digestive system
DESCRIPTION
Digestive System. Path of Digestion. Food is grasped and collected into the oral cavity This is called prehension Mastication (chewing) breaks food into smaller pieces Deglutition moves chewed food into the pharynx and on into the esophagus - PowerPoint PPT PresentationTRANSCRIPT
DIGESTIVE SYSTEM
PATH OF DIGESTION Food is grasped and collected into the oral
cavity This is called prehension
Mastication (chewing) breaks food into smaller pieces
Deglutition moves chewed food into the pharynx and on into the esophagus The epiglottis closes off the entrance to the trachea
Food moves down the esophagus by gravity and peristalsis Peristalsis is a series of wavelike contractions of
smooth muscle -stalsis means contraction
PERISTALSIS VERSUS SEGMENTATION Food moves through
the small intestines by peristalsis and segmentation
Peristalsis is a series of wavelike contractions that move ingesta caudally toward the anus
Segmentation involves the side-to- side mixing of ingesta
STRUCTURES AND FUNCTIONS
• The organs of the gastrointestinal tract (GI) form a tubelike passage through the body cavaties.– From the mouth to the anus by way of the
pharynx, esophagus, stomach, and intestines
• The main functions of this system is – Prehension– Transport– Breakdown of food– Absorption of nutrients– Eliminate waste
STRUCTURES AND FUNCTIONS
• Food moves through the digestive system aided by peristalsis, an involuntary, wavelike movement.
• The digestive tract in all mammals generally has the same parts– Mouth– Teeth– Tongue– Pharynx– Esophagus– Stomach– Small intestine– Large intestine
THE MOUTH
Lips form the entrance to the mouth. The lips of sheep, goats, and horses are soft and flexiable and aid in picking up food.
Lips of cattle and swine are stiff and immobile and do little more than close the mouth.
TEETH
• The number of deciduous (baby teeth) and permanent teeth vary with the species and the natural diet of an animal.
• Teeth provide a variety of functions– Cutting and grinding of food– Defense mechanism
• Ruminants do not have upper incisors, just a pad.
SALIVARY GLANDS
Saliva is produced in 4 salivary glands Parotid Sublingual Mandibular Zygomatic
Referred to as exocrine glands
Saliva begins the breakdown of some foods (carbohydrates) in the mouth.
Moistens food, lubricant for the bolus.
DIGESTION Digestion is the process of breaking down
foods into nutrients that the body can use Metabolism is the processes involved in the
body’s use of nutrients Meta- means change or beyond Anabolism is building up of body cells Catabolism is breakdown of body cells
ABSORPTION
Absorption is the process of taking digested nutrients into the circulatory systemalso called assimilation
Absorption occurs in the small intestineVilli are tiny hairlike projections that help
increase the surface area of the small intestine allowing more nutrients to be absorbed Vill/i means tuft of hair
The valleys that result from the projections of the small intestine are called crypts
DIGESTIVE SYSTEMS
Man and pig have a simple stomach with an extensive intestinal system
Ruminants have a complex stomach with a simpler intestinal system
Horses and rabbits have a simple stomach with an extensive intestinal system and an enlarged cecum
3 MAJOR DIGESTIVE SYSTEMS
All 3 systems will be addressed in detail in the lesson to follow:
Ruminants—have four stomach compartments
Monogastric—have one stomach Modified Monogastric—have one
stomach but the ability to digest roughages
Ruminant Digestive System
DIGESTIVE SYSTEM
Small Intestine: long coiled tube connecting stomach to large intestine rest of the digestion and absorption takes place here surface covered with villi (surface area)
3.5 times the length of animal – dog 18’
Large Intestine: Cecum, colon, rectum absorbs water (makes feces more solid) some vitamins and minerals absorbed here Cecal Fermenters (Horse): similar to rumen
DIGESTIVE SYSTEM
Accessory organs: Pancreas secretes enzymes to break down fat Liver (largest internal organ) secretes bile,
which digests fats also stores iron
DIGESTIVE SYSTEMS Man and pig have a ________stomach with an
extensive intestinal system Ruminants have a ___________ stomach with a
simpler intestinal system Horses and rabbits have a simple stomach
with an extensive intestinal system and an enlarged__________
DIGESTIVE SYSTEM Mouth: “Prehension” tool (grasps food)
___________________secrete juices containing enzymes (digest food)
Chewing food breaks down ____________: muscular tube that connects
mouth to stomach Peristaltic Movement: sequential contraction of ring
like___________ Reverse ___________= blowing chunks
SIMPLE STOMACH
Muscular contractions break down food Enzymes break down food:
Gastric: ___________ Liver and ____________: fats
Ruminant Digestive System
Ruminant Facts (Bovine) Chews cud
40,000-60,000 jaw movements/day
No upper incisors - dental pad
Does not “bite” grass - wraps tongue
Uses fermentation to digest plants
Symbiotic relationship with bacteria
Produces 13 gallons of gas/hour
Produces 40 liters of saliva/day
I thought Dumbo was an elephant
RUMINANT STOMACH Stomach occupies 3/4 of abdominal cavity,
mostly on the left side Rumen (paunch): 80% of stomach, lighter food
collects here microbes digest cellulose lots of water
Reticulum (hardware stomach): 5% of stomach, heavy foreign items are trapped here
RUMINANT STOMACH
Omasum (many plies): 8% of stomach, absorbs water
Abomasum (true stomach): 8% of stomach, typical enzyme activity
Rumination: regurgitation, rechewing of food
Rumen Largest compartment On left side of animal Contains micro-organisms Ferments cellulose Absorbs VFA’s Divided into chambers Continually contracting Contains papillae Produces CO2
pH close to neutral (6 - 7)
Reticulum Smallest compartment
Lies close to the heart
Small sac - part of rumen body
Catches dense, heavy feed for later rumination
Contracts for regurgitation
“Honeycomb” lining
Catches hardware and stores it
Omasum
Third compartment
Globe-shaped
Lining called “many plies”
Reduces feed particle size
Absorbs water and dries out ingesta
Absorbs volatile fatty acids
Abomasum Final compartment
Tubular in design
“True” stomach (glandular)
Secretes HCl and enzymes for chemical digestion
Reduces pH to 2.5 Dissolves minerals Kills rumen bacteria Breaks down proteins
Passes ingesta to small intestine
Ruminant Digestion
Ruminant Digestion Intake
Mastication (chewing)
Swallowing
Regurgitation
Remastication
Fermentation
Eructation
Absorption
Digestion
Rumination
Fermentation Anaerobic bacteria
break down cellulose
VFA’s released by bacteria passed to
bloodstream through papillae
CO2 and CH4 produced by bacteria
Bacteria controlled by protozoa
Ingesta passed to omasum by
contractions
DIGESTIVE SYSTEM Converts feed into a form that can be used for
maintenance, growth, and reproduction In a light horse, the tract is approximately 100
feet long and capacity of 40-50 gallons. Includes:
Mouth, esophagus, stomach, intestines, anus, liver, teeth, pancreas, and salivary glands
EQUINE DIGESTIVE SYSTEM Mouth
Lips, pharynx, soft palate Lips pick up loose feed which is then passed into
the mouth by the tongue Pharynx
Short, funnel shaped tube between the mouth and the esophagus Food and water cannot return through the mouth after
passing through Horse that chokes has food pass through nose
DIGESTIVE SYSTEM
Esophagus is a long muscular tube from the pharynx to the stomach.
Stomach is a U shaped muscular sac Peristalsis moves food through Gastric juices are expressed by the stomach
walls.
HORSE DIGESTIVE SYSTEM
1. Esophagus 5. Large intestine (80 quarts)
2. Stomach (8-16 quarts) 6. Pelvic flexure
3. Small intestine (48 quarts) 7. Colon
4. Cecum (28-32 quarts) 8. Rectum
LARGE INTESTINE, HORSES The large intestine makes up
approximately 60% of the total digestive tract.
Divided into cecum, large colon, small colon and rectum.
Cecum is an important organ in horses.Horses can use large amounts of
roughage because of the presence of bacteria in the cecum and colon.
These bacteria digest cellulose and ferment carbohydrates.
LARGE INTESTINE, HORSES IMPORTANT- because the large intestine of
the horse usually contains substantial quantities of ingested material, impaction occurs easily.
This impaction is the start of what horse ailment?
Signs and symptoms Kicking at abdomen, rolling, lying down and
standing up repeatedly, restlessness .