Unit 3 - Digestive System Flashcards
1
Q
What are the two types of breakdown processes?
A
Mechanical digestion -> gastrointestinal tract movements -> breakdown of the food into smaller parts
Chemical digestion -> reactions that break down bonds -> results into smaller molecules
2
Q
What is the GIT made up of?
A
Mouth, pharynx, esophogus, stomach, small and large intestine
3
Q
What are the accessory organs of the digestive system?
A
tongue, salivary glands, liver, pancreas, gall bladder
4
Q
What is the oral cavity?
A
Entrance of the GIT, contains the teeth, tongue and other structures needed for food ingestion
5
Q
What is the function of the mouth?
A
- preparation of food for swallowing
- prehension, mastication, insalivation
- intraoral “assessment” of ingested material
6
Q
What is the effect of forage particle size on chewing activity?
A
Rumination periods:
- high moisture corn and fine silage - less time
- high moisture corn and coarse silage - more time
Time chewing:
- high moisture corn and fine silage - less time
- high moisture corn and coarse silage - more time
7
Q
What is the effect of forage particle size on ruminal pH?
A
coarse silage: high pH
fine silage: low pH
8
Q
why does fine silage create a lower pH?
A
smaller particles have more SA per weight and therefore more microbes to break down food and therefore more acid produced
9
Q
What are the functions of the teeth?
A
- mastication or mechanical reduction in particle size
- facilitate swallowing
- increase surface area for chemical digestion by animal and microbial enzymes
10
Q
Which bones are the teeth embedded in?
A
Upper maxilla bone and lower mandibula bone
11
Q
What are the two types of muscles that make up the tongue?
A
Extrinsic muscles - anchor the tongue in place
Intrinsic muscles - make up the tongues majority mass
12
Q
What are the three anatomical regions that the tongue is divided into
A
Apex of the tongue
Body of tongue
Root of the tongue
13
Q
What are some characteristics of the apex of the tongue?
A
- freely movable
- only caudally attached to the floor of the oral cavity
- has 4 mucosa-covered surfaces: dorsal, 2 lateral borders and ventral surface
14
Q
What are some characteristics of the root of the tongue?
A
- attached to and supported by lingual process
- only dorsal surface is free and covered by mucosa
14
Q
What are some characteristics of the body of the tongue?
A
- ventrally anchroed to the mandible by the extrinsic lingual muscles
- has 3 surfaces
15
Q
What are the three types of papillae?
A
Lenticular
Conical
Vallate
16
Q
What is the function of the lenticular/conical papillae?
A
mechanical function, involving the mastication processing and digestion of food
17
Q
What is the function of the vallate papillae?
A
Taste function
18
Q
What is the gustatory furrow?
A
furrow in between papillae
19
Q
What is the function of the salivary glands?
A
- deposit saliva into oral cavity via ducts
20
Q
What is the function of saliva?
A
- lubrification
- antibacterial action
- pH regulation - ruminants
- digestion of carbohydrates
21
Q
What is saliva composed of?
A
water, electrolytes, antibodies, glycoproteins, bicarbonate, enzymes
22
Q
What is the function of salivary amylase?
A
monogastric - starts the breakdown of starchy carbohydrates in the mouth, in pigs amylase has significant importance
23
Q
What is special about ruminants’ saliva?
A
don’t have saliva that breaks down the food like alpha-amylase enzyme
24
What are the three animals that lack salivary amylase?
dogs, cats, ruminants
25
What happens to the saliva if the cow is not ruminating?
if a cow is not ruminating, and therefore not chewing/producing saliva, the pH level is dropped and can cause metabolic diseases
26
What are the main three salivary glands?
Sublingual salivary gland
Parotid salivary gland - located ventral to ear, produces most of the saliva
Mandibular salivary gland
27
What are some features of the pharynx/throat?
- common passage for food/air
- connects nasal and oral cavities with trachea and esophagus respectively
28
Where are the food/air separated in the throat?
air directed to ventral larynx during resp
food and water directed to dorsal esophagus during swallowing
29
What is the epiglottis?
A part of the pharynx/throat and the laryngeal cartilage, it covers the glottis during swallowing
30
What is the function of the epiglottis?
prevent the food to be aspirated into the trachea
31
What are some features of the esophagus?
collapsible, muscular tube that extends from pharynx to stomach, travels dorsal to the trachea until it reaches the thoracic cavity
32
What are the two layers of muscle that the esophagus contains?
Circular layer: inner
Longitudinal layer: outer
33
What is the muscle type variation between species?
skeletal muscle: horse, cattle, dogs
smooth muscle: cats, primates
34
What is peristalsis?
Waves of rhythmic, involuntary contractions of the smooth muscle in the esophagus to move food down
35
What are the two types of peristalsis?
One-way peristalsis - only down the esophagus
Two-way peristalsis - up and down the esophagus, done by ruminants
36
What is the function of the stomach?
1. storage of ingested food - enzyme break down
2. mechanical and chemical break down of the ingested food - decrease the particle size, increase the surface area
37
What are glandular vs non-glandular stomachs?
non-glandular - white, has no glands
glandular - pink, produces digestive enzymes and acids
38
What is a composite stomach vs a chambered stomach?
composite: one sac
chambered: more than one sac, divisions
39
What is special about pigs and horses stomachs?
composite stomach with both glandular and non-glandular tissues
40
What are the three main glandular regions of the stomach?
Cardia, fundus, pylorus
41
What is the function of the cardia?
- connects the esophagus to stomach
- glands produce a thick layer of alkaline mucus
- protects against gastric acid
42
What is the function of the fundus?
- region where the rugae is more prominent
- has capacity to expand as needed
- stores gas and food
- produces mucus to protect from gastric acid
43
What is the function of the pylorus?
- connects stomach to duodenum
- produces mucus that coats the stomach
- produces mucus to protect against gastric acid
44
What are the four functions of the simple stomach?
1. storage and mechanical breakdown of ingested food
2. controls the influx into the small intestine
3. secretes digestive juices - breakdown chemical bonds
4. production of intrinsic factors: facilitate vitamin B12 absorption in the small intestine
45
What are some characteristics of herbivores?
Conversion of eaten plants into usable molecules is dependent on fermentation that occurs in GIT
46
What are digestive differences between hindgut fermenters and ruminants
hindgut - well developed fermentation chamber (cecum)
ruminants - plant materials are partially broken down before reaching the true stomach
47
What are the four stomachs of a ruminant?
Rumen, reticulum, omasum, absomasum
48
Which ruminant stomachs are glandular/non-glandular?
Rumen, reticulum and omasum (first three) - non-glandular (no enzymes produced)
Abomasum - glandular (where digestive enzymes are produced)
49
What are some characteristics of the rumen?
- large expansible chamber, fermentation occurs
- occupies most of the left side of the abdominal cavity
- forces the organs to be placed on the right side
- presents structures represented by thick muscular bands, called pillars
50
What are the four sacs that the pillars divide the rumen into?
dorsal sac, ventral sac, blind dorsal sac, blind ventral sac
51
How are particles layered in the rumen?
small particles at the bottom and larger particles at the top, a gas cap sits at the most dorsal part of the rumen
52
What is the function of the rumen papillae?
extend the absorption surface of the products of the fermentation, vary in size and distribution throughout the rumen
53
What are the three types of contractions of the rumen/reticulum?
primary contractions, secondary contractions, third type
54
What is the function of primary contractions?
help ensure adequate movement of the contents back and forth between the reticulum and the rumen, it causes the separation of particles as well as forces the liquid content to the omasum
55
What is the function of secondary contractions?
associated with the rumination process
56
What is the function of third contractions?
involved in the eructation process, responsible to release gases produced during the fermentation process that occurs in the reticulorumen, important to avoid bloat
57
What are the three steps to rumination?
Regurgitation - contract to help the material go back to the mouth
Reinsalivation and remastication - important to reduce particle size and to produce saliva that helps to buffer ruminal pH
Reswallowing - when the bolus goes back down
58
What is bloat?
accumulation of gases that causes the expansion of reticulorumen
59
What is the issue with bloat?
- causes a compression on the thoracic and abdominal cavities
- reduces blood flow to the abdominal organs,
- compromise the lung function causing hypoxia
60
What are the two types of things in a ruminants diet?
Roughage (complex carbs) and grains (simple carbs - rapidly fermented, e.g. starch)
61
What are the main three VFA's?
Acetate, Propionate, Butyrate
62
What is the waste product of microbial metabolism?
VFA's
63
How does VFA concentration fluxuate?
total amount and proportion of VFA produced will vary according to diet, greater concentrate = greater the total VFAs because of less complex carbs
64
What are VFA's?
waste produced by microbial fermentation, absorbed in the rumen wall, they are processed in the liver and converted to glucose to produce ATP
65
How does the amount of VFA's affect the papillae?
more grain (concentrate) produces more VFA's and is quicker than feeding hay (roughage) therefore a greater amount of blood is needed to absorb these VFA's provides greater hormonal agents which leads to greater increase of the papillae
66
What are the characteristics of the reticulum?
- located cranially to the rumen
- rumen and reticulum freely connect to each other internally
- has numerous primary folds, approx 1cm high, called crests
- looks like a honeycomb
67
What is the function of the reticulum?
1. allow small particles to go to the omasum
2. leading to regurgitation of big particles
3. mastication will reduce the particle size
68
What are the characteristics of the omasum?
- located on the left between the rumen and the reticulum
- has a round shape in bovine and an oval shape in sheep
- absorption capacity of the omasal epithelium is similar to the ruminal papilla capacity
- gives a leafy aspect - increases absorptive SA
- most of the water and salt are absorbed in the omasum
69
What are the characteristics of the abomasum?
- pear-shaped sac that is bent on the abdominal floor
- a glandular compartment that is similar to the simple stomach of monogastric species
70
What are the 3 abomasum divided into?
fundus, body and pylorus
71
What can the abomasum be compared to?
simple stomach
72
What are the characteristics of a newborn ruminant?
- rumen, reticulum and omasum are small and non-functional
- no presence of microorganisms
- development occurs when the rumen-reticulum and omasum occur when the animal starts with a solid diet
73
What is the esophageal groove?
when calves drink milk, it directs the milk to the omasum because fermentation cannot occur as the epithelial of the rumen is not ready to absorb, temporary structure
74
What happens if milk goes into the rumen when the calf is not ready for it to?
fermentation of the milk will occur without absorption of nutrients in the epithelium and organic acids will cause bloating
75
What formulates the esophageal groove?
suckling actions and milk proteins stimulates formation of the groove
76
What are some characteristics of the small intestine?
- tube that carries chime from stomach and deposits it in the large intestine
77
What are the three parts of the small intestine?
- duodenum
- jejunum
- ileum
78
what is the characteristic of the duodenum?
part of the small intestine, starts at the pylorus of the stomach, has pancreatic and hepatic bile ducts to provide secretions to aid digestive process
79
What are the characteristics of the jejunum?
longest section in the small intestine and sit for most digestion and absorption
80
what are the characteristics of the Ileum?
extensive mucus secretion
81
What is the anatomy of the small intestine?
mucosa contains the plicae (folds that increase the absorptive SA), mucosa contains the villi (cells that helps to expand the SA), contains the microvilli which forms the brush boarder
82
What does the large intestine consist of?
cecum: blind sac with microbial ferrmentation
colon: with fermentation, VFA's produced and absorbed there
rectum: fecal storage
anal canal: anus as the exterior opening
83
What is special about the cecum and the colon of the horse and pig?
it is sacculated (appears segmented), this increases volume and retention time of digesta, it also maximizes the extent of microbial fermenation
84
What are some characteristics of the pancreas?
- extramural gland of the digestive system
- located outside lumen of GT, between stomach and small intestine
- it has duct that convey the pancreatic juice to duodenum
- the pancreatic duct enters proximal duodenum
85
What is the endocrine function of the pancreas?
produces hormones which are released in the blood stream
86
What are the three types of cells in the pancreas?
Alpha cells: produce the hormone glucagon (regulates blood glucose)
Beta cells: produce the hormone insulin (regulates blood glucose)
Acinar cells: functional unit of the exocrine pancreas. It synthesizes, stores and secretes digestive enzymes (activated only once they have reached he duodenum)
87
What are some characteristics of the liver?
- largest gland in the body
- located on the right side of the body under the diaphragm
- consists of four lobes suspended from the diaphragm and abdominal wall
- connected to a gall bladder via the common hepatic duct
88
What is the function of the liver?
- nutrient absorption
- detoxifies
- synthesizes bile salts
- stores vitamins, minerals and glycogen
- metabolizes carbs, proteins and lipids
89
What is the function of the gallbladder?
- used to concentrate and store bile which is needed for fat digestion
- enters proximal duodenum via a bile duct
90
What is the function of bile?
emulsifies lipids to enhance action of pancreatic lipase, breakdown of large globules of lipid into smaller more uniform particles, facilitate fat digestion and absorption
91
What are the four layers of the GI tract wall?
Mucosa
Submucosa
Muscular layers
Serosa
92
What are the three layers of the mucosa?
- Epithelium: in the mouth and anus it is stratified squamous epithelium
- Lamina propia: made of loose areolar connective tissue
- Muscularis mucosae: smooth muscle that helps make mucosa into folds for increased SA
93
What is the submucosa made of?
dense connective tissue
94
What are the muscular layers (GI tract wall) made up of?
inner circular and outer longitudinal
95
What is the serosa made up of?
loose connective tissue
96
Teeth structure?
*Found in cavities called alveoli
*Held in place by periodontal ligament
*Crown: part that projects above the gums (gingiva)
*Root: embedded in the alveoli below gingiva
*Apex: tip of tooth
*Neck: where crown and root meet
97
What are the three types of salivary glands?
parotid
mandibular
sublingual
98
What do the rumen pillars divide the rumen into?
dorsal sac
ventral sac
caudal sac
