stomach

Question 1

what is deglutition

Answer 1

swallowing = propulsion of food from oral cavity into oesophagus

Question 2

process of swallowing

Answer 2

food molded into bolus by tongue and moved upwards and backwards to pharynx - forces soft palette up to seal of nasal cavity - voluntary
pressure-sensitive sensory cells stimulated
swallowing centre in medulla initiates swallowing reflex - involuntary
epiglottis closes off trachea
complicated contraction/relaxation of muscles forces food into oesophagus

Question 3

what are the layers of the oesophagus

Answer 3

mucosal
submucosal
muscular
serosal

Question 4

what is the mucosal layer composed of

Answer 4

stratified squamous epithelium

Question 5

what is the muscular layer composed of

Answer 5

striated and smooth muscle

Question 6

what is the serosal layer composed of

Answer 6

adventitia - loose connective tissue only in neck

Question 7

what is the process of food being transported down the oesophagus

Answer 7

upper oesophageal sphincter closes behind food bolus
complicated peristaltic contractions force food down oesophagus
lower oesophageal sphincter opens to allow passage of food into stomach

Question 8

what is the lower oesophageal sphincter

Answer 8

cardiac sphincter
physiological - except in horses = anatomical
prevents regurgitation of acidic stomach contents

Question 9

what is emesis

Answer 9

vomiting - active propulsion of stomach contents into oral cavity

Question 10

where is the vomiting centre

Answer 10

medulla

Question 11

what is vomiting stimulated by

Answer 11

pharyngeal/gastric distension or irritation

Question 12

what is gastric torsion

Answer 12

stomach rotates 90-360 degrees
seals off cardiac sphincter preventing vomiting

Question 13

what animals does gastric torsion occur in

Answer 13

horses and dogs with wide chests

Question 14

what happens if rotation compromises blood supply in gastric torsion

Answer 14

gastric tissue becomes hypoxic and in severe cases necrotic

Question 15

what are the functions of the simple stomach

Answer 15

digestion
protection
storage
mechanical breakdown

Question 16

what is the ruminant equivalent of the simple stomach

Answer 16

abomasum

Question 17

what is the embryological regions of the stomach and what do they secrete

Answer 17

oesophageal - non-glandular, stratified squamous epithelium
cardiac - mucous
fundic -mucous and gastric juices
pyloric - mucous

Question 18

what is the cardia region

Answer 18

entrance to stomach

Question 19

what is the fundus

Answer 19

blind-ending part

Question 20

what is the corpus

Answer 20

body of stomach

Question 21

what is the pylorus

Answer 21

exit from stomach

Question 22

stomach cell types

Answer 22

mucous
parietal
chief
entero-endocrine

Question 23

function of mucous cells (goblet)

Answer 23

secrete mucus to protect against HCL

Question 24

function of parietal cells (oxytinic)

Answer 24

secrete HCL to digest protein

Question 25

function of chief cells (peptic)

Answer 25

secrete pepsinogen to digest protein

Question 26

function of entero-endocrine cells

Answer 26

secrete hormones

Question 27

what does motility do

Answer 27

prepare stomach to receive a meal mix and mechanically break down chyme empty stomach contents into small intestine prevent regurgitation of stomach contents into oesophagus

Question 28

what is the transmitter that allows initial relaxation of stomach smooth muscle to accommodate the meal

Answer 28

vasoactive intestinal peptide

Question 29

what is the main type of contraction involved in motility

Answer 29

peristalsis

Question 30

process of motility

Answer 30

fundus weak contractions propogate down corpus pyloric sphincter opens to allow chyme into duodenum when contraction reach pylorus the pyloric sphincter closes food forced back into corpus helps mixing

Question 31

what is stomach emptying regulated by

Answer 31

strength of contraction opening/closing of pyloric sphincter stimulation and inhibition of emptying

Question 32

what stimulates emptying of stomach

Answer 32

neural regulation - expansion of stomach increases strength of contraction hormonal regulation - release of gastrin increases strength of contraction and dilates pyloric sphincter

Question 33

what inhibits emptying of the stomach

Answer 33

increased pressure in duodenal walls, low PH, high fat/peptide contraction, high osmolarity. neural regulation by increased sympathetic activity/decreased parasympathetic activity hormonal regulation via secretin, CCK and GIP.

Question 34

what is digestion

Answer 34

enzymatic breakdown of nutrient macromolecules into smaller units that can be absorbed

Question 35

what is starch digested by and at what pH

Answer 35

amylase only active at pH greater than 6

Question 36

what is protein digested by and at what pH

Answer 36

pepsin active at low pH

Question 37

what is starch made from

Answer 37

amylose and amylopectin - complex carb

Question 38

what is starch digestion initiated by

Answer 38

salivary amylase in mouth

Question 39

what allows starch digestion to continue for a while

Answer 39

acid secreted from stomach walls so gradual decline in pH from centre of stomach to edge

Question 40

level of starch in omniverous diets

Answer 40

high

Question 41

level of starch in herbiverous diets

Answer 41

low

Question 42

levels of starch in carniverous diets and why

Answer 42

low - saliva does not contain amylase

Question 43

what does pancreas also produce

Answer 43

amylase

Question 44

what does gastric juices consist of

Answer 44

HCL and pepsinogen (inactive form of pepsin)

Question 45

what leads to ulceration

Answer 45

breach of mucosal barrier

Question 46

functions of HCL

Answer 46

convert inactive pepsinogen into active form pepsin provides required acidic environment for pepsin to digest protein prevents fermentation by killing microbes degrades large chunks of connective and muscle tissue into smaller more digestible particles

Question 47

when does maximum secretion of HCL occur

Answer 47

2-3 hours after a meal

Question 48

what is duration and volume of HCL dependent on

Answer 48

species dog produce 0.5-1L per hour where as horse produces 20-30L

Question 49

why does urine pH increase after a meal

Answer 49

delay between food passing stomach to pancreas

Question 50

how does pepsin initiate degradation of protein and collagen

Answer 50

breaking peptide links adjacent to aromatic amino acids

Question 51

what can pepsin activate

Answer 51

more pepsinogen

Question 52

what stimulates secretion

Answer 52

reflex arcs - long via vagus and short locally histamine, chief, parietal and mucin cells amplify each other gastrin

Question 53

what is cephalic phase caused by

Answer 53

sight, smell, taste, presence of food in mouth

Question 54

what does cephalic phase stimulate and how

Answer 54

secretion directly via acetylcholine indirectly via gastrin in blood

Question 55

what is gastric phase caused by

Answer 55

stomach expansion peptides in lumen

Question 56

what does gastric phase stimulate

Answer 56

secretion directly via acetylcholine indirectly via gastrin in blood

Question 57

what is stimulation/inhibition in the intestinal phase dependent on

Answer 57

acidity of chyme food components

Question 58

how is intestinal phase stimulated

Answer 58

neural (cholinergic) and hormonal (gastrin and CCK) signals

Question 59

what are most intestinal responses

Answer 59

inhibitory

Question 60

what is hormonal stimulation mediated by

Answer 60

gastrin