Download Digestive Tract Musculature

Dental Prophylaxis
 Small animals- scaling away of tartar from the teeth.
 Dental “__________”
 Horses- teeth are “___________”, which reduces points
on buccal and lingual edges of teeth.
 Salivary glands - saliva helps with
evaporative _________,
__________, and ___________;
usually three pairs with ducts to
oral cavity
_________ salivary glands ventral to ear canals
__________salivary glands ventral to parotid glands at the
caudal angle of the mandible
____________ salivary glands medial to the shafts of the
mandible just under the base of
the tongue
SALIVARY
GLANDS
• Muscular tube that extends from _________to the
__________ and is located DORSAL to the trachea. Transports
swallowed material to the stomach; No significant digestion
takes place
• Enters __________ of stomach at an angle.
• As stomach fills, fold of stomach closes lower end of esophagus
• Reduces risk for reflux
• In some species, closure is strong enough to prevent reflux
or vomiting (horse, rabbit)
Esophagus
Megaesophagus
 Loss of muscle tone causing
_________ of the esophagus
 Causes esophagus to relax
 Food accumulates in the
esophagus instead of being
transported to stomach.
 Animal _________________
undigested food.
 How do we treat?
 Feed liquid based diet
 Feed on an elevated surface
 Holding animal up and allowing
gravity to pull food down to
stomach.
*Can lead to aspiration pneumonia.
Monogastric (Simple) Stomach
1.
___________- area immediately surrounding the opening from the
esophagus into the stomach
- Cardiac sphincter helps to prevent reflux
2.
3.
_________- distensible blind pouch; expands as more food is swallowed;
rich with glands
_________ – distensible middle section; rich with glands
Monogastric (Simple) Stomach
4.
_________ ___________- distal portion that grinds up swallowed
food and regulates the HCl produced in the body and fundus
Pylorus is a sphincter that regulates movement of digested
stomach contents (chyme) from stomach to duodenum.
Prevents backflow of duodenal contents into the stomach.
Remains partially open.
_________ curvature- outer portion of
C-shaped stomach
_________ curvature- inner portion of
C-shaped stomach
Gastric Motility
 __________________ reflex- prevents
stomach from sending its’ contents into
the duodenum before the intestines
are ready.
 _______________________
hormone released when there is
excess HCl in the small intestines.
Slows stomach emptying.
Empty
 _______________________ (CCK)
hormone released when there are
large amounts of fat or protein in the
small intestines. Slows stomach
emptying.
Full
Gastric Glands- see chart/picture**
 FUNDUS & BODY: Both areas where rugae are rich with
glands containing the following cells:
 __________ cells
 Produce hydrochloric acid (HCl)
 __________ cells
 Produce pepsinogen, an enzyme precursor to pepsin
 __________ cells
 Produce a protective mucus
 PYLORIC ANTRUM
 ____ cells
 Endocrine cells that secrete the hormone gastrin into the blood when
food is present
 Gastrin stimulates the parietal cells to release HCl
 __________ cells
Gastric Ulcers
Deep erosions of the stomach’s epithelium
Rugae- long folds in the stomach.
Ruminants and
Complex Stomachs
 Only have one true
stomach
(abomasum), and 3
forestomachs
(reticulum, rumen,
and omasum).
 RUMINATION:




____________ food
____________ it
_______ it some more
____________it again
Reticulum
 Smallest and most cranial
compartment.
 _____________ arrangement
to increase absorption.
 Wall is continuous with the
rumen
 Rumen and Reticulum work
together and produce
Reticulorumen contractions.
 ___________ disease is
associated with the reticulum.
Rumen
 Reticuloruminal contractions allow:
 Regurgitation of partially-digested plant food (cud) to take place
 ______________: expulsion of built up carbon dioxide or methane gas
 If build up continues, may cause _________.
 Contains billions of microbes for __________________. Microbes contain
enzymes (____________ and ____________) that allow the
ruminant to digest cellulose and protein. Cellulose and protein are
broken down and converted into VOLATILE FATTY ACIDS, which the animal
can use for glucose and fat (energy sources).
Omasum
 Muscular with interior full of parallel,
longitudinal muscular folds.
 ________ VFA’s (that weren’t already absorbed
in rumen) and water from ingesta
 Removes _______________ (to preserve the pH
of the abomasum).
Abomasum
• “_______ __________”; functions very similar
to that of mongastric stomach.
• Only ______________ part of the stomach.
• Contains enzymes called __________ that
break down microbes “flushed out” from the
rumen
Young Ruminant
Digestive Tract
 Newborn’s stomach functions mainly as a monogastric digestive system.
 ______________ is the largest chamber in a newborn
 Rumen and reticulum are small and non-functional at birth (minimal
_________).
 Development of rumen and reticulum is dependent on rate of diet change to
grain.
 Milk in rumen can disrupt fermentation process so is carried directly to
omasum.
 ____________ groove (_______________ groove)- allows liquids to be carried
from esophagus directly to omasum, bypassing rumen and reticulum.
 As animal ages, groove disappears.
 Where majority of nutrients are
______________ into the bloodstream.
 Same anatomy for monogastrics and
ruminants
 Divided into:
 ______________
 Short, first segment that leaves
stomach. Pancreas is nearby.
 ______________
 Longest portion, makes up
majority of small intestines.
Large amount of mesentery
found here.
 ______________
 Short section that enters the
colon (large intestine). Leads
directly to cecum.
Small Intestines
Small Intestinal Wall
 Mucosa – increased surface area due to many
villi
 Each villus contains thousands of ___________
(brush border)
 Microvilli have both digestive enzymes and
carrier molecules for nutrients, vitamins, and
minerals embedded in cell membranes
 _______- invaginations of mucosa around each
villus. New cells are produced and pushed
from bottom of crypt to replace cells of
villus
 Goblet cells present. Mucus helps with flow of
ingesta.
Small Intestine Digestion
 _____________, _____________, _____________
 Absorbed intact across SI wall
 _____________, _____________, _____________
 Chemically digested via enzymes in the lumen and enzymes
on the microvilli b/c they are too large to pass through the
mucous membrane
 See charts provided*
Small intestine Motility
 Cholecystokinin (CCK)
 Fats/protein in the intestine stimulate the mucosa to
release CCK, which increases intestinal motility (opposite
of the effect on the stomach)
 Segmental contractions slow the movement of ingesta to
allow time for it to be both mixed with intestinal enzymes and
absorbed through the intestinal wall.
 Many times diarrhea is caused not due to increased peristalsis, but
lack of segmental contractions.
 Species variation in structure
 Components
1. ___________ - blind sac
2. ___________
3. ___________
 Primary functions :

Store feces

Recover fluid and
electrolytes
 Hindgut fermentation
(non ruminant
herbivores)
Large Intestine
Large Intestines
 ______________: simple, tubular
colon; poorly developed cecum
 ____________ _____________:
very large colon and cecum (hindgut)
 Fermentation site
 Modifications of cecum and
colon allow fermentative
digestion in hindgut
(similar to rumen)
 VFA’s (produced by microbes)
absorbed from cecum and
colon for energy needs (similar
to rumen)
 Consists of 4 sections:
 Cecum, Ventral colon, Dorsal
colon, Small colon
 Cecum is composed of:
 Base, Main body, Apex
 Cecum and dorsal and ventral
colons have longitudinal bands
that separate the structure into a
series of sacs called ________
 The role of the small colon is
to absorb electrolytes, water,
and any VFA’s that were not
previously absorbed.
Horse Hindgut
 Terminal portion of the large
intestine; an extension of colon
Rectum
 Capable of more expansion
than colon
 Mucus-secreting glands
___________ feces to aid their
passage
 Has sensory receptors that
detect stretching or
distention and stimulates
defecation response.

Internal sphincter under __________
control
 External sphincters under
____________ control
 Stretching of receptors increase the
sensation or need for defecation
 Surgery or disease in anal region can
damage sphincter muscles and nerves,
causing incontinence
Anus
Nervous System and the GI tract
 SYMPATHETIC RESPONSE:





Dry mouth
Decreased GI motility
Decreased GI blood flow
Decreased secretions
Increased tone of external anal sphincter
 PARASYMPATHETIC RESPONSE:





Salivation
Increased GI motility
Increased GI blood flow
Increased secretions
Decreased tone of external anal sphincter
Liver’s Role in the GI Tract
 Filters blood from the GI tract before it
enters the systemic circulation. This is
known as the hepatic portal system.
 Glucose absorbed by the GI tract can
be stored in the liver as
_____________ (glycogenesis).
 When glucose is needed in the blood,
glycogen is broken down by the liver
(glycogenolysis).
 _____________________ is the
process of glucose being made in the
liver by using amino acids.
 Major source of blood __________
 Albumin
Gallbladder
 The liver produces _______ which
contains bile acids, cholesterol,
and bilirubin
 Bile is secreted into the hepatic and
cystic ducts, which lead to the
____________for storage (not
horse)
 The gallbladder stores bile until it is
stimulated by CCK (due to fat in SI),
causing it to contract.
 Contraction forces bile down the
common bile duct into the
duodenum, where it aids in the
digestion of fat.
Pancreas’ Role in the GI Tract
 Exocrine functions:
 Produces _________, _________,
___________
 Secretes _____________ (HCO3-)into
duodenum to neutralize the acidity of
stomach contents
• Endocrine functions:
 Produces ___________ & _________
 Insulin decreases levels of blood
glucose
 Glucagon increases levels of blood
glucose