Digestion

Question 1

Organs of gastrointestinal tract

Answer 1

mouth>pharynx>oesophagus>stomach>small intestine>large intestine

Question 2

Accessory organs

Answer 2

exocrine pancreas
salivary glands
liver
gall bladder

Question 3

Layers of gastrointestinal wall

Answer 3

lumen>mucosa (mucous) >submucosa>muscularis externa(circular and longitudinal muscle) >serosa

Question 4

layers of the mucosa

Answer 4

epithelium>lamina propia>muscularis mucosa

Question 5

epithelium of the mucosa

Answer 5

single layer of both endocrine and exocrine cells secreting into the lumen and blood stream

Question 6

lamina propia of mucosa

Answer 6

loose connective tissue

Question 7

muscularis mucosa

Answer 7

layer of smooth muscle

Question 8

layers of submucosa

Answer 8

blood and lymphatic vessels penetrate layers above and below
submucosal plexus

Question 9

function of the blood and lymphatic vessels in the submucosa

Answer 9

provides nutrients to cells in the mucosa and transport their products

Question 10

submucosal plexus of the submucosa

Answer 10

network of neurones for control of muscular activity

Question 11

layers of the muscularis externa

Answer 11

circular muscle>myenteric plexus>longitudinal muscle

Question 12

role of circular muscle in the muscularis externa

Answer 12

contraction narrows lumen

Question 13

myenteric plexus of the muscularis externa

Answer 13

innervated by the autonomic nervous system
connected to submucosal plexus

Question 14

role of longitudinal muscle in the muscularis externa

Answer 14

contraction shortens the tract

Question 15

serosa

Answer 15

connective tissue surrounding outer surface of tract. sheets connect serosa to abdominal wall, holding the GI tract in place

Question 16

cephalic phase of digestion

Answer 16

brains anticipation of food
increase saliva production by PNS
stimulation of gastric juice secretion
insulin secretion

Question 17

components of saliva and their roles

Answer 17

bicarbonate>neutralise acid
mucus>lubrication and protects against abrasion from chewing
salivary amylase>breaks down CHO
lysozyme>destroys bacteria, prevents tooth decay

Question 18

epiglottis

Answer 18

closes to prevent aspiration into trachea

Question 19

sphincters

Answer 19

bottom of pharynx and opening to stomach
prevents movement of air and stomach contents entering oesophagus

Question 20

peristalsis

Answer 20

progressive muscular contraction to bring food to stomach as waves of compressing the lumen
if a food bolus does not reach stomach secondary peristalsis is initiated (reflex)

Question 21

functions of stomach

Answer 21

mixing of food with gastric juices to form chyme
secretion of HCl
pepsin secretion
gastric lipase secretion
storage

Question 22

functions of small intestine

Answer 22

chemical digestion of all nutrients
absorption of digestive end products, water, ions and vitamins
secretion of hormones
secretion of bicarbonate rich fluid

Question 23

functions of colon

Answer 23

absorption of water and ions
chyme>faeces
storage of faeces

Question 24

how is the stomach lining protected against abrasion

Answer 24

mucous cells release an alkaline solution along with mucous

Question 25

role of chief cell lining stomach

Answer 25

secretes pepsinogen which is inactive and activated by acidic environment

Question 26

role of parietal cells lining stomach

Answer 26

release intrinsic factor for B12 absorption releases HCl

Question 27

cycle of HCl production

Answer 27

enteric neurone releases acetylcholine>parietal cell>release HCl>increases somatostatin release from D cells>inhibits G cells from producing gastrin which normally increases histamine secretion from ECL cells. less histamine to act on parietal cell>less HCl

Question 28

motility in stomach is caused by

Answer 28

thick musculature in antrum

Question 29

how do bile salts work

Answer 29

Bile salts provide amphipathic emulsifying agents which associate with the nonpolar interior of lipid droplets, leaving the polar portions exposed at the water surface. They then repel other lipid droplets that are similarly coated, and thus prevent reaggregation to large fat droplets.

Question 30

what are micelles

Answer 30

Micelles are smaller fat droplets produced by the enzymatic action of lipases on fat droplets.

Question 31

enterokinase

Answer 31

embedded in the luminal plasma membranes of the intestinal epithelial cells. It is a proteolytic enzyme that splits off a peptide from pancreatic trypsinogen to form the active enzyme trypsin

Question 32

what is the primary stimulant of bicarbonate secretion

Answer 32

secretin

Question 33

signal for gall bladder contraction

Answer 33

CCK

Question 34

chylomicrons

Answer 34

lipoproteins that triacylglycerols are transported in