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PHASE 1 OWN STUFF > GI/LIVER > Flashcards

GI/LIVER Flashcards

1
Q

what are the three phases of swallowing?

A

oral
pharyngeal
oesophageal

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2
Q

of the phases of swallowing which are voluntary?

A

the oral phase is voluntary

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3
Q

of the phases of swallowing, which are involuntary?

A

the pharyngeal and oesophageal phases are involuntary

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4
Q

what can the oral phase of swallowing be broken down into?

A

the preparatory phase and the transfer phase

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5
Q

what happens during the preparatory phase of swallowing?

A

food mixes with saliva and a bolus is formed

during this stage, chewing, mastication and sucking all occur

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6
Q

what happens during the transfer phase of swallowing?

A
  1. the tip and sides of the tongue contract against the hard palate and the bolus passes into the oropharynx
  2. the soft palate lifts up to close off the nasopharynx
  3. the posterior pharyngeal wall begins contracting downwards and the soft palate also moves down
  4. the tongue contracts to close off the oral cavity and so the bolus is propelled into the oropharynx
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7
Q

what happens during the pharyngeal phase of swallowing?

A
  1. the tongue seals off the oropharynx and the airway is sealed off
  2. the vocal cords and arytenoids close off the larynx and the epiglottis swings down to prevent aspiration
  3. the larynx moves up and out
  4. the pharynx widens and shortens
  5. the upper oesophageal sphincter elevates
  6. food is propelled into the oesophagus and pharyngeal peristalsis occurs
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8
Q

what happens during the oesophageal phase of swallowing?

A
  1. oesophagus and lower oesophagus relax
  2. the bolus enters the oesophagus
  3. part of the bolus may enter the stomach - this is aided by gravity
  4. the residual bolus is then cleaved by peristaltic wave into the stomach
  5. a solid bolus generally requires contraction, rather than gravity alone
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9
Q

how long does it take for food to travel through the pharynx after chewing?

A

roughly 1 second

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10
Q

how long does it take for food to travel through the oesophagus?

A

roughly 5 seconds

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11
Q

what are mucous cells, what do they secrete and what is the function of their secretion?

A

mucous cells are gastric cells found in the cardia and pylorus of the stomach. they secrete mucin which helps lubricate and protect the mucosa

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12
Q

what are parietal cells, what do they secrete and what is the function of their secretion?

A

parietal cells are gastric cells found in the fundus and body of the stomach. they secrete:

  1. HCl which aids digestion, cleaves pepsinogen into pepsin and kills pathogens
  2. intrinsic factor which aids absorption of B12 at the terminal ileum
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13
Q

what are chief cells, what do they secrete and what is the function of their secretion?

A

chief cells are gastric cells found in the fundus and body of the stomach. they secrete the zymogen pepsinogen
pepsinogen is then cleaved into pepsin

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14
Q

what are ECL cells, what do they secrete and what is the function of their secretion?

A

ECL cells are gastric cells located in the gastric pits. they secrete histamine which stimulates the secretion of HCl

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15
Q

what are G cells, what do they secrete and what is the function of their secretion?

A

G cells are gastric cells and are most commonly found in the pyloric antrum. they secrete gastrin which stimulates the secretion of HCl and histamine

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16
Q

what are D cells, what do they secrete and what is the function of their secretion?

A

D cells are gastric cells found commonly throughout the GI tract. they secrete somatostatin which inhibits HCl secretion

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17
Q

how is pepsin produced?

A

pepsin comes from the zymogen pepsinogen which is secreted by chief cells
pepsinogen is converted to pepsin by HCl
this conversion is most efficient at a pH of less than 2

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18
Q

what are some of the protective mechanisms of the mucosa?

A
  • alkaline mucous (on luminal surface)
  • tight junctions between epithelial cells
  • rapid cell replacement of damaged cells by stem cells in the base of gastric pits
  • feedback loops which regulate the secretion of HCl
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19
Q

what are the consequences of insufficient protective mechanisms of the mucosa?

A

the formation of peptic ulcers

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20
Q

what causes peptic ulcers?

A

H. pylori
NSAIDs
chemical irritants
gastrinoma’s

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21
Q

what are the three phases of gastric acid secretion?

A
  1. cephalic phase
  2. gastric phase
  3. intestinal phase
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22
Q

what happens during the cephalic phase of gastric acid secretion?

A
  1. the cephalic phase of gastric acid secretion occurs in response to stimuli (e.g tase, smell, sight of food). this is a reflex mediated by the vagus nerve
  2. gastric juice is secreted in response to vagal stimulation and can occur either directly (via electrical impulses) or indirectly (via stimuli received through the senses)
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23
Q

what happens during the gastric phase of gastric acid secretion?

A
  1. the gastric phase of gastric acid secretion is mediated by the vagus nerve and the release of gastrin
  2. gastrin stimulates the release of HCl and histamine
  3. the acidity of the stomach is buffered to remain at a pH of 3 for roughly 90 minutes
  4. HCl continues to be secreted in response to distension and the presence of amino acids digested due to proteases
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24
Q

what happens during the intestinal phase of gastric acid secretion?

A

NOTE: this is complex!

  1. amino acids and small peptides that promote gastric acid secretion are infused into circulation
  2. meanwhile, chyme inhibits acid secretion
  3. gastrin secretion is inhibited when pH is below 2.5
  4. hormones that are released due to digestion (i.e glucagon, secretin) suppress HCl secretion

essentially the intestinal phase is the phase in which gastric acid secretion stops

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25
Q

what is the volume of the stomach when empty?

A

roughly 50ml

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26
Q

what is the maximum volume of the stomach?

A

1500ml

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27
Q

how does the stomach increase in volume?

A

the muscles in the body and fundus of the stomach relax

this is mediated by acetylcholine (parasympathetic innervation from vagus nerve) and nitric oxide + serotonin (enteric)

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28
Q

when does peristalsis occur?

A

in response to the presence of food in the stomach

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29
Q

what happens during peristalsis?

A
  1. a ripple movement begins in the body of the stomach
  2. a more powerful wave occurs at/in the antrum
  3. the pyloric sphincter closes which means that little chyme can enter the duodenum
  4. the antral contents are forced back into the body and mixing occurs
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30
Q

what mediates peristalsis?

A

the interstitial cells fo Cajal

these determine the frequency of peristaltic contractions

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31
Q

how many peristaltic contractions happen per minute

A

3

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32
Q

what can increase the strength of peristaltic contractions?

A
  • gastrin

- distension of the stomach

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33
Q

what can decrease the strength of peristaltic contractions?

A
  • duodenal distension
  • increase in duodenal fat/osmolarity
  • decrease in duodenal pH
  • increased sympathetic stimulation
  • decreased parasympathetic stimulation
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34
Q

what is BMI?

A

weight/height^2

kg/m^2

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35
Q

what is an underweight BMI?

A

below 18.5

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36
Q

what’s a healthy weight range BMI?

A

between 18.5 and 24.9

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37
Q

what’s an overweight range BMI?

A

between 25 and 29.9

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38
Q

what’s an obese range BMI?

A

between 30 and 39.9

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39
Q

define BMR?

A

the basal metabolic rate is the amount of energy needed to stay alive at rest
it is approximately 24 kcal/kg/day

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40
Q

what increases BMR?

A
  • being overweight
  • being male
  • being pregnant
  • caffeine
  • hyperthyroidism
  • exercise
  • low temperatures
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41
Q

what decreases BMR?

A
  • increase in age
  • being female
  • being underweight
  • malnutrition/starvation
  • hypothyroidism
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42
Q

what vitamins are fat soluble?

A

A, D, E, K

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43
Q

where and how are fat soluble vitamins absorbed?

A

they are absorbed along with fat, in micelles in the ileum

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44
Q

what are the water soluble vitamins?

A

B, C

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45
Q

where are water soluble vitamins absorbed?

A

in the jejunum

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46
Q

where is B12 absorbed?

A

in the terminal ileum, attached to intrinsic factor

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47
Q

what is the function of vitamin A?

A

cellular growth and differentiation, vision, lymphocyte production, skin and mucous membranes

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48
Q

what are some sources of vitamin A?

A

liver, dairy, fruit&veg. oily fish, margaine

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49
Q

what can a vitamin A deficiency cause?

A

night blindness, growth retardation, increased susceptibility to infection, impaired: hearing, taste + smell

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50
Q

what is the function of vitamin B12?

A

erythrocyte formation, DNA synthesis, brain development

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51
Q

what are some sources of vitamin B12?

A

meat, fish, eggs, milk

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52
Q

what can a vitamin B12 deficinecy cause?

A

pernicious anaemia (fatigue, shortness of breath, tingling)

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53
Q

what is the function of vitamin C?

A

collagen synthesis, antioxidant, absorption of non-haem iron

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54
Q

what are some sources of vitamin C?

A

citrus fruit, green veg, potatoes

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55
Q

what can a vitamin C deficiency cause?

A

scurvy, bleeding gums

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56
Q

what is the function of vitamin D?

A

calcium absorption in the gut and its reabsorption in the kidneys

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57
Q

what are some sources of vitaminD?

A 
D3 = plants, mushrooms, UV light
D2 = fish oils, egg yolks
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58
Q

what can a vitamin D deficiency cause?

A

frequent bone fractures, muscle weakness, bone pain

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59
Q

what is the function of vitamin E?

A

antioxidant, protects cell walls

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60
Q

what are some sources of vitamin E?

A

nuts, seeds, vegetable oils

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61
Q

what can a vitamin E deficiency cause?

A

muscle weakness, degeneration of retina

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62
Q

what is the function of vitamin K?

A

the formation of clotting factors: 2, 7, 9, and 10 in the liver

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63
Q

what are some sources of vitamin K?

A

leafy green veg, beef liver, chicken, soy oils

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64
Q

what can a vitamin K deficiency cause?

A

clotting factor deficiencies, bleeding, poor bone development

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65
Q

how is vitamin B12 absorbed?

A

vitamin B12 is a very large and charged vitamin that is ingested orally
it is absorbed bound to intrinsic factor because in this complex it is fat soluble
this intrinsic factor-B12 complex binds to specific sites on the epithelium of the terminal ileum.
it is here that B12 is then absorbed by endocytosis

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66
Q

what are carbohydrates?

A

sugars and starches found in food

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67
Q

what enzyme breaks down starch and glycogen?

A

salivary alpha-amylase

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68
Q

what breaks down maltose? what is it broken into?

A

the enzyme maltase. it breaks down into two glucose molecules

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69
Q

what breaks down sucrose

A

the enzyme sucrase

it breaks down into one glucose and one fructose molecules

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70
Q

what breaks down lactose?

A

the enzyme lactase

it breaks down into one glucose and one galactose molecule

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71
Q

what are the stages of carbohydrate absorption and digestion?

A
  1. digestion begins in the mouth as saliva from serous parotid glands contains alpha amylase which begins breaking down starches
  2. the vast majority of absorption/digestion occurs in the small intestine. pancreatic alpha amylase breaks polysaccharides down into disaccharides
  3. enzymes on the luminal membranes of epithelial cells of the small bowel break disaccharides into monosaccharides
  4. these monosaccharides can then be absorbed into the bloodstream
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72
Q

what are the stages of protein absorption?

A
  1. stomach stage
  2. small intestine stage
    3, final digestion
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73
Q

what happens to proteins in the stomach ?

A

proteins denature in the stomach and become polypeptides

the optimum pH for this to occur is 1.6-3.2

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74
Q

what happens to proteins in the small intestine?

A

polypeptides are further fragmented by pancreatic enzymes

endopeptidases such as trypsin, chymotrypsin, elastase and carboxypeptidase are all found here

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75
Q

what happens to proteins during final digestion?

A

polypeptides are broken into amino acids by exopeptidases
there are:
- amino peptidases found on the luminal membrane of epithelial cells
- intracellular peptidases then break fragments into single amino acids
the single amino acids an then be absorbed into the blood stream

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76
Q

what is chyme mostly made of?

A

water

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77
Q

how much fluid passes through the GI tract daily?

A

roughly 9 litres

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78
Q

where does 80% of water absorption occur?

A

in the small intestine

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79
Q

what absorbs most water?

A

the jejunum

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80
Q

how much of total fluid is reabsorbed?

A

98%

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81
Q

how much fluid is lost per day in stools?

A

roughly 200ml

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82
Q

how is sodium absorbed?

A

by active transport
it is co-transported with glucose and amino acids
water then follows sodium!

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83
Q

why is sodium an important ion?

A

it helps maintain the fluid balance, is needed for muscle contractions and helps with nerve signalling

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84
Q

how is potassium absorbed?

A

by passive diffusion

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85
Q

what can cause a loos of potassium ions?

A

diarrhoea

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86
Q

why is potassium an important ion?

A

it keeps blood pressure levels stable, regulates heart contracts and helps with muscle functions

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87
Q

how is chloride absorbed?

A

by active transport - it is exchanged for bicarbonate

this makes the intestinal contents more alkaline!

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88
Q

why is chloride an important ion?

A

it helps maintain fluid balance, helps maintain proper blood pH and is needed to make stomach acid

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89
Q

at what stage of development does the liver begin forming?

A

at week 3

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90
Q

what is the liver a derivative of?

A

the foregut

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91
Q

what do hepatocytes arise from?

A

the endoderm

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92
Q

at what stage does the liver start producing bile?

A

roughly at week 12

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93
Q

what do mesenchymal tissue and Kuppfer cells arise from?

A

the mesoderm

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94
Q

what important role does the liver play in the foetus?

A

it plays an important role in foetal haematopoiesisi

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95
Q

what is the arterial blood supply to the liver?

A

it comes from the hepatic artery proper and the hepatic portal vein

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96
Q

how much blood is supplied by the hepatic artery proper?

A

roughly 25%

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97
Q

how much blood is supplied by the hepatic portal vein?

A

roughly 75%

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98
Q

what is the venous drainage of the liver?

A

via the hepatic veins which then drain into the inferior vena cava

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99
Q

what does the hepatic artery proper carry?

A

oxygen rich blood

100
Q

what does the hepatic portal vein carry?

A

nutrient rich blood

101
Q

what is the functional unit of the liver and what does it contain?

A

the lobule is the functional unit of the liver. it is hexagonal in shape and has a central vein with the portal triad branches forming at each corned

102
Q

what does hepatic sinusoid contain?

A

hepatic sinusoid is a form of fenestrated epithelium that contains oxygen rich blood from the hepatic artery proper and nutrient rich blood from the hepatic portal vein

103
Q

what separates sinusoids from hepatocytes?

A

the space of Disse

104
Q

what key substances are commonly stored in the liver?

A

iron - stored as ferritin
copper
glycogen
vitamins (A,D,E,K + B12)

105
Q

how is iron transported?

A

in the plasma, bound to transferrin

106
Q

how is copper transported?

A

in the plasma, bound to ceruloplasmin

107
Q

what is the function of copper?

A

it helps to form erythrocytes and aids in iron absorption

108
Q

what are the three types of protein produced in the liver?

A

plasma proteins
clotting proteins
complement proteins

109
Q

what are some examples of plasma proteins?

A
  • albumin
  • fibrinogen
  • globulin
110
Q

what are some clotting proteins?

A 
clotting factors (except 3,4+8)
- vitamin K dependent ones! (2,7,9,10)
111
Q

what is albumin and what are its functions?

A

albumin is the most common plasma protein
it is involved in maintaining osmotic pressure
it binds to and transports large hydrophobic molecules

112
Q

what molecules does albumin transport?

A 
fatty acids
calcium
bilirubin
hormones
drugs
heavy metals
some steroid hormones
plasma tryptophan
113
Q

what are xenobiotics?

A

foreign chemicals that are not normally found or produced in the body and cannot be used to produce energy

114
Q

what is the aim of liver detoxification?

A

to transform a substance to be less toxic/more water soluble so it can be excreted

115
Q

what is the purpose fo a phase 1 liver detoxification reaction?

A

to transform a substance from one type to another using oxidation/hydrolysis reactions
often enzyme cytochrome p450 used

116
Q

what happens during phase 2 reactions of liver detoxification?

A
  • glucorinidation (addition of glucuronic acid)
  • conjugation (addition of a chemical group to a substance)
  • excretion - often in bile/urine

example: lipophilic molecule becomes hydrophilic

117
Q

what is the purpose of the glucose-alanine cycle?

A

to move proteins from muscle to the liver when glycogen is low

118
Q

what can be used to measure liver health?

A

alanine aminotransferase (ALT)

119
Q

what happens during the glucose alanine cycle?

A
  • excess alanine is transferred to the liver and converted to pyruvate (by transamination)
  • pyruvate can be used to produce glucose in gluconeogenesis (provides carbon)
  • glucose enters the blood and is then used by muscles (glycolysis)
  • this also removes excess ammonia
120
Q

how is excess ammonia removed in glucose-alanine cycle?

A
  • glutamate becomes ammonium by oxidative deamination
  • this then dissociates to ammonia
  • the ammonia is then converted to urea via the urea cycle
121
Q

what is the function of the urea cycle?

A

to dispose of excess nitrogen

- to remove excess ammonia (to make urea less toxic)

122
Q

what does arginine + arginase form?

A

urea and ornithine

123
Q

what does ornithine + ammonia + carbon dioxide form?

A

citrulline

124
Q

what does citrulline + ammonia form?

A

arginine

125
Q

what are the stages of the urea cycle?

A

arginine –> orthinine (urea made)
orthinine + CO2 + ammonia –> citrulline
citrulline + ammonia –> arginine

126
Q

why is it important to excrete ammonia?

A

it is neurotoxic, it can cross the blood brain barrier and cause damage
without the urea cycle, it would require a lot of water to excrete which would lead to dehydration

127
Q

what are micelles?

A

molecule produced by combination of lipids and bile salts

128
Q

how are free triglycerides formed?

A

by the reaction of lipids with pancreatic lipase

129
Q

how are lipids metabolised?

A
  1. fatty acids and monogylcerides are emulsified by bile salts to form micelles
  2. fatty acids enter the epithelial cells and link to form triglycerides
  3. triglycerides combine with proteins inside the Golgi body to form chylomicrons
  4. chylomicrons enter the lacteal and are transported away from the intestine
  5. from lacteal they enter the blood stream
  6. they are transported to the liver and are stored as very low density lipoproteins
  7. VLDL are used to transport lipids from the liver to the adipose tissue
130
Q

what are low density lipoproteins?

A

lipoproteins formed in plasma that enable cholesterol delivery to all cells in the body

131
Q

what are high density lipoproteins?

A

lipoproteins formed in the liver that remove excess cholesterol from blood + tissues via excretion in bile

132
Q

what are very low density lipoproteins?

A

lipoproteins synthesised in hepatocytes

they deliver triglycerides from the liver to adipocytes

133
Q

what is the purpose of fatty acid beta-oxidation?

A

it is the catabolism of fatty acids to produce energy

134
Q

where does fatty acid beta-oxidation occur?

A

in the mitochondria of hepatocytes

135
Q

what does the fatty acid beta-oxidation cycle lead to?

A

the production of CO2 and also ATP via the Krebs cycle

136
Q

where is bile produced?

A

in the liver, by hepatocyes

137
Q

what journey does bile go on to enter the duodenum?

A
  1. bile is produced by hepatocytes in the liver
  2. bile flows into the left and right hepatic ducts
  3. the left and right hepatic ducts join to form the common hepatic duct
  4. the common hepatic duct goes on to form the cystic duct
  5. bile can now flow in/out of the gallbladder
  6. the cystic duct then becomes the common bile duct
  7. the common bile duct and pancreatic duct join to form the hepatopancreatic ampulla of Vater
  8. bile then empties into the 2nd part of the duodenum (by the Sphincter of Oddi), at the major duodenal papilla
138
Q

what happens in bile production?

A

bile is produced in the liver and is continuously secreted by hepatocytes
it is released in response to increased fatty acid concentration in the duodenum - this is mediated by CCK

139
Q

what are the function of bile?

A

to emulsify fats and excrete certain drugs and toxins

140
Q

what is bile made of?

A
  • bile salts
  • phospholipids (lecithin)
  • bicarbonate
  • cholesterol
  • bile pigments (bilirubin)
141
Q

what is bilirubin?

A

a pigment found in bile

142
Q

what occurs during bilirubin metabolism?

A
  1. old/damaged red blood cells are ingested by macrophages
  2. the haemoglobin from these cells in broken down into haem + globin
  3. the globin is used to generate new RBC’s in bone marrow
  4. haem breaks down into biliverdin and Fe2+ (this is catalysed by heme oxygenase)
  5. biliverdin is converted to unconjugated bilirubin by biliverdin reductase
  6. unconjugated bilirubin is then transported to the liver by albumin
  7. unconjugated bilirubin is toxic + lipid soluble and so must be metabolised and excreted
  8. glucuronidation occurs by UDPGT to produce conjugated bilirubin
  9. conjugated bilirubin becomes bile which then enters the biliary system
  10. bile travles to the duodenum
  11. bile enters the terminal ileum and becomes urobilinogen
143
Q

what happens to urobiliogen?

A

10% of it is reabsorbed and recycled to bile

90% is oxidised to stercobilin which is then excreted in the faeces

144
Q

what makes urine yellow?

A

the presence of urobilin

145
Q

what makes faeces brown?

A

the presence of stercobilin

146
Q

what does the pancreas originate as embryologically?

A

2 buds:

  • dorsal bud
  • ventral bud
147
Q

what does the dorsal bud of the pancreas make up?

A

the neck, body, tail + part of the head

148
Q

what does the ventral part of the pancreas make up?

A

the uncinate process and part of the head

149
Q

what happens to the dorsal and ventral buds?

A

they undergo clockwise rotation so that the pancreas sits in the ‘C’ shape of the duodenum

150
Q

what are the exocrine and endocrine cells of the pancreas formed from?

A

the endoderm

151
Q

what is the mesenchymal tissue formed from?

A

the mesoderm

152
Q

when does insulin secretion begin?

A

at roughly 20 weeks of gestation

153
Q

what do alpha cells from the islets of Langerhans secrete?

A

glucagon

154
Q

what do beta cells from the islets of Langerhans secrete?

A

insulin

155
Q

what do delta cells from the islets of Langerhans secrete?

A

somatostatin

156
Q

what is the exocrine secretion pathway of the pancreas?

A

acini –> interlobular ducts –> pancreatic ducts –> pancreatic sphincter –> Sphincter of Oddi

157
Q

what lines the ducts found in the pancreas?

A

simple columnar epithelium

158
Q

which cells secrete pepsin?

A

NONE OF THEM!

chief cells secrete the zymogen pepsinogen which is cleaved to pepsin by HCl

159
Q

what is the main enzyme involved in phase 1 detoxification reactions in the liver?

A

cytochrome P450

160
Q

what are the 5 anatomical regions of the stomach?

A
  • cardia
  • fundus
  • body
  • antrum
  • pylorus
161
Q

what are the two sphincters of the stomach?

A

the cardiac and pyloric sphincters

162
Q

what are rugae?

A

muscular ridges of the stomach that enable distension

163
Q

what part of the duodenum has smooth mucosa?

A

the superior part

164
Q

what parts of the duodenum have plicae circularis?

A

the descending, inferior and ascending parts

165
Q

what are the four parts of the large intestine?

A
  1. ascending colon
  2. transverse colon
  3. descending colon
  4. sigmoid colon
166
Q

what is the arterial supply to the ascending colon?

A

the right colic artery from the superior mesenteric artery.

167
Q

what are 5 functions of the liver?

A

production of clotting factors (2,7,9+10)
production of bile
storage of glycogen
detoxification
production of proteins (plasma, clotting, complement)

168
Q

name two metals that the liver stores

A

copper and iron

169
Q

where are red blood cells broken down?

A

in the spleen and in the liver

170
Q

what is unconjugated bilirubin bound to in blood?

A

albumin

171
Q

what is the main exocrine function of the pancreas?

A

the production of digestive enxzymes
this occurs at the acini of the pancreas
the enzymes are then released via the pancreatic duct to the duodenum

172
Q

what are the 4 histological layers of the intestine?

A

mucosa
submucosa
muscularis mucosa
serosa

173
Q

give two histological descriptions of the duodenal epithelium

A

there are Brunner’s glands and few goblet cells

174
Q

what is key to activating zymogens?

A

enterokinase

175
Q

what stimulates the release of digestive enzymes?

A

cholecystokinin (CCK)

176
Q

what inhibits the release of digestive enzymes?

A

somatostatin

177
Q

why does the pancreas secrete bicarbonate ions?

A

to help neutralise chyme in the duodenum

178
Q

what stimulates the release of bicarbonate?

A

its stimulated by secretin release

bicarbonate is secreted into the lumen of the small intestine via the Cl-/HCO3- exchanger

179
Q

how is Cl- recycled back into the lumen after its been used in the Cl-/HCO3- exchanger?

A

by the CFTR channel

this is faulty in cystic fibrosis

180
Q

which of the following statements is false in regards to GI tract embryology?
A. the muscularis layer of the gut wall is formed by the mesoderm
B. endoderm forms the epithelial layer of the gut lining
C. the junction between the foregut and midgut is the proximal 2/3 of the transverse colon
D. the nerves that supplies the same embryological area of the gut as the inferior mesenteric artery has the nerve root T12
E. the structures formed from layers of the ectoderm and endoderm, the buccopharyngeal membrane and cloaca, form structures similar to the mouth and anus, respectively

A

C

181
Q

Where is vitamin E stored?

A

in non-adipose cells such as the liver and plasma cells and in adipose cells

182
Q

where is visceral pain of the hindgut felt?

A

in the suprapubic region

183
Q

where does the rectum start?

A

at the point where the circular muscle and longitudinal muscle coalesce

184
Q

where does the midgut embryologically start?

A

halfway along the duodenum, just distal to the entrance of the bile duct - the 3rd + 4th parts of the duodenum are the midgut

185
Q

where does the embryological midgut end?

A

at the junction of the proximal 2/3 of the transverse colon with the proximal 1/3
- the first 2/3 of the transverse colon are midgut

186
Q

where does the embryological hindgut start?

A

at the last 3rd of the transverse colon

187
Q

where does the embryological hindgut end?

A

at the upper 1/3 of the anal canal

188
Q

where does the embryological foregut start?

A

at the distal aspect of the oesophagus

189
Q

where does the embryological foregut end?

A

halfway along the duodenum - the first + second parts of the duodenum are foregut

190
Q

where do the ducts for the submandibular glands open into the mouth?

A

below the tongue

191
Q

what sympathetically innervates the midgut?

A

the lesser splanchnic nerve

192
Q

what sympathetically innervates the hindgut?

A

the least splanchnic nerve and the lumbar splanchnic nerves

193
Q

what sympathetically innervates the foregut?

A

the greater splanchnic nerve (T5/6-T9)

194
Q

what role does glucose play in erythrocytes?

A

it is used as a direct energy source by RBC’s as they do not have a mitochondria and so can’t make their own ATP

195
Q

what parasympathetically innervates the hindgut?

A

the pelvic splanchnics

196
Q

what parasympathetically innervates the midgut?

A

the vagus nerve

197
Q

what parasympathetically innervates the foregut?

A

the vagus nerve

198
Q

what mediates the cephalic phase of gastric acid secretion?

A

the hypothalamus and medulla (to stomach) via the vagus nerve

199
Q

what is the role of the sympathetic nerves in the colon?

A

they slow down gut action

200
Q

what is the role of the parasympathetic nerve supply to the colon?

A

it stimulates GI motility and certain hormones which make you poo
- mainly arises from vagus nerve

201
Q

what is the role of insulin in the liver?

A

it increases the uptake of glucose

202
Q

what is the rate limiting step of lipogenesis?

A

acetyl-CoA to malonyl-CoA

this is catalysed by Acetyl-CoA carboxylase

203
Q

what is the nerve supply to anterior 2/3 of the tongue?

A

general sensation = mandibular branch of the trigeminal nerve
taste sensation = facial nerve
muscle = hypoglossal nerve

204
Q

what is the most common cause of a peptic ulcer?

A

reduced mucosal defence

205
Q

what is the intrinsic nerve supply to the colon?

A

Meissners and Auerbach’s plexus
act as the bowels pacemakers
complete peristaltic waves
AND increase blood supply + absorption to the colon

206
Q

what is the gastro-colic reflex?

A

the stretching of the stomach and presence of food in the jejunum leads to the mass movement of the colon

207
Q 
what is the first layer of the anterior abdomen, excluding the skin?
A. Scarpa's fascia
B. Camper's fascia
C. external oblique
D. peritoneum
E. transversus abdominus
A

B - camper’s fascia

208
Q

what is the first branch of the abdominal aorta?

A. coeliac trunk
B. superior mesenteric artery
C. renal artery
D. inferior phrenic artery
E. gonadal artery
A

D - inferior phrenic

209
Q

what is the definition of an ulcer?

A

a breach in the mucosal surface

210
Q

what is the arterial supply to the hindgut?

A

inferior mesenteric artery

211
Q

what is the arterial supply to the midgut?

A

superior mesenteric artery

212
Q

what is the arterial supply to the foregut?

A

coeliac trunk

213
Q

what is the anatomy of the colon?

DETAILED

A

ileocaecal valve

  • appendix
  • caecum
  • ascending colon
  • hepatic flexure
  • transverse colon
  • splenic flexure
  • descending colon
  • sigmoid colon
  • rectum
  • anus
214
Q

what is the anatomical surface location of the appendix commonly referred to as?

A. Broca's area
B. Wernicke's area
C. McBurney's point
D. Space of Disse
E. Traube's space
A

C - McBurney’s point

215
Q

what hormone is essential for gylcogenolysis?

A

glucagon

216
Q

visceral pain of the foregut is felt where?

A

in the epigastric region

217
Q 
If:
1 = greater splanchnic nerve
2 = lesser splanchnic nerve
3 = least splanchnic nerve
4 = vagus nerve
5 = hypogastric plexus

which of the following statements is true regarding the innervation of the stomach?

A. the stomach receives input from 2 and 4
B. the stomach receives input from 4 and 5
C. the stomach does not receive input from 1, 4 or 5
D. the stomach receives input from 2 and 4
E. the stomach receives input from 1 and 4

A

E - the stomach receives input from 1 and 4

218
Q

which stomach cell produces the zymogen that helps break down protein in the stomach and what is the name of the zymogen?

A 
cell = chief cell
zymogen = pepsinogen
219
Q

which cells are responsible for triggering the peristaltic contraction of the stomach and where do these contractions begin?

A

interstitial cells of Cajal

the location of the contractions is the gastric body

220
Q

why is the action of pepsin terminated once it enters the duodenum?

A

the high pH of the duodenal lumen causes it to denature

221
Q

what percentage of water is absorbed in the small intestine?

A

80%

222
Q

how frequently does the large intestine contract?

A

every 30 minutes

223
Q

how long does ingested food stay in the large intestine before its excreted?

A

18-24 hours

224
Q

what sphincter can be voluntarily controlled to prevent defecation?

A

the external anal sphincter

225
Q

define and give examples of insensible water loss

A

insensible water loss = water lost through means that cannot easily be measured

examples = faeces, sweat, breathing

226
Q

which artery, sympathetic nerve and parasympathetic nerve supply the midgut

A

artery - superior mesenteric
sympathetic = lesser splanchnic
parasympathetic = vagus

227
Q

name the structures lying on Addison’s plane at the level of L1

A
  • gallbladder
  • pancreas
  • pylorus
  • duodeno-jejunal flexure
228
Q

which embryological structure forms the ligamentum teres?

A

the umbilical vein

229
Q

which cells produce the following hormones:

A. gastrin

B. somatostatin

C. histamine

A

A. G cells

B. D cells

C. ECL cells

230
Q

how many litres of water pass through the GI tract everyday?

A

9

231
Q

why are pancreatic enzymes produced in the form of zymogens?

A

to prevent auto digestion

232
Q

which cells produce bile?

A

hepatocytes

233
Q

in which organ is haemoglobin from red blood cells broken down into haem and globin?

A

the liver

the spleen

234
Q

which enzyme is responsible for converting haem into biliverdin?

A

haemoxygenase

235
Q

what feature of the epithelium of the gallbladder allows it to concentrate bile and what type of epithelium is it?

A 
feature = microvilli
epithelium = columnar
236
Q

what hormone causes the gallbladder to contract and release the bile stored within in and what stimulates this hormone to be secreted?

A 
hormone = cholecystokinin
stimuli = amino acids, acetylcholine
237
Q

when bilirubin enters the terminal ileum it is reduced by bacteria. what is the first (main) molecule it obtains?

A

urobilinogen

238
Q

which molecule, derived from bilirubin, is responsible for the brown colour of faeces?

A

stercobilin

239
Q

what are the functions of saliva?

A
  • it is a lubricant for mastication /swallowing/speech
  • important for oral hygiene
  • involved in maintaining oral pH
  • releases digestive enzymes
  • is an aqueous solvent necessary for taste
240
Q

what is the flow rate of saliva?

A

0.3-7 mL per min

241
Q

what is the daily secretion of saliva?

A

800-1500mL

242
Q

what are the three major pairs of salivary glands?

A

parotid, submandibular and sublingual

243
Q

what salivary glands are continuously active?

A

the submandibular, sublingual and minor glands are always active

244
Q

when does the parotid gland become the main source of saliva?

A

when it is stimulated

245
Q

what activates the salivary glands?

A

they are activated by the thought or smell of food

PHASE 1 OWN STUFF (7 decks)

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