Digestion and Absorption

Question 1

Digestion

Answer 1

the breakdown of nutrients into absorbable molecules

Question 2

Absorption

Answer 2

movement of nutrients, water and electrolytes from the gut lumen into the internal environment

Question 3

Surface of the small intestine is arranged in

Answer 3

in circular folds of Keckring

Question 4

Carbohydrates

Answer 4

• Starch
• Glycogen • Cellulose
• Disaccharides

Question 5

Lipids

Answer 5

Triacylglycerols (TAG) 90% (fats, oils) [Triglycerides]
• Phospholipids
• Cholesterol & cholesterol esters
• Free fatty acids
• Lipid vitamins

Question 6

Proteins

Answer 6

digestive enzymes & dead cells from GI tract

Question 7

Carbohydrate digestion

Answer 7

 Only monosaccharides can be absorbed

 Begins with salivary alpha-amylase (minor role)

Question 8

carb absorption in the duodenum

Answer 8

• pancreatic amylase
• brush border enzymes (maltase, sucrase and lactase)

act on disaccharides, producing monosaccharides-fructose, glucose & galactose

Question 9

lactose intolerance

Answer 9

(no enzyme so bacteria ferment sugar) – gas & diarrhoea)

Question 10

Amylases

Answer 10

free enzymes acting in the GI lumen and digest only internal α-1-4 glycosidic bonds

Question 11

Salivary amylases–

Answer 11

secreted from mouth in response to sight & smell of food - of lesser importance than

Question 12

Pancreatic amylases

Answer 12

secreted from pancreas into

Question 13

Products of amylase

Answer 13

now digested by oligosaccharidases (attached to the enterocyte mucosal membrane of the brush border of epithelial cells)

Question 14

α-glucosidase

Answer 14

cleaves α-1-4 glycosidic bonds to remove single glucose units from the non reducing end of the polymer

Question 15

Isomaltase

Answer 15

cleaves α-1-6 glycosidic bonds in the α-limit dextrin oligosaccharides

Question 16

Final products of carbohydrate digestion

Answer 16

 Glucose
 Galactose
 Fructose

Question 17

 Secondary active transport

Answer 17

• SGLT 1 (sodium dependent glucose transporter 1) located on the apical membrane transports glucose and galactose

Question 18

 Facilitated diffusion

Answer 18

• GLUT 5 (glucose transporter 5) transports fructose across the apical membrane