GI System Flashcards

1
Q

What are the digestive organs of the GI

A

Oesophagus
stomach
small I
Large I

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2
Q

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

A

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

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3
Q

What is a brief overview of digestion?

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

What is Prehension?

A
  1. Getting something into your mouth

lips, tongues, teeth

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5
Q

What is Mastication

A

Chewing

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6
Q

What is Motility

A

Movement of the gut - can change with chemicals

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7
Q

What is digestion (strictly speaking)

A

chemical breakdown (done by enzymes) of substances

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8
Q

What is the difference between egestion and excretion

A

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

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9
Q
What are the roles of 
a) teeth
b) salivary glands
c) Stomach
d) Liver/ gall bladder/ pancreas
e) SI
f) LI
in digestion
A

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

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10
Q

What are the digestive processes in the head?

A
  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
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11
Q

What are 3 types of salivary gland

A
  1. mandibular - around jaw
  2. buccal - cheek area
  3. sublingual - under tongue
    mixture of
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12
Q

What are the different types of salivary secretions?

A
  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
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13
Q

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

A
  1. complex = ruminants

2. Mainly serous saliva to provide optimum conditions for fermentation

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14
Q

What is the composition of saliva?

A
  • 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)
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15
Q

How is salivary secretion and digestive juices secreted

A
  1. SS = only neural
    sympathetic - reduced, para = increased
  2. DJS = neural and hormonal
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16
Q

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

A
  1. conditioned (learned)
    - pavlov dog
    - initiated by repeated sensory stimuli associated with feeding
  2. Congenital (innate)
    - initiated by taste, smell, food in mouth
17
Q

Motility

A
  1. applies to all aprts of GI tract
  2. too quick = diarrhoea
  3. too slow = constipaition
18
Q

What are the types of motility

A
  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
19
Q

What are the three main components of enzymes in digestion

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