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Flashcards in GI Tract: Fine-tuning revision Deck (98)
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1
Q

Does bile contain digestive enzymes

A

No

2
Q

Does bile contain conjugated or unconjugated bilirubin

A

Conjugated ONLY

3
Q

How does storage and concentration of bile in the gallbladder affect bile pH?

A

It DECREASES pH

4
Q

Difference in the type of saliva secreted in serous and mucous glands

A

Serous is very WATERY (remember serous is a mixture of water and amylase)

Mucous is very thick and viscous (needed for lubrication)

5
Q

Where is iodide mainly excreted

A

In the saliva

6
Q

What cation can be found in the saliva

A

Calcium ions

7
Q

What is the pH of saliva

A

6-7 (NEUTRAL)

8
Q

What happens to the rate of saliva secretion when vomiting is about to take place

A

It increases in order to buffer the contents before it can cause any damage

9
Q

Where is the swallowing reflex centre

A

Medulla oblongata

10
Q

Is the swallowing reflex more effective standing or laying down

A

Standing because we then have the assistance of gravity

11
Q

What needs to happen to iron before it can be absorbed at the duodenum

A

It needs to be reduced by HCL from trivalent ferric iron to divalent ferric iron

12
Q

What cleaves pepsinogen to pepsin

A

HCL

13
Q

Is vitamin C stored in the liver?

A

No

14
Q

Where is vitamin C excreted

A

In the kidneys

15
Q

How does ingestion of fibres influence bowel movement

A

It stimulates peristaltic waves by adding ‘bulk’ to the food residues

16
Q

How are mucosal cells protected from gastric juices

A

Due to a coating of mucous which is IMPREGNATED with HCO3-

17
Q

How will an increase in body fat affect body water volume

A

Will reduce it

18
Q

Is saliva essential for digestion?

A

Nope, enzymes like ptyalin and HCL only assist digestion and can be carried out by chymotrypsin and trypsin in the duodenum

19
Q

Where is calcium mainly absorbed

A

Duodenum

20
Q

Do fatty acids get absorbed in the capillaries

A

They can do if they are small enough. Most will move in via lymphatics (lacteals) if they are too big and need to be esterified and packaged into chylomicrons

21
Q

Where is cholesterol mainly excreted

A

In the bile (think HDL)

22
Q

What factor will cause an increase in the risk of gallstone development

A

An increase in cholesterol: Bile salts and Cholesterol: Lecithin ratios

23
Q

Will an increase in Bile salts: Cholesterol or Lecithin: Cholesterol increase the risk of gallstone formation

A

No, these favour micelle formation which reduces chances of gallstones forming

24
Q

Can removal of the stomach impair iron absorption

A

Yes because it can only be absorbed at the duodenum as divalent ferric iron

25
Q

What symptoms can I expect to see in Hepatic Jaundice

A

Low prothrombic levels
Low fibrinogen levels in the blood
Low albumin levels

26
Q

What papillae have no taste buds

A

FILLIFORM
FUNGIFORM
CIRCUMVALLATE
FOLATE

27
Q

Name the three branches of the coeliac trunk

A
  • Left gastric artery
  • Common hepatic artery
  • Splenic artery
28
Q

Is the duodenum retro or intraperitoneal

A

Retroperitoneal

29
Q

Where is Meckel’s diverticulum located

A

It is an appendix-like structure that is found at the ileum

30
Q

Describe absorption of amino acids and glucose at the SMALL INTESTINES

A

They are moved into the intestinal epithelial cells by SECONDARY ACTIVE TRANSPORT with Na+

31
Q

What ion moves into the intestinal epithelial cell with sodium ions

A

Cl-

32
Q

How does Cl- enter the intestinal epithelial cell

A

Counter-transport with HCO3- ions

33
Q

How does the Na+ and Cl- move out of the intestinal epithelial cells and into the interstitial

A

Na+/k+ ATPase

Cl- ion channels

34
Q

What other way does Na+ enter the intestinal epithelial cell

A

Na+/H+ ATPase

35
Q

What two major ions are secreted in the large intestines and ileum

A

HCO3- and Cl-

36
Q

Where is HCO3- absorbed , why and how

A

At jejunum and duodenum

H+ is exchanged with Na+ 
H+ reacts with HCO3- to give H2CO3
H2CO3 -> H2O + CO2
CO2 is re-absorbed and expired
H20 remains in chyme

Prevents pH from becoming too high

37
Q

Define Amphipathic

A

A compound that shows both lipophilic + hydrophilic properties

38
Q

Where are meissner’s plexus located

A

In gut submucosa

39
Q

Where is Auerbach’s plexus located

A

Between the two layers of the muscularis propria

40
Q

What is the head of the pancreas supplied by

A

Inferior pancreaticoduodenal artery branch of the superior mesenteric artery

41
Q

How does liver function affect the body if it fails

A

Increased size of male breasts as oestrogens and progesterones will not get conjugated
Increased unconjugated bilirubin
Increased tendancy to bleed

42
Q

Why is dividing the vagal nerve supply to the stomach helpful for treating peptic ulcers

A

Less ACh released so less gastrin acidity

43
Q

How will removing the pyloric antrum affect peptic ulcers

A

Reduce them as this removes a lot of the G cells in the stomach, reducing HCL release

44
Q

What receptors do histamine bind to

A

H2 receptors

45
Q

When does urobilin in the urine get darker

A

When exposed to light

46
Q

Where are chymotrypsin and trypsin produced

A

Pancreas

47
Q

Why can liver failure result in more salt and water retention

A

Because it is needed to conjugate aldosterone which won’t be able to function at the liver properly otherwise

48
Q

Can liver failure lead to oedema? If so, why?

A

Yes, because less albumin will be produced

49
Q

What receptors does ACh bind to at the stomach

A

M1 - muscarinic receptors

50
Q

How does portal hypertension affect vascular resistance through the sinusoids

A

Increases it

51
Q

How does portal hypertension affect blood flow through the liver

A

Decreases it as blood flow will be diverted straight to the central vein as opposed to circulating around the sinusoids for a while

52
Q

How will portal hypertension affect the volume of fluid in the peritoneal cavity

A

Increase it as there will be a higher hydrostatic pressure so more filtration will take place

53
Q

What is D3 also known as

A

Cholecalciferol

54
Q

What is D2 also known as

A

Ergocalciferol

55
Q

What is the main source of vit D

A

UV rays

56
Q

What do we have in our skin that starts off production of D3

A

7-Dehydrocholesterol

57
Q

What is 7-dehydrocholesterol

A

Inactive precursor of D3

58
Q

What happens to 7-dehydrocholesterol

A

It reacts with UV rays to produce cholecalciferol

59
Q

What wavelength of UV is needed for activation of D3 to take place in the skin

A

270-300nm (optimal between 295 to 297nm)

60
Q

Can we overdose from vit D with a lot of exposure from the skin?

A

Nope

61
Q

Wht happens to vit D at the liver

A

converted to calcidiol

62
Q

What happens to calcidiol at the kidney

A

Converted to calcitriol

63
Q

What is the formula for calcidiol

A

25(OH)D

64
Q

What is the formula for calcitriol

A

1,25(OH)2D

65
Q

Where does vit D act

A

Intestines, Kidneys + Bone

66
Q

Where is glucose absorped at the GI tract

A

Duodenum and small intestines

67
Q

What part of the brain co-ordinates the vomiting reflex

A

Medulla Oblongata

68
Q

What obstruction is vomiting indicative of

A

High intestinal obstruction

69
Q

When does muscle tone in the oesophagus increase

A

Gastrin secretion to prevent reflux of gastric contents

70
Q

When does muscle tone in the oesophagus decrease

A

During pregnancy - increases occurance of heart burn

71
Q

What secretion causes disaccharides to be broken down

A

Intestinal secretions

72
Q

What secretion causes triglycerides to be broken down

A

Pancreatic secretions

73
Q

What secretions causes breakdown of nucleic acids

A

Pancreatic secretions

74
Q

What compound causes contraction of the oesophageal-gastric sphincter

A

Gastrin

75
Q

At what vertebral level is the gastro-oesophageal junction at

A

T11

76
Q

What needs to happen to all carbohydrates before they can be absorbed by the body

A

They need to be broken down in to monosaccharides first

77
Q

What happens to carbohydrates in the mouth

A

They are broken down by Ptyalin - an alpha amylase

78
Q

What gland secretes ptyalin

A

Parotid Glands

79
Q

What is the optimal pH that ptyalin works at

A

6.7

80
Q

What happens to carbohydrates at the small intestines

A

The 1-4 glycosidic bonds of the carbohydrates are broken down but 1-6 glycosidic bonds are preserved

81
Q

What are the end-products of digestion of the 1-4 glycosidic bonds in carbohydrates

A
  • Maltose
  • Maltotriose
  • Alpha limit dextrins
82
Q

What are alpha-limit dextrins

A

These are branched units with 8 units in total

83
Q

What happens to maltose, maltotriose and alpha limit dextrins in the duodenum

A

They are broken down by oligosaccharidases in the microvilli:

Maltase
Lactase
Sucrase
Alpha-limit dextrase

This produce monosaccharides

84
Q

Name the three major monosachharides

A
  • Glucose
  • Galactose
  • Fructose
85
Q

How is Galactose absorbed

A

Galactose and glucose share the same SGLT co-transporter so compete with each other to be absorbed

Galactose then moves from the intestinal epithelial cells into the interstitium via facilitated diffusion through GLUT channels

86
Q

How does Fructose absorption differ from galactose absorption

A

Fructose has a different transporter - GLUT

87
Q

Where are most carbohydrates absorbed

A

Duodenum

88
Q

Where are these carbohydrates then moved from the duodenum

A

Into the hepatic portal vein and then on to the liver

89
Q

What three things happen to glucose in the liver

A
  • Glycogenesis
  • Production of glucose
  • Glycolysis
90
Q

Why does glycolysis take place in the liver

A
  • Production of alpha-glycerol phosphate and fatty acids that are needed to form triglycerides
91
Q

How are alpha-glycerol phosphates produce from glycolysis of glucose

A

Reduction of dehydroxyacetone phosphate

92
Q

What happens to triglycerides produced in the liver

A

They are placed into VLDLs

93
Q

What are VLDLs

A

Lipoproteins that contain more fat than proteins

94
Q

Why do lipoprotein lipases have to breakdown VLDLs as they circulate in the blood

A

Because they are too big to move through the capillary wall

95
Q

How long do glycogen stores last for

A

12 Hours

96
Q

How long do lipids last for in the body

A

3 months

97
Q

When does protein become a source of energy

A

During prolonged starvation

98
Q

How much of the body’s total energy requirement is contributed to by the liver and the brain

A

40%