Unit 3 Digestion and Absorption Flashcards

1
Q

What is Digestion?

A

Digestion is the hydrolysis of large, insoluble organic compounds into small soluble molecules, so that they can be absorbed into the blood. ​

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2
Q

Describe the complete digestion of starch

A

In the mouth;,
Salivary amylase,
Hydrolyses glycosidic bonds in starch to produce maltose;
In the duodenum,
Pancreatic amylase
hydrolyses starch into maltose;
In the ileum maltase hydrolyses maltose into glucose;

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3
Q

Describe the complete digestion of proteins

A

In the stomach;​
Endopeptidase (pepsin);​
hydrolyses internal peptide bonds in proteins;​
To produce smaller polypeptide chains;​
In the duodenum;​
Pancreatic juice contains endo and exopeptidase;
Exopeptidase hydrolyses external peptide bonds in proteins;​
To produce dipeptides and amino acids;
In the ileum;​
Dipeptidase;​
hydrolyses dipeptides;​
Into amino acids;

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4
Q

Describe the location of maltase

A

In the cell membrane of epithelial cells that line the ileum.

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5
Q

Name the four enzymes present in the cell membrane of the epithelial cells that line the ileum

A

dipeptidase
sucrase
lactase
maltase

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6
Q

What is the function of bile?

A

In duodenum;​
Bile salts emulsify fats;​
Increasing surface area;​
for faster digestion by pancreatic lipase;

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7
Q

Describe and explain what happens to the pH when lipids are hydrolysed.

A

Decreases/becomes more acidic;
Because fatty acids are produced and they are weak acids;

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8
Q

Describe the complete digestion of lipids.

A

In duodenum;​
Lipase in Pancreatic juice;​
Hydrolyses the ester bond in triglycerides;​
To produce glycerol and 3 fatty acids;

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9
Q

Describe the process of cotransport

A
  1. Sodium ions are actively transported out of the epithelial cells into the blood via the sodium-potassium pump​.
  2. maintaining a concentration gradient for sodium ions to diffuse into the epithelial cell from the lumen;
    3.Sodium ions move by facilitated diffusion from the lumen along with glucose by facilitated diffusion via the sodium-glucose co-transporter (symporter).​
  3. inside the cell glucose and sodium ions separate
    5.Glucose moves from the epithelial cell into the blood by facilitated diffusion via its carrier protein.
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10
Q

Describe how lipids are absorbed

A
  1. Fatty acids and monoglycerides surrounded by phospholipid and bile salts to form micelles;​
  2. Fatty acids and monoglycerides diffuse across the membrane;​
  3. Triglycerides resynthesized in the SER;​
  4. Short chain fatty acids move into blood by diffusion;​
  5. Triglycerides surrounded by protein in the golgi body;​
  6. Form chylomicrons; ​
  7. Diffuse into the lymph vessel/lacteal;​
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