Podcast
Questions and Answers
The ventral mesentery is absent in adult ______ except in the regions of the liver and the gall bladder.
The ventral mesentery is absent in adult ______ except in the regions of the liver and the gall bladder.
vertebrates
In mammals, the ______ of the stomach develops a special prolongation called the greater omentum.
In mammals, the ______ of the stomach develops a special prolongation called the greater omentum.
mesentery
Accessory organs include the ______, teeth, oral glands, pancreas, liver, and gall bladder.
Accessory organs include the ______, teeth, oral glands, pancreas, liver, and gall bladder.
tongue
Filter-feeding is the oldest ______ method of acquiring food.
Filter-feeding is the oldest ______ method of acquiring food.
Signup and view all the answers
The oral cavity begins at the ______ and ends at the pharynx.
The oral cavity begins at the ______ and ends at the pharynx.
Signup and view all the answers
The primary palate is the roof of the oral cavity of ______ and amphibians.
The primary palate is the roof of the oral cavity of ______ and amphibians.
Signup and view all the answers
Nasal passageways open into the ______ cavity in lobe-finned fishes.
Nasal passageways open into the ______ cavity in lobe-finned fishes.
Signup and view all the answers
The mouth is specialized to serve as a ______ and masticatory organ in mammals.
The mouth is specialized to serve as a ______ and masticatory organ in mammals.
Signup and view all the answers
The ______ is a distensible muscular tube connecting the pharynx and the stomach.
The ______ is a distensible muscular tube connecting the pharynx and the stomach.
Signup and view all the answers
In birds, the stomach is divided into the ______ and the ventriculus.
In birds, the stomach is divided into the ______ and the ventriculus.
Signup and view all the answers
The ______ are openings of auditory tubes in the pharynx.
The ______ are openings of auditory tubes in the pharynx.
Signup and view all the answers
The stomach of a ruminant serves mainly as a storage sac for large quantities of ______ matter.
The stomach of a ruminant serves mainly as a storage sac for large quantities of ______ matter.
Signup and view all the answers
The wall of the gut is composed of ______ layers caudad to the pharynx.
The wall of the gut is composed of ______ layers caudad to the pharynx.
Signup and view all the answers
In the absence of cellulase, little digestion takes place in the ______ intestine.
In the absence of cellulase, little digestion takes place in the ______ intestine.
Signup and view all the answers
The caecum houses a huge population of ______ that produce enzymes that convert cellulose to sugars.
The caecum houses a huge population of ______ that produce enzymes that convert cellulose to sugars.
Signup and view all the answers
In birds, the gizzard stones are lodged in the ______ stomach.
In birds, the gizzard stones are lodged in the ______ stomach.
Signup and view all the answers
The pharyngeal pouches may give rise to ______ in fishes.
The pharyngeal pouches may give rise to ______ in fishes.
Signup and view all the answers
Micromolecules are absorbed directly through the ______ of the caecum.
Micromolecules are absorbed directly through the ______ of the caecum.
Signup and view all the answers
The stomach is a muscular chamber that serves as a ______ and macerating site for ingested solids.
The stomach is a muscular chamber that serves as a ______ and macerating site for ingested solids.
Signup and view all the answers
The waste material is released into the ______ for disposal.
The waste material is released into the ______ for disposal.
Signup and view all the answers
Herbivores have modified the lower part of the esophagus and the ______ into 'four stomachs'.
Herbivores have modified the lower part of the esophagus and the ______ into 'four stomachs'.
Signup and view all the answers
The ______ is a muscular chamber that churns and grinds food against the stones in birds.
The ______ is a muscular chamber that churns and grinds food against the stones in birds.
Signup and view all the answers
The first compartment of a ruminant's stomach is the ______.
The first compartment of a ruminant's stomach is the ______.
Signup and view all the answers
Herbivorous birds have a ______ that is highly acidic.
Herbivorous birds have a ______ that is highly acidic.
Signup and view all the answers
The rumen is a ______ and fermentation vat.
The rumen is a ______ and fermentation vat.
Signup and view all the answers
The omasum is lined by ______ folds.
The omasum is lined by ______ folds.
Signup and view all the answers
The abomasum is a true ______ stomach.
The abomasum is a true ______ stomach.
Signup and view all the answers
Microbes provide ______ of cellulose to the ruminants.
Microbes provide ______ of cellulose to the ruminants.
Signup and view all the answers
Ruminants provide ______ with reliable heat to the microbes.
Ruminants provide ______ with reliable heat to the microbes.
Signup and view all the answers
Vertebrate intestines are differentiated into ______ and large intestines.
Vertebrate intestines are differentiated into ______ and large intestines.
Signup and view all the answers
Cartilaginous fishes have a ______ intestine with a spiral valve.
Cartilaginous fishes have a ______ intestine with a spiral valve.
Signup and view all the answers
Sharks are essentially ______ with their environment.
Sharks are essentially ______ with their environment.
Signup and view all the answers
In ______, the tract includes an expanded colon, cecum, or forestomach.
In ______, the tract includes an expanded colon, cecum, or forestomach.
Signup and view all the answers
In many ______, the hindgut includes a cecum, but neither the cecum nor colon are haustrated in most species.
In many ______, the hindgut includes a cecum, but neither the cecum nor colon are haustrated in most species.
Signup and view all the answers
The hindgut of ______ lacks a valvular separation from the midgut in some of these species.
The hindgut of ______ lacks a valvular separation from the midgut in some of these species.
Signup and view all the answers
The human ______ becomes well-developed during gestation.
The human ______ becomes well-developed during gestation.
Signup and view all the answers
The ______ is the principal site for microbial fermentation.
The ______ is the principal site for microbial fermentation.
Signup and view all the answers
The stomach is simple and ______ in OMNIVORES.
The stomach is simple and ______ in OMNIVORES.
Signup and view all the answers
Study Notes
Mesentery and Divisions of the Vertebrate Alimentary Canal
- Ventral mesentery is absent in adult vertebrates, except in the regions of the liver and gall bladder (falciform ligament)
- Special mesenteries for gonads and their ducts
- In mammals, the mesentery of the stomach develops a special prolongation called the greater omentum
- Accessory organs include the tongue, teeth, oral glands, pancreas, liver, and gall bladder
Anatomy of Vertebrate Digestive Tracts
- Differences in anatomy correlated with the nature and abundance of food
- Readily absorbed (e.g., hummingbirds) vs. requiring extensive enzymatic activity (e.g., carnivores)
- Constant food supply (e.g., herbivores) vs. scattered supply (e.g., carnivores)
- Filter-feeding is the oldest craniate method of acquiring food
- Still employed by lampreys, a few jawed fishes, and baleen whales
Oro-Pharyngeal Cavity
- Oral cavity begins at the mouth and ends at the pharynx
- Fishes have a very short oral cavity, while tetrapods typically have longer oral cavities
- Primary palate - roof of the oral cavity of fishes and amphibians; secondary palate in reptiles and mammals
Nasal Passageways and Oral Glands
- Nasal passageways open into the oropharyngeal cavity in lobe-finned fishes, and into the oral cavity in tetrapods with primary palate
- Multicellular oral glands open onto the roof, walls, and floor of the cavity
- May contain venom, saliva, including several enzymes, anticoagulant (lampreys, bats), nutrients in catfish, and mucus
- Oral glands are scarce in fishes
Mammals
- Mouth specialized to serve as a suckling and masticatory organ (with muscular cheeks)
- Oral vestibule separates the gums or alveolar ridges from the cheek and mouth
Pharynx
- Pharyngeal pouches may give rise to gill slits
- Fishes - gills and gill slits
- Tetrapods - includes glottis (slit leading into the larynx), openings of auditory (Eustachian) tubes, opening into esophagus, and location of tonsils in mammals
Esophagus
- Distensible muscular tube connecting the pharynx and the stomach
- Fishes - closes so the stomach doesn't become filled with respiratory water
- Birds - may have a diverticulum called the crop, which has digestive enzymes and allows hoarding of food
- Pigeon milk is an esophageal secretion in doves for nestlings
Stomach
- Muscular chamber(s) at the end of the esophagus that serves as storage and macerating site for ingested solids and secretes digestive enzymes
- Vertebrate stomachs:
- Cyclostomes - weakly developed; similar to esophagus
- Fish, amphibians, and reptiles - increasing specialization (more differentiated from the esophagus)
Birds
- Store large quantities of food temporarily in the crop, releasing it for digestion as needed
- Stomach is divided into:
- Proventriculus (glandular stomach)
- Ventriculus (muscular stomach, or gizzard)
- Lacking teeth, they swallow small stones which lodge in the muscular gizzard
- As the gizzard churns, the stones grind against the food like numerous tiny millstones
- Birds must constantly replace their gizzard stones by swallowing new gravel
Ruminant Stomach
- Serves mainly as a storage sac for large quantities of vegetable matter
- In the absence of cellulase, little digestion takes place in the small intestine, and food is diverted into a long dead-end side branch, the caecum
- The caecum houses a huge population of bacteria, some of which produce enzymes that convert cellulose to sugars, while others manufacture amino acids and other nutrients
- Micromolecules are absorbed directly through the epithelium of the caecum, and the waste material is released into the colon for disposal
Intestines
- Located between the stomach and the cloaca or anus
- Vertebrate intestines are differentiated to varying degrees into small and large intestines
- Cartilaginous fishes - have a short, thick, tapering intestine with a spiral valve where food passes slowly as it moves toward the colon
Herbivores
- The tract includes an expanded colon, cecum, or forestomach
- An enlarged colon is the principal site for microbial fermentation
- Haustrations extend over the cecum and the entire length of the colon of most species
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Quiz about the anatomy and development of the vertebrate alimentary canal, including mesenteries, accessory organs, and digestive system components.
