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[Y1] Anatomy and Physiology > The gastrointestinal tract > Flashcards

The gastrointestinal tract Flashcards

1
Q

a balanced diet it made up of what 6 major components?

A
  • carbohydrate
  • fats
  • proteins
  • vitamins
  • minerals
  • water
  • dietary fibre
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2
Q

define digestion

A

hydrolyses complex macromolecules into simpler forms

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3
Q

what is food energy measured in?

A

calories
(1kcal = energy to heat 1g water by 1oC)

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4
Q

how do you calculate BMI?

A

BMI = weight(kg) / height(m)^2

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5
Q

how much water should you drink per day in a climate like the UK?

A

1.2L

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6
Q

what are the 5 major digestion processes?

A
  • ingestion
  • propulsion
  • mechanical and chemical digestion
  • absorbtion
  • defecation
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7
Q

give 2 examples of mechanical digestion

A
  • chewing
  • churning segmentation
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8
Q

what is used to chemically digest foods?

A

enzymes

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9
Q

what are the 4 layers of the tissue from the stomach to the anal canal?

A
  • serosa (adventita)
  • muscularis externa (circular and longitudinal smooth muscle)
  • submucosa
  • mucosa
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10
Q

what are the 4 functions of the mucosa membrane?

A
  • Protect gut from abrasions
  • Secretes substances into gut
  • Enteroendocrine cells release hormones into lamina propria and capillaries
  • Absorbs material into capillaries or thin lymph vessel-lacteals
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11
Q

what type of tissue is the mucosa membrane?

A

layer of epithelial cells

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12
Q

what type of tissue is the lamina propria made up of?

A

connective tissue

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13
Q

what are the 3 layers of the mucosa?

A
  • the mucosa membrane
  • lamina propria
  • muscularis mucosa
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14
Q

what 3 things does the lamina propria contain?

A
  • blood vessels
  • lymph vessels
  • lymphoid follicles
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15
Q

what is the function of the muscularis mucosa?

A

controls folding of the mucosa

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16
Q

what is the smooth muscle arrangement of the muscularis externa?

A
  • outer layer runs longitudinally
  • inner layer have a circular arrangement
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17
Q

what is the role of the muscularis externa?

A

produce waves of contraction (peristalsis or segmentation)

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18
Q

what tissue is the serosa made up of? what is its function?

A

Loose connective tissue and membrane that protects the gastrointestinal tract when it moves

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19
Q

what are the function of the mouth in digestion?

A
  • reduce the size of food
  • prepare food for swallowing
  • starting point for chemical breakdown of carbohydrates
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20
Q

state the anatomy of the tongue

A
  • Formed from skeletal muscle and occupies the floor of the mouth
  • Upper surface is covered by keratinised stratified squamous epithelium
  • Underside is covered with a non-keratinised mucous membrane
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21
Q

how much saliva does an adult produce per day?

A

1.5L per day

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22
Q

what is the pH of the saliva?

A

~pH 7

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23
Q

what percentage of the saliva is water?

A

97%

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24
Q

what are the 4 main functions of the saliva?

A
  • protection (e.g. temperature, neutralises acids)
  • taste
  • lubrication (mucus coats food: less abrasive, easier to swallow)
  • digestion (saliva contains amylase)
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25
Q

what is the lining of the oesophagus?

A

stratified squarmous epithelium

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26
Q

what is the function of the oesophagus?

A

conveys bolus to the stomach

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27
Q

what are peristaltic contractions?

A

Propulsion of food along the tract and consist of successive waves of contraction and relaxation

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28
Q

what does the stomach secrete? why?

A
  • enzymes and other molecules (for digestion)
  • intrinsic factor (needed to absorb vitamin B12)
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29
Q

what is the capacity of a full stomach?

A

4L

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30
Q

what is the capacity of a contracted stomach?

A

50 ml

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31
Q

what leads to the small volume when the stomach is contracted?

A

due to inner surface folding called rugae

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32
Q

what are the 4 parts to the stomach?

A

fundus, cardia, body and pyloric region

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33
Q

what is the function of the pyloric region?

A

responsible for churning and emptying food. Strong contractions needed - thick muscle layers

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34
Q

what is the stomach acid secreted by?

A

parietal cells (oxyntic cells), predominantly in the fundus and body

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35
Q

what are the 4 functions of stomach acid?

A
  • Breakdown of connective tissue and muscle fibres of ingested meat
  • Activate pepsinogens
  • Optimal conditions for the activity of pepsiin
  • Defence mechanism - killing microorganisms that may cause infection
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36
Q

what are the pepsinogen secretions produced by?

A

chief cells

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37
Q

what is the optimal pH for pepsinogen secretions?

A

pH 3

38
Q

what is peptin?

A
  • a protease
  • breaks protein into peptide fragments
39
Q

what are the 2 layers of mucus in the stomach?

A
  • outer thick layer
  • inner watery layer
40
Q

what are the 3 functions of vitamin B12?

A

maintenance of the CNS, metabolism and maturation of RBC

41
Q

what are the 3 symptoms of vitamin B12 deficiency?

A
  • fatigue
  • high heart rate
  • shortness of breath
42
Q

what is the proper name for vitamin B12 deficiency?

A

pernicious anaemia

43
Q

what part of the gastrointestinal tract has the greatest digestion and absorption?

A

the small intestine

44
Q

what is the length of the small intestine in adult females and males?

A

Male: 6.9m
Female: 7.1m

45
Q

what are the 3 regions of the small intestine?

A
  • duodenum
  • jejunum
  • ileum
46
Q

state 2 things about the duodenum

A
  • attached to stomach
  • about 0.27m long
47
Q

state 2 things about the jejunum

A
  • between duodenum and ileum
  • about 2.5m long
48
Q

state 2 things about the ileum

A
  • Terminal part of small intestine
  • About 3.6m long
49
Q

what is the maximum diameter of the small intestines?

A

4cm

50
Q

what is the function of segmentation?

A
  • Slow contractions of the circular muscle layer, occlude the lumen and drive contents forward and backwards (1-4cm of intestine at a time)
  • Mix and chyme with digestive enzymes
  • Ensures all absorbable molecules are removed from the lumen
51
Q

what is the function of peristalsis?

A
  • Rhythmic propulsive movements to move chyme along small intestines
  • Mix chyme with digestive enzymes
52
Q

what 3 modifications in the small intestines increase the surface area?

A
  • Permanent folds called plicae circulares
  • Entire surface of the small intestine is covered by finger like projections of mucosa called villi
  • Epithelial surface is columnar and its luminal surface has microvilli (brush border)
53
Q

why is it important the the small intestines has a large surface area?

A

to increase absorption

54
Q

what are the 3 secretions from the small intestines?

A
  • mucus
  • water
  • bicarbonate
55
Q

what is the function of the mucus?

A

protect mucsa fromactions of acids and protease

56
Q

what is the function of water in the small intestine?

A
  • makes the mucus runny (for movement)
  • functional environment for enzymes
57
Q

what produces the bicarbonate in the small intestines?

A

Brunner’s gland

58
Q

what is the function of bicarbonate in the small intestine?

A

protection from acidic chyme, alkaline conditions for enzymes

59
Q

what is the function of the pancreas as an endocrine gland?

A

secreting insulin and glucagon into the bloodstream

60
Q

what is the function of the pancreas in digestion?

A
  • Accessory digestive (exocrine) organ-secreting enzyme-rich fluid into the duodenum
  • Rich in bicarbonate - neutralises acidic gastric contents that enter small intestine
  • Complete digestion of ingested carbohydrate, protein and fat
61
Q

what is the function of the acinar cells?

A
  • Production and export of large quantities of protein
  • Contain secretory granules at the apical pole - mixture of zymogens and enzymes required for digestion
  • Also secrete isotonic, plasma-like fluid (rich in chlorides)
62
Q

what is the function of duct cells?

A
  • The epithelial cells are involved in the secretion of bicarbonate rich serous fluid
63
Q

how much fluid is secreted from the pancreas each day?

A

1500ml

64
Q

what is the approximate pH of pancreatic juices? why?

A

pH 8 (rich in bicarbonate)

65
Q

what are the 2 largest organs after the skin?

A

liver and brain

66
Q

what is the average weight of the liver?

A

1.3 kg

67
Q

what is the only human organ that is capable of natural regeneration?

A

liver

68
Q

what ar 3 key functions of the liver?

A
  • Important filtering mechanism for the circulation by removing foreign particulate
  • Synthesis and secretion of bile
  • Detoxification
69
Q

what is the function of the gallbladder?

A

Storage of bile that is not required immediately for digestion

70
Q

what are the 2 functions of bile?

A
  • Elimination of waste products from body – bilirubin and cholesterol
  • Promotion of digestion and absorption of lipids in the intestine
71
Q

what are the 3 steps to bile production?

A
  1. Hepatocytes secrete bile into the bile caniliculi
  2. Ductal epithelial cells modify primary secretion by secreting a watery, bicarbonate-rich fluid
    3.Between meals, half of hepatic bile is diverted to the gallbladder – concentrated and stored.
72
Q

what are composition of bile acids (g/L) in both hepatic and gallbladder bile?

A

hepatic bile: 3-45
gallbladder bile: 32

73
Q

what are composition of bilirubin (g/L) in both hepatic and gallbladder bile?

A

hepatic bile: 1-2
gallbladder bile: 3

74
Q

what are composition of cholesterol (g/L) in both hepatic and gallbladder bile?

A

hepatic bile: 1-3.2
gallbladder bile: 6.3

75
Q

what links the liver and cholesterol?

A

the liver is primerily responsible for the synthesis and excretion of cholesterol

76
Q

what percentage of bile salts are reabsorbed into the small intestines?

A

95%

77
Q

why do people get gallstones?

A

Any excess cholesterol that cannot be dispersed into micelles will form crystals in the bile

78
Q

when is bilirubin formed?

A

when old RBCs are broken down in the spleen

79
Q

what causes jaundice?

A

high concentration of bilirubin in the blood (about 34µmol/L)

80
Q

what are the 5 causes of jaundice?

A
  • Excessive destruction of RBCs – hemolytic jaundice
  • Impaired uptake of bilirubin by hepatocytes - hepatic jaundice
  • Decreased conjugation of bilirubin – hepatic jaundice
  • Obstruction of bile flow – obstructive jaundice
  • Liver damage
81
Q

what is amino acid catabolism?

A

The breakdown of amino acids occur by transamination and deamination. The by-product of this reaction (NH4+) will be detoxified in a series of reaction known as the urea cycle

82
Q

why do we need the orithine cycle? what is it?

A
  • ammonia is very toxic to the body
  • Ammonia released during deamination is rapidly removed by the liver and converted to urea
83
Q

what test can indicate liver injury?

A

Elevated serum enzyme test results

84
Q

what is protein broken down by?

A

gastric and pancreatic protease enzymes

85
Q

where are most amino acids absorbed?

A

in the first part of the intestine (duodenum)

86
Q

what is lipid hydrolysis carried out by?

A

lipases

87
Q

where does the digestion of lipids take place?

A

Some digestion occurs in the mouth and stomach but most takes place in the small intestine

88
Q

what are 4 functions of the large intestines?

A
  • remove water and salts
  • storing and concentration of faecal matter
  • discharge of faecal matter
  • bacteria produce vitamin K
89
Q

what are the 5 regions of th large intestines?

A
  • caecum
  • appendix
  • colon (ascending, transverse, descending, sigmoid)
  • rectum
  • anal canal
90
Q
A

[Y1] Anatomy and Physiology (23 decks)

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