Digestive System Flashcards
1
Q
What is the digestive system of poultry referred to as?
A
Very simple but efficient.
2
Q
Why is the avian digestive system simple?
A
To allow for flight, as a simpler digestive system is lighter.
3
Q
What kind of diet do fowl need?
A
High quality and easily digestible.
4
Q
What is the digestive system responsible for?
A
- Ingestion of food.
- Breakdown of food into its constituent nutrients.
- Absorption of nutrients into the bloodstream.
- Elimination of waste.
5
Q
What is the alimentary canal?
A
A long, tube-like organ that starts at the beak and ends at the cloaca.
6
Q
What are the orientations of the muscles surrounding the alimentary canal?
A
Longitudinal and perpendicular.
7
Q
What is the inside of the alimentary canal lined with?
A
Mucous membranes.
8
Q
What happens after food in the alimentary canal has been digested?
A
It is absorbed through the walls and into the circulatory system to be transported to the liver or other parts of the body.
9
Q
What happens to the remaining waste after absorption?
A
It is eliminated via the cloaca.
10
Q
What is the beak?
A
An area of horny and dense skin lying over the mandible and incisive bones.
11
Q
What is the egg tooth?
A
A keratinous point that allows newly hatched chicks to escape
12
Q
How long does the egg tooth last?
A
24-48 hours.
13
Q
What is the hard palate?
A
A long, narrow median slit that forms the roof of the mouth and communicates with the nasal cavity.
14
Q
What does the hard palate have 5 transverse rows of?
A
Backwards pointing, hard, conical papillae.
15
Q
The ducts of what glands pierce the hard palate?
A
The salivary glands.
16
Q
What kind of tissue covers the free surface of salivary glands?
A
Stratified squamous epithelium.
17
Q
What do the salivary glands of the hard palate merge to form?
A
One mass of glandular tissue.
18
Q
Where are the palatine salivary glands located?
A
One either side of the nasal opening in the roof of the mouth.
19
Q
What are the 7 salivary glands?
A
- Maxillary.
- Palatine.
- Apheno-pteryoid.
- Posterior sub-mandibular.
- Lingual.
- Circo-arytenoid.
- Anterior sub-mandibular.
20
Q
Where are the maxillary salivary glands located?
A
The roof of the mouth.
21
Q
Where are the apheno-pteryoid salivary glands located?
A
In the roof of the pharynx on each side of the common opening for the eustachian tubes.
22
Q
Where are the anterior sub-mandibular salivary glands located?
A
In the angle formed by the upper and lower beak.
23
Q
Where are the posterior sub-mandibular salivary glands located?
A
In the angle formed by the upper and lower beak.
24
Q
Where are the circo-arytenoid salivary glands located?
A
Around the glottis.
25
Where are the lingual salivary glands located?
In the tongue.
26
What structure is continuous with and follows the mouth?
The pharynx.
27
What is the oropharynx?
The mouth + the pharynx.
28
What is the tongue in poultry described as?
1. Pointed.
2. Long.
3. Conformed to the shape of the beak.
29
What is the epithelium of the tongue described as?
1. Horny.
2. Thick.
*Especially towards the tip.
30
What is located on the posterior end of the tongue?
A transverse row of large, simple, rear-facing, horny papillae.
31
What bone provides the framework for the tongue?
The hyoid bone.
32
In what plane does the entoglossal bone extend?
Longitudinally in the median plane.
33
Which directions are the mucous glands of the tongue pointed?
Rearward.
34
How strong is a bird's sense of taste?
Very weak if present at all.
35
What are the 2 major functions of the mouth?
1. Pick up food.
2. Direct food in to the esophagus.
36
What is the esophagus capable of?
Significant stretching.
*Is already wide.
37
What is the esophagus in close association with?
The trachea.
38
How many layers of tissue compose the wall of the esophagus?
4.
39
What is the innermost layer of the esophageal wall composed of?
Mucous membrane.
40
What is the mucous membrane a barrier against?
Microbes.
41
What does the mucus act as?
A lubricant that aids in the passage of food.
42
What does the esophagus connect the mouth to?
The crop.
43
What is the crop?
A large dilation of the esophagus.
44
Where is the crop located?
Just before the esophagus enters the thoracic cavity.
45
What is the function of the crop?
Hold food before further digestion, allowing for periodic feeding but continuous digestion.
46
Are there glands in the crop in chickens?
No.
*Ducks and geese do.
47
What is unique about pigeons?
Surface cells in the crop slough off during brooding, forming pigeon milk.
48
After the crop, what structure does the esophagus enter/become?
The proventriculus/glandular stomach.
49
How is the proventriculus described?
1. Small.
2. Tubular.
3. Thick-walled.
50
How many layers compose the wall of the proventriculus?
5.
51
What are the 5 layers that compose the five layers?
1. Outer serous membrane.
2. Muscle layer composed of:
a. Areolar tissue containing blood and lymph vessels.
b. Thick layer composed mainly of glandular tissue.
c. Mucous membrane.
52
What forms the greater part of the thickness of the proventriculus?
Glands.
53
What do the proventriculus glands produce?
Enzymes for breaking down food into its constituent nutrients.
54
What does the mucous membrane in the proventriculus look-like?
Raised folds that contains glands that secrete HCL.
55
What is the function of HCL?
To neutralize the alkaline coating on the food from the saliva.
56
What is located directly after the proventriculus?
The muscular stomach or gizzard.
57
What is the gizzard described as?
1. Flattened.
2. Round shape.
3. Convex lens-like.
4. One side is slightly larger than the other.
58
What is the gizzard covered by?
Tendinous tissue that thins at the edges.
59
What kind of tissue is found underneath the tendinous tissue?
Very powerful red muscle.
60
What is the inner surface of the gizzard described as?
1. Creamy-colored.
2. Horny with raised ridges.
3. Thick.
61
What does the gizzard sometimes contain?
Hard objects that aid in the disintegration of food.
62
What is the innermost layer of tissue that forms the gizzard wall described as?
1. Strong.
2. Flexible.
*Able to withstand the presence of the hard objects and the mechanical breakdown of food.
63
What kind of substance do glands in the gizzard produce?
A liquid form of keratinized material that continuously replaces the innermost lining of the gizzard due to wear and damage.
64
Where does the small intestine begin and end?
Start: The exit from the gizzard.
End: The ceca/colon.
*Constant diameter the entire way.
65
What are the three parts of the small intestine?
1. Duodenum (easily distinguishable in fowl).
2. Jejunum.
3. Ileum.
66
What are 3 functions of the small intestine?
1. Site of much of food absorption.
2. Produce a number of enzymes involved in the digestion process.
3. Site of much of food digestion.
67
Why does the small intestine take on a velvety appearance when submerged in water?
Due to the presence of villi.
68
What are villi?
Long, flattened, fingerlike projections that extend into the lumen of the small intestine.
69
What is the function of villi?
To increase the surface area of the small intestine, allowing for more efficient absorption. Also improves nutrient collection ability once it has moved through the small intestine wall.
70
What type of cells are villi?
Simple columnar epithelium and goblet cells.
71
What is the primary function of goblet cells?
To secrete mucus.
72
What is found at the core of each villi?
1. Lacteal (lymph vessels).
2. Bundles of plain muscle.
3. Capillaries.
4. Nerves.
5. Other.
73
What is the name of the membrane that suspends the jejunum and ileum from the dorsal wall of the abdomen?
The mesentery.
74
What does the mesentery contain?
Blood vessels associated with the intestine.
75
Where does the duodenum begin?
At the exit of the gizzard.
76
What shape does the duodenum form?
A loop.
77
What lies in the center of the loop formed by the duodenum?
The pancreas.
78
What things enter the small intestine via a common papilla at the caudal end of the duodenum?
1. Bile ducts.
2. 2-3 pancreatic ducts.
79
What is different about the the villi in the jejunum and ileum?
They are shorter.
80
What is Meckel's Diverticulum?
A small projection halfway along the small intestine that is a remnant of where the yolk sac was attached.
81
How does the large intestines size compare to that of the small intestine?
Lengthwise it is much shorter, width wise it is the same.
82
What does the large intestine run a nearly straight line to?
The cloaca.
83
What is the large intestine sometimes divided into?
The colon and rectum.
84
What is the bursa of Fabricius?
A structure located immediately above the cloaca that is critical to B-cell development that disappears when the bird reaches one year of age.
85
What are the ceca described as?
Blind pouches that extend alongside the small intestine towards the liver.
86
What are the ceca attached to the small intestine by?
Mesentery.
87
What are the three parts of each cecum?
1. Narrow base w/ thick walls at the ileo-colic-cecal junction.
2. Thin walls in the middle.
3. Wide, blind, thick walled apex.
88
What are the four tissues layers contained in the ceca from outermost to innermost?
1. Serous membrane.
2. Outer longitudinal membrane.
3. Circular membrane.
4. Inner longitudinal muscle.
89
What is the cloaca?
A tubular cavity that opens to the exterior of the body and is common to the digestive and urogenital tract.
90
What are the three chambers of the cloaca?
1. Copradaeum.
2. Urodaeum.
3. Proctodaeum.
*There is no clear separation.
91
What is the copradeum?
A continuation of the colon and rectum.
92
What is the urodaeum?
Where the ureters and genital ducts open.
93
What is the proctodaeum?
The portion that opens to the exterior of the vent.
94
Where is the liver located in the body?
Ventral and posterior to the heart. Close to the proventriculus and spleen.
95
Which lobe of the liver is larger?
The right.
96
What color is the liver?
Dark brown.
97
During what period of time is the liver not dark brown?
The first 10-14 days of life due to absorbing lipids from the yolk as an embryo.
98
What is the weight of the liver in adult birds?
50g.
99
What is the covering of the liver called?
The capsule or gliosis.
100
Where is the gallbladder located?
Behind the right lobe of the liver, beneath the spleen.
101
How many bile ducts emerge from the right lobe of the liver and what does each connect to?
Two. One connects the gallbladder to the small intestine and the other connects the liver to the small intestine.
102
How are the right and left lobe of the liver connected?
By a series of ducts.
103
What are the 6 functions of the liver?
1. Bile formation (fats to fatty acid and glycerol).
2. Carbohydrate, protein, and lipid metabolism.
3. Production and destruction of blood cells.
4. Storage of glycogen, fat-soluble vitamins (ADEK), and fat.
5. Synthesis of plasma proteins and fibrinogen.
6. Detoxification of certain substances.
104
What are hepatocytes known for having a high rate of?
Destruction, but a good regenerative capability.
105
What are the two blood supply systems for the liver?
1. Colic artery.
2. Hepatic portal system.
106
What does the blood supplied by the colic artery allow for?
Normal maintenance of the liver.
107
What does the blood supplied by the hepatic portal system allow for?
The transportation of nutrients from the small intestine to the liver before distribution to the rest of the body.
108
What do the hepatic veins drain into?
The posterior vena cava.
109
What structures within the liver allow for the blood vessels of the hepatic portal system, capillaries of the arterial blood supply, and the hepatic veins to be in close association with one another?
Sinusoids.
110
What is bile made from?
Cells within the liver.
111
How does the bile made in the liver get into the gallbladder?
Minute canals in the tissues that eventually fuse to form the two bile ducts.
112
How many lobes does the pancreas have?
3.
113
Where is the pancreas located?
Between the arms of the duodenum.
114
What is the function of the 2-3 ducts running from the pancreas to the distal end of the duodenum?
To pass secretions.
115
What cells in the pancreas are less defined in poultry than in mammals?
The cells in the islet of Langerhans.
116
What are the two functions of the pancreas?
1. Produce pancreatic enzymes.
2. Produce insulin and glucagon.
117
Why do chickens need to continuously eat?
Due to their high metabolic rate.
*There is variability within flocks as to how frequently a bird will be seen picking up food.
118
How does the crop affect food restriction programs?
Due to its storage capacity, a longer period is needed to achieve the required degree of control.
*No relationship between length of food deprivation and amount of food consumed.
119
What is the time interval that chickens commonly eat in?
15 minutes.
120
When do chickens eat the most?
Sunrise and the late evening.
121
What ten factors affect food intake and rate of movement through GI tract?
1. Age.
2. Live weight.
3. Health status of the flock.
4. Environmental temperature.
5. Water quality.
6. Water temperature.
7. Energy content of food.
8. Egg production.
9. Food texture.
10. Level of other key nutrients.
122
How long does it take for food to pass through young stock?
4 hours.
123
How long does it take for food to pass through laying hens?
8 hours.
124
How long does it take for food to pass through broody hens?
12 hours.
125
Which type of grain is easier to digest, intact or cracked?
Cracked.
126
What enzyme is found in saliva?
Amylase.
*Minimal enzyme action.
127
What is secreted in the proventriculus and why?
1. HCL, pepsin, lipase, amylase,
2. To lower the pH, to act on protein, to act on lipids, to act on carbohydrates.
128
What hormone stimulates the secretion of gastric juices in the proventriculus and pancreatic juice from the pancreas?
Gastrin.
129
What enzymes are present in the duodenum?
1. Chymotrypsin.
2. Trypsin.
3. Amylase.
4. Lipase.
5. Carboxypeptidase.
6. Collagenase.
7. Cholesterol esterase.
130
In what two ways does the gizzard help with enzymatic activity?
1. It breaks the food into smaller pieces, making them easier to digest.
2. It mixes the enzymes with the food, improving their ability to do their work.
131
Where does bile and pancreatic enzymes enter the duodenum?
The distal end, but backflow occurs that places the bile and enzymes near the proximal end.
132
What does the pancreas release in addition to digestive enzymes?
1. Insulin.
2. Glucagon.
3. Sodium Bicarbonate.
133
What enzymes does the small intestine produce?
1. Peptidase.
2. Maltase.
3. Lactase.
4. Sucrase.
134
What happens to food material that escapes enzymatic activity?
They are subjected to bacterial breakdown in the ceca.
*Allows for at least partial nutrient recovery.
135
What is mixed in the cloaca?
Urine, undigested food, and waste.
136
What is the typical consistency of poultry feces?
Brown to grey, rounded, topped with white uric acid.
*Occasionally brown, glutinous material.
137
How many grams of feces per day does a laying hen produce in grams?
100-150.
138
What is the water content of fresh droppings? Dry?
1. 75%.
2. 30%, under favorable conditions.
