Lecture 27

Question 1

What is the name of the out-pocketing of the oesphagus within avian species?

Answer 1

the crop

Question 2

What is the function of the crop within avian species?

Answer 2

has a storage function

Question 3

What is the name for mixing and grinding of by the antrum within the monogastric stomach?

Answer 3

trituration

Question 4

What percentage of water and electrolytes are absorbed within the GIT tract?

Answer 4

approximately 99% is reabsorbed

Question 5

What is the order of the nerve, arteriole, venule and lymphatic systems in order from most medial to the most lateral?

Answer 5

Venule to nerve to arteriole to lymphatic

Question 6

What are the two different nervous plexuses that are found within the enteric nervous system?

Answer 6

Myenteric plexus

Submucosal plexus

Question 7

Where is the myenteric plexus located and what is the function of it?

Answer 7

circular and longitudinal muscle layers, primarily regulates motility (controls smooth muscle and secretory cells)

Question 8

Where is the submucosal plexus located and what is the function of it?

Answer 8

between submucosal circular muscle layers, primarily regulates secretion and absorption (endocrine cells and blood vessels)

Question 9

Briefly describe the pathway of the parasympathetic control of the gastro-intestinal system:

Answer 9

1. Pre-ganglionic sympathetic fibres arise from the medulla and the (vagus nerve) and the pelvic nerve
2. Synapse with post-ganglionic cholinergic fibres in ganglia within enteric nervous system
3. Mediator at the target cells is acetylcholine
4. Stimulates intestinal motility, secretion + release of hormones

Question 10

Briefly describe the pathway of the sympathetic control of the gastro-intestinal system:

Answer 10

1. Pre-ganglionic cholinergic receptors synapse in sympathetic ganglion
2. Form ganglia the post-ganglionic fibres innervate cells in myenteric and submucosal plexuses + direct post-ganglionic innervation to some blood vessels and muscularis mucosa
3. Constriction of blood vessels
4. Inhibition of intestinal motility + secretion + hormone release

Question 11

Which nerve has 75% sensory (afferent) fibres and is not consciously perceived?

Answer 11

vagus nerve (mainly associated with reflexes)

Question 12

50% of the GIT ___(1 word)_______ nerves are afferent. They go to the __(2 words)_____ where they are ________. They have little reflex activity

Answer 12

1 word = sympathetic

2 words = consciously perceived

Question 13

GASTRIN

a. ) state whether it is endocrine, paracrine, or neurocrine
b. ) where is it released from?
c. ) what is the stimulation for its release?
d. ) what are the actions of it?

Answer 13

a. ) Endocrine
b. ) released from G-cells within the intestinal mucosa (antrum)
c. ) response to a meal, vagal stimulation, distension of the gastric wall
d. ) stimulates gastric acid secretion and also the growth of gastric oxyntic glands

Question 14

CHOLYCYSTOKININ

a. ) state whether it is endocrine, paracrine, or neurocrine
b. ) where is it released from?
c. ) what is the stimulation for its release?
d. ) what are the actions of it?

Answer 14

a. ) Endocrine
b. ) I cells in duodenal and intestinal mucosa
c. ) response to fatty acids
d. ) pancreatic enzyme secretion, gall bladder contraction, potent inhibitor of gastric emptying

Question 15

SECRETIN

a. ) state whether it is endocrine, paracrine, or neurocrine
b. ) where is it released from?
c. ) what is the stimulation for its release?
d. ) what are the actions of it?

Answer 15

a. ) Endocrine
b. ) S cells in duodenal mucosa
c. ) in response to acid and fatty acids
d. ) potent stimulator of pancreatic bicarbonate and water secretion and inhibits gastric acid secretion

Question 16

SOMATOSTATIN

a. ) state whether it is endocrine, paracrine, or neurocrine
b. ) where is it released from?
c. ) what is the stimulation for its release?
d. ) what are the actions of it?

Answer 16

a. ) Paracrine
b. ) released D cells in the antrum
c. ) acid
d. ) somatostatin acts as a paracrine, inhibiting the release of gastrin and gastric acid secretion

Question 17

What are the three digestive phases?

Answer 17

A.) Cephalic
B.) Gastric
C.) Intestinal

Question 18

For the cephalic stage of digestion state:
A.) Stimulus
B.) Effects
C.) Regulation

Answer 18

A.) Changes in response to sight + smell + mastication of food
B.) Input of CNS
C.) Long reflexes (vagus nerve)

Question 19

For the gastric stage of digestion state:
A.) Stimulus
B.) Effects

Answer 19

A.) gastric digestion + release of peptides

B.) release of gastrin and activation of both long and short reflexes

Question 20

For the intestinal stage of digestion state:
A.) Stimulus
B.) Effects
C.) Regulation

Answer 20

A.) change in GI secretion and motility
B.) initiated by changes in volume and composition of digesta
C.) release of secretin, CCK and activation of both long and short reflexes.