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Biochemistry > B21 Lipids And Carbohydrates > Flashcards

B21 Lipids And Carbohydrates Flashcards

1
Q

What si the mucosa like in the small intestine

A

Folded into villi
Goblet cells
Microvilli on top of each enterocyte

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2
Q

What are enterocytes responsible for

A

Absorption and some digestion

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3
Q

What dos the mucosa lead to for absorption

A

Increased surface area for nutrient absorption

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4
Q

What does each villus contain

A

Capillary network and a central lacteal/lymphatic vessel

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5
Q

Enterocytes are short lived… What are they replaced with and by what

A

Replaced by new enterocytes

Form stem cells what migrate form the crypts

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6
Q

What are the crypts called between each villus

A

Crypts of lieberkuhn

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7
Q

What are some mechanisms of how moelcules are transported across membranes

A 
Simple diffusion 
Facilitated diffusion 
Active transport 
Receptor mediated endocytosis 
Pinocytosis 
Exocytosis
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8
Q

What moelcules undergo simple diffusion

A

Small non polar molecules and uncharged polar molecules

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9
Q

How is facilitated diffusion carried out

A

Via transmembrane PROETINS

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10
Q

What does active transport use

A

Primary - atp directly

Secondary - uses electrochemical gradient

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11
Q

What is pinocytosis

A

Cell drinking cell takes extracellular fluid and soluble molecules

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12
Q

What si symporter

A

Mem protein transports two different molecules or ions across a cell mem in same direction

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13
Q

What is anti port

A

A type of cotransport in which a mem protein trans two diff molecules in opposite direction

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14
Q

Endocytosis is receptor mediated therefore

A

Specific and saturable

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15
Q

Where do endoscopes originate

A

Form the golgi and are part of the endocytotic pathway

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16
Q

What is endocytosis fundamental to

A

Neurotrans mission
Signal transduction
Regulation of plasma mem activities

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17
Q

What si endocytosis exploited by

A

Viruses
Bacteria
Toxins
To get into the cell

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18
Q

What is a tag composed of

A

Three fatty acids and one molecule of glycerol

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19
Q

What must happen to dietary fat before digestion can occur

A

Must be emulsified

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20
Q

What is emulsion

A

A fine dispersion of minute droplets of one liquid into another in which it is not miscible

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21
Q

What are large fat globules formed with

A

Hydrophobic tags cores surrounded with polar molecules (phospholipids, cholesterol, fatty acids, ionised protien)

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22
Q

What si emulsification aided by

A

Hydrolysis of TaGs

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23
Q

Form the hydrolysed TAGs in emulsification what do the fatty acids do

A

Released as surfactants reducing the surface tension

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24
Q

What happens to the emulsion when it enters into the small intestine

A

Undergoes major Digestion using pancreatic enzymes

25
Q

What hormone stimulates the release of the panc enzymes and release of bile

A

Cck

26
Q

What are some lipases secreted by the pancreas

A

Pancreatic lipase
Carboxyl ester lipase
Phospholipase A2

27
Q

Where is digestion completed

A

Intestinal lumen

28
Q

What happens int he intestinal lumen to complete digestion

A

Emulsions of fat globules mixed with bile salts and pancreatic juice containing lipases to = aq suspension

29
Q

Where is bile made and form what

A

Liver form cholesterol

30
Q

Where is bile stored

A

Gallbladder

31
Q

What are the major components of bile

A 
Bile acids 
Phospholipids 
Cholesterol 
Bilirubin 
Electrolytes 
Calcium
32
Q

What enzyme does bile inhibit and how is this overcome

A

Inhibits pancreatic lipase

Overcome by secretion of co lipase form pancreas which anchors enzyme

33
Q

Prior to secretion what happens to bile salts

A

Cholic acid is conjugated to glycine or taurine

Hydrophobic ad side chain is hydrophillic

34
Q

Above a certain concentration what do bile acids form

A

Micelles where hydrophillic heads point outward and hydrophobic inward

35
Q

What forms a Micelle core

A

Cholesterol esters
Free fatty acids
Monoglycerides
Fat soluble vitamins (adek)

36
Q

What does the formation of a Micelle allow

A

Transport of lipids it the brush border of enterocyte where abs by diffusion

37
Q

What are some products of dietary lipid digestion

A 
Fatty acids 
Cholesterol 
Glycerol 
Phospholipids
Monoglycerides
38
Q

Inside the cells what are TAGs resynthesised by in the ER

A

By enzymes

Acyltransferases

39
Q

How are cholesterol esters formed

A

Cholesterol actuated by acytltransferase

40
Q

What forms chylomicrons

A

Tags + cholesterol esters and apolipioprotein B

41
Q

How to chylomicrons enter the circulation

A

Through the lymph exit via basolateral border of enterocyte

42
Q

What does the fate of a fatty acid depend on

A

The length of its chain

43
Q

If a fatty acid chain is

A

Pass through. The cell directly by hepatic portal vein

44
Q

What happens to a fatty acid with a carbon chain >12

A

Binds to a binding protien and then trans to RER and resyn into TAGs

45
Q

All long chain fatty acids abs in enterocyte are reused to make

A

TAGs

46
Q

Chylomicrons lipid and protien percentages

A

Lipid 99%

Protien 1%

47
Q

What does starch require for its digestion

A

Salivary and pancreatic amylases

48
Q

What does the salivary and pancreatic amylases do to the starch

A

Hydrolyses alpha 1,4- glycosidic bonds

49
Q

What ares some of the disaccharide enzymes attached to the micorvilli of the small intestine

A

Sucrose
Maltese
Lactase

50
Q

What si the rate limiting step of absorption of disaccharides

A

Transport of monomeric sugars

51
Q

What si the disaccharide deficiency

A

Causes carb intolerance induced by bacterial fermentation of undigested sugars which dele viewed at colon
Most common is lactose intolerance

52
Q

How is galactose transported form the lumen of the gut to the blood

A

Via SGLT 2
Secondary active transport
Symport

53
Q

What is SGLT 2 driven by

A

Conc grad driven by Na/k ATPase at basolateral mem

54
Q

What transports monosaccharides into the circulation

A

Facilitated
GLUT 2
Uni porter

55
Q

How is fructose ttansported across the brush border mem into the enterocyte

A

Glut 5
Sodium indept
Glut 2

56
Q

What si the glut transporter family

A

Facilitated sugar transport

57
Q

What do glut transporters do

A

Form an aq lore across the mem for sugars to move

58
Q

What are the parts of the small intestine

A

Duodenum, jejunum, ileum

Biochemistry (13 decks)

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