GI physiology

Question 1

prehension

Answer 1

the act of moving food into the mouth

Question 2

what directly controls prehension

Answer 2

CNS- facial nerve, glossopharyngeal and the motor branch of the trigeminal nerve

Question 3

mastication

Answer 3

the first act of digestion (in the mouth eg- chewing)

Question 4

what is the purpose of mastication

Answer 4

break down food particles to increase surface area for digestion, it moistens and lubricates food

Question 5

3 main salivary glands in all animals

Answer 5

-parotid
-mandibular
-sublingual

Question 6

salivary gland unique to dogs

Answer 6

zygomatic

Question 7

what type of saliva comes from the zygomatic and sublingual glands

Answer 7

mucous

Question 8

mucous saliva properties

Answer 8

thicker, important for binding food into a bolus

Question 9

what type of saliva comes from the parotid gland

Answer 9

serous

Question 10

properties of serous saliva

Answer 10

watery, contains amylase

Question 11

what controls the salivary glands

Answer 11

parasympathetic nervous system

Question 12

where do nerve fibres end in the salivary gland

Answer 12

the acini

Question 13

mucins (glycoproteins) role in saliva

Answer 13

lubrication, mix with water to form mucous

Question 14

HCO3- role in saliva

Answer 14

pH regulation, neutralisation

Question 15

lysosomes and antibodies role in saliva

Answer 15

antibacterial, keep the amount of bacteria in check

Question 16

how is starch digested

Answer 16

amylase

Question 17

how is fat digested in young cows

Answer 17

lingual lipase

Question 18

how does thermoregulation occur in canines and rodents

Answer 18

panting, spreading saliva (evaporative cooling)

Question 19

how does urea get to the saliva

Answer 19

diffuses from the blood

Question 20

why is ruminant saliva alkaline

Answer 20

necessary for neutralisation of fermentation products

Question 21

deglutition

Answer 21

action/ process of swallowing

Question 22

2 phases of deglutition

Answer 22

voluntary and involuntary

Question 23

voluntary

Answer 23

chewed food is moulded into a bolus and moved to the pharynx

Question 24

involuntary phase of deglutition

Answer 24

1) breathing stops momentarily
2) soft palate is elevated
3) tongue is pressed against the hard pallet
4) glottis is pulled under the epiglottis
5) when all openings into the pharynx are closed a wave of muscular contraction passes over the walls of the pharynx
6) the upper oesophageal sphincter relaxes

Question 25

what controls the involuntary phase of deglutition

Answer 25

motor neurons- efferent nerve fibres travel in the facial, vagus, hypoglossal and glossopharyngeal nerves

Question 26

3 layers within the tunica mucosa

Answer 26

epithelium, lamina propria, muscularis mucosae

Question 27

what type of muscle is found in dog, cow and sheep oesophagus

Answer 27

striated

Question 28

what type of muscle is found in horse, primates and cats oesophagus

Answer 28

smooth muscle

Question 29

what nerve innovates striated muscles

Answer 29

vagus nerve

Question 30

what innovates smooth muscle

Answer 30

ENS

Question 31

oesophagus during deglutination

Answer 31

oesophagus is relaxed but upper and lower sphincters are tightly constricted

Question 32

where does peristalsis occur

Answer 32

at all levels of the gut

Question 33

what is peristalsis

Answer 33

moving ring of constriction

Question 34

what are the three main tasks of the stomach

Answer 34

- temporary food store -some degradation of protein and starch -hydrochloric acid kills bacteria in food

Question 35

what part of the stomach is the proximal stomach referring to

Answer 35

cardia and funds

Question 36

is contraction maintained when stomach is emptying

Answer 36

yes

Question 37

when do promiml stomach muscles relax

Answer 37

when animal eats regulated via vagus nerve

Question 38

what is the distal stomach relating to

Answer 38

pyloric region

Question 39

why does more active digestion occur in the distal stomach

Answer 39

stronger peristaltic contractions

Question 40

4 types of cells in pits in the stomach wall

Answer 40

1) mucin producing 2) parietal 3) chief 4) endocrine

Question 41

what type of epithelium lines the lumen of the stomach

Answer 41

simple columnar

Question 42

in which parts of the stomach are most of the gastrin juices produced

Answer 42

fundus and corpus (body of the stomach)

Question 43

what do glands in the cardia region of the stomach produce

Answer 43

mucus

Question 44

what do gastric juices mainly consist of

Answer 44

HCl and pepsinogen

Question 45

which gland secretes HCl

Answer 45

parietal

Question 46

what does HCl do to pepsinogen

Answer 46

transforms it to pepsin

Question 47

why does pepsinogen. only turn to pepsin with stomach HCl

Answer 47

pepsinogen is inactive, pepsin would degrade connective tissue and muscle

Question 48

how is HCl produced

Answer 48

H/K ATP-ase pump (provides H+) HCO3-/Cl- pump (provides Cl-)

Question 49

what cells synthesise and store pepsinogen

Answer 49

chief cells

Question 50

what is the role of pepsin

Answer 50

degrades proteins to peptides

Question 51

what 3 substances exert stimulatory effects on regulating gastric secretions

Answer 51

ACH, Gastrin, Histamine

Question 52

what happens when gastrin is released into the blood

Answer 52

stimulates the secretion of HCl, pepsinogen and promotes gastrin motility

Question 53

what is the role of histamine

Answer 53

acts as a pancreatic hormone, stimulating HCl secretions

Question 54

what reflexes are stimulated by stomach expansion

Answer 54

vagal

Question 55

what organ inhibits secretion

Answer 55

signals from the duodenum

Question 56

what causes secretion to be inhibited

Answer 56

if pH falls too low At the start of eating a meal HCl secretion is high but then the stomach is supplied with a buffer which decreases gastrin release

Question 57

why does food layer in the order we eat it in the order it was eaten in the proximal stomach

Answer 57

contractions here are weak

Question 58

factors affecting rate of stomach emptying

Answer 58

expansion of the stomach wall and gastrin

Question 59

what is optimal digesting

Answer 59

when the rate of the stomach emptying equals the capacity of intestines to digest food

Question 60

distension of the duodenum in affecting rate of stomach emptying

Answer 60

as duodenum fills the pyloric sphincter will close, slowing and eventually stopping the transfer of chyme from the stomach to the intestine

Question 61

reduced pH in affecting rate of stomach emptying

Answer 61

If more acid is transferred to the duodenum than can be neutralised then intestinal enzymes cannot function

Question 62

what mediates the rate of stomach emptying

Answer 62

secreting, CCK and GIP

Question 63

what do young ruminate produce in the abomasum to aid milk digestion

Answer 63

rennin