5. Absorption And Digestion

Question 1

What does glucose need to be absorbed with?

Answer 1

Na+

Question 2

How do we break down starch?

Answer 2

Amylase breaks down alpha 1-4 bonds
Isomaltase breaks down alpha 1-6 bonds
Maltase breaks down maltose into 2 glucose

Question 3

What monosaccharides are produced from breakdown of common dietary carbs?

Answer 3

Glucose
Galactose
Fructose

Question 4

What is transported across SGLT1?

Answer 4

Glucose or galactose once they have been bound to Na+

Question 5

What is transported across gLUT5?

Answer 5

Fructose

Question 6

What are the transporters on the basolateral membrane of gut epithelia?

Answer 6

GLUT2

Na+/K+ ATPase transporter

Question 7

What is the first stage of protein digestion?

Answer 7

Stomach
Pepsinogen is released from chiefs cells in gastric glands
HCL then activates it to pepsin
Protein the broken down into oligopeptides and amino acids

Question 8

What is the second stage of protein digestion?

Answer 8

Intestinal lumen

Zymogens released from pancreas and activated in lumen

Question 9

How are all inactive enzymes activated?

Answer 9

Trypsinogen activated by enteropeptidase to trypsin

Trypsin can then activate trypsingogen, chymotrypsinogen, proelastase, procarboxypeptidase A and B

Question 10

Where is the 3rd and 4th places that proteins are broken down?

Answer 10

Brush border

Cytosolic peptidase - breakdown dipeptides into amino acids

Question 11

How can water move across enterocytes?

Answer 11

Transcellularly

Paracellularly

Question 12

What happens if cAMP levels rise in the enterocytes?

Answer 12

Cl- is secreted into the lumen via the cystic fibrosis transmembrane conductance regulator (CFTR)
Causes water to then move into the lumen

Question 13

What are the signs and symptoms of vit b12 deficiency?

Answer 13

Neurological problems

Megaloblastic anaemia

Question 14

What are the causes of vit B12 deficiency?

Answer 14

Lack of intrinsic factor
Hypochlorhydria - gastric atrophy, PPI
Not enough B12 in food
Inflammation of terminal ileum - Crohn’s disease

Question 15

What is lactose intolerance?

Answer 15

Deficiency of enzyme lactase
Lactose cannot be broken down, draws water into lumen of gut, causes diarrhoea
In colon its fermented which causes flatus and bloating

Question 16

What are the symptoms of IBS?

Answer 16

Abdominal pain
Bloating
Flatulence
Diarrhoea/constipation
Rectal urgency

Question 17

What is coeliac disease?

Answer 17

Immunological response to gluten
Damage to mucosa - flattening of villi, hypertrophy of crypt, lymphocytes in epithelium/LP
Leads to impaired digestion and malabsorption

Question 18

What are the causes of coeliac disease?

Answer 18

Genetic factors

Question 19

What are the symptoms of coeliac disease?

Answer 19

Malabsorption

• diarrhoea
• weight loss
• flatulence - pain
• anaemia
• neurological symptoms

Question 20

What are the investigations for coeliac disease?

Answer 20

Blood tests - IgA to smooth muscle endometrium and tissue transglutaminase
Upper GI endoscopy - duodenal biopsy