Digestion

Question 0

Mouth-esophagus-crop

Answer 0

• mucus production

* amylase

Question 1

Beak and mouth

Answer 1

Beak: acquisition and apprehension
Mouth: ingestion and swallowing 
•Adapted to flight 
•Taste salt, bitter, and acid 
••Salivary glands for mucus and enzyme    secretion.

Question 2

Proventriculus

Answer 2

• mucus
• hydrochloric acid( lowers pH and denatures proteins).
• enzymes-pepsinogen( pepsinogen is an inactive form of pepsin).

Question 3

Eyes and prehension

Answer 3

Positioning of the eyes are capable of a “panoramic view with binocular vision. This allows for prehension with high accuracy”.
Huge eye ball and retinal surface relative to the brain.
High concentration of rod and cone cells for light detection: detection of dim light and bright colors are needed;(bright colors yellow/red on feeders and water; combs for reproduction). color is needed for good seeking and reproduction.

Question 4

Mouth

Answer 4

Beak: hard and fixed-no flexibility for manipulating feedstuffs.

Question 5

Mouth

Particle size:

Answer 5

Can not adapt to particle size and pellet size is dependent on bird age. Crumbles vs pellets. “Crumbles are fed during starter period then introduced to pellets”.

Question 6

Mouth

Answer 6

Birds pick up feed with beak and opens back of the mouth and rolls it’s tongue to place feed to the back of the mouth.

Question 7

Mouth

Answer 7

Fine or sticky particles can be a problem. Less energy is used for prehension than with pellets.

Question 8

Esophagus

Answer 8

Contains crop (lower). Crop acts as a storage pouch. 
There is also mucus production in the esophagus but none in the crop.

Question 9

Pancreas

Answer 9

Has exocrine and endocrine function

Question 10

Proventriculus

Answer 10

Functions very similar to stomach

Question 11

Jejunum

Answer 11

Runs from end of duodenal loop to the meckels diverticulum. Then ileum and small intestine to ileocecal junction and cecal tonsils.

Question 12

Absorption

Answer 12

Occurs at duodenum and jejunum

Question 13

Specific enzymes are pH dependent and pH _________.

Answer 13

Increases along digestive tract.

Question 14

What happens if nipple waterers are too high?

Answer 14

The birds will have to stretch which will result in water going down the trachea and the birds will back off feeding and water.

Question 15

Beak and eyes

Answer 15

Eye is very large compared to head, so birds have large surface area.
Beak is very hard so it can not adjust we’ll to pellet feed size.

Question 16

Crop

Answer 16

•Functions mainly as food storage.
-no mucus glands (very little amylase).
•digestive activity is small.
-starch

Question 17

Protein digestion

Answer 17

Stomach/Proventriculus 
•HCL (is a strong acid and will drop pH)
   - secreted from parietal cells
   - denaturization of protein
   - HCL denature proteins, activate 
     Pepsin, pepsin cleaves peptide 
     Bonds. 
•pepsinogen 
   - secreted by chief cells. 
   - activation requires HCL and Pepsin
   - pepsin cleaves peptide bonds. 
   - ( on eve pepsinogen is activated by 
        HCL it becomes pepsin and will
       Cleave peptide bonds in the 
       Middle of chains).

Question 18

Gastric degestion

Answer 18

Goals: destroy physical integrity of feedstuffs and improve enzyme access.
First stage of digestion = proteolysis
(Proteolysis is the first stage of digestion. Upon a very low pH, protein denaturation occurs. Proteins unfold and peptide bonds are cleaved).
Very low pH (HCL)= protein denaturation, unfolding of proteins, and cleavage of peptide bonds (pepsin).

Question 19

Gastric digestion

Answer 19

Proventriculus: produces HCL and pepsinogen and (pepsin cleaves protein into peptides). ( chief cells are producing pepsinogen).
Gizzard: physical grinding with formal digestion

Question 20

Proventriculus

Answer 20

• ovoid egg shaped structure located between the lower esophagus and gizzard. (HCL is produced by periateal cells and pepsin is produced by chief cells)
• gastric glands located in the mucosa
• mucosa contains oxynticopeptic cells, tertiary, secondary, and primary ducting.

Question 21

Gizzard

Answer 21

• organ that is equipped with both large and small muscles.
• grinding is performed by the larger or thicker muscles.
• smaller muscles position luminal contents for particle size reduction and gastric digestion.

Question 22

Gizzard

Answer 22

• lumen contents undergo abrasion and smaller particles enter the small intestine by contraction of muscles.
• grit in the gizzard improves digestion when birds are consuming whole or coarse grains.
• providing grit provides little advantage when birds are consuming mash diets.

Question 23

Pancreas

Answer 23

(Pancreas secretes insulin and glucagon. “Endocrine” no ducts required to reach target tissue. •amylase, protease, lipase requires ducts to reach target tissues “exocrine”

Question 24

Pancreas secretes

Answer 24

•bicarbonate 
•alpha amylase (starch to glucose) 
•zymogens target proteins and peptides ( trypsin, chymotrypsin, an elastase).
•exopeptidases 
   - carboxypeptidases A and B
•collagenases

Question 25

Functions of the pancreas

Answer 25

Exocrine: supply digestive enzymes for fat, protein, and starch digestion.
   - pancreas is 82% acinar cells on a  
     Volume basis. 
   - acinar cells secrete zymogens and 
     Inactive enzymes into the 
     Pancreatic duct. 
• endocrine: produce glucagon and insulin (hormones) that are utilized in energy metabolism. 
   - islets of langerhans cells produce 
     These hormones, but are they less 
     Than 2% of the pancreas on a 
      Volume basis.

Question 26

Small intestine

Answer 26

Major site of digestion and absorption.
Three segments ( duodenum, jejunum, ileum).
Lined with villi and microvilli ( where absorption will occur).
Short with high passage rate.
•• Exo= cleaving outside AA
Endo= cleaves inner AA
HCL activates pepsinogen and denatures proteins. Pepsin cleaves peptide bonds. Gizzard = mechanical grinding.

Question 27

Small intestine

Answer 27

Site of majority digestion occurs as we’ll as significant amount of nutrient absorption.
Goal: large proteins and peptides from the gizzard must be broken down into small peptides and amino acids for absorption.
Enzymes from the pancreas and small intestine play a central role.
•• growth and body weight during first few days is dependent on small intestine development.

Question 28

Digestion: small intestine functions to

Answer 28

Break down of:
-proteins to amino acids 
-carbohydrate to sugars 
-fats to fatty acids 
• mucus and bicarbonate increase pH 
( moving from low to higher pH) Proventriculus =2 
Small intestine= 8

Question 29

Small intestine

Answer 29

Goblet cells: mucin production
• direct absorption into portal blood system to liver
• epithelium has high rate of regeneration
• fate of sloughed cells
• production of globular leukocytes ( si does play a role in the immune system.

Question 30

Protein digestion

Answer 30

Duodenum
Pancreas
- trypsinogen produced (activation requires enterooeptidase at pH of 8.
- chymotrypsinogen (activation requires trypsin)
- precarboxypeptidase ( activation requires trypsin)
•••

Question 31

Protein digestion

Answer 31

Duodenum
Mucosal cells
- enterooeptidase (activates trypsinogen/initiates cascade)
- aminopeptidase ( exopeptidase for terminal end).
- dipeptidase ( dipeptide cleavage)

Question 32

Nutrient absorption

Answer 32

Passive transport (diffusion by concentration from high to low) 
Active transport (requires carrier and energy) 
Numerous pathways

Question 33

Protein absorption

Answer 33

For example:
Free amino acids peptides and dipeptides are absorbed in the jejunum and upper ileum.
Specific carriers exist for active or passive transport of amino acids

Question 34

Digestion

Answer 34

Liver= bile production, gall bladder.

Intestinal mucosa= brush border, numerous enzymes complete breakdown.

Question 35

Carbohydrate digestion

Answer 35

Must be broken down into monosaccharide(alpha amylase) for absorption from the digestive system.
Primarily enzymatic breakdown

Question 36

Lipid digestion

Answer 36

Enzymatic lipase (fat/oil) 
Micelle formation 
Transported to liver
- receptor 
- synthesis 
Transported to target tissue

Question 37

Ceca

Answer 37

•Paired blind ended tubes at the junction of small and large intestine
• three regions 
- narrow neck 
- wide body 
- rounded end 
•Microbial fermentation (microbes) 
•Villi like projections for adsorption 
Size proportional to amount of fiber intake

Question 38

Large intestine or colon

Answer 38

Short and small

Villi projections for water absorption

( digesta is we’ll over 90% water)

Question 39

Cloaca

Answer 39

Common chamber where digestive and Uro genital tracts converge

Reservoir for feces and urine

Useful tool for expulsion