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Y2 - GI > Absorption And Digestion > Flashcards

Absorption And Digestion Flashcards

1
Q

What form does a carbohydrate have to be in order to be absorbed into the body?

A

Monosaccharide

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2
Q

What ion needs to be present for glucose to be absorbed?

A

Na+

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3
Q

What are the 3 main absorbable monosaccharides?

A

Glucose
Galactose
Fructose

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4
Q

What are the 2 types of bonds found in starch?

A

Alpha 1-4 and 1-6 bonds

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5
Q

What are the 2 types of chains in starch?

A

Amylose (joined by a 1-4 bonds)

Amylopectin (joined by a 1-6 bonds)

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6
Q

What enzyme breaks a 1-4 bonds in amylose in starch?

A

Amylase

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7
Q

What is the product of amylase breaking down the amylose in starch?

A

Maltose

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8
Q

What is the enzyme that breaks a 1-6 bonds in amylopectin in starch?

A

Isomaltase

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9
Q

What is left behind when isomaltase breaks down the 1-6 bonds in amylopectin?

A

Alpha dextrin which = chains of amylose

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10
Q

What enzyme breaks down maltose to glucose and glucose?

A

Maltase

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11
Q

What type of carb is lactose?

A

Disaccharide

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12
Q

What enzyme breaks down lactose?

A

Lactase

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13
Q

What 2 monosaccharides are formed when lactose is broken down to lactase?

A

Glucose + galactose

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14
Q

Where is the enzyme lactase located?

A

Brush border of enterocytes

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15
Q

What enzyme breaks down sucrose?

A

Sucrase

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16
Q

What is sucrose broken down into?

A

Glucose + fructose

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17
Q

How are glucose and galactose absorbed from intestinal lumen through enterocyte into blood?

A

SGLT1 with Na+
Then across GLUT2 into veins that drain to portal vein

Na+/K+ ATPase creates gradient

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18
Q

How is Fructose absorbed from intestinal lumen through enterocyte into blood?

A

Through GLUT 5 into enterocyte then across GLUT2 into veins leading to portal vein

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19
Q

What are zymogen?

A

Granules containing inactive enzymes

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20
Q

Where does protein digestion begin?

A

Stomach

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21
Q

What cells are important in starting protein digestion in the stomach?

What do they secrete?

A

Chief cells

Produce Pepsinogen (inactive pepsin)

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22
Q

How does pepsin become activated to start digesting protein in the stomach?

A

Hydrochloride acid activates pepsinogen to pepsin

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23
Q

What is the function of pepsin?

A

Breaks down proteins to oligopeptides and some free amino acids in stomach

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24
Q

Where in the stomach are chief cells located?

A

Gastric glands

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25
Q

What happens when the broken down proteins and acidic chyme enter into duodenum (what is the pancreas stimulated to do)?

A

Zymogen/inactive digestive enzymes secreted

26
Q

What are the 5 major zymogens (proteases) produced by the pancreas?

A

Trypsinogen
Chymotrypsinogen
Proelastase
Procarboxypeptidase A
Procarboxypeptidase B

27
Q

What are the active forms of the 5 zymogen proteases produced by the pancreas?

A

Trypsin
Chymotrypsin
Elastase
Carboxypeptidase A
Carboxypeptidase B

28
Q

How does Trypsinogen activated and why is this important?

A

Enteropeptidase in brush border of small lumen activates it

Trypsin then goes on to activate the other inactive Proteases

29
Q

What are endopeptidases?

What are exopeptidases?

A

Endopeptidases make shorter peptide chains by breaking in middle

Exopeptdiases break bonds at the ends leading to amino acids and shorter peptides being made

30
Q

What are the endopeptidases?

A

Trypsin
Chymotrypsin
Elastase

31
Q

What are the exopeptidases?

A

Carboxypeptidase A
Carboxypeptidase B

32
Q

What is the function of the brush border proteases?

A

Further break down di and tri peptides to individual amino acids

33
Q

How are dipeptides and tri-peptides brought into the enterocyte?

A

PepT1

34
Q

What happens to the dipeptides and tripeptides in the enterocyte?

A

Broken down to amino acids

35
Q

What ion are amino acids absorbed with into the enterocyte?

A

Na+

36
Q

Briefly outline where proteins are digested?

A

Starts in stomach
Pancreas releases inactive proteases into small intestine
Brush border enzymes in intestine break down di-tripeptides
Enzymes in enterocyte break down tri/di peptides

37
Q

What are the 2 ways water is absorbed from the intestinal lumen into the body?

A

Paracellularly
Transcellularly

38
Q

How is an osmotic gradient created so water can be absorbed from the intestinal lumen?

A

Na+/K+ ATPase on basolateral membrane pumps sodium into blood out of enterocyte

39
Q

What is drawn into the enterocyte then to the interstitial space due to the Na+ gradient?

How does this help draw water through?

A

Glucose and amino acids

Makes solution in intercellular space/interstital space very hypertonic

40
Q

What is the important ion needed for water secretion?

A

Cl-

41
Q

What protein moves Cl- out of the cell so water can be secreted?

A

Cystic Fibrosis Transmembrane Conductance Regulator protein

42
Q

What leads to increased CFTR expression?

A

cAMP levels rise
More CFTR
More Cl- removed

43
Q

Describe trans cellular absorption of water:

A

Water follows sodium as it enter enterocyte

44
Q

Describe paracellular absorption of water:

A

Sodium pumped into intercellular space between cells
Creates hyperosmotic environment so water moved through tight junctions

45
Q

What are some symptoms of vitamins B12 deficiency?

A

Neurological problems
Megaloblastic anaemia

46
Q

What can cause Vitamin B12 deficiency?

A

Lack of intrinsic factor
Hypochlorhydria
Inadequate B12 intake
Crohn’s disease (inflammatory disorders of ileum where B12 absorbed)

47
Q

What cells produce intrinsic factor?

A

Parietal cells

48
Q

What is hypchlorhydria?

A

Inadequate stomach acid production

49
Q

What can cause hypochlorhydria?

A

Gastric atrophy
Proton Pump inhibitors (omeprazole)

50
Q

What causes lactose intolerance?

A

Deficiency in lactase

51
Q

What age does lactase levels usually drop from?

A

2

52
Q

What symptoms do people with lactose intolerance have?

A

Diarrhoea
Bloating
Flatulence

53
Q

What leads to diarrhoea in lactose intolerance?

A

Lactose remains in lume of gut
Leads to oncotic pressure in lumen increasing drawing water into gut lumen

54
Q

What leads to flatulence and bloating in lactose intolerance?

A

Lactose fermented in intestine releasing gases

55
Q

What are the symptoms of irritable bowel syndrome?

A

Abdominal pain(cramping)
Bloating
Flatuelnce
Diarrhoea
Rectal urgency
Constipation

56
Q

Who is IBS most common with?

A

Women
Between 20s and 40s and often associated with psychological disorders

57
Q

What is Coeliac disease?

A

An immune response to Gluten (specifically the gliadin fraction)

58
Q

What happens as a result of the immunological response to gluten in coeliac disease?

A

Damages the intestinal mucosa
Flattening the villi
Hypertrophy of crypts
Lymphocytic invasion into epithelium and lamina propria

This leads to impaired digestion and malabsorption

59
Q

What are the symptoms of Coeliac disease?

A

All symptoms of malabsorption

Diarrhoea (osmotic pressure in lumen)
Weight loss
Flatulence (sugars fermented) leading to distension
Anaemia (reduced Fe absorption)
Neurological symtpoms (reduced calcium)

60
Q

How is Coeliac disease treated?

A

Strict gluten free diet

Leads to improvement in symptoms and intestinal healing

61
Q

How is coeliac disease diagnosed?

A

History
Blood tests for IgA to smooth muscle endomysium + tissue

Upper gastrointestinal endoscopy with biopsy of duodenum

Y2 - GI (35 decks)

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