2. Digestive Systems- Comparative Anatomy Flashcards
Why does the body need nutrients?
Growth, Repair, Maintenance, Energy supply, Reproduction
What is the general process of digestion?
The food is ingested, then digested and broken down by an enzymatic process into small chemical units.
The absorbed chemical units are carried to the liver where they are metabolised for use by the body.
Any indigestible material is excreted from the body.
What types of animals are there (based on their digestive system)?
Carnivore, omnivore, browser, herbivore
What are the anatomical differences of the tongue in the dog, cat, goat and bird?
Dog- stretch receptors in the tongue and can use the tongue to lose heat (panting)
Goat- heavily keratinised with long papillae for eating (protective surface)
Cat- long papillae for grooming
Bird- contains a bone used for food manipulation. Parrots use tongue to produce sound
What is the Buccal cavity and how is it used in different animals?
A cavity lying within the mouth (cheeks)
Rodents- cheek pouches to store food
Ruminants- papillae are present on the medial surface of the cheeks to provide protection to the underlying epithelium due to diet
What anatomical differences are there to the soft palate in equine, canine and avian species?
Equine- tight laryngeal cuff so that the soft palette can not be raised for a long period of time- prevents vomiting
Canine- soft palate can obstruct breathing in brachycephalic breeds
Avian- birds lack a soft palate
What components make up saliva?
Water, inorganic salts, mucin, salivary analyse, electrolytes, antimicrobial agents, lingual lipase
How much saliva do animals produce in a 24hr period?
Equine- 40L
Bovine (cattle)- 110-180L
Porcine (pigs)- 15L
What are the 3 types of digestive system?
Mono gastric- carnivores and omnivores
Ruminant- herbivore and browses
Hind gut fermenter- herbivore and browser
What is Proteases and how/where are they secreted?
Pepsinogen-Secreted as an inactive sumo hen, activated by hydrochloride acid; active pepsin produces and completed near brush border to generate small peptides and individual amino acids; starts in the stomach and continues into the small intestine.
What are carbohydrase and where/how are they secreted?
Eg Amylase are within salivary and pancreatic secretions and act to produce disaccharides; disaccharides are converted to monosaccharides near the brush border
What are lipases and how/where are they secreted?
Assisted by bile salts which neutralise stomach acids and emulsified fats- process generates free fatty acids
What is the small intestine responsible for?
Main site of chemical degradation and absorption of chyme, breaks down fats, absorbs starch, lipids and proteins
What is the pancreas made of and what is the role?
It is a pink lobulated mixed gland made up of Islets of langerhans.
It secreted exocrine (enzymes) and endocrine (hormones)
What makes up pancreatic juices?
Produced by the exocrine part in a response to gastrin (from stomach) and secretin (from duodenum)
Contains:
- Bicarbonate (neutralise acid in chyme)
- Digestive enzymes
- Proteases
- Lipases
- Amylases
Which animals have a caecum and why?
Herbivores/ruminants
Houses fermenting bacteria to breakdown cellulose
What is the function of the large intestine?
- Absorption of water
- Absorption of water soluble vitamins (B&C)
- Storage of faeces
- Mass movement of faeces through the descending colon stimulating defaecation
What is the role of the Rectum?
Although empty most of the time, the rectum holds the faeces before defecation
What is the anus made up of?
Internal anal sphincter- smooth muscle, involuntary
External anal sphincter- striated muscle, voluntary
What is different about avian anatomy?
Mouth- no teeth, crop, proventriculus, gizzard and cloaca
What is the role of the crop?
To store food and water until ready to be passed to the rest of the GI tract. When empty it stimulates the bird to eat more
What is the role of the proventriculus?
True stomach where digestion begins. HCl and digestive enzymes break down feed further than the enzymes secreted in salivary glands
What is the role of the gizzard?
Mechanical breakdown - made up of two sets of strong muscle that act as teeth
What is the role of the cloaca?
Digestive and urinary waste mix together to be excreted. Also the exit of the reproductive tract
How is feeding controlled?
Hormones, neurotransmitters and reflexes are involved in the feeding of animals.
Secretions and motility of the GI tract are stimulated and regulated by numerous factors, including environmental stimuli and the presence of food in different parts of the GI tract.
When a harmful substance is ingested, the body acts to eliminate it in different ways to prevent illness eg vomit or diarrhoea
