Absorption And Digestion Flashcards

(61 cards)

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
What happens when the broken down proteins and acidic chyme enter into duodenum (what is the pancreas stimulated to do)?
Zymogen/inactive digestive enzymes secreted
26
What are the 5 major zymogens (proteases) produced by the pancreas?
Trypsinogen Chymotrypsinogen Proelastase Procarboxypeptidase A Procarboxypeptidase B
27
What are the active forms of the 5 zymogen proteases produced by the pancreas?
Trypsin Chymotrypsin Elastase Carboxypeptidase A Carboxypeptidase B
28
How does Trypsinogen activated and why is this important?
Enteropeptidase in brush border of small lumen activates it Trypsin then goes on to activate the other inactive Proteases
29
What are endopeptidases? What are exopeptidases?
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
What are the endopeptidases?
Trypsin Chymotrypsin Elastase
31
What are the exopeptidases?
Carboxypeptidase A Carboxypeptidase B
32
What is the function of the brush border proteases?
Further break down di and tri peptides to individual amino acids
33
How are dipeptides and tri-peptides brought into the enterocyte?
PepT1
34
What happens to the dipeptides and tripeptides in the enterocyte?
Broken down to amino acids
35
What ion are amino acids absorbed with into the enterocyte?
Na+
36
Briefly outline where proteins are digested?
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
What are the 2 ways water is absorbed from the intestinal lumen into the body?
Paracellularly Transcellularly
38
How is an osmotic gradient created so water can be absorbed from the intestinal lumen?
Na+/K+ ATPase on basolateral membrane pumps sodium into blood out of enterocyte
39
What is drawn into the enterocyte then to the interstitial space due to the Na+ gradient? How does this help draw water through?
Glucose and amino acids Makes solution in intercellular space/interstital space very hypertonic
40
What is the important ion needed for water secretion?
Cl-
41
What protein moves Cl- out of the cell so water can be secreted?
Cystic Fibrosis Transmembrane Conductance Regulator protein
42
What leads to increased CFTR expression?
cAMP levels rise More CFTR More Cl- removed
43
Describe trans cellular absorption of water:
Water follows sodium as it enter enterocyte
44
Describe paracellular absorption of water:
Sodium pumped into intercellular space between cells Creates hyperosmotic environment so water moved through tight junctions
45
What are some symptoms of vitamins B12 deficiency?
Neurological problems Megaloblastic anaemia
46
What can cause Vitamin B12 deficiency?
Lack of intrinsic factor Hypochlorhydria Inadequate B12 intake Crohn’s disease (inflammatory disorders of ileum where B12 absorbed)
47
What cells produce intrinsic factor?
Parietal cells
48
What is hypchlorhydria?
Inadequate stomach acid production
49
What can cause hypochlorhydria?
Gastric atrophy Proton Pump inhibitors (omeprazole)
50
What causes lactose intolerance?
Deficiency in lactase
51
What age does lactase levels usually drop from?
2
52
What symptoms do people with lactose intolerance have?
Diarrhoea Bloating Flatulence
53
What leads to diarrhoea in lactose intolerance?
Lactose remains in lume of gut Leads to oncotic pressure in lumen increasing drawing water into gut lumen
54
What leads to flatulence and bloating in lactose intolerance?
Lactose fermented in intestine releasing gases
55
What are the symptoms of irritable bowel syndrome?
Abdominal pain(cramping) Bloating Flatuelnce Diarrhoea Rectal urgency Constipation
56
Who is IBS most common with?
Women Between 20s and 40s and often associated with psychological disorders
57
What is Coeliac disease?
An immune response to Gluten (specifically the gliadin fraction)
58
What happens as a result of the immunological response to gluten in coeliac disease?
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
What are the symptoms of Coeliac disease?
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
How is Coeliac disease treated?
Strict gluten free diet Leads to improvement in symptoms and intestinal healing
61
How is coeliac disease diagnosed?
History Blood tests for IgA to smooth muscle endomysium + tissue Upper gastrointestinal endoscopy with biopsy of duodenum