low Glucose Conditions (FASTING STATE)?

A

Secondary active transport coupled to Na+ (Maintained by basolateral Na/K Exchanger)

  • Glucose/Galactose:: hitches a ride across apical w/ Na via SGLT1 Co-Transporter (Sodium/Glucose enter at 2:1 ratio)
  • Fructose has its own transporter: GLUT (facilitated diffusion across apical)

Facilitated transporter (GLUT2) allows all to exit on the Basolateral Surface (along concentration gradient w/o ATP)

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15
Q

Absorption of Carbohydrates in High Glucose Conditions (AFTER MEAL)?

A
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16
Q

Adults vs. Neonates Protein Absorption?

A

Adults: Peptides, Dipeptides and Tripeptides transported across brush border (Proteins do NOT Need to be in simplest form to be absorbed)

Neonates: In addition to the above are also capable of taking up larger protein molecules via receptor mediated endocytosis of immunoglobulins in colostrum

17
Q

Transport of single amino acids usually ________ than di/tripeptides

Stereospecific: higher affinity for____-amino acids

A

Transport of single amino acids usually slower than di/tripeptides

Stereospecific: higher affinity for L-amino acids

18
Q

Digestion of proteins begins in the _______________

_________, _____________ and ____________ proteases digest peptides

A

Digestion of proteins begins in the Stomach

Pancreatic, Brush Border and Intracellular Proteases digest peptides

19
Q

Amino Acids vs. Peptide Absorption?

A

Dipeptides/Tripeptides: co-transported into cell w/ Hydrogen ions. Catabolized to AAs by peptidases within cell

Amino Acids: Absorbed by SPECIFIC amino aid transporters for acid, basic and neutral amino acids!! (FAST)

  • Absorption of neutral amino acids is very similar to the mechanism used for absorption of glucose (Na- Contransporter)
20
Q

3 lipases secreted by Pancreas:

  • ____________________________=> 2 free fatty acids + monoglyceride
  • _____________________________=> 1 free fatty acid + cholesterol
  • ____________________________ => 1 free fatty acid + lysophosphatide
A

3 lipases secreted by Pancreas:

  • Triacylglycerol Hydrolase => 2 free fatty acids + monoglyceride
  • Cholesterol Ester Hydrolase => 1 free fatty acid + cholesterol
  • Phospholipase => 1 free fatty acid + lysophosphatide
21
Q

Steps of Absorption of Lipids?

A

Step 1: Emulsification of fat via Bile Salts and Phospholipids

Step 2: Smaller Emulsion Droplets via Bile Salts and Pancreatic Lipase (Lipases water soluble, only access lipids at the interface)

Step 3: Micelle Formation (Biles Salts/Phospholipids)

Step 4: Passive Diffusion across epithelial cell

Step 5: Resynthesis of lipids in SMOOTH ER of epithelial cells

  • 2-monoglycerides => Triglycerides
  • Lysophospholipids => Phospholipids
  • Cholesterol is re-esterified (some free cholesterol remains)

Step 6: Chylomicron Formation and Transport

22
Q

Bile acids require __________ to emulsify lipids into 1μm droplets

A

Bile acids require lecithin to emulsify lipids into 1μm droplets

23
Q

Bile salts and phospholipids form _________ for the transport of Monoglycerides , cholesterol and Fat soluble vitamins

A

Bile salts and phospholipids form micelles for the transport of Monoglycerides , cholesterol and Fat soluble vitamins

24
Q

In the __________________ the bile salts are re-cycled by Enterohepatic Re-Circulation:

  • _____________ – Apical sodium-dependent bile salt transporter
  • _____________ – Baslolateral sodium-independent bile acid transporter
A

In the Terminal Ileum the bile salts are re-cycled by Enterohepatic Re-Circulation:

  • ASBT – Apical sodium-dependent bile salt transporter
  • OSTa/b- Baslolateral sodium-independent bile acid transporter
25
Q

> ____ g of fat in faeces/day is defined as fat malabsorption. Causes?

A

>7g of fat in faeces/day is defined as fat malabsorbtion

Causes:

  • RAPID TRANSIT
  • LUMINAL DIGESTION REDUCED
  • BILE ACID DEFICIENCY - Gall Bladder Removal
  • MUCOSAL/LYMPHATIC TRANSPORT REDUCED
  • GLUTEN ENTEROPATHY Lipid malabsorption
26
Q

Triglyceride Transport

  • Triglycerides delivered to adipose tissue via __________ from the GIT (Mainly Triglycerides, some cholesterol, phospholipids, and protein)
  • Triglycerides are delivered to the adipose tissue via ________ from liver
  • Remnant Chylomicrons are processed in the liver where new _________________ are formed
A

Triglyceride Transport

  • Triglycerides delivered to adipose tissue via Chylomicrons from the GIT (composed mainly of Triglycerides, some cholesterol, phospholipids and protein)
  • Triglycerides are delivered to the adipose tissue via VLDL from liver
  • Remnant Chylomicrons are processed in liver where new liposomes (HDL + LDL) are formed
27
Q

TG Storage in Adipose Tissue: TAG Synthesis (_____________)?

Chylomicron (via __________________ in adipose endothlium)=> Fatty Acid Release (Via _________________________) => Triglycerides Storage

A

TG Storage in Adipose Tissue: TAG Synthesis (Esterification)?

Chylomicron (via Lipoprotein Lipase in adipose endothlium)=> Fatty Acid Release =(Via a- glycerol phosphate (from glucose)) => Triglycerides Storage

Sem3: PHYS30240 GI and Renal Physiology (24 decks)

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