GI System

Question 1

What are the digestive organs of the GI

Answer 1

Oesophagus
stomach
small I
Large I

Question 2

What are the Accessory Organs and what are they in the GI

Answer 2

An organ that helps with digestion but is not part of the digestive tract.
The accessory digestive organs are the tongue, salivary glands, pancreas, liver, and gallbladder

Question 3

What is a brief overview of digestion?

Answer 3

1. Mechanical Breakdown
   - Prehension (grasping/seizing)
   - Mastication
   - Motility
2. Chemical breakdown:
   - Secretion
   - Digestion
3. Absorption
4. Metabolism
5. Egestion

Question 4

What is Prehension?

Answer 4

1. Getting something into your mouth

lips, tongues, teeth

Question 5

What is Mastication

Answer 5

Chewing

Question 6

What is Motility

Answer 6

Movement of the gut - can change with chemicals

Question 7

What is digestion (strictly speaking)

Answer 7

chemical breakdown (done by enzymes) of substances

Question 8

What is the difference between egestion and excretion

Answer 8

egestion: get rid of substances that has never been absorbed in the first place
excretion: get rid of substances that have been absorbed into the blood stream

Question 9

What are the roles of 
a) teeth
b) salivary glands
c) Stomach
d) Liver/ gall bladder/ pancreas
e) SI
f) LI
in digestion

Answer 9

a) teeth - mechanical breakdown
b) salivary glands - secretion
c) Stomach - motility/ secretion
d) Liver/ gall bladder/ pancreas - secretion
e) SI - motility/ digestion/ absorption
f) LI - motility/ fermentation/ absorption/ egestion

Question 10

What are the digestive processes in the head?

Answer 10

1. Prehension
   - movement of food into oral cavity (lips, tongue, teeth, head movement)
2. Mechanical Breakdown
   - mastication (reduce size food particles
3. Salivation
   - Mucous to lubricate food
   - saliva contains amylase in some species to start the digestion of carbs

Question 11

What are 3 types of salivary gland

Answer 11

1. mandibular - around jaw
2. buccal - cheek area
3. sublingual - under tongue
   mixture of

Question 12

What are the different types of salivary secretions?

Answer 12

1. Serous- if saliva secreted to fill up a part of GI to create good environment for digestion to occur
2. mucous - enable lubrication of food so it can pass easily down GI

Question 13

What is the main type of saliva in the complex stomached animals

Answer 13

1. complex = ruminants

2. Mainly serous saliva to provide optimum conditions for fermentation

Question 14

What is the composition of saliva?

Answer 14

• dependant on diet and which glands are stimulated*
  1. Mucin (+ water = mucus)
  2. amylase (omnivores/ horses NOT carnivores/ ruminants)
  3. Bicarbonate (neutralise/ buffering = create constant pH for digestion)
  4. Phosphate (buffering) (ruminants)
  5. Lysozyme/ antibodies (reduce infection = prevent bacteria)
  6. Protein binding tannins (leaf and bud eaters)
  7. Urea (ruminants)

Question 15

How is salivary secretion and digestive juices secreted

Answer 15

1. SS = only neural
   sympathetic - reduced, para = increased
2. DJS = neural and hormonal

Question 16

what are the 2 pathways for the neural reflex to secrete saliva

Answer 16

1. conditioned (learned)
   - pavlov dog
   - initiated by repeated sensory stimuli associated with feeding
2. Congenital (innate)
   - initiated by taste, smell, food in mouth

Question 17

Motility

Answer 17

1. applies to all aprts of GI tract
2. too quick = diarrhoea
3. too slow = constipaition

Question 18

What are the types of motility

Answer 18

1. Segmental contractions: mix food
2. Peristalsis = gradual movement from mouth to anus
3. Anti-peristalsis: back up to mouth: protection: vomiting
4. Mass movement: large intestinal thing only

Question 19

What are the three main components of enzymes in digestion

Answer 19

1. carbohydrates: hydrolysable and non: amylase, disaccharidases
2. protein: pepsin, trypsin, peptidases
3. fat: lipase, phospholipase