Transcript Digestion - Tomball FFA

Digestion
the process of breaking feed
down into simple substances that
can be absorbed by the body.
3 metabolic processes that
contribute to this break down:
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anabolism
catabolism
oxidation
Anabolism:
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is the set of metabolic pathways that construct
molecules from smaller units.
These reactions require energy
Anabolism is powered by catabolism
Examples: "building up" organs and tissues.
anabolic processes include the growth and
mineralization of bone and increases in muscle
mass.
Catabolism:
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the breakdown of body tissue into simpler
substances and waste production
Oxidation:
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what happens to nutrients that provide
energy for the animal
Absorption:
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refers to taking the digested parts of the
feed into the bloodstream
movement of nutrients across the lining of
the intestinal tract into blood and lymph
system.
Metabolism:
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the chemical reactions in cells
The appetite of the animal is controlled by
the hypothalamus gland
Functions of the digestive system
of animals:
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1. Ingestion (eating)
2.grinding
3.digestion
4.absorption of nutrients
5. elimination of waste
Mechanical Activities of the
Stomach:
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mastication (chewing)
deglution (swallowing
regurgitation (throwing up)
gastric and intestinal motility (peristalsis)
defecation (eliminate waste)
Chemical Activities of the Stomach:
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Actions of enzymes and other substances
produced and secreted by digestive glands
Microbial Activities of the Stomach:
1. activites of bacteria and protozoa
(especially in the use of roughages)
2. substances produced and secreted by
digestive glands
Ruminants: stomach is divided into
four parts
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1
2
3
4
rumen
reticulum
omasum
abomasum
Examples: cows, deer
Ruminants are cud-chewing animals. They can
digest large quantities of roughages (such as
hay and pasture)
Non-ruminants: have simple, onecompartment stomachs.
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Examples: pig, horses, poultry, humans
They need high-energy, low-fiber rations
such as grain
Grains and protein supplements are called
concentrates.
*most expensive part of a ration
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high fiber feeds such as hay, silage,
and pasture
44 percent of the roughages cattle
and sheep eat, they actually digest.
 39 percent are digested by horses.
 22percent are digested by swine
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Ruminants can digest large quantities
of roughage because of the bacteria
present in their digestive system.
Mouth: start of digestive tract
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saliva contains enzymes, salivary amylase,
salivary maltase
Horses saliva doesn’t contain enzymes.
Saliva moistens the feed for chewing and
swallowing
mucin lubricates the feed for swallowing
prostaglandin secretions and bicarbonate
buffer the pH in the stomach
Enzymes:
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organic catalysts that cause and or speed
up digestive action
Teeth:
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Incisors: Cutting or shearing food
Premolars and molars: Grinding food
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Ruminants: no upper teeth and a hard
upper dental pad
Hard palate: roof of the mouth
-Turns to soft palate toward the rear of the
mouth
Salivary glands:
-Common in mucous membrane lining of
the mouth, except on the tongue, hard
palate, and gums
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Tongue: Mass of muscle covered by a
mucous membrane
Covered with finger-like projects called
papillae
Contain taste buds
Cheeks: Are made mostly of muscle lined
with a mucous membrane and line food up
with teeth
Pharynx
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Common passage for food and air
Several structures open to the pharynx:
mouth
nasal cavity
Eustachian tubes from the ears
larynx
esophagus
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Non ruminants have two striated muscles
that control the passage of food in and
out of the stomach
Esophageal Groove:
Extends from the initial opening of the
stomach to the omasum
Causes food to bypass to the rumen and
reticulum
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Cardia: Sphincter muscle located at the
junction of esophagus and stomach
Pylorus is another sphincter muscle
located at the bottom of the stomach
These control the passage of food in and
out of the stomach
Rumen
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80% of the stomach
food goes from the esophagus to this part
of the stomach first
-AKA - fermentation vat
Digestion in the Ruminant:
Rumen provides favorable environment for
microbial growth due to:
a.
b.
c.
d.
e.
f.
Buffered pH
Temperature maintained at 101 to 103 degrees
Primarily a liquid media
Food supply replenished daily
End products of digestion removed
Anaerobic
Rumen Feed Storage:
Gas
Today’s Hay
Yesterday’s Feed
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Microbes use ammonia and amino acids,
energy, and minerals for growth
cheap type of ammonia = urea
Papillae (tripas):
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finger like lining of the rumen.
honeycomb lining of the reticulum
Reticulum
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food goes back and forth from the Rumen to
Reticulum to break down to particle size
Considered the “honeycomb”
Site of Hardware Disease
Helps move and regurgitate digesta
Collects objects that shouldn’t be in the digestive
system.
 Nails
 Screws
 Baling wire
Reticulum
(Hardware Stomach or Tripe)
Function – Site of microbial action &
absorption of Volatile Fatty Acids
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Pacemaker for rumen contractions
a.
b.
c.
d.
Contractions start in reticulum spread to
rumen
Mixes rumen contents
Heavy particles move to bottom, lighter ones
float
Lighter particles subject to rumination
(Rumination = regurgitation, remastication,
resalivation, reglutition)
Omasum:
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Increases size but may squeeze some water out
of the feed (H2O absorbed here)
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Acts like a filter, holds back feed stuff that hasn’t
been broken into smaller particles
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Regulates particle size flowing to abomasum/S.I.
“many piles”, lamina propia
-has a lot of leaves and folds called papillae
-Function is unclear
-Some mechanical digestion from lamina
Omasum (manyplies)
Abomasum
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(true stomach)
everything done like a non-ruminant’s
stomach
Secretes digestive juices.
Breaks down food stuff further for
absorption.
Absorbs some nutrients.
Abomasum
Eructation:
Belching of gas
 Improper eructation
leads to bloat
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Gallbladder:
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Horses don’t have one
It empties waste as bile through the
common bile duct into the duodenum
Pancreas:
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produces the
hormone insulin
which deposited into
the bloodstream
located in the first
loop of the duodenum
Liver
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worn out red blood cells are destroyed
here
has a duct that merges with the pancreas
and empties into the small intestines
Bile
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yellowish-green, alkaline, bitter liquid
aids in the digestion of glycerol and fatty
acids
Hydrochloric Acid
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Aids in the dissolving of minerals in diet
Small Intestines:
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work to break down solids
The end product of digestion of protein
are amino acids
Go through the blood stream to cells.
Villi:
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Finger-like projections line small intestine
Primary site of absorption of nutrients
Duodenum:
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first part of the small intestines
secretions from the pancreas, liver, and
intestinal walls occur here
is secreted here.
Jejunum
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middle part of the small intestines
nutrient absorption occurs here
Ileum
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last part of the small intestines
nutrient absorption occurs here
Layers in the intestine
Large intestines:
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Vitamins E and K are synthesized in
the large intestine. These are fat
soluble vitamins.
Bacteria in the LI produce some
amino acids, but mostly fatty acids
Fatty acids = energy
Amino acids = protein synthesis
Large Intestine:
Divided into:
1 cecum
2 blind pouch
3 colon
4 ends in the rectum and anus
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Cecum:
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first part of the large intestine
ruminants have bacteria here which allows
it to use large amounts of roughages
primary water absorption site.
 Fermentation occurs in the cecum,
similar to the action that takes
place in the fore-stomach of the
ruminant
colon
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middle and largest part of the large
intestine
Rectum
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Connects the small colon with the anus.
Receives feces from the small colon,
which formed the characteristic balls of
horse manure.
Reabsorbs water that was not absorbed
in the cecum.