Case 3 - The pancreas Flashcards

1
Q

Where are proteins digested and what are they digested to?

A

stomach, pancreas, brush border,

amino acids, dipeptides and tripeptides

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2
Q

Where are polysaccharides digested and what are they digested to?

A

saliva, pancreas, brush border

monosaccharides

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3
Q

Where are triglycerides digested and what are they digested to?

A

free fatty acids and monoglycerides

stomach, pancreas, bile salts

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4
Q

What are the different methods of absorption across the SI

A

simple diffusion - lipids

carrier mediated - amino acids and sugars e.g. facilitated diffusion and secondary active transport

receptor mediated - B12 and intrinsic factor, cholesterol e.g. endocytosis

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5
Q

What is the main site of absorption

A

small intestine - duodenum and jejunum

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6
Q

What is absorbed in the ileum?

A

vitamin B12, bile salts and potassium

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7
Q

What causes the surface area of the SI to decrease and what are the consequences?

A

Crohns or coeliac disease

Leads to malabsorption

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8
Q

What mechanism is used for carbohydrate absorption

A

carrier mediated - secondary active transport

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9
Q

Describe the process of carbohydrate absorption from the lumen into isf

A

absorbed as monosaccharides, glucose/fructose via a sodium coupled transporter

SGLT1
glucose and sodium bind to the carrier, sodium binds first x2 and opens the binding site for glucose, transport channel undergoes a conformational change and empties the glucose into the cell.

accumulation of glucose moves glucose out of the cell via GLUT2 carrier facilitated diffusion

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10
Q

What is the function of an SGLT1 transporter

A

sodium and glucose transporter

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11
Q

How are peptides absorbed?

A

Absorbed via pep T1 co transporter with Hydrogen ions, the peptides are hydrolysed to amino acids in the enterocytes

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12
Q

How is alanine absorbed

A

Via Bo contrasporter sodium

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13
Q

How is glutamate absorbed?

A

Via Xag: a co-transporter of alanine, sodium x2 and others e.g. glutamate.

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14
Q

What is Hartnup disease

A

rare genetic disease,c causes appearance of amino acids in urine

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15
Q

Why is fat digestion dependent on bile salts?

A

Bile salt emulsify the fat droplets to increase surface area for digestion by lipase

formation of mixed micelles will stabilise the products of tg hydrolysis (mg +fa) while they are transported to apical membrane

absence of bile leads to steatorrhoea

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16
Q

What is the function of pancreatic lipase?

A

Breaks down triacyglycerol into monoaglycerol and x2 free fatty acids

17
Q

How is fat absorbed

A

simple diffusion

FFA transporters

MA - carrier mediated mechanisms

18
Q

Describe the absorption and re-synthesis of triaglycerol

A

FFA and monoacyglycerol are absorbed in the same way via carrier mediated

triaglycerol is resynthesises in the SER and packaged in chylomicrons which then leave the cell by exocytosis into the lymphatics and travel to the liver

19
Q

How is cholesterol absorbed from the lumen to i.s.f. how can this be targeted pharmacologically

A

Occurs in the duodenum, receptor mediated endocytosis

ezetimibe inhibits endocytosis, decreasing plasma cholesterol

20
Q

How are short chain fatty acids absorbed?

give examples of SCFA

A

e.g. butyrate, propionate, acetate

absorbed via a SMCTI co transporter with sodium and is used by the colonocyte for intracellular metabolism

21
Q

What are the route for water absorption

A

via functional complexes between cells

via