B2.1.1 Absorption of the Products of Digestion Flashcards

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1
Q

What happens to triglycerides which have been reformed in the endoplasmic reticulum of epithelial cells lining the ileum?

A

They are associated with cholesterol and lipoproteins to form chylomicrons.

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2
Q

What does the diagram show?

A

Simple diffusion through a cell membrane from a high to low concentration

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3
Q

Diffusion and facilitated diffusion are both passive processed. What is meant by this?

A

They do not require ATP (energy)

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4
Q

What is the function of the endoplasmic reticulum in lipid absorption?

A
  • An organelle in the epithelial cells lining the ileum where monoglyerides and fatty acids are recombined to make triglycerides.
  • Triglycerides begin to associate with cholesterol and lipoproteins here also.
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5
Q

Why does having many capillaries optimise absorption in the ileum?

A

Nutrients absorbed in the blood are carried away quickly which maintains the concentration gradient between the ileum and the blood.

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6
Q

Define active transport

A

the movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using ATP (energy) and carrier proteins.

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7
Q

What does the diagram show?

A

Facilitated diffusion via a carrier protein from a high to low concentration

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8
Q

What happens to the chylomicrons that are produced in the epithelial cells lining the ileum?

A

They exit the cells via exocytosis and enter the lymphatic system via lacteals.

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9
Q

How are villi adapted to optimise absorption of nutrients?

A
  • They increase the surface area for diffusion
  • Very thin walls so less diffusion distance to the blood.
  • Many blood capillaries- blood can carry nutrients away and maintain diffusion gradients.
  • Epithelial cell lining contains microvilli increasing surface area for absorption further.
  • They contain muscle so can move contents of the ileum to maintain concentration gradients.
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10
Q

What is a lacteal?

A

A lymphatic capillary that is found in the centre of each villus of the small intestine.

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11
Q

Describe the process of active transport.

A
  • Molecule or ion binds to carrier protein.
  • ATP binds to carrier protein, gives a phosphate and ADP is released.
  • Carrier protein changes shape and moves molecule to opposite side of membrane.
  • Phosphate is released from carrier protein and protein reverts back to start position.
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12
Q

Identify the label on the diagram and the type of transport that take place.

A

Sodium-Potassium Pump (carrier protein)

Active Transport

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13
Q

What is a protein channel?

A

A protein that spans a cell membrane and will only allow specific molecules to pass through. Involved in facilitated diffusion.

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14
Q

What is facilitated diffusion?

A
  • Diffusion of molecules or ions aided by carrier proteins or protein channels.
  • Does NOT use ATP (energy),
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15
Q

Name the products of digestion

A

Monosaccharides

Amino Acids

Monoglycerides

Fatty Acids

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16
Q

Where are the products of digestion absorbed?

A

Ileum (small intestine)

17
Q

How is the ileum adapted to carry out the process of absorption of nutrients?

A

Its wall contains many villi, which greatly increases the area for nutrient absorption

18
Q

How does the thin wall of the ileum help to optimise absorption?

A

Less distance for nutrients to diffuse across before reaching the blood.

19
Q

What does the diagram show?

A

Facillitate diffusion via a channel protein from high to low concentration

20
Q

What happens to monoglycerides and fatty acids after they have entered the epithelial cells lining the ileum?

A

They are transported to the endoplasmic reticulum where they are recombined into triglycerides.

21
Q

Micelles are created by an asociation between bile salts and triglycerides. After lipase has acted on micelles of triglyceride we are left with…

A

Micelles of monoglycerides and fatty acids (still asociated with bile salts)

22
Q

How do monoglycerides and fatty acids enter the epithelial cells lining the ileum?

A

Simple diffusion

23
Q

Bile salts emulsify fatty acids into smaller structures called…

A

micelles

24
Q

Define diffusion

A

the net movement of molecules or ions from a region where they are highly concentrated to a region where they are less concentrated until evenly distributed.

25
Q

Why can monoglycerides and fatty acids enter the epithelial cells of the ileum via simple diffusion?

A

Because they are non polar molecules so can bypass the non polar fatty acid section of the cell membrane.

26
Q

What is the function of the golgi apparatus in lipid absorption?

A

An organelle in the epithelial cells lining the ileum where triglycerides association with cholesterol and lipoproteins takes place.

27
Q

What is meant by a chylomicron?

A

A triglyceride associated with cholesterol and a lipoprotein which aids lipid transport into the lymphatic system.

28
Q

What happens to chylomicrons when they enter the lymphatic system?

A

They are hydrolysed by an enzyme and enter the blood

29
Q

What is a carrier protein?

A
  • A protein spanning a cell membrane that specific molecules or ions bind to, which causes the protein to change shape and carry the molecule onto the other side of the membrane.
  • Involved in facilitated diffusion and active transport.
30
Q

How do fatty acids and glycerol molecules enter the intestinal epithetial cell?

A

Diffusion

31
Q

Explain the advantage of lipid droplet and micelle formation

A

droplets increase SA for enzyme action so FASTER hydrolysis

micelle formation carries FA and glycerol through the intestinal membrane

32
Q

How is the golgi involved in the absorption of lipids?

A

modifies triglycerides

adds protein on/.forms lipoproteins

packages them for their release

/forms vesciles