What is/are the function(s) of the digestive system?
What structures are necessary?
How does function varywith form?
Introduction to Digestive System
Graphic overview of alimentary canal
How are we similar to a tall donut?
Introduction to Digestive System
How does this system develop embryologically?
Endoderm is the epithelial lining of the alimentary canal.
Mesoderm splits into somatic and splanchnic mesoderm.
Splanchnic mesoderm contributes to substance of G.I. Viscera (visceral and parietal peritoneum).
Yolk or membrane connection is the midgut
Anterior = foregut and posterior = hindgut.
Introduction to Digestive System
What are features of the mouth and oral cavity?
Oropharyngeal cavity in jawed fishes
Oral cavity in tetrapod
What comprises the cavity?Laterally… the cheeks (mucousa, buccinator, hypodermis, dermis, and epidermis)
Superiorly… the palate (primary and secondary)
Oral Cavity
Oral CavityWhat are features of the mouth and oral cavity?
Reptiles have palatal fissure, this channels air from internal nares to pharynx.
Anurans can have openings that lead to evaginations of the oral cavity (vocal sacs) extending below the phayrnx.
Seed eating birds can have a similar evagination (seed pouch) suspended by the mylohyoid.
Granivorous mammals can have cheek pouches
http://content.answers.com/main/content/wp/en/thumb/7/7d/240px-Litoria_chloris_calling.jpg
http://www.birdandhike.com/Wildlife/Mamm/06Rod/04_Het/Dip_mer/D_mer.htm
Hard and Soft palates
Cleft lip/palate:congenital defect where embryonic tissues fail to fuse
What can your palate do for you?
Oral Cavity
Tongue
Tongue
Tongue
TongueWhat are the functions of the tongue?
Assist in forming a bolus
Facilitate taste
Used to capture food
Used to thermoregulate
Cleaning body (fur, eyelids etc.)
Bound by the frenulum
Receptors for stereognosis
What are the functions of the oral glands of tetrapods?
Assist in forming a bolus
Facilitate taste
Can make tongue sticky
Can produce toxins (palatal in 4 snake groups, sublingual in lizard)
Initiate digestion (amylase/ptyalin)
Aid in immunity (lysozyme)
Goblet cells in fish… papa catfishes
Oral Glands
3 paired glands:ParotidSubmandibularSublingual
Scattered small tubular glands
How do you salivate?
Secrete mucus, serous fluid and enzymes
Endocrine or Exocrine?
Oral Glands
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