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Anatomy 241 Exam I chapter 2


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organisms with bilaterial symmetry
organisms with a fluid filled body cavity
"first mouth" Animals which develop a mouth from the blastopore
"second mouth" Animals which develop a mouth from the opposite end of the digestive tract.
What are the four fundamental features that chordates share?
dorsal hollow nerve cord
postanal tail
pharyngeal slits
The notochord serves as an "_" and flexes laterally from side to side.
elastic rod
the notochord with a fluid core may be classified as a _
hydrostatic organ
the pharynx, part of the digestive tract, is located just _ to the mouth
pharyngeal slits likely first evolved to aid in _ and later with _
feeding, respiration
cilia that line the pharynx establish the _ of water and move _ into the digestive tract
current, food laden mucus
_ are an assortment of invertebrates whose structure and design may represent chordates at their origins
the three protochordates:
Defination of
1. Hemichordata
2. Urochordata
3. Cephalochordata
1.half chordates
2.tail backstring
3.head chordate
Hemichordates are marine worms that appear to link _ and _

they lack a _ and _
Echinoderms, Chordates, notochord, tail
hemichordates have a structural _ which was thought related to the notochord, but has failed genetic comparisions.
Hemichordates exist within 1 of 2 taxonomic groups
1. enteropneusta
2. pterobranchs
1. burrowing animals
2. sessile animals
enteropneusta "_ worms" are marine burrowing worms
Their body is divided into three regions:
1. proboscis
2. collar
3. trunk
each region of enteropneusta has its own coelom (3)
protocoel, mesocoel, metacoel
The first "true" members of the phylum chordata and at some point of their life cycle they generally show all four of the characteristics common to chordates.
Urochordates may be divided into 3 taxonomic groups:
_ - sessile
_ and _ - pelagic (plankton)
Larvacea & Thaliacea
Ascidians "_" do not greately resemble what we think of as chordates, but the _ state exhibits all 4 chordate characteristics.
sea squirts, larval
Ascidians often refered to as "_" because the adult forms are covered by a covering called a tunic
Amphioxus is a _ that we studied in lab
cephalochordata, anatomically simple animals that are designed to be suspension feeders based on their _ (much like _)
pharyngeal filtering aparatus, protochordates
The oldest known member of the cephalochordate is the _ which is an extant version of the _ (Amphioxus)
Pikala, Branchiostoma
Amphioxus has muscles arranged in segments (_) which are seperated from one another by partitions (_)
myomeres, myosepta
The _ and _ contraction of these muscles propels amphioxus through the water and aides in burrowing into the sediment.
orderly, sequential
In the digestive system of the Amphioxus food first moves into the _ before entering the pharynx.
oral hood
_ project outward from the oral hood and prevent large particles from entering
Buccal cirri
_ tracts inside the oral hood give the impression of rotation and are collectively termed the "_"
ciliated, wheel organ
_ - one of the dorsal tracts in the vestibule (similar to the wheel organ)
Hatschek's pit
some propose that the Hatschek's Pit may be the forerunner to the vertebrate _ gland.
The trapping of food (Amphioxus) occurs in a _ - _ direction.
ventral - dorsal
the _ secretes mucus to trap food
_ move the mucus dorsally
the food trapped in the mucus is directed to the _ and then into the digestive tract.
The posterior wall of the oral hood is defined by a diaphragm called the _
sensory structures (_) sense and sort material before it passes through the opening of the velum and into the pharynx
velar tentacles
water that enters the pharynx passes through the pharyngeal slits and exits the body via the _ in the posterior portion of the _
atriopore, atrium
the midgut diverticulum (cecum) is thought to be the forerunner of the liver due to: (2)
anatomical location
blood supply
the hepatic diverticulum may also be related to the _ because cells in the wall secrete digestive enzymes.
The digestive (GI tract) of the anphioxus includes: (3)
ileocolic ring
Waste materials exit the body via the
The amphioxus has _ heart
the task of pumping blood for the amphioxus is distributed among several _
blood vessels
Blood circulation is laid out on the same general pattern as that of the _:
_ carries blood anteriorly
_ carries blood posteriorly
vertebrates, ventral aorta, dorsal aorta
amphioxus exchange gasses via _
in the amphioxus gases are exchanged between the water and vessels of the _ within the pharyngeal bars
pharyngeal complexes of blood vessels

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