What are the three divisions of the embryonic vertebrate tract? What happens to each of these as development proceeds?
How and why is the oral cavity of mammals specialized? What is a primary palate, secondary palate? How is it known that vertebrate teeth are derived from “dermal armor” of early vertebrates?
- Oral cavity of mammalian mouth is specialized by the suckling and masticatory organ (with muscular cheeks)
- Primary palate: internal nares lead into the oral cavity anteriorly
- Secondary palate: nasal passages are located above the secondary palate and open at the end of the oral cavity
- Vertebrate teeth are derived from "dermal armor" of early vertebrates, we know this because of placoid scales, composition of teeth, and variations in evolution
How do variations in vertebrates affect "dermal armor"?
What are the main constituents of teeth? In which groups of vertebrates are found species without teeth? What is the relative abundance and distribution of teeth in fish, early tetrapods, crocodilians, toothed birds, and mammals?
- Enamel, Dentin, Cementum, Root Canal (Dental pulp)
- Toothless vertebrates are found in every class and include agnathans, sturgeons, some toads, birds, turtles, and baleen whales
- Fish: teeth are numerous and widely distributed in the oral cavity and pharynx
- Early tetrapods: widely distributed on the palate; most amphibians and some reptiles still have teeth of the vomer, palatine, and pterygoid bones
- Crocodilians, toothed birds, and mammals: teeth are limited to the jaws
What is cementum?
What is the general trend among vertebrates in terms of numbers of teeth, distributions of teeth within the oral cavity, and degree of permanence? What are the two sets of teeth found in mammals?
What is homodont dentition and which groups exhibit such dentition? What is heterodont dentition and which groups exhibit such dentition? What are the various types of teeth found in groups that exhibit heterodont dentition and what is the general function of each type of tooth?
- Homodont dentition: dentition in which the teeth are similar in general appearance throughout the mouth - fish, amphibians, and reptiles
- Heterodont dentition: dentition in which the teeth are different in general appearance throughout the mouth - mammals
- Incisors, canines, premolars, and molars
What is the general function of each type of tooth?
What is the primary tongue and which groups possess such a tongue? What is the glandular field and lateral lingual swelling?
Characterize the tongues of amphibians, reptiles, birds, and mammals. How “mobile” is the tongue of turtles, crocodilians, whales, snakes, lizards, birds, and mammals? What is frenulum? What are the various functions of vertebrate tongues?
- Gnathostome fish and primitive amphibians: tongue is a simple crescent shape; elevation in the floor of the oral cavity caused by the underlying hyoid skeleton called the primary tongue
- Most amphibians: primary tongue + glandular field
- Reptiles and mammals: primary tongue + glandular + lateral lingual swelling
- Birds: lateral lingual swellings are suppressed and intrinsic muscle is usually lacking
- Tongue Mobility:
- Human speech, swallowing, grooming, capturing and gathering food, taste, thermoregulation, manipulate fluids and solids in oral cavity
What types of secretions are produced by oral glands and what are the functions of those secretions?
- Oral glands secrete a variety of substances: saliva, poisons, and anticoagulants
What is the pharynx? What is the glottis and epiglottis? Which groups possess an epiglottis and what is its function?
- Pharynx is part of digestive tract exhibiting pharyngeal pouches (at least in the embryo) that may give rise to slits
- Glottis is a muscular slit leading into the larynx
- Epiglottis sits above the larynx, and the trachea sits below it; flap of cartilage at the root of the tongue - which is depressed during swallowing to cover the opening of the windpipe
- Mammals: an epiglottis is positioned over the glottis so that, when a mammal swallows, the larynx is drawn forward against the epiglottis & the epiglottis blocks the glottis (which prevents food or liquids from entering the trachea)
What is the function of the esophagus? What is the crop and which groups have such a structure? What is the function of the crop? What is “pigeon milk” and how is it formed?
- Esophagus is a distensible muscular tube connecting the pharynx to the stomach
- Crop is a baglike expansion of the esophagus; found only in birds
- Crop function as a storage place for food
- Pigeon milk is a milky substance made from their crop that is fed to the young for the first few days after hatching
What is/are the function(s) of the vertebrate stomach? Characterize the stomach of cyclostomes, amphibians, reptiles, birds, and mammals.
- Stomach is a muscular chamber at the end of esophagus
- Functions of the stomach: Serves as storage, macerating site for ingested solids, and secretes digestive enzymes
Cyclostomes: weakly developed, similar to esophagus
Fish, amphibians, and reptiles: increasing specialization (more differentiated than esophagus
Birds: proventriculus (glandular stomach) and ventriculus (muscular stomach, or gizzard)
Mammals: well developed stomach
What are the components and functions of the avian stomach? What are the components and function of the ruminant stomach?
What is(are) the function(s) of the vertebrate intestine? Characterize the intestine of fish and tetrapods. Which groups have a spiral valve and what is its function? What is the duodenum, jejunum, and ileum?
What is(are) the role(s) of the liver, gall bladder, and pancreas in digestion? Which groups have a large intestine? What is the colon and rectum?
What is a cecum and what is the function of such structure? Which groups have ceca associated with their digestive tracts and where are ceca located? Which groups have a cloaca and what is its function?
What is a bolus? What is peristalsis? What is chyme and digesta? What is the buccal cavity? What is the GI tract? What are cheek pouches and which groups have them?
What is the hard palate and soft palate? What are the functions of teeth? What are the three hard tissues composed of the tooth? What is the ‘role’ of each of these substances?
What is the advantage of recurved teeth and which vertebrates have such teeth? What are the four types of teeth found in mammals? What is the function of each type?
What are carnassials? Which mammals have them and what is their function? What is lingual feeding and which groups exhibit such feeding behavior?
What do woodpeckers use their tongue for? What is intraoral transport?
In adult vertebrates, what is the function of the pharynx? Which animals have stomachs that serve as storage compartments?
What is the predominate function of the stomach? What is gastric juice? How is the mucosa of the intestines distinctive?
What are the three successive parts of the small intestines (in some vertebrates)?
Where is the ileocolic valve located and what is its function? What are the functions of the intestines?
- A sphincter between the ileum of the small intestine and the large intestine
- Function of ileocolic valve: regulates movement of food into the large intestine
- Functions of intestines: peristalsis of food, add secretions to food, lubricate food, absorb products of digestions – amino acids, fatty acids, carbohydrates, water is absorbed
What is the cloaca? Which groups have no cloaca?
What are some specializations of the alimentary canal that prolong passage of digesta? What is the rectal gland and which groups have such a gland?
- Structural modifications accommodating specialized diets, expansions or extensions of the canal may develop to accommodate specialized diets, differentiation of the canal may occur through regionalization
- Rectal gland opens into the cloaca; eliminates excess salt ingested during feeding
- Rectal glands are found in elasmobranchs and coelacanths
What are pyloric ceca? Which group has them and what is their function?
What are the four chambers of the ruminant stomach? Know the material in Box Essay 13.5 – The “Spare” Appendix (p. 497). What are the functions of the liver?
What is the ‘exocrine’ product of the liver and what is its function? Where is bile stored in most vertebrates? What is pancreatic juice and where does it enter the digestive tract?
Where does absorption of food begin and what is absorbed? Where are the end products of digestion usually formed and absorbed? What does the appearance of a long, distinct large intestine correlate with?
Why does the large intestine retain digesta? What is coprophagy and which groups exhibit such behavior?
What is the purpose of mechanical manipulation of food?
What is mastication and what group is this characteristic of? How are different types of foods chewed?
Which vertebrates are able to produce cellulases? What microorganisms break down cellulose in the digestive tracts of host vertebrates? What is fermentation? What is foregut fermentation?
In which groups does foregut fermentation occur? What is hindgut fermentation and which groups are examples of hindgut fermenters?