Digestive System Flashcards

1
Q

What is physical digestion?

A

Using teeth and muscle action to break down food into smaller pieces to increase its surface area for absorption

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2
Q

What is chemical digestion?

A

Breaking down large, insoluble molecules into smaller, soluble molecules using hydrolysis by enzymes

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3
Q

What are the 2 main functions of the digestive system?

A
  1. To break down food into nutrients needed for metabolic processes
  2. Remove waste products
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4
Q

What are the 5 main constituents/ nutrients of food?

A
  1. Carbohydrates
  2. Protein
  3. Fats
  4. Vitamins and Minerals
  5. Dairy
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5
Q

What are the 2 parts of the digestive system?

A
  1. Alimentary Canal (GI Tract)

2. Accessory Organs

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6
Q

What are the 6 parts of the alimentary canal?

A
  1. Mouth
  2. Pharynx
  3. Oesophagus
  4. Stomach
  5. Small Intestine
  6. Large Intestine
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7
Q

What are the 5 accessory organs?

A
  1. Teeth
  2. Salivary Glands
  3. Pancreas
  4. Liver
  5. Gall Bladder
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8
Q

What is another name for the mouth and what is it lined with?

A

Oral cavity, lined with a mucous membrane

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9
Q

What forms the lateral walls of the oral cavity?

A

Cheeks

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10
Q

What forms the anterior and posterior roof of the oral cavity?

A
Anterior = hard palate
Posterior = soft palate
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11
Q

What is the uvula?

A

A fleshy finger-like projection of the soft palate which extends downwards

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12
Q

What is the vestibule?

A

The space between the lips and cheeks externally and the teeth and gums internally

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13
Q

Describe the tongue

A

Muscular and has several bony attachments such as the hyoid bone and styloid processes of the skull

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14
Q

What is the lingual frenulum?

A

A fold of mucous membrane which secures the tongue to the floor of the mouth

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15
Q

What is the name of the situation in which the lingual frenulum is very short?

A

Tongue-tie

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16
Q

What are the 3 types of salivary gland?

A
  1. Parotid gland
  2. Sublingual gland
  3. Submandibular gland
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17
Q

What are tonsils?

A

Collections of lymphatic tissue located at the posterior end of the oral cavity

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18
Q

What are the 4 main types of tonsils?

A
  1. Palatine
  2. Pharyngeal
  3. Lingual
  4. Tubal
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19
Q

What is tonsillitis?

A

An illness in which the pharyngeal tonsil becomes inflamed and swollen and obstructs the nasopharynx, forcing the person to breathe through their mouth and making swallowing difficult and painful

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20
Q

What are the 3 sections of the pharynx?

A
  1. Nasopharynx
  2. Oropharynx
  3. Laryngopharynx (continuous with the oesophagus)
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21
Q

Where is the oesophagus located?

A

Runs from the mouth to the stomach passing through the diaphragm

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22
Q

What are the 4 layers of the oesophagus wall?

A
  1. Mucosa (inner)
  2. Submucosa
  3. Muscularis Externa
  4. Serosa (outer)
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23
Q

What are the 2 nerve plexuses in the alimentary canal and what is their function?

A
  1. Submucosal nerve plexus
  2. Myenteric nerve plexus
    To regulate mobility and secretory activity
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24
Q

Where is the stomach located?

A

On the left side of the abdominal cavity, hidden mostly by the liver and diaphragm

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25
Q

What is the small intestine and where is it located?

A
  • The major digestive organ
  • Muscular tube extending from the pyloric sphincter to the large intestine
  • The longest section of the alimentary tube
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26
Q

What is the average length of the small intestine?

A

2.5 - 7m

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27
Q

What are the 3 subdivisions of the small intestine and what percentage do they account for?

A
  1. Duodenum (5%)
  2. Jejunum (<40%)
  3. Ileum (<60%)
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28
Q

What is significant about the walls of the small intestine?

A

They have microvilli in the absorptive cells that increase surface area and the plasma membrane bears enzymes that complete the digestion of proteins and carbohydrates

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29
Q

What 3 accessory organs are associated with the small intestine?

A
  1. Pancreas
  2. Liver
  3. Gall Bladder
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30
Q

What is the pancreas and what is its function?

A
  • A triangular gland that extends across the abdomen to the spleen and duodenum
  • Produces enzymes that break down digestible foods by secreting them into the duodenum
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31
Q

What is the liver and what is its function?

A
  • Largest gland in the body
  • Located under the diaphragm on the right side of the body
  • Has 4 lobes
  • Produces bile, a yellow-to-green watery fluid that leaves the liver via the common hepatic duct
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32
Q

What is the gall bladder and what is its function?

A
  • Thin-walled, green organ

- Stores bile when food digestion is not occurring

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33
Q

What is mastication?

A

Chewing

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34
Q

Outline the 5 steps of ingestion

A
  1. Food is placed in mouth, triggering large amounts of saliva to be produced
  2. Tongue mixes the food and saliva
  3. Mastication occurs, breaking down food into smaller pieces
  4. A bolus is created ready for swallowing
  5. Salivary amylase begins chemical digestion of starch to maltose
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35
Q

What is propulsion and what are the 2 phases?

A
  • Swallowing and peristalsis
  • 1st phase = buccal phase = voluntary
  • 2nd phase = pharyngeal-oesophageal phase = involuntary
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36
Q

What is the name for the process of swallowing?

A

Deglutition

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37
Q

Which parts of the digestive system must work together to achieve Deglutition?

A
  1. Tongue
  2. Soft palate
  3. Pharynx
  4. Oesophagus
38
Q

Describe the process of Deglutition

A
  • The tongue blocks off the mouth and the soft palate closes off the nasal passages
  • The larynx rises and is covered by the epiglottis
  • Food moves into the pharynx and then the oesophagus
39
Q

What is Peristalsis?

A

Wave-like contractions of the muscular wall of the oesophagus to propel food along

40
Q

Describe the process of Peristalsis

A
  • First longitudinal muscles contract and then the circular muscles
  • Food at the distal end of the oesophagus presses against the cardioesophageal sphincter, opening it
41
Q

How long does food take to reach the stomach?

A

3-4 seconds

42
Q

How long does liquid take to reach the stomach?

A

1-2 seconds

43
Q

What liquid is produced in the stomach and what is it’s function?

A
  • Gastric juices, secreted by glands in the stomach lining

- Contain protein-digesting enzymes, mucous and HCl

44
Q

What is unique about the stomach lining?

A

It has a protective mucosal layer to protect the lining and the rest of the gut from HCl

45
Q

What does HCl activate and what does this substance do?

A

Activates pepsinogen to pepsin, a protein-digesting enzyme

46
Q

What do the pancreatic juices contain?

A

Secondary amylase to continue breaking down carbohydrates

47
Q

Why is secondary amylase required?

A

Salivary amylase is denatured by stomach acid

48
Q

Describe the process of digestion in the stomach

A
  • 3 muscle layers compress and pummel the food to break it down to form Chyme
  • Peristalsis moves food through the stomach to the pyloric valve, which only allows liquids and small particles through into the small intestine
  • When the duodenum is filled with Chyme and the wall is stretched, the enterogastric reflex occurs
49
Q

How long does food stay in the stomach for?

A

4 hours (or 6 hours for meals high in fat)

50
Q

How much Chyme does the pylorus of the stomach hold?

A

30ml

51
Q

Why is the stomach acidic?

A

To kill bacteria

52
Q

What is the enterogastric reflex?

A

Stimulated by a pH of 3-4 (duodenum) or 1.5 (stomach), causing the stomach to stop releasing gastric acid which stops digestion

53
Q

How long does the food spend in the small intestine?

A

3-6 hours

54
Q

Which 2 liquids digest food in the small intestine?

A

Pancreatic juices and bile

55
Q

How is food absorbed in the small intestine?

A

By the epithelial cells, which are renewed every 2-3 days

56
Q

What are the 4 main enzymes in the small intestine and what do they break down?

A
  1. Pancreatic amylase (starch)
  2. Trypsin (secreted as trypsinogen and activated by Enterokinase - digests protein)
  3. Chymotrypsin and Carboxypeptidase (protein)
  4. Pancreatic Lipase (fat)
57
Q

What are the 3 main disaccharides broken down into?

A
  1. Maltose –> Glucose + Glucose
  2. Sucrose –> Glucose + Fructose
  3. Lactose –> Glucose + Galactose
58
Q

What are the 2 main functions of Secretin?

A
  1. Increases the output of pancreatic juice rich in bicarbonate and bile from the liver
  2. Inhibits gastric mobility and gastric gland secretion
59
Q

What are the 3 main functions of Cholecystokinin?

A
  1. Increases output of pancreatic juice rich in enzymes
  2. Stimulates gall bladder to expel stored bile
  3. Relaxes sphincter of duodenal papilla to allow bile and pancreatic juice to enter the duodenum
60
Q

What is the function of bile?

A
  • Acts as a ‘detergent’ to emulsify large fat globules into small ones which increases surface area for the action of pancreatic lipase
  • Aids absorption of fats and fat-soluble vitamins (A, D, E and K)
61
Q

What is intrinsic factor and what is it needed for?

A
  • A glycoprotein produced in the parietal cells of the stomach
  • Aids absorption of vitamin B12
62
Q

How are most digestive products absorbed?

A

By active transport into the capillary beds of the villi to be transported to the liver

63
Q

How are lipids absorbed?

A

Passive diffusion into the villi and are transported to the liver by the blood and lymphatic fluids

64
Q

What is left at the end of the ileum?

A

Water, indigestible food and bacteria

65
Q

How long does food stay in the large intestine for?

A

12-24 hours

66
Q

What is the function of bacteria in the large intestine?

A

Metabolise remaining nutrients, release gas and make vitamins B and K

67
Q

What is absorbed in the large intestine?

A

Vitamins and water

68
Q

What are the 2 types of contraction in the large intestine?

A
  1. Haustral Contraction - slow segmenting movements lasting 1 minute
  2. Mass Movement - long slow-moving powerful waves that force the food residue to the rectum
69
Q

Describe the Defecation reflex

A
  • Spinal reflex from the sacral region
  • Causes the walls of the sigmoid (descending) colon to contract and the anal sphincters to relax
  • Faeces is forced through the anal canal
  • Voluntary control
70
Q

What may cause involuntary defecation problems?

A

Damage/injury to the spinal cord

71
Q

What are the 2 sub-groups of Carbohydrates?

A
  1. Sugar

2. Starch

72
Q

Give 3 sources of sugar

A
  1. Fruit
  2. Sugar cane
  3. Milk
73
Q

Give 3 sources of starch

A
  1. Grains
  2. Legumes
  3. Root vegetables
74
Q

What are the 4 sub-groups of Lipids?

A
  1. Saturated fats
  2. Unsaturated fats
  3. Cholesterol
  4. Protein-rich sources (incomplete)
75
Q

Give 2 sources of saturated fat

A
  1. Animal products (meat and dairy)

2. Coconut

76
Q

Give 2 sources of unsaturated fat

A
  1. Seeds

2. Nuts

77
Q

Give 2 sources of cholesterol

A
  1. Egg yolk

2. Meat

78
Q

Give 2 sources of protein-rich sources

A
  1. Legumes

2. Nuts

79
Q

What are the 4 main Vitamins?

A

A, C, D and E

80
Q

Give 2 sources of vitamin A

A
  1. Liver

2. Carrots

81
Q

Give 2 sources of vitamin C

A
  1. Strawberries

2. Kiwi

82
Q

Give 2 sources of vitamin D

A
  1. Tuna

2. Orange juice

83
Q

Give 2 sources of vitamin E

A
  1. Almonds

2. Spinach

84
Q

What are the 5 main minerals?

A
  1. Iron
  2. Calcium
  3. Zinc
  4. Phosphorus
  5. Potassium
85
Q

Give 2 sources of iron

A
  1. Liver

2. Meat

86
Q

Give 2 sources of calcium

A
  1. Seeds

2. Cheese

87
Q

Give 2 sources of zinc

A
  1. Spinach

2. Beef

88
Q

Give 2 sources of phosphorus

A
  1. Meat

2. Fish

89
Q

Give 2 sources of potassium

A
  1. Avocado

2. Potato

90
Q

Give 5 problems caused by lack of a balanced diet

A
  1. Malnourishment
  2. Vitamin deficiency
  3. Obesity
  4. Fatigue
  5. Constipation (lack of fibre)
91
Q

What is the daily recommended intake of fibre?

A

24g