Virtual Chicken: Full Digestive System — Transcript

Full transcript

1. 0:04[Music]
2. 0:05the gastrointestinal tract of an avian
3. 0:08is unique in comparison to those of
4. 0:10mammals
5. 0:12it contains an intestinal tract that is
6. 0:14shorter than that of mammals the
7. 0:16digestive tract begins with the mouth
8. 0:20chickens don't have teeth or jaw muscles
9. 0:23instead they use a lightweight beak to
10. 0:25swallow food particles whole
11. 0:28these particles are later broken down by
12. 0:30the ventriculus or the gizzard which is
13. 0:33located within the body cavity
14. 0:35the upper beak is covered in hard
15. 0:37keratin
16. 0:42next is the tongue which is used for
17. 0:44collecting moving and swallowing food
18. 0:48the tongue which is covered in lateral
19. 0:50barbs is used to brush food to the back
20. 0:54salivary glands are less developed in
21. 0:57birds but are present at the roof of the
22. 0:59mouth
23. 1:00they secrete mucus which lubricates the
24. 1:03food and allows it to move down the
25. 1:05esophagus
26. 1:06taste buds are located in the upper beak
27. 1:09and are also in small numbers on the
28. 1:11anterior of the tongue
29. 1:14chickens have up to 300 taste buds
30. 1:17behind the tongue is the laryngeal mound
31. 1:20that contains a narrow slit that opens
32. 1:22into the glottis of the larynx
33. 1:25its function is to aid in moving food
34. 1:27toward the esophagus during swallowing
35. 1:30[Music]
36. 1:34the esophagus of a chicken is a
37. 1:36thin-walled expansive tube that
38. 1:38transports food from the mouth of the
39. 1:40pharynx to the stomach
40. 1:44as food is moved towards the back of the
41. 1:46tongue the koana reflexively closes
42. 1:49in the pharyngeal phase the infundibular
43. 1:52mound and glottis close
44. 1:56the tongue is moved backward and the
45. 1:58esophagus is moved forward decreasing
46. 2:00the distance between the oral cavity and
47. 2:02the esophagus
48. 2:05the avian esophagus allows birds to
49. 2:07swallow their food whole
50. 2:09its walls are made up of four layers
51. 2:12mucosal submucosal
52. 2:15muscle tunic and the serosa layer which
53. 2:18contains only smooth muscle cells
54. 2:21in addition the esophagus is divided
55. 2:23into two sections
56. 2:25the cervical near the beak and the
57. 2:28thoracic region near the crop
58. 2:30the esophagus is lined with epithelium
59. 2:33tissue which contains mucous glands
60. 2:36these glands are more numerous in the
61. 2:38thoracic esophagus while being absent in
62. 2:40the cervical region
63. 2:42food is moved through the esophagus via
64. 2:45the excitement of the myenteric plexus
65. 2:47nerve rather than the muscles
66. 2:52in the chicken digestive system the crop
67. 2:54is an extension of the esophagus
68. 2:56it's a thin walled pouch at the base of
69. 2:58the thoracic section of the esophagus
70. 3:01the walls and lining of the crop are
71. 3:03made up of the same four layers as the
72. 3:05esophagus the mucosal submucosal muscle
73. 3:09tunic and the cerosal layer
74. 3:12the main function of the crop is to hold
75. 3:14food in storage until it can be released
76. 3:16to the stomach or the pro-ventriculus
77. 3:19the crop fills only after the
78. 3:21pro-ventriculus is full
79. 3:24food can remain in the crop for up to 12
80. 3:26hours until it is transferred via
81. 3:29peristalic action
82. 3:31no actual digestion takes place in the
83. 3:33crop as there are no digestive chemicals
84. 3:36secreted there to begin the process
85. 3:38however softening and swelling of the
86. 3:41feed will occur during the storage time
87. 3:44this can lead to a condition called sour
88. 3:46crop where the contents of the crop
89. 3:48ferment and a bacterial yeast infection
90. 3:51can occur
91. 3:54after the food leaves the crop via
92. 3:56peristolic action it moves into the
93. 3:58proventriculus
94. 4:00also known as the true stomach the
95. 4:03pro-ventriculus is where actual
96. 4:04digestion begins
97. 4:07the walls of the pro-ventriculus are
98. 4:09thick and composed of five layers
99. 4:11a muscle layer itself composed of three
100. 4:14individual layers
101. 4:16a thick layer of glandular tissue and
102. 4:19the inner mucous membrane layer
103. 4:21the glandular tissue produces secretions
104. 4:24which begin the process of
105. 4:26digestion these secretions include
106. 4:29hydrochloric acid which lowers the ph of
107. 4:32the digestive system and food mixture
108. 4:34the enzyme pepsin which helps break down
109. 4:37protein
110. 4:38and the hormone gastrin which stimulates
111. 4:41gastric and pancreatic juice production
112. 4:44the acid and digestive enzymes in the
113. 4:47proventriculus break down food more
114. 4:49significantly than the enzymes secreted
115. 4:51by the salivary glands
116. 4:53but at this point the food has not yet
117. 4:55been ground only softened before it
118. 4:58moves to the gizzard
119. 5:02the gizzard or ventriculus is the
120. 5:04muscular stomach where the grinding of
121. 5:06food takes place
122. 5:08after being softened by the
123. 5:10proventriculus
124. 5:11food moves into the gizzard
125. 5:14it's a round organ with two lobes one
126. 5:16larger than the other
127. 5:18each surface of the gizzard is covered
128. 5:20by a shiny layer of tendinous tissue
129. 5:23which is thicker at the center and
130. 5:25thinner out by the edges
131. 5:27under this outer layer are located very
132. 5:30powerful masses of red muscle
133. 5:32the inner surface is lined with a creamy
134. 5:35colored thick horny tissue raised in
135. 5:37ridges
136. 5:39this surface acts as the bird's teeth
137. 5:41and is made up of a strong keratinized
138. 5:43material called coilin that is able to
139. 5:46withstand the potentially damaging
140. 5:48effects of the hydrochloric acid and
141. 5:50pepsin coming from the pro-ventriculus
142. 5:52and the muscular action of grinding food
143. 5:55as the coiling wears down from the
144. 5:57grinding action glands in the gizzard
145. 6:00produce more coiling that passes to the
146. 6:02surface where it hardens to replace the
147. 6:04worn tissue
148. 6:06though the gizzard consists of very
149. 6:08powerful muscles it alone can't
150. 6:10pulverize everything the typical bird
151. 6:12eats
152. 6:13grit and small rocks are picked up as
153. 6:16birds peck and feed
154. 6:18this mineral matter accumulates in the
155. 6:20gizzard
156. 6:21and the particles help pulverize the
157. 6:22seeds and grain
158. 6:24once the food is ground it passes into
159. 6:27the small intestine
160. 6:29feed passes from the gizzard into the
161. 6:31small intestine where digestion and
162. 6:33absorption occur
163. 6:35the small intestine of a mature chicken
164. 6:38is more than four and a half feet in
165. 6:39length and has three distinct areas
166. 6:43the duodenum or the duodenal loop where
167. 6:45the pancreas lies in the center the
168. 6:48jejunum
169. 6:49and the ilium
170. 6:51collectively the jejunum and ilium are
171. 6:54called the lower small intestine
172. 6:57as food leaves the gizzard and enters
173. 6:59the duodenum hormones are released which
174. 7:02signal the pancreas to release digestive
175. 7:04hormones and bicarbonate
176. 7:10this acts to dilute the hydrochloric
177. 7:12acid from the proventriculus
178. 7:14the enzymes trypsin and chymotrypsin
179. 7:17digest proteins
180. 7:18amylase breaks down carbohydrates and
181. 7:21lipase breaks down fat
182. 7:24insulin and glucagon hormones that
183. 7:27maintain blood glucose are also produced
184. 7:29in the pancreas
185. 7:31all these combine with bile from the
186. 7:33gallbladder in the common bile duct to
187. 7:36continue the digestive process
188. 7:40the saturated and ground-up food mixture
189. 7:42known as chyme moves through the jejunum
190. 7:45and then through the nearly four feet of
191. 7:47ilium where most of the released
192. 7:49nutrients are absorbed
193. 7:51inside the small intestine villi
194. 7:54flexible finger like protrusions line
195. 7:56the inner wall providing needed surface
196. 7:59area for adequate absorption of
197. 8:01nutrients like glucose calcium and
198. 8:03vitamin b12 and remaining products of
199. 8:06digestion not absorbed elsewhere
200. 8:10the large intestine at four inches in
201. 8:13length is actually shorter than the
202. 8:15small intestine
203. 8:16it runs in a nearly straight line below
204. 8:19the vertebra and ends at the cloaca
205. 8:22sometimes this section is referred to as
206. 8:24the colon the last of water reabsorption
207. 8:27occurs in this organ creating and
208. 8:30storing undigested waste material that
209. 8:32is eventually excreted through the
210. 8:34cloaca
211. 8:38the sica are two blind pouches located
212. 8:41where the small and large intestines
213. 8:43join
214. 8:44some of the water remaining in the
215. 8:45digested material is reabsorbed here
216. 8:48additionally any remaining coarse
217. 8:51materials are broken down in the sika
218. 8:53through fermentation
219. 8:55during this fermentation process the
220. 8:57bacteria in the zika produce several
221. 9:00fatty acids as well as the eight b
222. 9:02vitamins
223. 9:03thiamine
224. 9:05riboflavin
225. 9:06niacin
226. 9:07pantothenic acid pyridoxine
227. 9:10biotin folic acid and vitamin b12
228. 9:15because the zika are located so close to
229. 9:17the end of the digestive tract however
230. 9:20few of those produce nutrients are
231. 9:21absorbed and available to the chicken
232. 9:26the large intestine connects to the
233. 9:28front part of the cloaca
234. 9:30this organ is a flexible cavity that
235. 9:32represents the junction of the digestive
236. 9:35and urinary tracts
237. 9:37in hens the reproductive tract also
238. 9:40joins at the cloaca
239. 9:42here digestive waste mixes with urinary
240. 9:45waste and passes out of the body through
241. 9:47the vent
242. 9:48the cloaca in chickens is also flexible
243. 9:51enough to accommodate an egg passing
244. 9:53through it from the reproductive system
245. 9:57[Music]
246. 10:05you