Digestive System Flashcards
(161 cards)
1
Q
Prehension
A
Taking a hold of food/water into the oral cavity
2
Q
Mastication
A
Mechanical breakdown of food and mixing it with saliva in the oral cavity
3
Q
True or false:
When you swallow food, it is considered to be INSIDE the body
A
False
Good remains OUTSIDE of the body until it is absorbed
4
Q
Carnivores
A
Eats meat and no fibres
5
Q
How much fermentation does a carnivore have going on
A
Little to none
6
Q
Who is the one true carnivore
A
The cat
7
Q
Herbivore
A
Eats mostly plant matter
8
Q
How much fermentation is required for a herbivore
A
A lot
The will either have a large cecum (horses) or a rumen
9
Q
What is cellulose
A
The most abundant plant sugar
10
Q
True or false
There are mammalian enzymes that can break down cellulose
A
False
11
Q
What is needed to break down cellulose
A
Fermentation
12
Q
Omnivores
A
Eats both plants and meat
13
Q
How much fermentation is needed for omnivores
A
Some fermentation in an enlarged colon
14
Q
True or false
Dogs are considered omnivores
A
True
15
Q
Monogastric
A
Have a single true stomach
16
Q
Ruminants
A
Have one true stomach and 3 forestomachs including a large rumen/fermentation chamber
17
Q
Cecal or hindgut fermenters
A
Have a large cecum and sometimes a big large intestine for a fermentation chamber
18
Q
Name the 3 salivary glands and where they are
A
Parotid: below the ear canal caudal to the mandible
Mandibular: medial to the bones of the mandible
Sublingual: below the base of the tongue
19
Q
What enzymes are in saliva
A
Amylase
Lipase
Lysozyme
20
Q
What does amylase do
A
Breaks down amylose/starch
21
Q
True or false
Amylase is present in omnivores but not in dogs, carnivores and ruminants
A
True
22
Q
What does lipase do
A
Breaks down lipids
23
Q
What does lysozyme do? And what is it considered?
A
Considered a antibacterial enzyme
Breaks down bacteria
AIDS in cleaning the food
24
Q
A Function of saliva in dogs
A
Evaporative cooling (panting)
25
What does saliva help to do in ruminants
High amounts of sodium bicarbonate and phosphate buffers (with a high pH) help neutralize rumen acids from fermentation
26
What can cause acidosis in ruminants
Large amounts of carbohydrate feeds result in an increase in the process of fermentation and the build up of acids in the rumen
27
True or false
| Salivary fluid and buffers are recycled in ruminants
True
28
A row of teeth is called an
Arcade
29
A tooth is embedded in a socket, a socket is called an
Alveolus
30
The crown is the part of the tooth
Above the gums
31
The root is the part of the tooth
Below the gum in the alveolus
32
Internal structure of the tooth:
Enamel is the____
Dentin is the____
Pulp cavity is the___ and contains ___
Enamel is the outer surface of the tooth
Dentin is the majority of the tooth
The pulp cavity is the central cavity and contains blood vessels and nerves
33
The soft palate separates
The oropharynx(throat) and the nasopharynx
34
Two orientations of muscle in the esophagus
Longitudinal and circular
35
Explain Deglutition (swallowing)
Starts a voluntary action (tongue moves food to o the back of the throat)
Relaxation of the esophagus and closure of the larynx
Peristalsis in the esophagus by contraction of the longitudinal muscles on aboral side
Contraction of circular muscles on the oral side and relaxation of circular muscles on the aboral side
36
Aboral
Away from the mouth
37
Cardiac sphincter prevents what
Reflux of stomach contents into the esophagus
38
True or false
| Horse can vomit
False
| The cardiac sphincter prevents this
39
Myasthenia Gravis or megaesophagus
Interference with muscles function and tone in the esophagus and causes muscle tone loss and dilation of the esophagus
Food cannot move down the esophagus and is often regurgitated
Normally mistaken for vomiting
Makes animal more prone to pneumonia
40
Vomiting (emesis) is controlled where
A centre in the brainstem
41
Emetics
Drugs that Stimulate the brainstem to induce vomiting
42
Antiemetics
Drugs that prevent vomiting
43
Process of vomiting (emesis)
Pyloric sphincter relaxes
Reverse peristalsis moves food from SI to stomach
Relaxation of cardiac sphincter
Inspiratory movements and contraction of abdominal muscles result in vomiting
Closed epiglottis prevents aspiration and the soft palate directs food out of the mouth
44
Rumination
Masticated partially digested food gets regurgitated and chewed on again, swallowed and re-digested
Called “chewing a the cud”
45
Why do ruminants ruminate their food
Efficient fiber digestion: mixed with saliva and chewed again to increase surface area exposed to microbes
46
How long does each rumination cycle last
About 1 minutes between regurgitation and swallowing
47
Where is the reticulum in ruminants
Most cranial compartment
48
What appearance does the reticulum have
A honey comb appearance to increase surface area
49
Reticulorumen contractions
Coordinated contractions to move food to the rumen
50
The rumenoreticular fold
Separates the rumen from the reticulum
51
Where is the rumen in ruminants
Occupies the left half of the abdominal cavity
52
True or false
| the rumen is the largest forestomach compartment
True
53
What appearance does the rumen have
Pile rug appearance
54
Function of the rumen
Site of fermentation digestion
55
What separates the rumen into different compartments
Rumenal pillars -long muscular folds
56
Compartmentalization in the rumen
Contractions that assist in mixing of rumen contents controlled by the vagus nerve (parasympathetic NS)
57
What affects compartmentalization in the rumen
```
Distension of the rumen
PH
Presence of VFAs
Consistency of contents
And feedback from other areas
```
58
Eurctation
The expulsion of CO2 and methane gas from fermentation that accumulates in the rumen
Contractions of rumen and relaxation of the esophagus result in belching
59
Why is cellulose and pectin indigestible in monogastrics
Due to the fiber linkage of the molecules
60
Microbes convert saccharides into
Volatile fatty acids
61
3 most important VFAs in rumen
Propionic acid
Butyric acid
Acetic acid
62
VFAs are absorbed across the rumen wall and go to the liver for conversion to
Glucose (mostly propionic acid) to make adipose tissue or to be burnt for energy
63
True or false
| Things are normally absorbed where they are created
True
64
Cellulase breaks down cellulose to _____, microbes convert this to _____, liver of ruminants converts VFAs back to _____
Glucose
Propionic acid
Glucose
65
Proteases break down protein into
Amino acids
66
Amino acids are used to
Make proteins
| Or converted to VFAs and ammonia
67
Some ammonia is absorbed and ends up in the liver to be converted to___
Urea
68
What happens to urea
Secreted back into the salivary glands and eventually the rumen to provide microbes with a nitrogen source
Or secreted in urine after the digestion process
69
Why do farmers add chicken waste to cattle feed
To add urea/ammonia to aid in protein synthesis
70
Microbes from fermentation sometimes slip into the small intestine as ingests moves, what happens to them
They provide an important source of protein for the ruminant when they get digested
71
Where are vitamins B and K made
In the rumen
72
Any alteration in balance of microbes, feed, pH and gas production can cause
Bloat
Acidosis
Death
73
The omasum
The third chamber
74
Appearance of the omasum
Large surface area due to large mucosal folds “many piles”
| Looks like leaves or pages of a book
75
Omasum has strong muscular walls for
Mechanical break down
76
Absorptive function of the omasum
VFAs, water and bicarbonate
| To prevent neutralization of the abomasal acid (a change in the acidity can inhibit function)
77
The abomasum
The true stomach in ruminants similar to the stomach of a monogastrics
78
A milk diet does not require fermentation so young nursing calves have underdeveloped ____ , ___and ___ and have a presence of a _____
Rumen, reticulum, and omasum
| A reticular/esophageal groove
79
What does the reticular groove do for nursing cattle
Allows milk to Bypass the rumen, reticulum and omasum into the abomasum
80
5 parts of the monogastric stomach
```
Cardia (cardiac sphincter)
Fundus
Body
Antrum
Pylorus (pyloric sphincter)
```
81
The cardia (cardiac sphincter)
The area around the opening of the esophagus into the stomach
82
The fundus
Area that forms a distensible pouch that expands as food enters
83
What allows the fundus to expand the way it can
The Rugae (folds) flatten out as it distends
84
The body
Also distensible, middle portion of the stomach
85
The antrum
Distal portion of the stomach that grinds food, regulates acid production, and produces mucus
86
The pylorus
Muscular sphincter that regulates the movement of chyme into the SI
Prevents back flow from SI to the stomach
87
The inside curve of the stomach is called
The lesser curvature of the stomach
88
The outside curve of the stomach is called
The greater curvature of the stomach
89
Pepsinogen is secreted by
Chief cells in response to gastric stimulation
90
Pepsinogen is the precursor for
Pepsin
| Made my cleaving Pepsinogen with HCL (in the stomach)
91
Pepsin catalyses _____ into smaller amino acids called____
Protein
| Peptides
92
Pepsin is inactivated by the more ____ pH in the duodenum
Alkaline
93
Mucus is a mixture of mucin, water and bicarbonate ions, what does this help with
Assists in mucus’ ability to neutralize stomach acid
94
Mucus is important in the stomach, to protect it from
Autodigestion due to pH of 2-3
95
Why must mucus be continuously secreted in the stomach? What can happen if it doesn’t?
Because it is broken down by HCL and can cause gastritis and ulcers
96
Hydrogen and chloride ions (HCl) are secreted by
Parietal (oxyntic) cells as separate ions
97
What does HCL do in the stomach
Sterilizes the food and protects GIT from infections and aids in denaturation of proteins
98
Secretion of HCl is controlled by receptors on parietal cells for
Gastrin
Acetylcholine
Histamine
(Need all 3 receptors to be stimulated for optimal HCL release)
99
When the pH of gastric contents drops below 3, gastrin is inhibited, what does this do to the release of HCl
Inhibits it
100
Can inhibit the release of HCl by the use of Drugs that block the
Histamine receptor
Acetylcholine receptor
The proton pump
101
Stomach Contractions stimulated by the parasympathetic nervous system
Relaxes the fundus and increases antrum and body contractions
Prepares the stomach to accept food
102
Stomach contractions stimulated by the sympathetic nervous system
Decreases stomach motility and can result is gastric atony (decreased muscle tone)
103
Stomach contractions stimulated by gastrin
Produced by G cells in the antrum in response to filling and peptides
Increases HCl production and Pepsinogen in the fundus
Causes muscular relaxation in the fundus to allow filling
104
Muscle contractions stimulated by secretin
Produced in the duodenum in response to excess stomach acid in SI
Causes relaxation of the fundus
Inhibits peristalsis to delay movement of ingesta into the SI
105
Stomach contractions stimulated by cholecystokinin (CCK)
Produced in response to fats and proteins in the duodenum
Inhibits gastric contractions and slows gastric emptying
106
Carnivore stomachs empty within
A few hours
107
Horse and pigs stomachs take about __ hours to empty
24
108
Duodenum
First part of the SI, extends from the pylorus to the jejunum
109
The duodenum receives 3 things
Ingesta from the stomach
Bile from the liver
Pancreatic secretions
110
Jejunum and ileum are
Indistinguishable from each other
111
The ileum connects to the colon of the large intestine by the
Ileocecal sphincter
112
What 4 things increase surface area of the SI
Folded walls
Intestinal crypts (depressions)
Intestinal villi
Microvilli on the villi
113
The microvilli cells have enzymes for digestion and ___ for absorption in/on the cell membrane
Carrier molecules
114
All parts of the SI are divided into 3 major layers
The luminal mucosa with microvilli
An outer serosa which is continuous with the visceral peritoneum
115
Segmental contractions in the SI
Mixing and churning of food
Increases exposure of food to the villi
Slow movement of ingesta through the GIT
more random than peristalsis and compartmentalization
116
Amylase in carbohydrate digestion
May be present in saliva, always secreted by the pancreas into the duodenum
Converts starch to disaccharides
117
Sucrase, Maltase, isomaltase, and lactase in carbohydrate digestion
Enzymes in the microvilli cell membrane
Convert disaccharides to monosaccharides
Proportion of these enzymes depend on diet, age and species
118
True or false
| Young animals often have a lot of lactase to digest milk, but may lose it as adults if not fed milk continuously
True
119
Glucose is absorbed by using transport proteins on the cell membrane of the brush border by secondary active transport, explain
Na-K ATPase maintains a low sodium level inside of cells
Glucose and sodium are co-transported into the cell using the concentration gradient of sodium
Glucose leaves the cell for the blood by diffusion through the basement membrane
120
Examples of proteases produced by the pancreas that further break down proteins in the small intestine
Trypsin
Chymotrypsin
Elastase
Carboxypeptidase
121
The pancreatic proteases are secreted as inactive precursors and are activated in the lumen of the GIT, why?
To prevent autodigestion
122
Luminal digestion of proteins yields
Free amino acids and small peptides
123
Fat is digestion by
Emulsification
124
Explain emulsification of fats
Fats are warmed and mixed in the antrum to change to an oil/liquid
Bile salts are added in the SI (secreted by the liver through the bile duct into duodenum)
The bile salts are bipolar, they bond to the fat with their hydrophobic head and hold onto water with their hydrophilic tail
125
Emulsification makes fats into small droplets with large surface area, this allows
Fat soluble vitamins to attach to the fats
Pancreatic lipases to digest the fat
126
Main dietary fat
Triglycerides (3 fatty acids and 1 glycerol)
127
Triglycerides are hydrolyzed by lipase into free fatty acids and monoglycerides, what do the bile salts do?
With bile salts, these form small water soluble micelles that carry fat to the microvilli
Bile salts stay in the lumen and the free fatty acids and monoglycerides are reassembled into a triglyceride
These are excreted with protein as chylomicrons from the cell and transported in the lymphatics to the vena cava
128
Sudden diet changes can result in incompletely digested food, leading to
Diarrhea
| That’s why diet changes should be gradual
129
Functions of the large intestine
Recover water and electrolytes
Store feces
Ferment fiber
130
The cecum
A blind diverticulum (sac) at the ileocecal junction
131
The cecum in carnivores, ruminants and hind gut fermenters
Carnivores: poorly developed
Ruminants: moderately sized
Hindgut fermenters: large and highly developed
132
3 portions of the colon
Ascending: most cranial
Transverse: courses from right to left
Descending: connects to the rectum
133
The colon has many mucus secreting glands to___ and uses ____ to control movement through it
Lubricate feces
Peristalsis and segmental contractions
134
The horse’s cecum and large colon
Where fermentation takes place (like the reticulum and rumen in a cow)
Ascending colon is usually called the large colon
Consists of 4 large banks stacked in pairs running cranially and caudally along the sides of the abdomen
135
The cecum and large colon in a horse are divided into sacculations called
Haustra
136
The longitudinal muscles that form prominent bands in the cecum and large colon of a horse are called
Tenia
137
In ruminants the ascending colon is called the spiral colon, why?
It is long and doubles into a spiral that runs in the mesentery supporting the small intestine
138
The difference between the layers of the large intestine and the small intestine are that the mucosa is
Not as extensively folded, and contains more mucous cells
139
Differences in fermentation from ruminants in hind gut fermenters:
Much of starch and protein digested and absorbed in the small intestine of hindgut fermenters (in the rumen for ruminants)
Microbial protein cannot be absorbed
Bicarbonate secreted directly to cecum and colon wall into the lumen
140
The rectum
Terminal portion of the colon which continues into the pelvic cavity
Stores feces prior to defecation
Has many mucus secreting glands for lubrication
Has sensory receptors for stretch -stimulates defecation response
141
The anus has an internal and external muscular sphincter to allow controlled passage of feces. Explain the nervous control for both
Internal sphincter:
Parasympathetic: causes relaxation
Sympathetic: causes constriction
External sphincter:
Voluntary control
142
What happens when the internal sphincter relaxes and allows fecal contents to contact the anal mucosa
Stimulates conscious need to defecate
143
What happens when muscles and nerve supply in the anus/rectum are damaged by perianal surgery, trauma and perianal tumours?
Can cause fecal incontinence (loss of control of defecation)
144
Exocrine functions of the pancreas for digestion
Secretion of proteases, amylase and lipase from acinar cells into the duodenum
Secretes bicarbonate into the duodenum to neutralize stomach acid
145
Second largest organ in the body
The liver
146
Hepatic portal system
System of veins that Drains the intestine and deliver blood to the liver to be filtered
147
What does the liver do to filter toxins
Has phagocytize cells in the hepatic sinusoids (blood filled cavities) to filter and remove toxins and other substances from the blood
148
What does the liver absorb
Trace Minerals
Fat soluble vitamins (also stores them)
Glucose (stored as glycogen)
149
The liver makes bile which contains bile acids/salts, cholesterol and bilirubin, it is collected in canaliculi, and drained into bile ducts, is stored in the gallbladder and can lead to the pancreatic duct into the duodenum. The gallbladder releases bile in response to what
Cholecystokinin which is released in response to fats and proteins therefore providing the bile for fat emulsification
150
How are bile salts reabsorbed
Through the hepatic portal system, they are removed from the blood and recycled by the liver to make more
151
The liver makes albumin, what is that
A blood protein that maintains blood oncotic pressure
152
Why do starving kids have pot bellies
Due to protein deficiencies that cause ascites
153
How is the liver important in glucose metabolism? What processes does it use?
Glycogenesis: makes glycogen from sugars to store in liver
Glycogenolysis: breaks down glycogen to maintain blood glucose
Gluconeogenesis: makes glucose from non carbohydrate substances such as amino acids (ruminants and true carnivores) or propionate (VFA) in herbivores
154
True or false
| Horses have gallbladders
False
155
Cleft lip
Due to a disturbance of the process making the jaws and face during development
156
Cleft palate
Defect may involve the soft palate alone or extend rostrallu to the maxillary bones and lips
157
Salivary Mucocele
An excessive accumulation of saliva in or around the gland due to traumas or inflammation that occluded the duct/gland
158
Megaesophagus
Esophagus dilates proximal to a constriction
| Congenital cause: persistent aortic arch
159
Choke
Obstruction in the esophagus of horses due to dry feed
160
Abdominal hernia
Protrusion of abdominal contents through an opening in the wall
Umbilical, inguinal and scrotal
161
GVD
gastric torsion or volvulus
Large dee chest animals
Exercise after a heavy meal
Distension due to gas
