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1BDS Biochemistry > Digestion 1 > Flashcards

Digestion 1 Flashcards

1
Q

What are the 6 types of membrane transport?

A
  • Simple Diffusion
  • Facilitated Diffusion
  • Active Transport
  • Receptor Mediated Endocytosis
  • Pinocytosis (cell drinking like pint)
  • Exocytosis
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2
Q

What is the action of an antiporter?

A

EXCHANGE - A goes in, B goes out

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3
Q

What is the action of a symporter?

A

COTRANSPORT - A and B simultaneously go in/out

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4
Q

Endocytosis is _______ and therefore is ________.

A

receptor mediated and therefore is specific and saturable.

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5
Q

Where do endosomes originate?

A

The golgi aparatus

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6
Q

What is endo/exocytosis fundamental to and what is it exploited by?

A

Fundamental to neurotransmission, signal transduction and regulation of plasma membrane activities

Exploited by viruses, bacteria and toxins to gain entry into the cell

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7
Q

What is the key structural component of the human small intestine?

A

Villi

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8
Q

What 2 types of cells are villi covered in?

A

Mature cells (enterocytes) and mucus producing goblet cells

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9
Q

Histologically, what type of cells are enterocytes?

A

Columnar epithelial cells

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10
Q

Thousands of what are present of on the luminal surface of each enterocyte?

A

Thousands of Microvilli

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11
Q

What are enterocytes responsible for?

A

Absorption and some digestion

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12
Q

What do the microvilli provide?

A

A large surface area to facilitate absorption

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13
Q

What must happen to large globules of dietary fat before digestion can occur?

A

globules must be emulsified

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14
Q

By which enzyme does partial lipid hydrolysis occur in the stomach?

A

gastric lipase

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15
Q

Why is partial lipid hydrolysis in the stomach slow?

A

due to separate aqueous and lipid phases

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16
Q

What is the abbreviation for a triacylglyceride molecule?

A

TAG

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17
Q

Where does emulsification happen?

A

In the stomach

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18
Q

What does the fat globule contain?

A

TAGs, Cholesterol esters, phospholipids

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19
Q

What 2 major components of bile are necessary for the breakdown on the fat globule?

A

Bile salts and phospholipids

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20
Q

What component of bile breaks down the big fat globule into the small fat droplet?

A

Phospholipids

21
Q

What does the breakdown into small fat droplets allow for?

A

Allows the small fat droplets to interact with the watery secretion (intestinal chyme)

22
Q

What component of bile facilitates the binding of the co-factor for pancreatic lipase and also the breakdown of the small fat droplet into the even smaller micelle?

A

Bile salts

23
Q

What is the name of the co-factor which helps pancreatic lipase to further break down the small fat droplet?

A

Co-lipase

24
Q

What does pancreatic lipase break the small fat droplet into?

A

FFAs and MAGs

25
Q

What are the other pancreatic enzymes which breakdown the cholesterol esters and the phospholipids of the big fat globule?

A

PLA2 and Carboxyl Ester Lipase

26
Q

What hormone stimulates the release of bile and pancreatic enzymes for digestion of big fat globules in the small intestine?

A

CCK

27
Q

What occurs when the small fat droplets start to get broken down into FFAs and MAGs?

A

Fat soluble vitamins are absorbed and micelle formation occurs

28
Q

What are the 5 products of lipid digestion?

A
  • Fatty Acids
  • MAGs and DAGs
  • Cholesterol
  • Phospholipids
  • Glycerol
29
Q

What is the function of micelles?

A

To deliver the products of lipid digestion to the brush border of the enterocytes where they diffuse into the cell

30
Q

How are TAGs and CEs formed again inside the enterocyte?

A
  • TAGs are re-synthesised by acyltransferases
  • phospholipids are acylated into phosphatic acid and then into TAG
  • Cholesterol is acylated by acyltransferases to form cholesterol esters
31
Q

What do the TAGs and CEs inside the enterocyte join with and to produce what?

A

TAGs and CE join with apolipoprotein to produce a chylomicron

32
Q

Where do these chylomicrons go next?

A

Lacteal –> lymph –> back into circulation at the thoracic duct

33
Q

Give examples of MONOSACCHARIDES

A

glucose, galactose, fructose

34
Q

Give examples of DISACCHARIDES

A

maltose, sucrose, lactose

35
Q

Give examples of POLYSACCHARIDES

A

starch, glycogen

36
Q

What must happen to di- and polysaccharides before absorption?

A

Digestion

37
Q

How are disaccharides digested/broken down and where?

A

Disaccharides are broken down by specific disaccharidases on the intestinal brush border

38
Q

How are polysaccharides digested/broken down?

A

Polysaccharides require salivary and pancreatic enzymes for digestion

39
Q

What are the names of the specific disaccharidases for the examples of disaccharides already given?

A

maltase, sucrase, lactase

40
Q

What is the one disaccharidase that is non-inducible?

A

Lactase

41
Q

What is the rate limiting step for the absorption of disaccharides with inducible disaccharidases?

A

Transport of the monomeric sugars

42
Q

What is the rate limiting step for the absorption of disaccharides with non-inducible disaccharidases?

A

hydrolysis

43
Q

By what mechanism are primary monosaccharides (glucose, galactose, fructose) absorbed?

A

Carrier-mediated mechanisms

44
Q

What is the function of the Sodium-Dependent Glucose Transporter?

A

To transport glucose (and galactose) into the enterocyte across the brush border.

45
Q

What is the function of the Sodium-Independent GLUT5?

A

To transport fructose into the enterocyte across the brush border.

46
Q

What is the function of the GLUT2?

A

To transport glucose, galactose and fructose into the blood from the enterocyte.

47
Q

What maintains the concentration of sodium for the sodium-dependent glucose transporter?

A

Na+/K+ ATPase

48
Q

Give 1 example of why the relationship between sodium and glucose has vast clinical consequences

A

Dehydrated patients where found to absorb sodium much better when glucose was also provided

49
Q

The GLUT family have been looked at when the studying the pathogenesis of which disease?

A

Diabetes Melitus

1BDS Biochemistry (5 decks)

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