Digestive System

What are the functions of the digestive system?

• Prehension

• Mastication

• Salivation

• Swallowing

• Digestion/fermentation

• Absorpotion

Is waste excretion a function of the digestive system?

No

The digestive system contains components from which embryonic layer?

All three

Which embryonic layer is the gut lining formed from?

Endoderm

Which embryonic layer are the embryonic gut walls and muscles (majority of digestive system) formed from?

Mesoderm

Which embryonic layer is the mouth and anus formed from?

Ectoderm

What is the invagination of the ectoderm in embryos that forms the mouth?

Stomadaeum

What is the invagination of the ectoderm in embryos that forms the anus/cloaca?

Proctodaeum

Describe the primitive gut in embryonic development.

Blind-ended gut tube

Describe the accessory digestive organs in embryonic development.

Outpouchings of primitive gut tube

Describe the intestines in embryonic development.

Herniate into umbilical cord and then retract back into abdominal cavity

Which part of the primitive gut runs from the oropharyngeal membrane to pharynx?

Proximal foregut

Which part of the primitive gut runs from the proximal foregut to liver bud?

Distal foregut

Which part of the primitive gut runs from the distal foregut to transverse colon?

Midgut

Which part of the primitive gut runs from midgut to cloacal membrane?

Hindgut

What composes the digestive tract?

Buccal cavity → pharynx → alimentary canal

What composes the alimentary canal?

Esophagus, stomach, intestines, cloaca, and accessory glands

What type of feeding involves filtering small particles out of the water?

Suspension feeding

What type of feeding involves opening the mouth and sucking in food?

Suction feeding

What type of feeding involves opening the mouth and swimming over food?

Ram feeding

What type of feeding involves using the inertia of food to move it into the oral cavity?

Inertial feeding

What is the term for movement of food within the oral cavity, through water currents or the tongue?

Transport

What is the term for reduction of food size by chewing?

Mastication

What makes up the buccal cavity?

Lips, cheeks, tongue, palate, teeth, and salivary glands

What part of the tooth is located above the gingival line?

Crown

What part of the tooth is located below the gingival line?

Root

What is the outer layer of the crown that is also the hardest substance in the body (unique to vertebrates)?

Enamel

What arrangement does dentin grow in?

Lines of von Ebner

What part of the tooth is located under the enamel and is harder than bone and continues to grow?

Dentin

What part of the tooth contains nerves and blood?

Pulp cavity

What part of the tooth is located outside the dentin in the root?

Cementum

Which embryonic layer does enamel originate from?

Ectoderm

Which cells form enamel?

Ameloblasts

Which embryonic layer does the dental papilla (dentin) originate from?

Mesoderm

Which cells form dentin?

Odontoblasts

Which embryonic cells form odontoblasts?

Neural crest cells

What is arrow 1 pointing to?

Enamel

What is arrow 2 pointing to?

Ameloblasts

What is arrow 3 pointing to?

Dentin

What is arrow 4 pointing to?

Odontoblasts

What is arrow 1 pointing to?

Odontoblasts

What is arrow 2 pointing to?

Ameloblasts

What is arrow 3 pointing to?

Enamel

What is arrow 4 pointing to?

Dentin

What is the term for animals with a single set of teeth?

Monophyodont

What is the term for animals with two sets of teeth?

Diphyodont

What is the term for animals with continuous tooth replacement?

Polyphyodont

Which animals are monophyodont?

Rodents

Which animals are diphyodont?

Mammals

Which animals are polyphyodont?

Vertebrates except mammals

Which tooth arrangement structure involves having teeth of similar shape along the jaw?

Homodont

Which tooth arrangement structure involves having teeth of different shapes along the jaw?

Heterodont

What is special about lungfish teeth?

Tooth plate → teeth are fused together

What term describes molar teeth with low crowns?

Brachydont

What term describes molar teeth with high crowns?

Hypsodont

What term describes molar teeth with rounded peaks for crushing?

Bunodont

What term describes molar teeth with cusps in ridges for grinding?

Lophodont

What term describes molar teeth that are crescent-shaped for lateral chewing?

Selenodont

What type of tooth is this?

Brachydont

What type of tooth is this?

Hypsodont

What type of tooth is this?

Bunodont

What type of tooth is this?

Lophodont

What type of tooth is this?

Selenodont

Which two terms describe human teeth?

Brachydont and bunodont

What is a unique adaptation of beaver and rabbit teeth?

Continual growth

What is a unique adaptation of elephant molars?

Fused together → sequential eruption

What somite muscles does the tongue originate from?

Hypobranchial muscles

What are the three functions of the tongue?

• Lingual feeding

• Taste

• Transport of bolus

What is the difference between fish and tetrapod tongues?

• Fish: limited structure to allow suction feeding

• Tetrapods: mobile, muscular tongue

What type of cell are taste buds?

Chemoreceptor cells

Which type of papilla is square-shaped?

Fungiform papillae

Which type of papilla has a sharp point and moves food around?

Filiform papillae

What type of papilla is this?

Fungiform

What type of papilla is this?

Filiform

What do oral glands secrete?

Mucus and serum

Do fish have oral glands?

Rarely

What is the most common type of oral gland?

Salivary

What type of oral gland do reptiles have?

Supra- and -infralabial

What type of oral gland do poisonous snakes have?

Venom

What type of gland is associated with the snout?

Premaxillary/nasal

What type of gland is associated with the eye?

Lacrimal

What are the three functions of salivary gland secretions?

• Lubrication

• Buffers

• Digestive enzymes

What condition results from a buildup of fluid from the sublingual gland?

Salivary mucocele

What are the three salivary glands?

Parotid, mandibular, and sublingual

Which part of the digestive tract is the passageway to the esophagus?

Pharynx

Which specific part of the pharynx transports food from the oral cavity to the rest of the digestive system?

Oropharynx

What are the layers of the alimentary canal, from innermost to outermost?

Mucosa → submucosa → muscularis externa → serosa

Which embryonic layer is the mucosa derived from?

Endoderm

Which embryonic layer is the submucosa derived from?

Mesoderm

Which embryonic layer is the muscularis externa derived from?

Mesoderm

What is the function of the esophagus?

Transport food from the oropharynx to the stomach

What two structures keep food within the esophagus?

Upper and lower esophageal sphincter

What muscular action of the esophagus moves food to the stomach?

Peristalsis

What glands produce mucus that lubricates the esophagus?

Luminal glands

What are the three functions of the stomach?

1. Store food → carnivores

2. Mix/churn food

3. Digestion

What types of epithelium make up the stomach?

Glandular and nonglandular

Which area of the glandular stomach comes out of the esophagus and contains mucus glands?

Cardia

What is the function of mucus secreted in the stomach?

Lubricate/soften bolus

Which area of the glandular stomach contains parietal and chief cells?

Fundus

What do parietal cells in the fundus secrete? What type of digestion is this?

HCl → acid digestion