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102 terms

Digestion and Absorption

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Digestion
the breakdown and absorption of food
Herbivors
eath plant matter, some are monogastric and some are ruminants
Carnivores
eat flesh, all are monogastric
Omnivores
eat it all, all are monogastric
Monogastric
single chambered stomach
Ruminants
multichambered, usually 4 chambers, mixing and fermentation
Prehension
grasping of food with lips or teeth
Mastication
mechanical breakdown of food, mostly chewing
Oral Cavity or Buccal Cavity
where digestion begins
Salivary Glands
has digestive and lubrication fuction, most domestic animals have three matching pairs
Perotid salivary glands
below the ear canal, caudal to the mandible
Mandibular salivary glands
ventral to parotid glands at caudal angle of the madible
Lingual Salivary glands
sublingual salivary glands, medial to shafts of madible just under the base of the tounge
Sypathetic nervous system
causes decreased salivation
Parasypathetic nervous system
increases saliva output
Oropharynx
the opening at the back of the throat through which food and air pass
Upper Arcade
upper teeth, in maxilla and incisive bones
Lower Arcade
lower teeth, in the madible
Incisors
most rostral, front teeth, in incisive bone used for grasping
Canines
typically longer than other teeth with pointed tips, tearing
Premolars
rostral to molars, large occlusal surfaces, used for grinding and cutting
Molars
the most caudal, used for grinding
Lingual surface
inner surface of the lower arcade, faces the tongue (lingual refers to tongue)
Palatal Surface
innter surface of the upper arcade, faces the hard palate
Labial Surface
outer surface of the rostral teeth , faces the lips
Buccal Surface
outer surface of caudal teeth, faces the cheeks
Occlusal Surface
the surface used for chewing
Lower Case, Decidous teeth
baby teeth
Upper Case
permanent teeth
Carnassial teeth
the upper 4th premoler and the lower 1st molar (site of deep infection for dogs and are difficult to extract
Esophagous
a hollow tube that moves food towards the stomach
Lumen
the open space where food travels
Mucosa
the layer nearst the lumen, epithelial tissue and loose connective tissue
Submucosa
a thicker layer beneath the mucosa, gland and denser connective tissue
Muscle Layer
thick, has longitudinal and circular smooth muscle layers serves to propel material through the tract
Serosa
the outermost layer of the GI tract, thin tough connective tissue
Cardia
surrounding the opening of the esophagus, cirucular muscle maintains tone to reduce reflux of stomach material back into the esophagous
Fundus
blind pouch that expands as more food is swallowed
Body
middle of the stomach, also distensible
Cheif cells
produce pepsinogen, enzyme precursor for pepsin
Mucus Cells
produce protective mucus
I 3/3 C 1/1 P 4/4 M 2/3
canine adult dental formula
I 3/3 C 1/1 P 3/2 M 1/1
feline adult dental formula
Parietal or Oxyntic cels
produce HCI
Antrum
distal part that grinds up food and regulates hydrochloric acid
Pylorus
muscular sphincter that regulates the movement of ingesta from the antrum protion of the stomach to the duodenum (small intestines) , also helps to prevent backflow from duodenum back into the stomach
Lesser curvature of the stomach
the inside curvature
Greater curvature of the stomach
the outside curvature
Rugae
long muscular folds in the stomch lining which stretch , allow stomach to expand
Erosions
breaks in the stomch mucosa
Gastric Ulcers
deep erosions in the stomch mucosa
Gastritis
inflammation of the stomach
Chyme
semifluid partially digested food
Gastric Atony
inhibition of stomch movement from sypathetic nervous input, ie from illness or surgery
Enterogastric reflex
feedback loop from intestines
Gastrocolic reflex
filling of stomach triggers signal for colon to empty, great for housetraining
Secretin
released from the duodenum in response to excess stomach acid entering the small intestines
Cholecystokinin
released in response to excess fats or proteins present in the duodenum
Gastrin
causes increased HCL production & inhibits muscle activity of the fundus, greater relaxation and filling of the stomach
Pepsiongen/Pepsin
from chief cells, is the precurser for the proteolytic enzyme
Mucins
produced by goblet cells, main constituents of mucus coating which helps protect stomach lining
Bicarbonate Ion
secreted onto the surface of the stomach to make the mucus coat more alkaline and thereby protect stomach lining from the HCL
Hydrochloric Acid
produced by the parietal cells, starts breaking down food and converts pepsinogen to pepsin
Gastrin
stretching of the body or antrum by food stimulates release
Acetylcholine
from the parasympathetic nervous system , binds to recpetor on the parietal cell producing more HCL also causes more gastrin release
Duodenum
small intestine attached to the stomach
Jejunum
the longest portion of the smalls intestine
Ileum
connects to the large intestine at the ileocecal sphincter(junction of ileum and colan)
Cecum
blind pouch the sphincter regulates movement of material from teh small intestine to the colon
Mucosal layer
built for absorption, large surface area augmented by villi and microvilli
Villi
project off of the wall of the small intestine, finger like projections of the mucosa, each villus has thousands of microvilli
Microvillia (brush boarder)
cells in this have many digestive enzymes and carrier molecules embedded in their cell membranes for the digestion and absorption or nutrients, vitimins and minerals
Crypt
invagination around each villus, old cells are shed at the tip of the villus. The cells in this produce new cells to constantly replace old cells that are shed
Peristalsis
coordinated contractions of longitudinal and circular muscle which move ingests or chyme through the intestine
Segmental Contractions
Adequately mix chyme and expose fully to intestinal lining, slow movement, allow for water absorption. A lack of this movement causes diarrhea
Ileusa
a lack of peristalsis resulting in decreasesd movment of ingesta through the intestine, can be caused by disease and stress
Polysaccharides
starch, glycogen, sugars are complex carbohydrates
Amylase
and enzyme released by the pancreas, breaks down carbohydrates
Proteases
breaks down proteins into amino acids or dipeptides before they can be absorbed
5 basic proteases
Etypsin, chymotrypsin, elastase, aminopeptidase, carboxypeptidase
Emulsification or Micelle Formation
fats broken into smaller pieces, contractions of the stomach start the process
Triglycerides (fats)
need lipase for pancreas, fat digesting enzymes that penetrate the bile acid coating and break triglycerides down into glycerol, fatty acids, and monoglycerides
Liver
makes bile
Gall Bladder
stores bile
Bile Duct
carries bile from the gall bladder to the duodenum
Bile Acids
prevent fat from re-clumping, are secreated into the duodenum from the liver, these help to prevent the fat droplets from recombining into larger globules again. These have a hydrophobic end to hold onto fats, and a hydrophilic end to hold onto water, making fats more soluble
Lipases
fat digesting enzymes that penetrate the bile acid coating and break triglycerides down into glycerol, fatty acids, and monoglycerides
Fatty acids, Glycerol, and Monoclycerides
micelles which can be absorbed through the brush border
Large Intestine
water nad some electrolyte absorption, stores feces
Colon
3 portions which then connects to the rectum
Rectum
terminal colon, stretching of the rectum stimulates defecation
Internal Sphincter
smooth muscle and under autonomic control
External Sphincter
skeletal muscle and under voluntary control
Liver
largest organ inside the body, considered an accessory organ to digestion, filtration and detoxification
Glycogenesis
the formation of glycogen from glucose
Glycogenolysis
the breakdown of glycogen back into glucose
Gluconeogenesis
the formation of glucose from amino acids
Pacreas
located in the curve of the duodenum
Exocrine Function
enzymes through ducts, fuction involves amylase, lipase, and proteases, also release bicarbonate into the duodenum to help maintain pH
Endocrine Function
hormoses, ductless, involves maintence of blood glucose levels through the use of insulin and glucagon
Insulin
secreted by beta cells in the islets of langerhans in the pancreas. Acts to move glucose from the blood into the cells.
Glucagon
pancreatic hormone produced in the alpha cells has the opposite effect, mobilzes glucose from the liver to preven hypoglycemia