Digestive system part 2 Flashcards
General pathway of food in the RUMINANT stomach
- Food enters rumen and reticulum, and microorganisms digest the cellulose
- Ruminant regurgitates and rechews ‘cud’ to break down fibers
- Cud goes to omasum where water is removed
- Cud goes to abomasum (true stomach) to be digested by the cows enzymes.
Protein digestion in RUMINANT STOMACH
- Fermentation happens before chemical digestion in stomach.
- Nutrients are available in the reticulorumen, where peptidase breaks proteins into peptide chains.
3/ Microbes convert nitrogen compounds to synthesize amino acids from ammonium - Enzymatic action in SI breaks them down and they go to liver to metabolise. Urea is produced.
What is the rumen and what are its adaptations
It is a large chamber where fermentation occurs.
-it has papillae to increase the surface area and pillars that divide it into 4 sacs.
What is the reticulum and what adaptations does it have
It acts as one with the rumen and lies against the diaphragm.
-It has mucousa with a honeycomb pattern
-Reticulorumen has bacteria to break starch and cell walls into VFAs
What is the omasum and what adaptations does it have
It connects the reticulorumen to the abomasum. Its function is absorption of water and salt.
-it has laminae with papillae to direct the flow of food
What is the Abomasum and what adaptations does it have
It is the true stomach and acts as a monogastric stomach without the storage. It secretes pepsinogen and hydrogen.
-It has rugae which increase surface area.
What are functions of the Small intestine
-Carries chyme from stomach to LI
-Is the main site of enzymatic digestion and absorption for animals who don’t rely on fermentation
-It mixes food with more digestive juices
What are the parts of the SI and what do they do
- Duodenum: Receives chyme from pyloric sphincter and has digestive enzymes.
- Jejunum: Is a major site of chemical digestion and absorption. Paneth cells release digestive enzymes.
- Ileum: Empties into LI and has Peyers patches for disease protection.
What adaptations does the small intestine have
-Its long and has loops.
-It has fold in the lining for increased surface area
-It has villi which help membranous digestion.
-It has Crypts of Langerhans
What and where is the pancreas
It is a gland located in the U of the duodenum that performs essential secretions for digestive processes.
-It functions as a mixed gland
What is the pancreas’ endocrine function
-It has islet cells that secrete hormones.
1. B cells secrete insulin to decrease blood glucose
2. A cells secrete glucagon to increase blood glucose
What is the pancreas’ exocrine function
-It secretes digestive enzymes via the pancreatic duct that are vital for digestion, eg. lipase, amylase, protease.
-It also has pancreatic juices to neutralise stomach contents before entering the duodenum.
Where is the liver
It is near the stomach and behind the diaphragm
What are the functions of the liver
-Processes blood leaving GI tract to prevent toxins entering circulation
-Secretes substances for digestion and nutrient absorption
-Excretes toxic substances
-Produces energy
-Plays a role is keeping blood glucose normal
What does bile do
- Bile salts are secreted into canaliculi and draw water out of hepatocytes to make liquid bile.
- This goes to the intestine to emulsify fat
- The ileum reabsorbs the bile salts and sends them to the liver via hepatic portal vein to be recycled back to bile.
How does the liver regulate blood glucose levels
- Glucose arrives in liver and is metabolized to produce energy
- Excess glucose is stored as glycogen
- Glycogen can be broken down to glucose when needed (Glycogenolysis)
What are functions of the gallbladder
-Stores bile
-Allows liver to excrete waste products even when an animal isn’t eating.
What are functions of the large intestine
-Absorption of water/ions
-Absorption of carbohydrates and proteins
-Microbial digestion
What are the parts of the Large intestine
-Cecum
-Colon
-Rectum
-Anus
Hindgut fermentation in horses
- Fermentation occurs in the colon, and is required for energy.
- Bicarbonate neutralizes acids to maintain optimal conditions for organisms.
- Urea is transferred to LI.
What happens in the large intestine
- Certain areas of muscle contract and relax, and then different areas in another location contract/relax.
- This prolongs the time contents stay which helps absorption.
- To empty, sensory receptors in the rectum cause the colon and rectum to contract and the anal sphincters to relax.
What are the components of the bird digestive system
-Crop
-Stomach
-Small intestine
-Caeca
-Cloaca
What is the crop
An expanded portion of oesophagus that acts as a storage pouch
What is different about a birds stomach
It has 2 parts;
1. The Proventriculus is glandular for chemical digestion
2. The Gizzard is muscular for grinding up food.
What are the Caeca
Paired sacs at the junction of SI and LI used for water reabsorption and fermentation of cellulose.
What are the sections of the cloaca
- Coprodeum: gets excrement from intestines
- Urodeum: gets discharge from the kidneys
- Proctodeum: stores excrement and is close to the anus, which ejects waste through the vent.
