GI Tract

Question 1

What are the 6 parts of the GI system?

Answer 1

1. Mouth
2. Esophagus
3. Stomach
4. Small intestine
5. Large intesine
6. Anus

Question 2

What is another name for the gastrointestinal tract?

Answer 2

Digestive tract or alimentary canal

Question 3

What is another name for the mouth? What is its function

Answer 3

AKA: oral cavity
Function: Where food is take into the body

Question 4

Define: Soft palete

Answer 4

Tissue that separates the oropharynx and nasopharynx, prevents food from going into the nasal passageways when swallowing

Question 5

Define: Hard palate

Answer 5

Bony partition between the mouth and nose

Question 6

Define: Oropharynx

Answer 6

The part of the pharynx between the tongue and the soft palate

Question 7

What is the function of the salivary glands

Answer 7

To secrete saliva (mandibular, submandibular, parotid)

Question 8

What is the fucntion of the teeth

Answer 8

Used for biting/mastication

Question 9

Define: Mastication

Answer 9

Chewing

Question 10

How does the mouth contirbute to the GI tract?

Answer 10

• Starts mechanical digestion of food by increasing the surface area of the food by chewing
• Chemical digestion of food is accomplishe by secretion of enzymes that help to break down sugar, fat, and protein
• Bolus is created, then passed through the esophagus
• Plays a KEY role in coolin off dogs via the evaporation of salvia, thereby cooling blood in mucus membranes

Question 11

Define: Bolus

Answer 11

Ball of food

Question 12

Define: Esophagus

Answer 12

Tubular organ that connects the mouth to the stomach

Question 13

Anatomy of the Esophagus

Answer 13

• 2 layer of lining: mucos and submucosa
• 2 layers of mucsle: longitudinal and circular

Question 14

What are the functions of the Esophagus

Answer 14

• Moves food through peristalsis:
  
  • The bolus is moved through the esophagus in this manner until it reaches the stomach

Question 15

What are the 4 compartments in the ruminant stomach in order? Examples of ruminant species

Answer 15

1. Reticulum
2. Rumen
3. Omasum
4. Abomasum

Ruminants: Cow, sheep, goats

Question 16

What are the 3 parts in the ruminant stomach in order? Examples of Monogastric species

Answer 16

1. Fundus
2. Body
3. Antrum

Monogastic (single stomach): Dog, cat, horse

Question 17

What are the 4 functions (physiology) of the stomach

Answer 17

1. Further digest food by peristalsis
2. Produce hydrochloric acid (via parietal cells) which aids in the breakdown of food.
   
   • The pH of the stomach is tightly controlled by active transport
3. Enzymes, most notably pepsin, break down proteins into amino acids.
4. The stomach itself is not digested by its own secretions because it produces a layer of mucus
   containing mucin and bicarbonate to protect itself from acidity.

Question 18

Define: Peristalsis

Answer 18

alternating contraction and relaxation of the the muscles to push contents forward

Question 19

What is the function of the small intestine

Answer 19

• Peristalsis occurs
• Segmental contractions also take place here, moving contents more slowly through the system allowing for more contact time with the intestine and greater nutrient uptake.

Question 20

What are the 3 parts of the Small intestine in order?

Answer 20

1. Duodenum - upper small intestine which is connected to the stomach and on which the
   pancreas is attached
2. Jejunum – makes up the majority of the small intestine (middle segment)
3. Ileum - connects to the cecum

Question 21

What are the 2 functions (physiology) of the small intestine?

Answer 21

1. Absorb nutrients, water, vitamins, and electrolytes
   
   • Due to the large surface area created by the folds in the intestinal wall and the millions of villi along its surface
   • The villi themselves contain microvilli, which secrete digestive enzymes and absorb nutrients (the brush border)
2. Alter Fats, carbohydrates and proteins before absorption
   
   • Must be altered prior to absorption, through enzymes associated with the lumen or microvilli

Question 22

How are fats, carbohydrates, & proteins digested?

Answer 22

Fats: Emulsification and micelle formation

Carbohydrates:
- Ruminates: Via the fermentation process
- Monogastric animals: amylase, lactose, sucrase, maltase, isomaltase, and lactase convert carbohydrates into monosaccharides that are then absorbed across the brush border

Proteins: Enzymes made by the small intestine & pancreas known as proteases
- Help woth chemical digestion
- Break down proteins into amino acid chains that are then absorbed across the brush border

Question 23

What is the large intestine responsible for?

Answer 23

1. Recovery of fluid and electrolytes
2. store feces prior to elimination

Question 24

What are the 2 components of the large intestine? What are their functions in each species

Answer 24

1. Cecum: Blind sac, where the small and large intesine meet
   - Monogastric: Less developed
   - Ruminant: More advanced than monogastric animals, some ferentation
   - Hindgut: More developed than the small intestine in the horse and has a much greater capacity for absorbing nutrients
2. Colon
   - Monogastric: Tubulor organ that uses peristalsis and segmental contractions
   - Main functions:
   - Absorb nutrients and water not already absorbed by the small intestine
   - Store feces (rectum)

Question 25

What is a hindgut fermenter? What species?

Answer 25

Hindgut fermenter with large fermentation compartments in the cecum, colon, and rectum

Question 26

What is the function of the Anus

Answer 26

The sphincter muscle that controls defecation

Question 27

What are the 2 components of the Anus and their functions?

Answer 27

1. Interal Sphincter (under involuntary control)
   
   • Relaxes and allows for fecal material accumulation
   • Fecal material comes into contact with the anal mucosa and this stimulates the mucosal receptors
2. External sphincter (under voluntary control)
   
   • Mucosal receptors in the internal sphincter signal the need for defecation
   • Allows for voluntary control of defecation