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Alimentary System: Physiology SA > Nutrients and Digestion Absorption: Fats, Vitamins and Minerals ** > Flashcards

Nutrients and Digestion Absorption: Fats, Vitamins and Minerals ** Flashcards

1
Q

What form is all fat ingested in and what components make this up

A

Triaglycerol

Made up of one Glycerol and three stearic acids

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2
Q

What breaks down fat

A

Pancreatic lipase

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3
Q

Why does fat digestion take place at the surface of the lipid droplet

A

Triaglycerol is a Lipid droplet and is insoluble in water

and Lipase is a water soluble enzyme so breaks down from the outside in - very slow

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4
Q

What is the products of lipase break down of triaglycerol

A

Monoglyceride and 2 fatty acids

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5
Q

What is the purpose of emulsification

A

Increasing the surface area so is more accessible to lipase to quicken the process of digestion

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6
Q

Define emulsification

A

Dividing large lipid droplets into smaller lipid droplets

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7
Q

What is the requirements of Emulsification

A

Mechanical disruption

Emulsifying agent

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8
Q

How does mechanical disruption occur in the small intestine

A

smooth muscle from the muscular externia contracts grinding and mixing lumenal contents

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9
Q

What is the purpose of emulsifying agents

A

Prevent smaller droplets reforming into larger droplets again

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10
Q

What are the emulsifying agents used in fat digestion and where are they secreted from

A

Bile salts and phospholipids secreted in bile

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11
Q

What is the purpose of emulsifying agents being amphiphatic

A

The non polar molecule is lipid soluble to acts on lipid droplet while the polar molecule is non lipid soluble so sits on the water surface/outside the lipid and because its charged repels other lipid molecules re-combining with lipid droplet

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12
Q

Why is absorption still considered slow after emulsification and what enhances the absorption further from the small intestine

A

Lipids are still water insoluble and surrounded by an Aq environment

Micelles enhance further absorption

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13
Q

What is the purpose of Micelles

A

Transport the fat droplet to the intestinal cell for absorbtion

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14
Q

What is a micelles composed of

A

bile salt + monoglyceride + fatty acids + phospholipid

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15
Q

Whats the position of the the polar and non polar lipid molecule in reference to the micelle

A

Polar portions of molecules at micelle surface; non-polar portions form micelle core

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16
Q

What is the purpose of the polar portion of the lipid molecule being at the micelle surface

A

Prevent combining of micelles

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17
Q

What is the main difference between an emulsification droplet and micelle droplet

A

Micelles similar to emulsion droplets but much smaller (4-7 µm diameter compared to 1mm diameter)

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18
Q

Why is the micelle not absorbed across into the Intestinal cell

A

Destabilised as the hydrogen ions in the acid microclimate bind to the negatively charged part of the stearic acid (part of fatty acid molecule) and cause the micelle to breakdown

19
Q

What does the Micelle release for diffusion across the intestinal epithelia cell

A

Fatty acids and monoglyceride

20
Q

How can the contents of the micelle now diffuse across the Intestinal epithelial cell

A

As The products of fat digestion are now uncharged and lipid soluble so can cross the intestinal cell membrane

21
Q

How is a dynamic equilibrium created in fat absorption

A

Dynamic equilibrium between fatty acids and monoglycerides in solution and in micelles

Micelle retains most products of fat digestion and constantly supply free molecules for absorption - Basically an ongoing process until all products of fat digestion are absorbed

22
Q

What is the fate of product of fat digestion once the enter intestinal cells

A

Enter Smooth ER and are synthesised back to triaglycerol

23
Q

What coats the surface of triaglycerol droplets in the intestinal cell

A

Amphiatic proteins

24
Q

How do Triaglycerlol droplets reach and diffuse across the intestinal epithelial membrane into the extracellualr fluid

A

Triacylglycerol droplets transported through cell in vesicles formed from sER membrane - processed through Golgi apparatus and exocytosed

25
Q

How is the products of fat digestion transported in the extracellular fluid

A

as a chylomicron

26
Q

What is further contained in a chylomicron

A

contain phospholipids, cholesterol & fat-soluble vitamins

27
Q

How do chylomicrons reach the blood stream

A

By passing into the Lacteals of the small intestine (the lymphatic vessels of the small intestine)

28
Q

What are the two classes of Vitamins and examples

A

Fat soluble
A, D, E, K

Water soluble
B, C, and Folic acid

29
Q

What class of vitamins has the same absorption pathways a products of fat digestion

A

Fat soluble Vitamins

A, D, E, K

30
Q

How are water soluble vitamins absorbed across the small intestine

A

Either absorbed by passive diffusion or carrier-mediated transport.

31
Q

Why cant vitamin B12 not undergo passive diffusion

A

Large charged molecule

32
Q

How is vitamin B12 absorbed across the small intestine

A

Binds to intrinsic factor, forming complex and is absorbed via specific transport mechanism in distal ileum

33
Q

Where is the intrinsic factor secreted from

A

Stomach

34
Q

What is the importance of Vitamin B 12

and what can a deficiency of Vitamin B12 cause

A

Affects the shape of RBC, therefore affecting oxygens carrying capacity

Deficiency means RBC don’t mature properly =pernicious anemia

35
Q

How is Iron transported across the brush boarder of the small intestine

A

DMT1 transporter

36
Q

What does iron bind to intracellualrly for storage

A

Irons locks into a complex with ferritin

37
Q

What is the pathway of unbound iron

A

Transports across the small intestine brush border membrane into the blood and bind with transferrin

38
Q

What is the importance of biding of ingested minerals e.g. iron

A

Safe, as prevents the formation of oxygen free radicals

39
Q

What is ferritin regulation dependant on

A

Dependant on how much iron you have in your body

40
Q

What happens when ferritin levels increase

Hyperanemia

A

more iron is bound in enterocytes

41
Q

What happens when ferritin levels decrease = anaemia

A

More iron is released into he blood

42
Q

Why is to much iron in your body not of clinical importance

A

As around every 5 days epithelia cells will die, therefore ferritin complexes will be shed out

43
Q

where in the small intestine does iron absorption occur

A

duodenum

Alimentary System: Physiology SA (9 decks)

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