Chapter 13 Part 1 Flashcards
Name the general steps of the Digestive System
Ingestion and Processing –> Digestion, Absorption, Egestion
Name the major subdivisions of the digestive system:
Buccal Cavity, Pharynx, Esophagus, stomach, small intestine, large intestine, and cloaca
Name the accessory organs of the digestive system
oral glands, liver, gallbladder, pancreas
What germ layers contribute to the gut?
Gut forms from Splanchnic lateral plate mesoderm and endoderm
Buccal Cavity
Boundaries of the buccal cavity: The extent to which the embryonic stomodeum contributes to the mouth, can be followed by two markers
These two markers remain outside the mouth in cyclostomes
What two markers measure contribution to mouth development?
the nasal placode and hypophyseal pouch
Hypophyseal pouch in sharks and bony fishes
pinched off from the mouth
Name farther to short anterior margins of the mouth
cylcostomes, bony fish, shark, Rhipidistians, Tetrapods
Ratkes
outgrowth of the roof of mouth, forms part of the pituitary (hypophyseal pouch = Ratkes)
Oropharyngral cavity in fish
o Made up of the pharynx and buccal cavity
o Seen in sharks(cartilaginous fish) and other fish
What can buccal cavity develop into that is used for storage?
- cheek pouches
- food storage in monkeys, rodents
Primary palate
In fishes, amphibians, and reptiles – roof of mouth bottom of skull, does not divide buccal cavity (oronasal cavity)
Secondary Palate
divides oronasal cavity into nasal cavity on top and oral cavity below; in crocodiles, birds, and mammals
-Secondary palate: single opening called choana; septum divides nasal cavity into two sides
How does the primary palate differ from the secondary palate?
The primary palate does not divide the buccal cavity, while the secondary palate divides the buccal cavity
Where do tongue muscles come from?
hypobranchial muscles
What is the origin of the hypobranchial muscles?
Derived from the hypaxial muscle group
Tongue
Tongue: primary purpose to grasp and manipulate food
Specialized fish mouth
Fish have a series of curved bones called the branchial arches
The bone closes to the mouth is the hyoid; the arches behind it support the gills
Early tetrapod tongues
Over time, the hyoid of early tetrapods got more complex, with perhaps the first of a tongue
▪ Some arches disappeared as lungs replaced gills
▪ Hyoid skeletal associated with muscles
Land Vertebrate tongues
With the skeleton and musculature to support and operate a protrusible tongue, land vertebrates became adept at feeding on land
