Comparative Anatomy I Flashcards
Chordates comprise 3 subphyla that make up the phylum chordata. What are the 3 subphyla?
Cephalochordata (amphioxus)
Urochordata (sea squirts)
Vertebrata
What are the 2 superclasses of subphylum vertebrata?
Pisces
Tetrapods
What does the Pisces superclass of subphylum Vertebrata include?
All fishes, extant and extinct
What does the Tetrapods superclass of subphylum Vertebrata include?
All tetrapods, both extant and extinct
What is characteristic of Agnathans?
They lack jaws and paired appendages
The group of Agnathans includes both extinct ostracoderms and living marine hagfishes and marine and freshwater lampreys. Ostracoderms are the oldest known vertebrates. During what period did they first appear?
Cambrian
What subgroup of Pisces do placoderms belong to? What is unique about these?
Gnathostomes - first vertebrates with jaws. All placoderms are extinct
All vertebrates other than _________ possess jaws
Agnathans
What are the four major anatomical features that an animal must possess in order to be included in the phylum Chordata?
Dorsal hollow nerve cord
Pharyngeal “gill” slits, arches, and pouches
Notochord
Post-anal tail
[the first 3 are considered “the big 3”]
True or false: the “big 3” anatomical features necessary to be considered phylum chordata do NOT have to be present in adult, but they must be present in embryo or larva
True; adult sea squirts have a notochord in the tail in the larval form, but it is lost in the sessile adults
What anatomical feature is only found in vertebrates?
The vertebral column
What 2 individuals contributed to the theory of natural selection?
Charles Darwin
Alfred Russel Wallace
______________ refers to similarity in function in structures in 2+ species. Although the function is similar, neither the anatomy nor the embryological development is similar.
Analogy
__________ refers to structural similarity uniquely evolved (due to inheritance from a common ancestor or developed from a common embryonic anlage). Anatomy and development are similar, but function does not have to be similar.
Homology
A dolphin fin and a carp fin are an example of ____________ structures
Analogous
A dolphin fin and a lizard arm are considered ____________ structures
Homologous
Diapsid dinosaurs are classified into 2 groups based on what?
Pelvic girdle
What are considered the bird-hipped dinosaurs?
Ornithischians
What are considered the lizard-hipped dinosaurs?
Saurischians
The outermost layer of the vertebrate integument is the epidermis, which is derived from what germ layer?
Ectoderm
What type of epithelium is the epidermis?
Stratified squamous
Is the epidermis innervated? Is it vascularized?
It is innervated but not vascularized
The dermis layer of the vertebrate integument is derived from what germ layer?
Mesoderm
What type of tissue is the dermis?
Irregular, dense fibrous connective tissue
What characteristic of the epidermis is unique to vertebrates? [BOLD]
The stratified nature of the epidermis is unique to vertebrates
[other animals have no more than a simple epithelium in their integument]
In fishes, the dermal derivatives (scales) are usually much more developed and complex than the epidermal derivatives. The integument of the first vertebrates was __________, a characteristic which would be detrimental for a terrestrial lifestyle
Armored
What were the specific integumentary terrestrial adaptations from the first vertebrates to amphibians?
Armor tended to disappear
Skin became softer and smoother, which put them at risk for dessication because it was less adapted for water conservation
In amphibians, the epidermis became more complex and culminated in the formation of what epidermal layer?
Keratinized stratum corneum
What is the outermost layer of the integument and in what species did it first appear in? [BOLD]
Stratum corneum
First appeared in amphibians
The stratum corneum first appeared in amphibians, but it became extremely well-developed in __________
Reptiles
What are the benefits to a highly well-developed stratum corneum?
Reduces water loss, and also the necessity for many epidermal glands
What is the major derivative of the stratum corneum in reptiles? [BOLD]
Epidermal scales
What are the major epidermal derivatives/hallmarks of avian integument? [BOLD]
Feathers
[also note that birds have relatively thin skin with a well-developed stratum corneum]
What do the designations of thick skin vs. thin skin refer to?
This designation refers to the complexity of the epidermis and not to the overall thickness of the skin
“Thick skin” (which may be thinner than some skin elsewhere on the body) is ONLY found on palms of hands and soles of feet
Describe the regional variation of the vertebral column in fishes (what 2 types do they have and do these have hemal arches?)
Precaudal - include all the more cranial vertebrae that lack a hemal arch
Caudal - include all the vertebrae caudal to the precaudal vertebrae; these possess hemal arches
What part of the amniote vertebra functionally replaces the notochord?
Centrum
The classification of the centrum is based on the shape of the cranial and caudal ends. What term refers to a vertebra with a centrum that is concave at both ends?
Amphicoelous (some reptiles)
The classification of the centrum is based on the shape of the cranial and caudal ends. What term refers to a vertebra with a centrum where only the cranial end is concave?
Procoelous (most reptiles)
The classification of the centrum is based on the shape of the cranial and caudal ends. What term refers to a vertebra with a centrum where only the caudal end is concave?
Opisthocoelous
The classification of the centrum is based on the shape of the cranial and caudal ends. What term refers to a vertebra with a centrum where both ends are flat?
Acoelous (mammals)
Describe regional variation in amniote vertebrae (what 4 types do we have?)
Cervical
Trunk (thoracic and lumbar)
Sacral
Caudal
How many cervical vertebrae do almost all mammals have?
7
In what species does the atlas/axis complex first appear? [BOLD]
Reptiles
In what 2 ways do sacral vertebrae articulate with the ilium? [BOLD]
Directly or via sacral ribs
What type of amniote vertebrae are variable with hemal arches? [BOLD]
Caudal
The pectoral girdle is composed what 2 components?
Dermal and endochondral
What are the 3 dermal components of the pectoral girdle?
Cleithrum
Clavicle (only one left in humans)
Interclavicle
[dermal components provide surfaces for muscle attachment]
What are the 3 endochondral components of the pectoral girdle?
Procoracoid
Coracoid
Scapula
Which components of the pectoral girdle carry the limb articulation - Dermal or Endochondral?
Endochondral components carry the limb articulation - Glenoid cavity
The pelvic girdle lacks ________ components in all vertebrates
Dermal
The pelvic girdle consists of 3 paired endochondral bones, what are they?
Pubis
Ischium
Ilium
All 3 bones of the pelvic girdle carry limb articulation in most vertebrates via the _______________ ____________
Acetabular fossa
Which 2 components of the pelvic girdle are primarily for muscle attachment?
Pubis and ischium
In bony fishes, the pelvic girdle consists of a pair of ventral triangular plates fused along their midline. Are these ever articulated with the axial skeleton?
No
What 3 groups can skeletal muscles be divided into?
Axial
Branchiomeric
Appendicular
Describe axial skeletal musculature in terms of derivation, segmentation, and innervation
Derived from myotome portions of somites
Demonstrate segmentation
Innervated by spinal nerves
Describe branchiomeric muscles in terms of derivation, segmentation, and innervation
Derived from pharyngeal arches
Demonstrate segmentation
Innervated by cranial nerves
Describe appendicular skeletal musculature in terms of derivation and innervation
Derived from body wall or limb bud mesenchyme
Innervated by spinal nerves
When looking at the cross-section of a fish’s axial musculature, which muscle group is located dorsally? Ventrally?
Dorsally = epaxial Ventrally = hypaxial
These layers are divided by horizontal septum
True or false: migration of branchiomeric musculature usually occurs before the muscle has been innervated
False - it occurs after, so the nerve is dragged along the muscle during migration
What is another name for gill arch I and what is it innervated by?
Gill arch I = mandibular arch
Innervated by CN V (trigeminal)
What is another name for gill arch II and what is it innervated by?
Gill arch II = hyoid arch
Innervaed by CN VII (facial)
What is gill arch III innervated by?
CN IX (glossopharyngeal)
Gill arches I, II, and III have specific CN’s innervating them. What CN innervates the remaining gill arches?
CN X (vagus)
The digastric muscle consists of 2 bellies, each of which is derived from a different pharyngeal arch.
The anterior digastric belly is derived from the ______ pharyngeal arch and is innervated by the ______ nerve.
The posterior digastric belly is derived from the ______ pharyngeal arch and is innervated by the ________ nerve
First; trigeminal
Second; facial
The adductor mandibulae is the main jaw closing muscle in fishes and amphibians. What muscle is this homologous to in mammals?
Masseter
The gill arch levators (cucullaris) in fishes are homologous to what muscle in tetrapods?
Trapezius
The muscles of mastication are derived from which pharyngeal arch?
First (so innervated by CN V)
What are the 4 primary muscles of mastication?
Masseter (elevates+protracts)
Temporalis (elevates+retracts)
Lateral pterygoid (protracts+depresses)
Medial pterygoid (protracts+elevates)
What muscle group serves to abduct the thigh in tetrapods?
Gluteal complex
What muscle group serves as the thigh flexor in tetrapods? What is this homologous to in reptiles?
Quadriceps complex, specifically rectus femoris
Rectus femoris = iliotibialis in reptiles
Leg extensors in tetrapods include rectus femoris and vasti (lateralis, medialis, intermedius). What are these homologous to in reptiles?
Femorotibialis
How many chambers in an amphibian heart?
- 2 atria + 1 ventricle
The right atrium receives deoxygenated systemic blood. The left atrium recieves oxygenated pulmonary blood via pulmonary vein
What serves as the right-left bypass WITHIN the heart of mammalian embryos?
Foramen ovale
What structure is a remnant of the left 6th aortic arch and connects the left 4th aortic arch with the 6th aortic arch to provide a right-left bypass during fetal development?
Ductus arteriosus
What is the fate of the first and second pairs of aortic arches in mammalian embryos?
They form but later degenerate
What is the fate of the 3rd pair of aortic arches (plus dorsal aortae cranial to 3rd arches) in mammalian embryos?
Form internal carotids
What vessels are derived from the ventral aortae between the 3rd and 4th aortic arches?
Common carotids
What is the fate of the right 4th aortic arch in mammalian embryos?
Forms right subclavian
What does the left fourth aortic arch form?
Aortic arch
What happens to the fifth pair of aortic arches in mammalian embryos?
They degenerate (just barely form - only remnants)
Which pair of aortic arches becomes associated with the pulmonary system
The sixth pair
Describe the functionality of amphibian lungs
Even in those amphibians that utilize lungs, the simplicity of them necessitates the use of skin for additional gas exchange
Where does most the the absorption occur in the gut track?
Small intestine
What anatomical adaptation is found in sharks to increase the surface area of their intestines?
Spiral valve
_________ are folds of mucosa in the gut track, each with a submucosal core
Plicae
What two structures constitute glands of the small intestine?
Crypts and villi (each villi contains core of lamina propria)
What are the 4 types of teeth found in heterodont mammals?
Incisors
Canines
Premolars
Molars
____________ = all teeth on a single plain
Bunodont
What type of teeth are used for cutting?
Incisors
What type of teeth are used for piercing?
Canines
What type of teeth are used for mastication?
Premolars and molars
_________ is a space without teeth (e.g., no canines)
Diastema
Do strict herbivores have canines?
No. Only omnivores and carnivores have canines
What is the functional kidney in all amniote embryos, including humans, and in most adult fishes and all amphibians?
Mesonephros
[this develops caudal to the pronephros]
Even though the reproductive system is either male or female in a given individual, it begins in the embryo as a _____________ system that has the ability to develop either into a male or female system. The main factor that determines whether this system will become male or female is the _____ gene located on the ____ chromosome
Bipotential
Sry; Y
The ___________ ducts degenerate in the male and form the oviducts in the female
Mullerian
Typically, the cranial end of the oviduct is expanded into a funnel-like structure called the ______________
Infundibulum (this receives the eggs when they are ovulated)
Birds are now thought to be most closely related to which of the following groups of reptiles?
A. Pelycosaurs
B. Pterosaurs
C. Dinosaurs
D. Cotylosaurs
C. Dinosaurs
Which component of the synthetic theory of evolution was proposed jointly by Darwin and Wallace?
A. Organic evolution
B. Genetic diversity
C. Paedogenesis
D. Natural selection
D. Natural selection
Which of the following characteristics is unique to chordates?
A. Coelom
B. Triploblasty
C. Deutrostomous
D. Dorsal hollow nerve cord
D. Dorsal hollow nerve cord
The similar body shapes in the shark and the dolphin represent an evolutionary phenomenon referred to by which of the following terms?
A. Parallelism
B. Convergence
C. Paedogenesis
D. Neoteny
B. Convergence
The agnathans are the earliest known vertebrates. Which of the following would not be characteristic of agnathans?
A. Armor plates covering much of the body
B. Lack of jaws
C. Pineal opening
D. Paired fins
D. Paired fins
The vertebrate epidermis is classified as which type of epithelium?
A. Simple squamous
B. Simple cuboidal
C. Stratified squamous
D. Simple columnar
C. Stratified squamous
A typical shark vertebrae is described as amphicoelous; this term refers to what?
Shape of ends of centra
Hemal arches are associated with which type of vertebrae?
A. Cervical
B. Thoracic
C. Sacral
D. Caudal
D. Caudal
The atlas/axis complex first appears in which groups of vertebrates?
A. Placoderms
B. Anurans
C. Reptiles
D. Therapsids
C. Reptiles
Which types of vertebrae typically have articulation facets for ribs?
A. Cervical
B. Sacral
C. Lumbar
D. Thoracic
D. Thoracic
Which of the following statements is correct regarding the mammalian dens?
A. It is a process found on the atlas
B. It is embryologically derived from the atlas
C. It is associated with the mammalian jaw articulation
D. It is a tooth-like process associated with the secondary palate
B. It is embryologically derived from the atlas
Which of the following lack canine teeth?
A. Squirrels
B. Humans
C. Walrus
D. Cat
A. Squirrels
Which of the following vertebrates rely primarily on their skin for respiration?
A. Teleosts
B. Lung fish
C. Amphibians
D. Reptiles
C. Amphibians
Which of the following has a spiral duct instead of increasing length to increase the surface area of the intestine?
A. Salamanders
B. Sharks
C. Crocs
D. Birds
B. Sharks
In which vertebrate does the atrium first become completely divided?
A. Sharks and teleosts B. Lungfish C. Amphibians D. Reptiles E. Mammals
C. Amphibians
Which of the following mechanisms is used to bypass the lungs in the mammalian fetus?
A. Ductus arteriosus B. Foramen ovale C. Ductus venosus D. All of the above E. A and B only
E. A and B only
Which aortic arches does the ductus arteriosus connect?
A. From the right third to the right third
B. From the left fourth to the left third
C. From the left fourth to the right sixth
D. From the left fourth to the sixth
D. From the left fourth to the sixth
Which of the following is the functional kidney type in an adult teleost?
A. Pronephros with a large corpuscle
B. Mesonephros with a large corpuscle
C. Pronephros with a small corpuscle
D. Metanephros with a small corpuscle
B. Mesonephros with a large corpuscle
