WEEK 1

Question 1

functions of the digestive system

Answer 1

digestion
secretion
absorption
motility

Question 2

function of mouth

Answer 2

foodstuffs broken down by chewing; saliva added as lubricant

Question 3

function of oesophagus

Answer 3

conduit between mouth and stomach

Question 4

function of stomach

Answer 4

digestion of proteins; foodstuffs reduced to liquid form; storage; sterilization

Question 5

function of pancreas

Answer 5

digestive enzymes for digestion of fats, CHOs and proteins

Question 6

function of liver

Answer 6

bile salts for digestion/absorption of fats in small intestine

Question 7

function of gallbladder

Answer 7

stores and concentrates bile

Question 8

function of small intestine

Answer 8

final stages of chemical digestion and nutrient absorption

Question 9

function of large intestine

Answer 9

water absorption, bacterial fermentation and formation of faeces

Question 10

what are the 4 distinctive layers of the alimentary canal

Answer 10

mucosa
submucosa
muscularis externa
serosa/adventitia

Question 11

within the mucosa - what are the 3 layers

Answer 11

epithelium
lamina propria
muscularis mucosae

Question 12

describe mucosa epithelium

Answer 12

mouth, oesophagus, anal canal = stratified squamous
stomach, small and large intestine = simple columnar
barrier separating lumen of alimentary canal from body
synthesis and secretion of digestive enzymes, hormones, mucus
absorbs products of digestion
epithelium differs along length of gut tube, adaptation for function

Question 13

describe lamina propria

Answer 13

loose connective tissue (glands, blood/lymph vessels)

Question 14

describe muscularis mucosae

Answer 14

thin smooth muscle layer

Question 15

describe submucosa

Answer 15

thick, irregular connective tissue - supports mucosa
contains neurones, blood vessels (mucosa, muscularis externa, serosa), lymphatic vessels
neurones from extensive network - submucosal (Meissner’s) plexus (parasympathetic)
submucosal glands in oesophagus and duodenum

Question 16

describe serosa/adventitia

Answer 16

connective tissue outer layer of alimentary canal
outside peritoneal cavity: adventitia attaches oesophagus and rectum to surrounding structures
inside peritoneal cavity: serosa surrounds stomach, small intestine and large intestine

Question 17

describe muscularis externa

Answer 17

two concentric thick layers of smooth muscle
inner layer = circular muscle (constricts lumen)
outer layer = longitudinal muscle (shortens tube)

produce motility : peristalsis, segmentation
myenteric (Auerbach’s) plexus between circular and longitudinal muscle
submucosal + myenteric plexuses = enteric nervous system (ENS) : independent control of gut function

Question 18

nervous control of alimentary function

Answer 18

autonomic control : long (parasympathetic) and short (ENS) reflexes
parasympathetic: vagus nerve (except salivation, facial (VII) and glossopharyngeal (IX)
stimulatory : secretion , motility
sympathetic: splanchnic nerve
inhibitory (except salivation) : secretion, motility

Question 19

arterial supply to GI tract

Answer 19

descending abdom aorta
3 branches =
celiac trunk which supplies stomach, small intestine, pancreas and liver
superior mesenteric artery which supplies small intestine, caecum, asc colon and trans colon
inferior mesenteric artery which supplies desc colon, sigmoid colon and rectum

Question 20

venous drainage from GI tract

Answer 20

stomach -> gastric veins
pancreas -> splenic vein

small intestine, caecum, asc and trans colon => SMV -> hepatic portal vein -> hepatic vein -> IVC
desc and sigmoid colon and rectum => IMV