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Anatomy of Amphioxus Flashcards

1
Q

Vertical longitudinal plane passing from head to tail through the center of the body from dorsal to ventral surfaces

A

Median Plane

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2
Q

Any vertical longitudinal plane through the body- that is, the median plane or any plane parallel to it, sometimes designated as parasagittal

A

Sagittal Plane

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3
Q

Any horizontal longitudinal section through the body- that is, all planes at right angles to the median plane and parallel to the dorsal and ventral surfaces

A

Horizontal or frontal Plane

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4
Q

Section cuts vertically across the body at right angles to the sagittal and horizontal planes

A

Transverse or cross-plane

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5
Q

Line in the median sagittal plane extending from head to tail

A

Longitudinal or anteroposterior axis

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6
Q

Any line in the median and sagittal plane extending from dorsal to ventral surfaces

A

Sagittal or dorsoventral axis

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7
Q

Any line in the transverse plane running from side to side

A

Transverse or mediolateral

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8
Q

Three axes of bilateral symmetry

A

Longitudinal, transverse, and sagittal

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9
Q

Plane which passes through the longitudinal and Sagittal axes

A

Median Sagittal Plane

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10
Q

Regular repetition of body parts along the anteroposterior axis

A

Metamerism or Segmentation

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11
Q

Each division is termed a (3 divisions)

A

Metamere, segment, somite

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12
Q

Animal is said to exhibit both external and internal segmentation;

A

Internal metamerism is present

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13
Q

The segmentation of the animal body into nearly- like segments is spoken of as

A

Homonomous

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14
Q

The majority of segmented animals in which the various segments differ from each other to a greater or less extent

A

Heteronous

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15
Q

Is a primitive and generalized state in which the various segments are more or less independent and capable of performing all necessary functions

A

Homonomous segmentation

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16
Q

The segmented groups of animals are (3)

A

Annelids, anthropods, chordates

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17
Q

Metamerism in the chordate line began in the hemichordates , where gonads show evidence of serial repetition

A

Pseudometamerism

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18
Q

An intrinsic similarity indicative of a common evolutionary origin

A

Homology

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19
Q

Animals closely related by descent may differ greatly in general appearance after a long sojourn in different environments, such as seals and cats

A

Divergence

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20
Q

They have a notochord which is a dorsal nerve cord and gill slits

A

phylum Chordata

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21
Q

Phylum Chordata comprises of 4 subphyla

A
  • Hemichordata (acorn worms)
  • Urochordata (tunicates)
  • Cephalochordata (amphioxus)
  • Vertebrata
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22
Q

Cephachordates consists of 2 genera

A

Branchiostoma and Asymmetron

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23
Q

Means sharps both ends is a member of the genus

A

Branchiostoma

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24
Q

Small animal, only about 2-3 inches in length, that can be found lying along sandy seashores in temparate zones

A

Amphioxus

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25
What differs in amphioxus and other fishes
Lack of skull, vertebrae, brain, heart, and kidneys
26
The epithelium covering is but a single cell in thickness covered in what tissue?
Connective tissue is gelatinous
27
The muscle masses, the myomeres are separated by?
Myosepta
28
Extends the entire length of the body
Median dorsal fin
29
An expanded continuation of the median dorsal at the posterior end of the body
Caudal Fin
30
An anterior continuation of the caudal fin extending to the atriopore
Ventral Fin
31
The opening of an internal cavity, the atrium, located just in front of the ventral fin
Atriopore
32
The snout like anterior end of the body that projects over the oral hood
Rostrum
33
22 still tentacle-like structures projecting from the free edge of the oral hood. They are thought to contain sensory elements that might be used for taste
Buccal Cirri
34
The longitudinal series of about sixty angularly shaped muscle segments, known also as myotomeres
Myomeres
35
The connective tissue partitions separating the myomeres
Myosepta
36
The row of rectangular bulging masses located beneath the ventral ends of the myomeres
Gonads
37
A pair of integumentary folds that extend along the ventrolateral surfaces from the anterior pharyngeal region almost to the atriopore
Metapleural folds
38
A funnel shaped membrane located at the ventral part of the anterior end of the body; it helps to direct the water vortex, created by the wheel organ , into the mouth
Oral hood
39
Funnel shaped cavity enclosed by the oral hood
Vestibule
40
The internal connective tissue rods that are present as supporting elements in both the dorsal and ventral dins. They are absent from the caudal fin
Fin rays
41
The supporting rod that extends almost the entire length of the body
Notochord
42
The elongated cylindrical mass of nervous tissue that lies above the notochord, it is almost as long as the notochors
Nerve cord
43
A linear series of pigment cells lying along the ventral wall of the nerve cord. They may possibly serve as photoreceptors
Ocelli
44
A mass of pigment cells located at the anterior end of the nerve cord. Its sensory function has not been established
Eyespot
45
A series of finger-like projections, lined with cilia, that lies on the the inner lateral and dorsal walls of the oral hoods.
Wheel organ
46
The cilia beat in such a way as to suggest a turning wheel, and they help to create a vortex of water that is directed towards the mouth by the oral hood
Wheel organ
47
The vertical membrane located just behind the base of the wheel organ, it regulates the amount of water entering the pharynx
Velum
48
The opening in the velum
Mouth
49
Short tender projections extending from the margin of the velum that rings the mouth, by bending across the mouth, they may prevent sand or particles from passing into it
Velar tentacles
50
The chambar, interrupted by gill slits that extends from the mouth to the intestine
Pharynx
51
Slender parallel oblique bar supported by branchial rods
Gill Bars
52
That make up the side wall of the pharynx, cross pieces (synapticulae) link the bars
Branchial rods
53
The large cavity surrounding the pharynx, its ventral boundary is visible as a line extending below the pharynx to the atriopore
Atrium
54
The digestive tube that extends from the pharynx to the anus
Intestine
55
The pouch that projects forwards as an outpocketing of the intestine (midgut), it extends along the right side of the posterior part of the pharynx
Hepatic diverticulum
56
The outer cellular layer of the body, consisting of a single layer of columnar cells, it is covered by an acellular cuticle and rests upon a thin layer of a connective tissue
Epidermis
57
A short projection from the dorsal midline region that is supported by the gelatinous fin rays
Dorsal Fin
58
Masses of muscle under the skin, separated by connective tissue partitions, the myosepta
Myomeres
59
The somewhat triangular structure located on the midline, slightly ventral to the dorsal fin
Nerve cord
60
A very narrow cavity
Neurocoel
61
The larger rounded structure that lies beneath the nerve cord, it is surrounded by a connective tissue sheath
Notochord
62
The central cavity of the oral hood, located under the front part of the notochord
Vestibule
63
The thickened ciliated epithelial masses of the wheel organ are found on the
Inner hood wall
64
A number of these, cut transversely, are present at the lower boundary of the vestibule
Buccal Cirri
65
These project down from ventrolateral corners of the body
Metapleural fold
66
This lies in the wrinkled body wall between the metapleural folds. It extends from the myomeres on one side to those on the other. When it contracts, it compresses the atrial cavity dorsal to it from the side, thus expelling its water
Transverse muscle
67
The narrow cavity limited laterally by gill bars that extend between the notochord and transverse muscle
Pharynx
68
2 types of gill bars
Primary and Secondary gill bars
69
The gill bars are braced by small bridges
Synapticulae
70
The deeply grooved structure in the floor of the pharynx
Endostyle
71
The cells of endostyle are (2)
Ciliated and glandular cells (Inset B)
72
Located on the roof of the pharynx opposite the endostyle
Epipharyngeal groove
73
The cavity that surrounds the pharynx laterally and ventrally
Atrium
74
These are located ventrolateral in most, they protrude into the atrium from the body wall, still bounded by the atrial lining
Gonads
75
In sections near the posterior end of the pharynx, this hollow oval shaped structure is seen on the right side of the pharynx
Hepatic diverticulum
76
It lies within the atrial cavity
Coelem
77
Present in the cross section as three sac
- Ventral coelemic cavity (lies beneath the endostyle) - Dorsolateral
78
Are located on both sides of the epipharyngeal groove
Coelemic Cavities
79
The paired dorsal aortae may be seen between the notochord and the dorsal end of each of the paired coelemic cavities
Blood Vessels
80
Enclosed within the ventral coelemic
Ventral aorta
81
Are present close to the midpoint of the medical border of the gonads
Cardinal Veins
82
This is a large hollow oval structure lying ventral to the unpaired dorsal aorta
Intestine
83
Beneath the intestine
Subintestinal Vein
84
This fin is seen cross sections of the intestine at levels posterior to the atriopore, at levels anterior to the atriopore, metapleural folds will be seen in its place
This rather than dorsal or ventral fins, is present, it is narrower and higher than either

Comparative Anatomy (6 decks)

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