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