Digestive System
Q: What are the components of the digestive tract?
A: Buccal cavity, mouth opening (± lips/teeth/cheeks), palate, tongue, pharynx, esophagus, stomach(s), small & large intestines, cecum, cloaca, anus/vent.
Q: What are the accessory digestive organs?
A: Salivary glands, liver, pancreas.
Q: What are the functions of the digestive system?
A: Acquire food, mechanical/chemical breakdown, absorb nutrients, fermentation, detoxification, waste elimination, immune defense, communication.
Q: What is the difference between primary and secondary palate?
A: Primary palate is bone-supported and connects nares to mouth; secondary palate separates nasal cavity from oral cavity (in mammals & crocodiles).
Q: What is a cleft palate?
A: Abnormal opening between oral and nasal cavities due to incomplete palate formation.
Q: What are the components of a tooth?
A: Enamel (outer surface, no regrowth), dentin (beneath enamel, grows), cementum (covers root below gum).
Q: What are the main types of teeth in mammals and their functions?
A:
Incisors: clipping/shearing
Canines: puncturing/holding
Premolars & Molars: grinding/crushing
Q: What are dental formulas used for?
A: To describe number and types of teeth in each half of the upper/lower jaws.
Q: Give an example of a dental formula.
A: Dog: I 3/3, C 1/1, P 4/4, M 2/3 = 42 teeth.
Q: What is polyphyodonty?
A: Continuous tooth replacement throughout life (e.g., reptiles, fish).
Q: What is diphyodonty?
A: Two sets of teeth: deciduous (baby) and permanent (adult); typical of mammals.
Q: What is the difference between brachydont and hypsodont teeth?
A:
Brachydont: short crowns, stop growing (humans, carnivores).
Hypsodont: tall crowns, continue growing (horses, rabbits).
Q: What happens if occlusion is improper in hypsodont animals?
A: Overgrowth or uneven wear (e.g., “wavemouth” in horses).
Q: What is the function of the tongue?
A: Taste, prey capture, swallowing, grooming, communication, vomeronasal sensing.
Q: How does tongue mobility vary among vertebrates?
A: Jawed fish: immobile; amphibians/reptiles: often extensible; birds/turtles/whales: limited; mammals: mobile (frenulum connects to floor).
Q: What is the pharynx and where is it located?
A: Passageway between nasal/oral cavities and esophagus.
Q: What is the esophagus and its function?
A: Tube connecting pharynx to stomach; moves food via peristalsis.
Q: What is a crop, and which species have it?
A: Diverticulum of esophagus for temporary food storage; in pigeons, doves, some raptors, and poultry.
Q: What are the functions of the stomach?
A: Store food, mechanically mix, and chemically digest using acid and enzymes.
Q: Describe the bird stomach structure.
A: Proventriculus (glandular) and ventriculus/gizzard (muscular, grinding, keratinized).
Q: What is the ventriculus (gizzard)?
A: Thick-walled muscular stomach region for grinding food in birds and some reptiles.
Q: What are the glandular and non-glandular parts of the mammalian stomach?
A: Glandular: secretes acid/enzymes; Non-glandular: no secretion, may store/ferment (seen in horses, ruminants).
Q: What is the margo plicatus in the equine stomach?
A: Line dividing glandular from non-glandular regions.
Q: Name the four chambers of the ruminant stomach and their functions.
A:
Rumen: fermentation vat
Reticulum: traps dense material (“hardware disease”), honeycomb wall
Omasum: absorbs water (“book stomach”)
Abomasum: true glandular stomach
Q: What is hardware disease?
A: Ingestion of metal objects lodging in reticulum, causing inflammation or perforation.
Q: What are the three sections of the small intestine (in order)?
A: Duodenum → Jejunum → Ileum.
Q: What are the main functions of the intestines?
A: Move food (peristalsis), secrete enzymes, absorb nutrients and water.
Q: How does diet affect intestine length?
A: Herbivores have longer intestines; carnivores shorter; fish/amphibians relatively simple.
Q: What is the spiral valve in cartilaginous fish?
A: Internal fold increasing surface area and slowing food passage for absorption.
Q: Describe the intestinal structure in reptiles, birds, and mammals.
A:
Reptiles: simple, ± cecum.
Birds: short, cloaca present, may have paired ceca.
Mammals: well-differentiated small/large intestines, ± cecum.
Q: What is a cloaca and which vertebrates have one?
A: Common opening for digestive, urinary, and reproductive tracts; found in fish (cartilaginous), amphibians, reptiles, birds, and monotremes.
Q: What is the cecum and its function?
A: Pouch at small–large intestine junction for microbial fermentation (especially in herbivores).
Q: What is the difference between foregut and hindgut fermentation?
A:
Foregut: fermentation in stomach (ruminants, camels).
Hindgut: fermentation in intestines/cecum (horses, rabbits, pigs).
Q: What is coprophagy, and which animals use it?
A: Re-ingestion of fecal pellets to recover nutrients; rabbits and some rodents.
Q: What is colic in horses?
A: Abdominal pain from gas, impaction, strangulation, or inflammation of intestines.
Q: What are salivary glands for?
A: Lubricate food, begin digestion, secrete toxins or nest glue in some species.
Q: Which vertebrates lack prominent salivary glands?
A: Fish and most birds.
Q: What are the major salivary glands in mammals?
A: Mandibular, sublingual, parotid, zygomatic.
Q: What are reptile venom glands derived from?
A: Modified oral glands (e.g., Duvernoy’s gland).
Q: What are the exocrine functions of the pancreas?
A: Secrete digestive enzymes and bicarbonate into duodenum to neutralize acid.
Q: What are the endocrine functions of the pancreas?
A: Secrete insulin and glucagon to regulate blood sugar.
Q: What is an insulinoma?
A: Pancreatic tumor causing overproduction of insulin → hypoglycemia.
Q: What are the functions of the liver?
A: Metabolism (fats, carbs, proteins), detoxification, bile production, nutrient storage.
Q: What is the function of bile?
A: Emulsifies fats for digestion; stored in gall bladder (if present).
Q: Which species lack a gall bladder?
A: Deer, rats, horses, whales, seals, many birds.
Q: What is the cloaca or vent used for in animals that have it?
A: Common exit for digestive, urinary, and reproductive products.
Q: What is the small intestinal submucosa (SIS)?
A: Collagen-based tissue layer used for medical grafting, derived from porcine intestine.
Q: What is the difference between ruminants and pseudo-ruminants?
A: Ruminants have four stomach chambers; pseudo-ruminants (camels, llamas) have three.
Q: What are carnassial teeth and in which animals are they found?
A: Shearing teeth (upper 4th premolar, lower 1st molar) found in carnivores.
Q: What is “floating” in equine dentistry?
A: Filing down overgrown molars to correct uneven wear.
Q: What is gastric dilatation and volvulus (GDV)?
A: Twisting of the stomach causing obstruction and shock in dogs (“bloat”).
Q: What is LDA (Left Displaced Abomasum)?
A: Abomasum shifts to left side post-calving; common in dairy cows.