Overview of the alimentary system Flashcards

1
Q

Overall function of digestive system

A

digest and absorb food

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2
Q

Definition of absorption

A

Transferring nutrients to the circulation

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3
Q

Which two groups of organs make up the alimentary system?

A

Digestive tract (oesophagus, stomach, small and large intestine) and accessory organs (salivary glands, gall bladder, liver, pancreas)

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4
Q

What are the three major pairs of salivary glands?

A

Parotid, submandibular, sublingual

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5
Q

What are the possible consistencies of saliva secretions?

A

Serous (watery), mucous (thick) or seromucous (mixed)

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6
Q

Function of the gall bladder

A

Stores concentrated bile (produced by the liver) and releases it into the duodenum when fatty food is consumed (bile emulsifies lipids and neutralises acid).

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7
Q

Description and function of the pharynx

A

a 12-15cm long muscular tube responsible for the passage of food and air - digestive and respiratory role

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8
Q

Description of oesophagus

A

a 20-25cm muscular tube which extends from the pharynx to the stomach, passing behind the trachea and the heart)

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9
Q

Description and function of stomach

A

muscular organ found in UL of abdomen. Churns food and drink to form chyme and secretes HCl and enzymes to digest food.

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10
Q

Function of sphincters

A

regulates the release of secretions e.g. from oesophagus to stomach or from stomach to small intestine.

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11
Q

What are the 3 parts of the small intestine?

A

Duodenum, jejunum, ileum

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12
Q

Parts of the large intestine

A

caecum, appendix, ascending, transverse and descending colon, rectum, anus

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13
Q

What are the layers of the gastrointestinal histology?

A

Mucosa, submucosa, muscularis externa/propria, adventitia/serosa

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14
Q

Which layers make up the mucosa?

A

Epithelium, lamina propria, muscularis mucosae

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15
Q

What is the epithelium type in the oral cavity, pharynx and oesophagus and why?

A

Non-keratinised stratified squamous epithelia - protective against mechanical abrasion

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16
Q

What is the lamina propria?

A

Thin layer of connective tissue found in the mucosa beneath the epithelial layer. Contains inflammatory cells and provides support and nutrients to the epithelium.

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17
Q

What is the muscularis mucosae?

A

Layer of smooth muscle continuous throughout the alimentary system (from oral cavity to anal canal). Found in the mucosa beneath the lamina propria, above the submucosa.

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18
Q

What is the submucosa?

A

Dense irregular connective tissue containing large blood vessels, nerves and lymphatic vessels.

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19
Q

What is the muscularis propria/externa?

A

Smooth muscle found below the submucosa made up of an inner circular layer and outer longitudinal layer of muscle. Contracts to aid digestion and movement of food via peristalsis.

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20
Q

What is the difference between adventitia and serosa?

A

Either one is found encapsulating an organ. Adventitia is a fibrous CT layer while serosa is a serous membrane which secretes serous fluid to reduce friction.

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21
Q

Which parts of the digestive system have adventitia?

A

Oral cavity, upper oesophagus, ascending and descending colon and rectum. Everything else has serosa

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22
Q

What is GORD?

A

Gastro-Oesophageal Reflux Disease. Continuous reflux of acid from stomach into oesophagus which may cause Barrett’s oesophagus.

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23
Q

Metaplasia definition

A

When epithelium changes from one type to another - can be part of normal maturation or pathological.

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24
Q

What is Barrett’s oesophagus?

A

The pathological change of oesophageal-epithelium from stratified squamous to simple columnar epithelium.

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25
Q

What is the risk of having Barrett’s oesophagus?

A

Risk of dysplasia and oesophageal cancer

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26
Q

What is dysplasia?

A

The abnormal growth of cells resulting in unequal cell size, abnormally-shaped cells, excess pigment and higher number of mitotic figures.

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27
Q

Which organ of the alimentary system has a secretory function?

A

Stomach

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28
Q

What are the names of the glands in the stomach?

A

Gastric glands - cardiac, fundic, pyloric glands

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29
Q

Which layer of the mucosa are glands located?

A

Lamina propria

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30
Q

What do the secretory cells secrete in the stomach?

A

HCl, mucus, enzymes, bicarbonate

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31
Q

What is the epithelium type in the stomach?

A

Simple columnar epithelium

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32
Q

Which organs of the alimentary system have an absorptive function?

A

Small (and large) intestine

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33
Q

What is the epithelium type in the small intestine?

A

Simple columnar epithelium

34
Q

What is the apical specialisation of epithelium in the small intestine?

A

Villi - finger-like extensions

35
Q

Function of villi

A

Increase surface are of the small intestine by about 30 times to aid digestion and absorption in the duodenum, jejunum, ileum.

36
Q

What is Coeliac disease and how does it affect the small intestine?

A

Autoimmune response when gluten is consumed. Causes villous atrophy, hyperplastic crypts and an increase in lymphoid cells.

37
Q

What is villous atrophy?

A

Destruction of villi causing a flattening appearance of the mucosa. Reduces surface area so small intestine unable to absorb nutrients.

38
Q

What are hyperplastic crypts?

A

When the grooves between the villi become stretched and elongated

39
Q

What are lymphoid cells?

A

Chronic inflammatory cells found in the lamina propria

40
Q

What is the function of the epithelium in the large intestine?

A

Absorb water and vitamins created by colonic bacteria (e.g. vit K - blood clotting), and secrete mucous to protect itself from undigestible materials.

41
Q

What are colonic crypts?

A

Intestinal glands in invaginations of the large intestine

42
Q

What is IBD?

A

Inflammatory Bowel Disease - divided into Crohn’s disease and ulcerative colitis

43
Q

What is Crohn’s disease?

A

Lifelong inflammation of tract lining which results in collection of granulomas (chronic inflammatory cells). Can affect anywhere in the GIT - e.g. lesions in the oral cavity. Symptoms of abdominal pain, vomiting, altered bowel habits…

44
Q

What is ulcerative collitis?

A

Inflammation and ulceration of the colon and rectum only. Symptoms of abdominal pain, diarrhoea…

45
Q

What are the 5 different roles of the alimentary system?

A

Secretory (lubrication too), Digestion, Motility, Absorption, Excretion

46
Q

What is the total amount of fluid (external and internal from secretions) that enters the GIT in a 24 hr period?

A

7600 ml (-100 ml of faeces = 7500 ml)

47
Q

What are some of the secretions that enter the GIT?

A

Saliva (600ml), Gastric juices (2000ml), Bile (500ml), Pancreatic juice (1500ml), Intestinal juice (1500ml)

48
Q

What are the two forms of digestion?

A

Mechanical and chemical

49
Q

What does the mechanical aspect of digestion involve?

A

Churning, mixing, propulsive motility

50
Q

What does the mechanical aspect of digestion involve?

A

Mainly enzymes secreted at different points in the GIT e.g. amylase in saliva, trypsin, amylase and lipase from the pancreas. Also HCl

51
Q

What is the motility occurring at each stage in the GIT?

A

Chewing and swallowing in the mouth -> churning and mixing in the stomach with acid, enzymes, bicarbonate -> peristalsis in the intestine -> defaecation

52
Q

How much fluid is absorbed in the GIT?

A

7500 ml (equal to secretions and intake).

53
Q

Where in the GIT does most absorption occur?

A

Most absorption occurs in the small intestine with some in stomach and large intestine.

54
Q

Functions of the mouth

A

Sensory function, motor functions, salivation, immunity (lymphoid tissue - tonsils), reflexes (protective)

55
Q

What are the sensory functions of the mouth?

A

Nociception (pain), mechanoreception (movement), thermoreception (temperature), gustation (taste), higher level perceptions e.g. evoke feelings/responses

56
Q

What are the motor functions of the mouth?

A

Feeding (breakdown, deglutition/swallowing into pharynx), Communication (speech, facial expressions)

57
Q

What is the function of saliva?

A

Protect the mucosa, lubricate, digest

58
Q

What is the name of the muscle that forms a hammock at the floor of the mouth?

A

mylohyoid

59
Q

What is the difference between the hard and soft palate?

A

The hard palate is made of bone whereas the soft palate is made of muscle, with mucous membrane on top. The soft palate is posterior to the hard palate.

60
Q

What is the lowest part of the soft palate?

A

Uvula

61
Q

What is the name of the pillars in the posterior part of the mouth?

A

Fauces

62
Q

Which tonsils are located on the fauces?

A

Palatine tonsils

63
Q

Function of palatine tonsils

A

Primary line of defence against pathogens

64
Q

Where is the sublingual duct found?

A

Under tongue

65
Q

Which two salivary glands release their secretions into the sublingual duct?

A

Submandibular and sublingual glands

66
Q

What is the name for the folds under the tongue?

A

Plica fimbriata

67
Q

What is the function of the lingual vein?

A

Drains the floor of the mouth

68
Q

What is the name of the structure which holds the tongue in place?

A

Lingual frenulum

69
Q

What might being tongue-tied / difficulty to eat and speak be caused by?

A

A short lingual frenulum

70
Q

What are the three groups of general muscles in the mouth?

A

Jaw muscles, facial muscles, buccinator

71
Q

What are the names and locations of the two jaw muscles?

A

Temporalis helps close the mouth - located over the side of the temple/scalp. Masseter helps close the mouth too - located over the jaw angle.

72
Q

What is the name of the facial muscle that surrounds the mouth?

A

Orbicularis oris

73
Q

Where is the buccinator located?

A

Cheeks

74
Q

Function of the buccinator

A

puffs out cheeks, moves food into the centre of the oral cavity during chewing

75
Q

What type of saliva secretion is produced by the parotid gland?

A

Serous

76
Q

What type of saliva secretion is produced by the submandibular gland?

A

seromucous

77
Q

What type of saliva secretion is produced by the sublingual gland?

A

mucinous

78
Q

How can mumps (paramyxovirus) affect salivary glands?

A

Swelling of parotid gland

79
Q

What is the name of the condition involving calculus /stone forming in a salivary gland?

A

Sialolithiasis

80
Q

Which salivary gland is typically affected by sialolithiasis?

A

Submandibular

81
Q

What is the name of the condition of inflamed salivary glands?

A

Sialoadenitis

82
Q

What must surgeons be cautious of when when removing a tumour near the parotid gland?

A

Facial nerve is close to parotid gland. Located first to avoid damage.