Topic 3: Digestive System Flashcards
(94 cards)
1
Q
What is Digestion
A
Part of the process in which larger molecules are broken down in their smaller component parts
2
Q
What are the different ways of Digestion
A
- Mechanical Digestion
- Chemical Digestion
3
Q
Explain mechanical digestion
A
Refers to Gastrointestinal tract movements, which physically break up food into its smaller parts then molecules get small enough to be absorbed through the intestinal membrane and enter the body
4
Q
Explain chemical digestion
A
Chemical reaction breaks the bonds holding macromolecules together, resulting in the production of smaller molecules, when they are small enough they are able to be absorbed across the intestinal membrane and enter the body
5
Q
What does the digest system made up of?
A
- Gastrointestinal tract aka alimentary tract
6
Q
What does the GI tract made up of and what is it considered?
A
- Made up of mouth, pharynx, esophagus, stomach, small & large intestine
- Organs: Tongue, salivary glands, liver, pancreas, gall bladder
- Considered a long tube from the mouth to the anus
7
Q
What does the oral cavity consist of?
A
- Mouth, Tongue, salivary glands, Teeth –> Everything needed to ingest food
8
Q
What is another word for oral cavity?
A
Buccal cavity
9
Q
Explain contents and functions of the mouth
A
- Opening to the GIT
- Contains: teeth, tongue and other structures to ingest food
- Functions: Prep for swallowing, prehension, mastication, insalvation
10
Q
What is prehension?
A
- Act of grasping food with lips, tongue, teeth
11
Q
What is mastication?
A
- Chewing to reduce the particle size
12
Q
What is insalvation?
A
Mixing the food with saliva
13
Q
Explain the contents and functions of teeth and where it is located
A
- Embedded in the upper maxilla bone & lower mandible bone
- Teeth are important in assisting the animal with the mechanical breakdown of food
- Food is broken into smaller pieces by tearing, cutting, and crushing action of the teeth that occurs during mastication
- Facilitate swallowing
- Increase the surfcae area for chemical digestion by animal and microbial enzymes
14
Q
What kind of teeth do carnivores have?
A
- Premolars and molars
15
Q
Explain where the tongue is located, its contents and function
A
- Occupies the greater part of the oral cavity
- Extends into oropharynx
- Consists of extrinsic muscles and intrinsic muscles
- Lies on the ventral surface of the oral cavity
- Is important for prehension
16
Q
What are extrinsic muscles and where are they located?
A
- Located in tongue
- Anchor the tongue in place and attaches tongue to the soft palate to allow movements
17
Q
What are intrinsic muscles and where are they located?
A
- Located in the tongue
- Makes up the tongues majority mass
- Makes the tongue flexible and maneuverable
18
Q
What are the three parts of the tongue?
A
- Apex
- Body
- Root
19
Q
What is the apex and where is it from and located
A
- From tongue
- The free unattached mobile tip of the tongue is the apex
- Freely moveable
- only caudally attached to the floor of the cavity
- has 4 mucosa-covered surfaces: dorsal, 2 lateral borders, and ventral surface
20
Q
What is the body of the tongue
A
- Ventrally anchored to the mandible by the extrinsic lingual muscles
- Has 3 surfaces
- Dorsal: Has taste buds
- Ventrical: Blood vessels
21
Q
What is the root of the tongue
A
- Attached to and supported by lingual process
- Only the dorsal surface is free and is covered by mucosa
22
Q
What are the papillae on the tongue responsible for and the types?
A
- mechanical function: helps the grooming process and moves food to the pharynx
-Specialized papillae contain taste buds and allow taste sensations
Types:
- lenticular
- Conical
23
Q
Explain shape of lenticular papillae and functions and where thet are located
A
- Shape: lens shaped (Big and round)
- aid in mechanical functions, mastication and processing of food
- Located in dorsal part of the tongue
24
Q
Explain the shape of conical papillae and functions and where they are located
A
- Shape: cone-shaped (long and skinny)
- aid in mechanical functions, mastication and processing of food
- Located in dorsal part of the tongue
25
Explain vallate papillae and what they contain
- Located on the back of the tongue
- Contains multiple taste buds
- Detects bitter tastes
- Large and circular
- contain the gustatory furrow
- Contain the taste buds
26
What is the gustatory furrow
- Enhances taste buds for saliva
27
What do taste buds do?
- Detects chemical stimuli
- Sensory structure
- Epithelial part of the papilla
28
Explain what salivary glands and what are they important for
- Deposit saliva into the oral cavity via ducts
- Important for digestion process
29
What is saliva composed of?
- Water, electrolytes, antibodies, glycoproteins, bicarbonate, enzymes
30
What are the two important enzymes present in saliva?
1. Lysozyme
- Helps to control the bacteria population in the oral cavity
2. Amylase
- Starts break down of starchy carbohydrates in the mouth
31
What are the functions of saliva
- Lubrification
- Antibacterial action
- pH regulation
- Digestion of carbohydrates
32
In what animals is salivary amylase important?
- In pigs, rats and humans, salivary amylase has a significant contribution to the breakdown of starchy carbohydrates in the proximal stomach before the amylase is inactivated by HCl in the stomach
33
What animals lack salivary amylase?
- Dogs, cats and ruminants
- Horses produce a limited amount
34
What are the three main salivary glands
1. Mandibular Gland
2. Sublingual Salivary Gland
3. Parotid Salivary Gland
35
What does the mandibular gland do and where is it?
- Produce mixed saliva of serous (watery) and mucous (viscous)
- Located under the tongue caudal to the angle of the jaw
36
What does the Sublingual salivary gland do and where is it located?
- Produce mixed saliva of serous and mucous
- Located under the tongue and caudal to the angle of the jaw
37
What does the Parotid salivary gland do and where is it located?
- Produces most of the saliva
- Located ventral to the ear and has a long duct extending to the oral cavity
- Secretion is serous
38
What is the pharynx also known as
The throat
39
What is the function of the pharynx?
- Common passage for food and air
- Connects nasal and oral cavities with trachea and esophagus
- Air is directed to the ventral larynx during respiration
- Food and water directed to the dorsal esophagus during swallowing
40
What is the epiglottis and where is it
- "Leaf-shaped"
- located part of the laryngeal cartilage
- Covers the glottis during swallowing
- It prevents food from being aspirated into the trachea
41
Explain the esophagus
- Collapsible, muscular tube that connects the pharynx to the stomach
- Travels dorsal to the trachea unit it reaches the thoracic cavity
42
What is the inside of the esophagus lined with?
- Mucosa that is formed into folds, allowing for expansion or dilation necessary when food passes through it
43
What are the muscles that the esophagus has?
1. Inner: Circular layer
2. Outer: Longitudinal muscles
- These are needed to move the food down the esophagus
44
What species have skeletal muscle and what is skeletal muscle?
- Horses, cattle, dogs, ruminants
- Voluntary muscle
45
What species have smooth muscle, and what is the smooth muscle?
- Cats and primates
- Involuntary muscle
46
How does food move down through GIT for digestion to occur though
- Peristalsis: Occurs via waves of rhythmic, involuntary contraction of smooth muscle
- Most species have one-way peristalsis
- In ruminants, two-way peristalsis occurs
47
Explain the ruminants two way peristalsis
- Regurgitation of food bolus: Allows food to be rechewed to decrease the particle size
- It improves the digestion by rumen microbes
48
What is the cardiac sphincter
- Thickening at the gastric end of the esophagus
- Functions to prevent highly acidic contents at the end of the stomach from backflowing/refluxing into the esophagus and damaging its mucosa
49
Explain the location of the stomach and its functions
- Located at the end of the esophagus
- Placed inside the abdominal cavity
- Functions include storage of ingested food, mechanical and chemical break down of ingested food to decrease the particle size, increase the surface area, and make it easier for chemical digestion
50
What is glandular and non glandular
- Glandular: Produces digestive enzymes: HCl and mocus
- Non- Glandular: Doesnt have a gland and is invloed in mechanical digestion, does not produce digestive enzymes
51
Are carnovores stomachs glandular?
Yes, and it only contains glandular tissue
52
What kind of stomach do pigs have
Composite stomach: meaning the stomach wall contains both glandular and non glandular tissue
53
What are the glandular regions?
1. Cardia
2. Fundus
3. Plyorus
54
Explain the cardia glandular region
-Part that connects to the esophagus
- Glands produce a thick layer of alkaline mucus to protect against gastric acid and the mucosa agaisnt damage from gastric acids
55
Explain the fundus glandular region
- Region where the rugae is more promondiant, so fundus can expand to store food after a large meal
- Leads into the body of the stomach - Links fundas w the distal part of the stomach called pylorus
- It functions to store gas
- It also produces mucus to protect it against gastric acid
56
Explain the pylorus glandular region
- Connects stomach to duodenum through pyloric sphincter
- Produces mucus to protect against gastric acid
- Produces mucus that coats the stomach
-Glands found in the pyloric region include mucus secreting cells & G cells
- Regulates the relsease of KIM
57
What is KIM
- Partially digested food
58
Why is secreation of proteoytic pro-enzymes important?
- Pepsinogen is essential in the digestive process because the constant presence of the active enzyme pepsin would lead to the breakdown of the very cell is making
59
What are the functions of the simple stomach?
- Storage and mechanical breakdown of ingested food
- Controls the influx into the small intestine
- Secreates digestive jucies that break down chemical bonds
- It produces intrinsic fibers which facilitate the vitamin B12 absorbtion in the small intestine
60
Why is B12 absorbtion important for the small intestine?
- It is important for red blood cells to mix with HCl/gastric juices and KIM
61
Explain mongastric animals
- Monogastric: Single/simple stomach with one chamber
- The stomach is C shaped abd located behind the diaphram cranial abdomen
- Digestive invloves mucus, HCl and enzyme secretion
- No micribial fermentation in the stomach
62
What are the anatomical differences in the GIT in non-rumiant herbivores, horses (hindgut fermenters) and cattle
- Herbovores: the conversion of eaten plants into usable molecules is dependant on fermentation that occurs in the gastrointestional tract
- horses GIT tract: well developed and expensive fermentation chamber (cecum)
- Ruminants: plants materials are partially broken down in the rumen before reaching the stomach
63
What does the cecum and what animal is it very prodominat in?
- Horses
- It allows microbes to help breakdown plant materials
64
What is the ruminant stomach made up of (4 chambers)?
- Consists of one stomach made up of 4 chambers
- First three are non-glandular:
1. Rumen
2. Reticulum
3. Omasum
- The last one is glandular
4. Abomasum
65
Explain the rumen
- Is the largest chamber
- It is expanible and where the fermentation occurs
- Contains microorganisms that assist in breaking down carb substances
- Occupues most of the left side of the abdominal cavity
- extends from the diaphram to the pelvis when full
- Contains a numberous amount of papilla
- Pillars which are musclar folds divide the rumen into dorsal sac, ventral sac, blind dorsal sac and blind vehtral sac
- Very sac like chamber
66
Explain the organization of the rumen
- The rumen organizes the feed particles
- Smaller parts are located in the ventral part of the rumen
- Medium particles stay over the smaller particles
- Larger particles float on the surface of the rumenial content
- The gas cap is on top of the large particles and fills up the dorsal part of the rumen which contains methane and CO2
67
What do large particles in the rumen do?
- Large particles are still in the need to go back to the mouth annd have regurgition and mastication to reduce their size
68
What does papillae do
- The size and distributution depends on the diet of the animal
- A healthy rumen is dark in colour from the large blood vessals and greater tissue mass
- Papillae should be able to be seen without a microscope
- Papillae increase surface area
- papillae depend on the production of VFA produced during fermentation
- Concentrate enriched diets leads to a greater production of VFA compared to forage based diets due to the type of carbohydrates
- The greater amount of blood to absorbs these VFA = greater hormonal and mitogenic agents, which leads to an increase in papillae
69
Explain the rumiant diet
- Roughage + Grains (concentrate) = Rumen break down
- Roughage has complex carbs (the structre if the plant)
- Grains (concentrate) has non strutural carbs (which energy reserves starch)
70
What are VFA and what are the main 3
- Volatile fattyu acids are the waste products of the rumen
1. Acetate: Major energy source
2. Propionate: Important for glucose production
3. Butyrate: Important for blood glucose
71
Explain the VFA production in the rumen
- VFA production will vary depenending on the diet
- More concentrate = the greater the VFA production becomes, due to a less complexity of carbohydraqtes found in the concentrate diets
72
Explain the reticulum "reticulorumen"
- Comprises a relatively spherical compartment located crainally to the rumen
- The rumen and reticulum freely connect to eachother internally
- Considered a conjugated compartment to the rumen
- Has a numerous amount of primary folds called crests which limit the "reticular cells" which resemble a honeycomb
- The reticulm acts as a filter and allows particles to go to omasum, which leads to the regurgiataion of bigger particles, after regurgitation, the mastication will help to reduce the particle size
73
Explain the omasum
- Located to the right side between the rumen and reticulum
- Has a round shape in bovine and oval shape in sheep
- The absorbtion capacity of the omasal is similar to the ruminal papilla capacity
- Presents hundreds of semilunar laminas which gives the omasum a leafy aspect
- These laminas are covered by short keratinzied papillae
- The omasum increases the absorptive surface area and most of the water salt are absorbed in the omasum
74
Explain the abomasum
- A pear shaped sac that is bent on the abdominal floor
- A glandular compartment that is similar to the simple stomach of monogastric speices
- Divided in to fundas, body and pylorus (divison is less precise)
- Has a mucosa full of rugae like the stomach of other mammals
- The presence of this rugae increases the surface area of the abomasum
- The mechanisms that happen in the abomasum are like the mechanisms that happen in the stomach of the monogastric animals (intense enzymic digestion)
75
Explain the newborn ruminant
- reticulum and omasum are small and non-functional
- It represents 40% of the fore stomach and does not have microragnisms
- There is presnce of rudmimetary papillae
76
How do you develop the ruminant, specifically the rumen, reticulum and omasum of a newborn
Occurs when the animal starts with a solid diet
77
What is the esophageal groove/ reticular groove
- Consists of muscular pillars that organize themselves on the dorsal wall of the reticulum
- Links esophasgus with the omasum- Forms a gutter
- Helps to protect young ruminant nursing by preventign the milk from entering the rumen
- If the groove did not act like a tube and the milk spilled into the rumen and bacteria would ferment the milk, producing lactic acid
78
Explain the small intestine and what is consists of
- Is the same in all animals
- It is a tube that carries chime away from the stoamch and deposits it in the large intetsine
- Extends from the pyloric sphinchter of the stomach to the large intestine
- Consists of:
- Duodenum
- Jejunum
- Ileum
79
Expalain what part of the GIT is the duodenum from and what it does
- starts at the pylorus of the stomach (shortest section of the small intestine)
- receives chyme from stomach
- horses do not have a gallbladder
- pancreatic + hepatic bile ducts enter to provide secreations to aid digestion process
80
Expalain what part of the GIT is the Jejunum is from and what it does
- Small intetsine - most important part
- longest part of the small intestien
- main site for chemical digestion and absorbtion
- Absrobs fatty acids, amino acids and has large folds that increase surface area
81
Expalain what part of the GIT is the Ileum is from and what it does
- Ending of small intestine
- It is an extensive mucus secreation and mostly digests vitamins
- Helps to protect animal from disease by controlling local populations of bacteria and aiding in filteration of fluids
- Empties into the large intestine at cecum in the horse, colon in dog and cat, and cecum and colon in ruminants and pigs
82
What features of the small inestine help to increase surface area?
- Small intestine consists of many loops
- The mucosa (contains plicae) lining the small intestine is thrown into folds that increase the absorbative surface area
- Mucosa also contains villi which turn conatin smaller projections called microvilli. The villi helps to move liquid contents into close conatact with the mucosa
- Microvilli form a brush boarder which provides most of the surface area
83
Explain the large intestine
- Last part of GIT
Consists of
- Cecum
- Colon
- Rectum
- Anal
84
Expalain what part of the GIT is the cecum and what it does
- Blind diverticulum at the begginin gof the colon
- In carnovores little fermintation is requires
- Equine species relys on it to helo with microbial fermentation
85
Expalain what part of the GIT is the colon and what it does
- Horse has the most complicated colon
- Allows time for absorbtion and microbial digestion
- produces methane and co2
- It breaks down carbs and VFA
86
Expalain what part of the GIT is the rectum and what it does
- Used for fecal storage
87
Expalain what part of the GIT is the anal canal and what it does
- Is the exterior opening
88
Explain the difference in the large intestine in different animals
Horse: most complex large intestine
- Has the large capacity of cecum and colon which can be compared to the rumen in rumiants
- Not only in horses but also pigs the cecum and colon are sacculated which increase volume and retention time of digesta and maximizes the extent of microbial fermentation
89
Explain the pancreas
- panceraatic duct empties into the duodenum
- It is the extramural gland of the digestive system
- It is located outside lumen of gastdrointinal tract between the stomach and small intesting
90
What are the endocrine functions of the pancreas and what are the different types of cells
- Produces hormones which are relased into the blood stream
- Has alpha cells which produces the hormone glucagon
- Has glucagon: which plays an important role in blood glucose regulation
- Beta cells: which produce the hormone insulin
- Insulin: Plays a role in blood glucose regulation
- acinar cells: Functional unit of exocrine pancreas, synthesizes, stores and scecreates digestive enzymes
- Digestive enzymes: activated only when reaching the duidenum
91
Explain the liver
- Largest gland in the body
- outside of the lumen of the GI tract
- located on the right side of the body under the diaphram
- Has four lobes suspenede from the diaphram and abominal wall
- it is connected to a gall bladde via common hepatic duct
92
What are the functions of the liver
- First organ/gland to process the blood coming from the GIT via portal vein and carrying products of absorbyion
- It is the metabolic powerhousr of the body
- Carbs, protein, lipid metabolsm
- It removes waste products + detoxifies
- Syntheis of bile slats
- Storage of vitamins, minerals and glycogen
93
Expalin the gall bladder
- Found in all domestic animals (not horses)
- Located between specific lobes on liver
- Used to concetrate and store bile which is needed for fat digestion
-
94
Explain the bile in the gall bladder
- emulsifies lipids to enhance action of pancreatic lipase
- Breaks down large globules of lipid into smaller, more uniform particles
- It facilitcates fat digestion and absorbtion
- It is firmed in the liver and stored in the gall bladder
- It enters proximal duodedum via common bile duct near pancreatic duct enters
- Location is similar in all animals
