The digestive system Flashcards

1
Q

the digestive system is a tube called what?

A

the gastrointestinal tract (GI tract)

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2
Q

Where does the GI tract run from and to where?

A

runs from the mouth to the anus with everything in between

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3
Q

whats helps to aid digestion in the GI tract?

A

enzymes

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4
Q

A food and enzyme mixture is called what?

A

chyme

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5
Q

digested food is absorbed across what?

A

the intestinal epithelium

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6
Q

roughly how long is the GI tract?

A

8m long

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7
Q

What 3 structures are found in the small intestine?

A
  1. duodenum
  2. Jejunum
  3. Ileum
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8
Q

What structures are included in the large intestine?

A
  1. caecum
  2. ascending colon
  3. transverse colon
  4. descending colon
  5. sigmoid colon
  6. rectum
  7. anus
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9
Q

What are the functions of the Oral cavity and oesophagus?

A
  • digestion of carbohydrates
  • NO absorption
  • chewing and swallowing
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10
Q

What are the functions of the stomach?

A
  • digestion of proteins and fats
  • absoption of lipid soluble substances
  • peristaltic mixing and propulsion
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11
Q

what are the functions of the small intestine?

A
  • digestion of polypeptides, carbohydrates, fats and nucleic acids
  • wide range of absoption
  • mixing and propulsion
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12
Q

What are the functions of the large intestine?

A
  • no digestion
  • absorption of ions, mineral, vitamins and water
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13
Q

Label the GI tract

A
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14
Q

What do sphincters guard and control?

A

They guard different sections

they control movement through the digestive tract

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15
Q

Label the sphincters

A
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16
Q

Label the stomach

A
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17
Q

What are the 3 main areas of the stomach?

A
  • fundus
  • body
  • antrum
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18
Q

What does the folded area in the stomach help to increase?

A

the surface area which allows food to be moved around

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19
Q

What do stomach acid aid?

A

digestion

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20
Q

What does the stomach also produce and what does this provide?

A

the stomach also produces mucus which coats the inside lining of the stomach and provides protection

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21
Q

Label the small intestine

A
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22
Q

How many layers does the lining of the small intestine have?

A

4 layers

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23
Q

The small intestine has 2 layers of muscle, what does this allow?

A

allows contraction of the muscle which shortens and lengthen it, also contracts the diameter. This helps with digestion and propulsion

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24
Q

What are the 4 layers of the GI tract and the role/ importance/function of each layer?

A

Outside

1. Mucosa

includes transporting epithelial cells, connective tissue and nerve fibres and blood vessels

Lamina propria within this layer just under the epithelium

2. Submucosa

contains the submucosal plexus

3. Smooth muscle

important for lumen contraction, myenteric plexus

4. Serosa

outer layer

Inside

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25
Q

Label what region of the GI tract this electromicrograph was taken

A
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26
Q

why has the duodenum got such large micro villi?

A

a large surface area is needed

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27
Q

Label this sectional view of the stomach?

A
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28
Q

Label this sectional view of the small intestine?

A
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29
Q

Name the accessory organs of the digestive system? what do these organs provide?

A

The accessory organs

  • salivary glands
  • pancreas
  • liver and gall bladder

The provide secretions to enable digestive function

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30
Q

Label the salivary glands?

A
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31
Q

do the salivary glands secrete the same or different enzymes?

A

different enzymes

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32
Q

Label the pancreas

A
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33
Q

What does the bile duct in the pacreas lead to?

A

The liver

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34
Q

What is meant by the endocrine functions of the pancreas?

A

The release of hormones directly into the blood

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35
Q

What do Duct cells run along the edge of?

What do they secrete?

A

Duct cells run along the edge of the limen of pancreatic duct which secrete sodium bicarbonate that enters the digestive tract

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36
Q

what does sodium bicarbonate help to do?

A

neutrsalise acids

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37
Q

Label this cross-sectional area of the pancreas?

A
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38
Q

Label the liver

A
39
Q

What structures make up the triad in the liver?

A

Vein, artery and bile duct

40
Q

What does the Hepatic artery bring to the liver?

A

oxygenated blood from the tissues

41
Q

What does the Hepatic portal vein do?

What’s brought in the blood?

A

carries blood from the GI tract.

Brings nutrients with it and Haemoglobin from spleen which is secreted from liver as bile

42
Q

What does the common bile duct do?

A

carries bile from the gall bladder to the intestine

43
Q

What does the gall bladder do?

A

stores and concentrates bile

44
Q

What are hepatocytes arranged in?

A

lobules around a central vein

45
Q

When hepatocytes produce bile, what must it flow through to get to the bile duct?

A

the bile canaliculi

46
Q

what is water and bicarbonate added by?

A

duct epithelial cells

47
Q

Label this cross-sectional area of the liver

A
48
Q

What does the microbiome a host to?

What is its role?

A

The microbiome is a host to thousands of bacteria

  • They produce vitamins
  • They break down out food
  • They teach our immune system how to recognise pathogens
  • produce helpful anti-inflammatory compounds that fight off other dieases-causing microbes
49
Q

When there is movement in the digestive system, what is moved along and what does this help to do?

A

chyme is moved along and this helps to mix food as its exposed to digestive enzymes

50
Q

What is smooth muscle controlled by?

A

the nervous system and paracrine signals

51
Q

What type of muscle is the GI tract mainly made up of?

A

smooth muscle

52
Q

What do muscle cells have and what does this allow?

A

muscle cells have gap junctions, this makes contracting segments

53
Q

What are the two types of contraction?

A

phasic contractions

and

tonic contractions

54
Q

What are phasic contractions?

A
  • interstitial cells of cajal general slow wave potentials
  • produced cyclic relaxation e.g. sphincters
55
Q

What are tonic contractions?

A
  • long term contractions e.g. sphincters
56
Q

Whats peristalsis?

A

the involunary constriction and relaxation of the muscle of the intestine of another channel, creating wave like movements that push the contents of the canal forwards

57
Q

What are the two types of movement (motility) that occurs in the stomach?

A

peristalsis and segmentation (mixing)

58
Q

the enteric NS helps with the control of the digestive system, what are the two sections that do this and what do they control?

A

Submucosal plexus

contains sensory neurone that recieve signals from the lumen and control secretion

Myenteric plexus

Controls motility

59
Q

Where do short relfexes originate and what are they integrated without?

A

they originate in the ENA and integrate without the CNS

60
Q

What do long refelxes inegrate into?

A

the CNS

61
Q

what is a cephalic reflex?

A

long refelxes that originate in the CNS

62
Q

What does the ENA respond to?

A

higher centre inputs (long reflexes)

63
Q

Whats a healthy status of the brain gut axis?

A
  • normal behaviour, cognition, emotion and nociception
  • healthy levels of inflammatory cells and/or mediators
  • normal gut microbia
64
Q

whats the stress/disease data of the brain gut axis?

A
  • alteration in behaviour, cognition, emotion and nocicption
  • altered levels of inflammatory cells and/or mediations
  • intestinal dysbiosis
65
Q

Where are secretions from the digestive system released?

A
  • into the blood
  • into the lumen
  • into neighbouring cells (paracrine)
66
Q

whats meant by secretion?

A

movement of materials from cells into lumen or ECF

67
Q

Whats meant by digestion?

A

chemical and mechanical breakdown of food inot absorbable units

68
Q

whats meant by absorption?

A

movement of materual from GI lumen to ECF

69
Q

whats meant by motility?

A

movement of material from GI tract as a result of muscle contraction

70
Q

Name a GI hormone in the stomach

  • the stimulus for release
  • primary target(s)
  • primary effect(s)
A

Gastrin (secreted from G cells)

Stimulus for release: peptides and amino acids; neutral reflexes

primary target(s): ECL cells and parietal cells

Primary Effect(s): stimulates gastric acid secretion and mucosal growth

71
Q

Name 5 GI hormones in the intestine?

A
  1. cholecystokinin (CCK)
  2. secretin
  3. Motilin
  4. Gastric inhibitory peptide (GIP)
  5. Glucagon- Like peptide-1 (GLP-1)
72
Q

For the GI hormone Cholecystokinin (CCK) tell me the following:

  • stimulus for release
  • primary target(s)
  • primary effect(s)
A

stimulus for release: fatty acids and some amino acids

Primaty target(s): gallbladder, pancreas, stomach

Primary effect(s): stimulates gallbladder contraction and pancreatic enzyme secretion, inhibits gastric emptying and acid secretion

73
Q

for the GI hormone secretin tell me the following

  • stimulus for release
  • primary target(s)
  • primary effect(s)
A

stimulus for release: acid in the small intestine

primary target(s): pancreas and stomach

primary effect(s): stimulates HCO3- secretion, inhibits gastric emptying and acid secretion

74
Q

For the GI hormone Motilin, tell me the following

  • stimulus for release
  • primary target(s)
  • primary effect(s)
A

stimulus for release: fasting: periodic relase every 1.5-2 hours

primary target(s): gastric and intestinal smooth muscle

primary effect(s): stimulates migrating motor complex

75
Q

For the GI hormone gastric inhibitory peptide (GIP), tell me the following

  • stimulus for release
  • primary target(s)
  • primary effect(s)
A

stimulus for release: glucose, fatty acids and amino acids in small intestine

primary target(s): beta cells of pancreas

primary effect(s): stimulates insulin release (feedforward mechanism), inhbiits gastric emptying and acid secretion

76
Q

For the GI hormone Glucagon-1 like peptide-1 (GLP-1), tell me the following

  • stimulus for release
  • primary target(s)
  • primary effect(s)
A

stimulus for release: mixed meal that includes carbohydrates or fats in the lumen

primary target(s): endocrine and pancreas

primary effects: stimulates insulin rleease, inhibits glucagon release and gastric function

77
Q

Name some salivary glands and what they secrete?

A
  • serous glands contain serous acini which is a group of cells that secrete amylase and lipase
  • mucous acini contain mucous cells which secrete mucous
  • *duct cells** secrete water and hydrogen carbonate ions
78
Q

What does salivary gland secretion respond to?

A
  • parasympathetic inputs
  • taste, smell, touch
  • protective reflexes from stomach and intestine (dilution)
  • learned (conidtioned) reflexes
79
Q

Name the secretory cells of the gastric mucosa?

A
  1. mucous surface cell
  2. mucous neck cell
  3. parietal cells
  4. enterochromaffin- like cells
  5. chief cells
  6. D cells
  7. G cells
80
Q

what is secreted from the mucous surface cell?

The function of secretion and the stimulus for release?

A

substance secreted: mucus

function of secretion: physical barrier between lumen and epithelium

stimulus for release: tonic secretion; irritation of mucosa

81
Q

what is secreted from the mucous neck cell?

The function of secretion and the stimulus for release?

A

substance secreted: bicarbonate

function of secretion: buffers gastric acid to prevent damage to epithelium

stimulus for release: secreted with mucous

82
Q

what is secreted from the parietal cells?

The function of secretion and the stimulus for release?

A

substance secreted: gastric acid (HCl) and intrinsic factor

fucntion of secretion: activates pepsin; kills bacteria and complexes with vitamin B12 to permit absorption

stimulus for release: acetylcholine, gastrin, histamine

83
Q

what is secreted from the enterochromaffin-like cells?

The function of secretion and the stimulus for release?

A

substance secreted: histamine

function of secretion: stimulates gastric acid secretion

stimulus for release: ACh, gastrin

84
Q

what is secreted from the chief cells?

The function of secretion and the stimulus for release?

A

substance secreted: pepsin(ogen) and gastric lipase

function of secretion: digests proteins and digests fats

stimulus for release: ACh, acid secretion

85
Q

what is secreted from the D cells?

The function of secretion and the stimulus for release?

A

substance secreted: somatostatin

function of secretion: inhibits gastric acid secretion

stimulus for release: acid in the stomach

86
Q

what is secreted from the G cells?

The function of secretion and the stimulus for release?

A

substance secreted: gastrin

function of secretion: stimulates gastric acid secretion

stimulus for release: ACh, peptides and amino acids

87
Q

Label the cells of the gastric mucosa…

A
88
Q

Label the mucous-bicarbonate barrier…

A
89
Q

How are the processes in the GI tract controlled?

A
  • long and short reflexes
  • food or cephalic reflexes to start cascade
  • caphalic reflex can directly stimulate ECL cells and parietal cells
  • acid acts on pepsinogen to form pepsin
  • no negative feedback
90
Q

Tell me the steps to pancreatic secretion of enzymes…

A
91
Q

Tell me the steps to pancreatic secretion of bicarbonate…

A
92
Q

What cell produces bile?

A

hepatocytes

93
Q

Name 2 examples of bile salts

A

cholesterol and bilibrium

94
Q

What two GI hormones help to control pancreatic and liver secretions and where are they secreted from?

A

CCK and Secretin in the intestine