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Comparative Anatomy 1 > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

3 Subphyla and their characteristics of the phylum Chordata

A

Cephalochordata - notochord in the head
Urochordata - notochord in the tail
Vertebrata - has a vertebral column

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2
Q

Similar feature of all Chordates

A

Notochord

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3
Q

Two superclasses of Vetebrata

A

Pisces and Tetrapods

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4
Q

Class characteristics for sub-classes in Pisces

A

Class agnatha - lack of jaws and paired appendages
Class acanthodii - “spiny sharks”, first vertebrates with jaws, extinct
Class placodermi - early jawed fishes with paired fins, extinct
Class chondrichthyes - lack ability to form bone, skeletal systems made entirely of cartilage (sharks, rays, skates)
Class osteichthyes - includes largest # of fish, skeletal systems of bone although many retain cartilage within skeletal system

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5
Q

Class characteristics for sub-classes in Tetrapods

A

Class amphibia - permeable skin, live on land and water
Class reptiles - covered in scales
Class aves - all birds, presence of feathers
Class mammals - presence of hair and mammary glands

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6
Q

List the Big Three (four) chordate characteristics

A

Dorsal hollow nerve cord
Pharyngeal slits, arches, pouches
Notochord
Post-anal tail

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7
Q

Describe the dorsal hollow nerve cord

A

Future brain and spinal cord located dorsal to notochord, hollow nature retained in brain (ventricles) and spinal cord (spinal canal)

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8
Q

Describe the pharyngeal slits and pouches

A
  • All chordate embryos are characterized by the presence of pharyngeal pouches (branchial pouches). These pouches may open to exterior as pharyngeal slits. In many chordates, these slits persist as gill slits in adults and connect interior of the pharynx with external environment
  • If walls of slits become highly vascularized, oxygen may be obtained from the water flowing through gill slits, original function was filter feeding
  • The pharynx is the cranial portion of the gut tube
  • ## The primitive veterbrate pharynx was used for filtering food out of a respiratory water stream
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9
Q

Describe pharyngeal arches

A
  • Portion of the pharyngeal wall between a pair of adjacent gill pouches is called a pharyngeal arch which consists of; a pharyngeal skeletal element, branchiomeric muscles, cranial nerve branches, an aortic arch.
  • A pharyngeal arch is also located in front of the first pharyngeal pouch and behind the last pouch; the first arch is the mandibular arch, the 2nd is the hyoid arch
  • First pair of pouches into which gill slits open become the auditory tubes and middle ear cavities in tetrapods
  • Second pair of pouches form the pouches of the palatine tonsils in mammals
  • External gills develop as outgrowths from pharyngeal arches
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10
Q

Describe the notochord

A
  • The notochord is formed in all chordates and serves as a primitive skeletal structure especially for the embryo
  • Consists of living cells located ventral to the dorsal hollow nerve cord and dorsal to the gut tube ( the cells resemble cartilage, but it is not cartilage or any true connective tissue)
  • In some lower vertebrates (lampreys) the notochord is the only adult axial support system
  • In modern birds, reptiles and mammals, the notochord is almost or completely obliterated, its remnants are found in the inter-vertebral discs as the nucleus pulposa
  • The notochord is responsible for initiating the formation of the CNS which is always located dorsal
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11
Q

List and describe the characteristics of the phylum Chordata that are shared with invertebrate phyla

A
  • Cephalization
  • Complete digestive tract
  • Bilateral symmetry
  • Metamerism (linear series of body segments)
  • Tripoblasty (3 germ layers)
  • Euceolomate body cavity
  • Closed circulatory system
  • Deuterostomy (mouth is 2nd)
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12
Q

Describe bilateral symmetry

A
  • Refers to a body organization such that the body may be divided into right and left halves that are more-or-less mirror images of each other at least externally
  • Organized around 3 axes oriented perpendicular to each other
  • 3 axes used because of 3 dimensional space
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13
Q

Describe axes

A
  • 3 axes intersect perpendicular with each other
    • Cranial/Caudal axis (vertical axis)
    • Dorsal/Ventral axis (sagittal, ant./post. axis)
    • Left/Right axis
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14
Q

Describe planes

A
  • Two intersecting axes define a 2D plane

- 3 planes (saggital, frontal, transverse)

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15
Q

Describe the sagittal plane

A
  • Defined by cranial/caudal and ant./post. axes
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16
Q

Describe the frontal (coronal) plane

A
  • Defined by cranial/caudal and left/right axes
17
Q

Describe the transverse (cross-section) plane

A
  • Defined by the dorsal/ventral and left/right axes
18
Q

Describe flexion

A
  • Bending movement that takes place in the sagittal plane around a left/right axis
  • Brings two parts closer together
19
Q

Describe extension

A
  • Takes place in the sagittal plane around a left/right axis

- Results in straightening out of a bent part

20
Q

Describe abduction

A
  • Takes place in the frontal plane around a sagittal axis

- Movement away from the midline

21
Q

Describe adduction

A
  • Frontal plane, sagittal axis

- Movement towards the midline

22
Q

Describe rotation

A
  • Movement of the body around its long axis (cranial/caudal) in a transverse plane
23
Q

Compare acoelmates, pseudocoelomates and eucoelomates

A
  • Acoelomates lack a body cavity separating the somatic tube from the visceral tube
  • Pseudocoelomates possess a cavity only partly derived from embryonic mesoderm
  • Eucoelomates possess a body cavity that is completely lined with derivatives of embryonic mesoderm (most animals)
24
Q

Describe general organization of the veterbrate body

A
  • Outer somatic tube interacts with the external environment (detects and responds to changes) and consists of skin, skeletal musculature
  • Inner splanchic tube includes the gut, liver and pancreas and processes nutrients
25
Q

Describe the vertebrate coelom

A
  • Space separating the somatic tube from the splanchich tube is the coelom and is lined with mesodermal derivatives that are associated with either the somatic (parietal peritoneum/pleura/pericardium)or splanchic tube (visceral peritoneum/pleura/pericardium)
  • Places where 2 layers of lining tissues meet form double-layered structures called mesentaries which support and provide pathways for blood vessels to reach visceral organs
26
Q

List vertebrate characteristics not unique to vertebrates

A
  • Paired appendages
  • Internal mesodermal skeleton
  • Epaxial/Hypaxial musculature
  • Subdivide coelom
  • Metamerism
  • Tripoblasty
  • Deuterostomy
  • Cephalization
27
Q

Describe paired appendages

A

All modern vertebrates other than cyclostomes have two paired appendages, pectoral (cranial end) and pelvic (caudal) which have similar anatomical patterns

28
Q

Describe internal mesodermal skeleton

A
  • Arises from mesoderm and may be constructed entirely out of cartilage, entirely out of bone or combination (most)
  • Bony portion may form directly as bone or is preceded by cartilage then replaced by bone
29
Q

Describe Epaxial/Hypaxial musculature

A
  • The vertebrate axial musculature is divided into dorsal columns
  • Epaxial is above the dorsal ribs and transverse processes, hypaxial lies below
  • Epaxial consists of segmentally arranged blocks of skeletal muscles (myomeres) - responsible for locomotion in fishes
  • Hypaxial includes layers of skeletal muscle that form walls of body cavities as well as muscle of the fish fins/ tetrapod limbs
30
Q

Describe subdivided coelom

A
  • Coelom consists of 2 subdivisions in most vertebrates (pericardial contains the heart and pleuroperitoneal - lungs and other viscera)
  • Coelom consists of 3 subdivisions in mammals (Pericardial - heart, pleural - paired cavities containing lungs, peritoneal - other viscera)
  • All cavities lined with mesodermal linings referred to as serous membrane which produce a watery lubricating fluid
  • Membranes lining the cavities are referred to as parietal layers, membranes covering the organs within the cavities are referred to as visceral layers
31
Q

Describe subdivided coelom: mesentaries

A
  • Transition parts where visceral and parietal peritoneum join form double layers called mesentary
  • Dorsal mesentary suspends gut tube from dorsal roof of the coelom, ventral mesentary connects the gut tube to the ventral floor of the coelom
  • Cranial part of the peritoneal coelom connecting liver to the floor, ventral mesentary forms the falciform ligament (VM-2)
  • Part of the ventral mesentary between liver and gut tube is the lesser omentum (VM-1)
  • Most of the ventral mesentary is obliterated during embryonic development due to elongation and coiling of the gut
  • Organs behind the peritoneum referred to as retroperitoneal
32
Q

Describe metamerism

A
  • Refers to segmentation of the body into repeating units from cranial to caudal end, observable in earthworms
  • Epaxial musculature divided into repeating blocks of skeletal muscle (myomeres) laying on either side of the notochord/vertebral column
  • Also evident in anatomy of vertebral column, nervous system and kidneys
33
Q

Describe tripoblasty

A
  • Embryonic term that refers to the origin of the body plan from 3 embryonic germ layers or primordia
  • Ectoderm - outermost layer, gives rise to outer layer of integument and nervous system
  • Mesoderm - middle layer, gives rise to bone, muscle, connective tissues, cartilage and related structures/tissues
  • Endoderm - innermost layer, gives rise to the gut and derivatives
34
Q

Describe deuterstomy

A
  • Not unique to chordates, original embryonic opening (blastopore) becomes the anus and mouth develops as secondary opening
35
Q

Describe cephalization

A
  • Not unique to chordates, refers to development of definite head (cranial end) and characterized by accumulation of sense organs

Comparative Anatomy 1 (9 decks)

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