comparative anatomy digestive system
TRANSCRIPT
Comparative anatomy( Chordates)
Digestive system 1-Human 2-Ruminant 3-Avian 4-Horse 5-Fish Dr.Omer
Digestive System
Introduction
• Three (3) basic types of digestive systems according to their stomachs :
►Monogastric – simple stomach.►Ruminant (cranial fermentor) – multi-compartmented
stomachs.►Hind gut (caudal) fermentor – simple stomach, but very
large and complex large intestine
Types of Digestive Systems
Cats
Chickens Pigs
DogsTurkeys
Monogastrics Ruminants Hind Gut Fermentors
Beef Cattle Dairy Cattle
Deer
SheepGoats
Horses
Rabbits
Ostrich
Types of Digestive Systems
• Are divided into three groups based on their food sources1. Herbivores are animals that eat plants
exclusively2. Carnivores are animals that eat other animals3. Omnivores are animals that eat both plants and
other animals
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Carnivore• Eat primarily
other animals.
Herbivore• Eat primarily
plant materials.
omnivore• Eat combination
of plant and animal material.
The Human Digestive System
Human
Kingdom AnimaliaPhylum ChordataClass MammaliaOrder PrimatesFamily HominidaeGenus HomoSpecies sapiens
Introduction• The digestive system is used for breaking down food into
nutrients which then pass into the circulatory system and are taken to where they are needed in the body.
Main Functions of Digestive Tract
• The major activities of GI tract• 1-Ingestion: taking in food
2.Motility • Propel ingested food from mouth toward rectum
3.Secretion of juices e.g. saliva • Aid in digestion and absorption
4.Digestion• Food broken down into absorbable molecules
5.Absorption• Nutrients, electrolytes, and water are absorbed or
transported from lumen of GIT to blood stream6.. Egestion (Elimination) : removing any leftover wastes
Digestion• Types– Mechanical (physical)• Chew• Tear• Grind• Mash• Mix
– Chemical• Enzymatic reactions to improve digestion of – Carbohydrates– Proteins– Lipids
Anatomy of the Digestive TractGIT consists of;– Oral cavity or mouth – Pharynx– Esophagus– Stomach– Small intestine– Large intestine– Rectum– Anus
Mouth or oral cavity
• Ingestion - bringing food into the body– tongue - taste buds detect chemical composition of food
• Mastication - chewing (physical digestion)– teeth and tongue
• Chemical digestion - saliva– moistens food– amylase - breaks down starch – lysozyme - antibacterial agent
Mouth and Teeth
Esophagus• Muscular tube connecting the pharynx to the stomach.• Functions include:1. Secretes mucus2. Moves food from the throat to the stomach using
muscle movement called peristalsis Cardiac Sphincter – connects esophagus and stomach• If acid from the stomach gets in here that’s heartburn.
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Stomach • Muscular sac-like organ• Chemical and physical digestion
– forms chyme • goblet cells – mucus
– forms a protective barrier against the high acidity of the stomach content.
– parietal cells – HCl– kills bacteria, denatures proteins
• chief cells - pepsinogen– pepsinogen activated by HCl pepsin – pepsin breaks down proteins
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The Stomach
Small intestine
FunctionsDigestion
Digest carbohydrates : amylase from pancreasDigest proteins : trypsin & chymotrypsin from pancreasDigest lipids (fats) bile from liver & lipase from pancreas
AbsorptionVILLI – small finger-like projections that increase the surface area
MICROVILLI – even smaller finger-like projections on the VILLILACTEAL – large lymph vessel found on each villus (Absorbs FAT)Capillaries – small blood vessels found on each villus (Absorbs all
nutrients EXCEPT Fat)
The Parts of Small intestine
1. Duodenum - most digestion occurs here 2. Jejunum - some digestion and some
absorption occur 3. Ileum - mostly absorption
SMALL INTESTINE
• The small intestine is divided • duodenum • jejunum • ileum.
• Pancreas has 2 functions:a) Endocrine functions: secretes insulin and glucagon
from islets of Langerhans b) Exocrine function: secretion of pancreatic juice• It has 2 components: aqueous and enzymatic
components.• Aqueous component (contains HCO3) is important for
neutralizing stomach acid in the duodenum so pancreatic enzymes can function properly
• Enzymatic component is essential for the proper digestion and absorption of carbohydrates, fats, and proteins
• Pancreatic enzymes include trypsin, chemotrypsin, lipase, and amylase
Functions of the Pancreas
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Liver
Functions of the Liver:1) Metabolic regulation
• Store absorbed nutrients, vitamins• Release nutrients as needed
2) Hematological regulation• Plasma protein production• Remove old RBCs
3) Production of bile• Required for fat digestion and absorption
Liver
Liver
The Large Intestine (colon)
• Much shorter than small intestine, but has larger diameter
Functions1. Goblet cells: create mucus that lubricates colon and
protects mucosa.2. Absortive cells: Maintain water balance, solidify
feces, absorb vitamins and some ions• Prepare waste for expulsion
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Digestive System– Ruminants –
Mouth, esophagus, liver, pancreas, gall bladder, small intestine, and large intestine have functions similar to monogastrics.
Cow
• • Kingdom Animal• Phylum Chordata• Class Mammalia• Order Artiodactyla• Family Bovidae• Genus Bos• Species indicus Asian humped cattle taurus European non-humped cattle
Reticulum
• Holding area for feed after it passes down esophagus.• Provides additional area for fermentation.• Contains microorganisms, like rumen• Collection compartment for foreign objects.• Helps open and close rumen.• Minimal separation with rumen.
“honeycomb”
Rumen
• Largest of the four components.• On the left side of the animal.• Storage site and fermentation .• Houses millions of microorganisms.• Lined with millions of finger-like projections (papillae) that are needed for
absorption.
“paunch”
Omasum
• A heavy, hard organ that has many folds or leaves.• Little, if any digestive activity.• Grinds feed particles.• Removes moisture.
“many piles”
Abomasum
• True, glandular stomach• Functions similarly to monogastric stomach• Secretes gastric juices which aid in digestion.
Infected with barber pole worms
Organs of the Digestive System– Hind Gut Fermentors –
Mouth, esophagus, stomach, liver, pancreas,, and small intestine have similar functions as compared to monogastrics.
Horse doesn’t have gall bladder
Digestive Tract - Horse-
Esophagus
Stomach
Duodenum
Small intestineCecum
Large colon
Small colon
Rectum
Organs of the Digestive System– Hind Gut Fermentors –
• Large Intestine► Major difference between monogastrics and hind gut fermentors is the large
intestine.► Large intestine is exceptionally large and complex compared to monogastrics
and ruminants.
The large intestine of hind gut fermentors is analogous to the rumen in ruminants.► Microbes digest structural carbohydrates (cellulose, hemicellulose) and
soluble carbohydrates that escape digestion in small intestine to VFA’s. VFA’s absorbed from large intestine and utilized by the animal.
► Microbial protein produced in large intestine is wasted (only very limited absorption from large intestine).
Avian Digestive System
Avian Digestive Systems
• Mouth – no teeth – Salivation excretion moistens food
• Esophagus – has a modification called the “crop” which stores
and moistens food– connects mouth and stomach
Avian Digestive Systems
• Stomach– Contains two parts• Proventriculus: same as monogastric stomach and
provides digestive excretions• Gizzard: located after proventriculus, very muscular,
used to grind food
Avian Digestive Systems
• Small Intestine– similar functions as in ruminants and monogastric
systems• Large Intestine– similar functions as in ruminants and monogastric
systems– “cloaca”: chamber into which urinary and genital
canals open– “ceca”: aids in fiber digestion and absorption
Digestive System Comparisons
Function Monogastric Ruminants Hind Gut Fermentors
Digest and extract energy from cellulose
Very limited(large intestine)
Yes(rumen/reticulum)
Yes(large intestine)
Utilize dietary sugar sources directly
Yes(absorbed as
glucose)
No(fermented to VFA’s)
Yes(absorbed as
glucose)
Utilize protein from feeds directly
Yes Limited(most converted to microbial protein)
Yes
Utilize fat from feeds directly
Yes Some(most fermented to VFA’s)
Yes
Utilize microbial protein
No Yes(60-80% of AA from
microbes)
No
Human Cattle Bird Horses Teeth 32 32 0 40-42
Organs of digestive system Comparisons
Ruminant
• Mouth• Esophagus• Stomach
– Reticulum– Rumen– Omasum– Abomasum
• Small intestines• Large intestines
Monogastric
• Mouth• Esophagus• Stomach• Small intestines• Large intestines
LiverPancreas
LiverPancreas
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