Diversity in the Digestive System Flashcards
Provide a brief overview of the digestive system in vertebrates
- complete tract from mouth to anus/cloaca
- receives, stores, breaks down and absorbs foos
- stores and removes waste
What organs/glands are considered accessory?
- tongue
- teeth
- salivary glands
- pancreas
- liver
What is the basic pathway of the digestive system?
Mouth > pharynx > esophagus > stomach > intestines > cloaca/rectum
What are some basic features of teeth?
- derived from bony dermal armor, similar to placoid scale
- made of dentin, covered in enamel
What are the different types of teeth attachment?
Acrodont: attached to outer surface/summit of jawbone, in many teleosts
Pleurodont: attached inner side, in anurans, salamanders, lizards
Thecodont: teeth in bone socket/alveoli, in fishes, crocs, mammals
What is the difference between homodont and heterodont?
Homodont: teeth same size and shape
Heterodont: teeth vary morphologically
What are some features of the salivary glands?
- moisten and lubricate food
- can assist in prey capture
- allows start of chemical digestion
- modified into poison glands in some snakes/lizards
T or F: the esophagus is modified into the crop of some birds
True
Can allow for food storage
What are some features of the stomach?
- muscular chamber between end of esophagus and start of pylorus
- gastric glands producing HCl
- storage sac
- mostly breaks food down, little absorption
How is the stomach modified in vertebrates like birds and crocodiles?
- becomes 2 parts
- proventriculus secretes digestive enzymes
- muscular gizzard/ventriculus grinds and mixes food
How is the stomach modified in ruminants?
- 4 compartments
- rumen: stores and churns, houses bacteria
reticulum: forms cud and regurgitates for further chewing - omasum: temporary storage
- abomasum: only place with gastric gland
Briefly explain features of the intestines
- small intestine mostly for absorption of nutrients
- large intestine mostly reabsorbs water
- liver and pancreas excrete enzymes and mucous into intestines
T or F: Carnivores have longer and more specialized guts/digestive tracts
False
Herbivores require a longer and more specialized gut to digest plants and their fibre
How can you tell if a ruminant is a hindgut or foregut fermenter?
- hindgut fermenters have a larger caecum which is further along digestive tract
- foregut fermenters have a larger stomach
What 4 layers make up the gut wall?
- serosa
- muscularis externa
- submucosa
- mucosa
