Overview of the alimentary system

Question 1

Overall function of digestive system

Answer 1

digest and absorb food

Question 2

Definition of absorption

Answer 2

Transferring nutrients to the circulation

Question 3

Which two groups of organs make up the alimentary system?

Answer 3

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

Question 4

What are the three major pairs of salivary glands?

Answer 4

Parotid, submandibular, sublingual

Question 5

What are the possible consistencies of saliva secretions?

Answer 5

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

Question 6

Function of the gall bladder

Answer 6

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

Question 7

Description and function of the pharynx

Answer 7

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

Question 8

Description of oesophagus

Answer 8

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

Question 9

Description and function of stomach

Answer 9

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

Question 10

Function of sphincters

Answer 10

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

Question 11

What are the 3 parts of the small intestine?

Answer 11

Duodenum, jejunum, ileum

Question 12

Parts of the large intestine

Answer 12

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

Question 13

What are the layers of the gastrointestinal histology?

Answer 13

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

Question 14

Which layers make up the mucosa?

Answer 14

Epithelium, lamina propria, muscularis mucosae

Question 15

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

Answer 15

Non-keratinised stratified squamous epithelia - protective against mechanical abrasion

Question 16

What is the lamina propria?

Answer 16

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

Question 17

What is the muscularis mucosae?

Answer 17

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.

Question 18

What is the submucosa?

Answer 18

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

Question 19

What is the muscularis propria/externa?

Answer 19

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.

Question 20

What is the difference between adventitia and serosa?

Answer 20

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.

Question 21

Which parts of the digestive system have adventitia?

Answer 21

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

Question 22

What is GORD?

Answer 22

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

Question 23

Metaplasia definition

Answer 23

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

Question 24

What is Barrett’s oesophagus?

Answer 24

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

Question 25

What is the risk of having Barrett's oesophagus?

Answer 25

Risk of dysplasia and oesophageal cancer

Question 26

What is dysplasia?

Answer 26

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

Question 27

Which organ of the alimentary system has a secretory function?

Answer 27

Stomach

Question 28

What are the names of the glands in the stomach?

Answer 28

Gastric glands - cardiac, fundic, pyloric glands

Question 29

Which layer of the mucosa are glands located?

Answer 29

Lamina propria

Question 30

What do the secretory cells secrete in the stomach?

Answer 30

HCl, mucus, enzymes, bicarbonate

Question 31

What is the epithelium type in the stomach?

Answer 31

Simple columnar epithelium

Question 32

Which organs of the alimentary system have an absorptive function?

Answer 32

Small (and large) intestine

Question 33

What is the epithelium type in the small intestine?

Answer 33

Simple columnar epithelium

Question 34

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

Answer 34

Villi - finger-like extensions

Question 35

Function of villi

Answer 35

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

Question 36

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

Answer 36

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

Question 37

What is villous atrophy?

Answer 37

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

Question 38

What are hyperplastic crypts?

Answer 38

When the grooves between the villi become stretched and elongated

Question 39

What are lymphoid cells?

Answer 39

Chronic inflammatory cells found in the lamina propria

Question 40

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

Answer 40

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

Question 41

What are colonic crypts?

Answer 41

Intestinal glands in invaginations of the large intestine

Question 42

What is IBD?

Answer 42

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

Question 43

What is Crohn's disease?

Answer 43

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...

Question 44

What is ulcerative collitis?

Answer 44

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

Question 45

What are the 5 different roles of the alimentary system?

Answer 45

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

Question 46

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

Answer 46

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

Question 47

What are some of the secretions that enter the GIT?

Answer 47

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

Question 48

What are the two forms of digestion?

Answer 48

Mechanical and chemical

Question 49

What does the mechanical aspect of digestion involve?

Answer 49

Churning, mixing, propulsive motility

Question 50

What does the chemical aspect of digestion involve?

Answer 50

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

Question 51

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

Answer 51

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

Question 52

How much fluid is absorbed in the GIT?

Answer 52

7500 ml (equal to secretions and intake).

Question 53

Where in the GIT does most absorption occur?

Answer 53

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

Question 54

Functions of the mouth

Answer 54

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

Question 55

What are the sensory functions of the mouth?

Answer 55

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

Question 56

What are the motor functions of the mouth?

Answer 56

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

Question 57

What is the function of saliva?

Answer 57

Protect the mucosa, lubricate, digest

Question 58

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

Answer 58

mylohyoid

Question 59

What is the difference between the hard and soft palate?

Answer 59

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.

Question 60

What is the lowest part of the soft palate?

Answer 60

Uvula

Question 61

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

Answer 61

Fauces

Question 62

Which tonsils are located on the fauces?

Answer 62

Palatine tonsils

Question 63

Function of palatine tonsils

Answer 63

Primary line of defence against pathogens

Question 64

Where is the sublingual duct found?

Answer 64

Under tongue

Question 65

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

Answer 65

Submandibular and sublingual glands

Question 66

What is the name for the folds under the tongue?

Answer 66

Plica fimbriata

Question 67

What is the function of the lingual vein?

Answer 67

Drains the floor of the mouth

Question 68

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

Answer 68

Lingual frenulum

Question 69

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

Answer 69

A short lingual frenulum

Question 70

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

Answer 70

Jaw muscles, facial muscles, buccinator

Question 71

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

Answer 71

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

Question 72

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

Answer 72

Orbicularis oris

Question 73

Where is the buccinator located?

Answer 73

Cheeks

Question 74

Function of the buccinator

Answer 74

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

Question 75

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

Answer 75

Serous

Question 76

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

Answer 76

seromucous

Question 77

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

Answer 77

mucinous

Question 78

How can mumps (paramyxovirus) affect salivary glands?

Answer 78

Swelling of parotid gland

Question 79

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

Answer 79

Sialolithiasis

Question 80

Which salivary gland is typically affected by sialolithiasis?

Answer 80

Submandibular

Question 81

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

Answer 81

Sialoadenitis

Question 82

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

Answer 82

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