1.3 regulation of GIT (motility)

Question 1

where does peristalsis starts

Answer 1

begins in the oesophagus

Question 2

which layer controls persistalsis

Answer 2

tunica muscularis

Question 3

what is mechanical digestion

Answer 3

it is the physical break down of food by non chemical means

Question 4

where does mechanical digestion starts

Answer 4

mouth by mastication

Question 5

what are the names of the 4 stomachs in ruminants

Answer 5

rumen, reticulum, omasum, abomasum

Question 6

which stomach does chemical digestion occurs

Answer 6

abomasum

Question 7

which stomachs does mechanical digestion occurs

Answer 7

rumen, reticulum, omasum

Question 8

the three mechanical digestion (aka the process of digestion) of ruminants

Answer 8

1. Mastication and mixing of food in mouth
2. Ingestion and fermentation in the rumen (fermentation is not chemical digestion as it doesn’t involve enzymes)
3. Regurgitation, re-mastication and eructation

Question 9

how is the rumen stimulated

Answer 9

The distension stimulates the stretch receptor, this sends a electrical impulses via vagus nerve

Question 10

what is the primary movement of the rumen

Answer 10

in order to mix the 4 layers, the ventral side contracts, there will then be a cycle of contractions, making sure everything is mixed up

Question 11

what is the secondary movement of the rumen

Answer 11

• There are lots of gases that are not wanted
  A caudal, cranial wave of contractions that push the dorsal side of the rumen, releasing the gases through the oesophagus

Question 12

what is the major muscle type in the intestines

Answer 12

smooth muscles

Question 13

the two type of motility in the small intestines and how they work

Answer 13

1. Segmentation

Chop, mix and roll the chyme, reducing size of the chyme

2. Peristalsis

Slowly propels food towards the large intestines

Question 14

what are the three forms of large intestine motility and how they work

Answer 14

1. Haustration

h

2. Antiperistaltic contractions

• Propagate toward the ileum (small intestines)
• Retards the movements of ingesta through the colon
• This is where absorption of water and electrolytes occur

3. Mass movements

• The final power given by the large intestines
• A very intense and prolonged peristaltic contraction which remove all contents in an area of the large intestines

Question 15

what are the digestive and interdigestive phases of persistalsis

Answer 15

Digestive phase

• Occurs after eating a meal and actively digesting food
• Peristaltic contractions pass over short segments of the intestine

Interdigestive phase

• Peristaltic contractions pass over large segements of the intestine

Question 16

when is migration motor complex involved

Answer 16

interdigestive phase

Question 17

2 functions of the MMC

Answer 17

• Sweep residual undigested material through the digestive tube
• Control the bacterial population

Question 18

the 4 extrinsic control of GIT motility

Answer 18

1. Endocrine

• Hormones released into blood stream to reach target

2. Paracrine control

• Agents (substances
  released from cells around the gut) for local diffusion to nearby cells
  
  • e.g. acetylcholine

3. nervous

• Intrinsic control from enteric nervous system which is controlled by the CNS
  ○ Myenteric plexus
  ○ Submucosal plexus

4. Autonomic control from CNS
   - Parasympathetic ‘rest and digest’