Comprehensive Final Flashcards
What are the subphyla of Chordates?
- Cephalochordata
- Urochordata
- Vertebrata
What are Agnathans?
Extinct and extant fishes which lack jaws and paired appendages. This includes ostracoderms, marine hagfishes, and marine and freshwater lampreys.
What is the oldest known vertebrates and when did they appear?
Ostracoderms are the oldest vertebrates and appeared during the Cambrian period (500 million years ago).
Which vertebrates were the first to possess jaws?
Gnathostomes were the first to possess jaws which include placoderms.
What are the 4 anatomical features of chordates?
- Dorsal hollow nerve cord
- Pharyngeal “gill” slits, arches and pouches
- Notochord
- Post-anal tail
Who is is responsible for the Theory of Natural Selection?
Charles Darwin and Alfred Russel Wallace
What is an Analogy?
Similarity in function but not in anatomy nor embryological development (wing of a bird and wing of an insect).
What is Homology?
Similarity in anatomy and embryological development from a common ancestor, but does not have to have similar function.
What are Ornithischians?
These are bird-hipped dinosaurs which possess a tetraradiate pelvic girdle. These include hadrosaurs, stegosaurs, and Triceratops.
What are Saurischians?
These are lizard-hipped dinosaurs which possess a triradiate pelvic girdle. These include Apatosaurus, Allosaurus, and Tyrannosaurus.
Describe the epidermis.
Derived from ectoderm, innervated and not vascularized, and is classified as stratified squamous epithelium which is unique to vertebrates.
Describe the dermis.
Derived from mesoderm, vascularized, and is classified as irregular dense fibrous connective tissue.
Describe the integument of the first vertebrates.
Fishes possessed an armored integument.
Describe the integument of amphibians.
- Armor disappeared
- Skin became softer and smoother; not for water conservation
- Possessed a stratum corneum
What is the stratum corneum?
First appears in amphibians and consists of multiple layers of flattened cells joined by tight junctions; becomes keratinized.
Describe the reptilian integument.
Stratum corneum = epidermal scales which reduced water loss and also the necessity for many epidermal glands.
Describe the avian integument.
Feathers are epidermal derivatives; have thin skin with a well-developed stratum corneum.
What is thin skin vs. thick skin?
Thin Skin = skin found on eyelids and back.
Thick Skin = skin on the palms of the hands and the soles of the feet
What type of vertebrae are found in the vertebral column?
Precaudal vertebrae = more cranial vertebrae and lack hemal arches
Caudal vertebrae = vertebrae caudal to the precaudal vertebrae and possesses hemal arches
What is the centrum?
The centrum functionally replaces the notochord.
What is Amphicoelous?
Both ends of the centrum are concave (some reptiles)
What is Procoelous?
Only the cranial end of the centrum is concave (most reptiles)
What is Opisthocoelous?
Only the caudal end of the centrum is concave.
What is Acoelous?
Both ends of the centrum are flat (mammals)
In the cervical vertebrae, how many do most mammals possess?
7
When does the atlas/axis complex first appear?
In reptiles
Describe the trunk vertebrae.
Divided into thoracic and lumbar vertebrae. The thoracic vertebrae are associated with ribs.
What does the sacral vertebrae articulate with?
It articulates with the ilium of the pelvic girdle directly or via sacral ribs.
Describe caudal vertebrae.
Variable with hemal arches.
What does the pectoral girdle consist of?
It is composed of dermal and endochondral components.
Describe the dermal components of the pectoral girdle.
- Supports the endochondral components and articulate them with axial skeleton
- Provide surfaces for muscle attachments
Describe the endochondral components of the pectoral girdle.
- Carries the limb articulation
2. Serve as major base of attachment for limb muscles
What do the endochondral components consist of?
- Procoracoid
- Coracoid
- Scapula
Describe the pelvic girdle.
- Lacks dermal components
- Consists of 3 paired endochondral bones: pubis, ischium, ilium
- Ilium articulates w/sacral vertebrae either directly or via sacral ribs
- Pubis and ischium are primarily for muscle attachment
What is the acetabulular fossa?
Where all 3 bones carry limb articulation in the pelvic girdle.
Describe the pelvic girdle in bony fishes.
Consists of a pair of ventral triangular plates fused along their midline that never articulate with the axial skeleton.
Describe the skeletal muscle divisions.
- Axial: derived from myotome of somites, segmental arrangement, and innervated by spinal nerves
- Branchiomeric: formed from embryonic mesenchyme associated w/pharyngeal arches, segmental arrangement, and innervated by cranial nerves
- Appendicular: formed from body wall or limb bud mesenchyme and innervated by spinal nerves
Describe the gill arches.
- Gill arch I (mandibular): innervated by CN V
- Gill arch II (hyoid): innervated by CN VII
- Gill arch III: innervated by CN IX (glossopharyngeal)
- Remaining gill arches: innervated by CN X
Describe the digastric muscle.
Consists of two bellies. The anterior digastric belly is derived from the 1st pharyngeal arch and is innervated by CN V. The posterior digastric belly is derived from the 2nd pharyngeal arch and is innervated by CN VII.
The adductor mandibulae is the main jaw closing muscle in fishes and amphibians and is homologous to what muscle in mammals?
Masseter muscle
Gill arch levators (cucullaris) in fishes are homologous to what muscle in tetrapods?
The trapezius
Where are muscles of mastication derived and innervated by what cranial nerve?
Derived from the 1st pharyngeal arch and is innervated by CN V.
Describe the muscles of mastication.
- Masseter: elevates and protracts mandible
- Temporalis: elevates and retracts mandible
- Lateral Pterygoid: protracts mandible; depresses chin (bilateral; grinding - unilateral)
- Medial Pterygoid: elevates, protracts, grinding (unilateral)
What are abductors of the thigh?
Gluteal complex
What is the thigh flexor?
Rectus femoris
What are the leg extensors?
The rectus femoris and vasti (lateralis, medialis, and intermedius)
Describe the amphibian heart.
The atrium first become completely divide; right atrium receives deoxygenated systemic blood; left atrium receives oxygenated pulmonary blood via pulmonary vein
What is the foramen ovale?
The right-left bypass within the heart of mammalian embryos.
What is the ductus arteriosus?
A remnant of the 6th aortic arch. It connects the 4th arch to the 6th arch in the embryo to provide a right-left bypass during fetal development.
Describe the flow of the mammalian heart.
See PowerPoint slide….
Describe the aortic arch pattern in mammalian embryos.
- 1st and 2nd arch form but later degenerate
- 3rd arch = internal carotids
- Common carotids are derived from ventral aortae between the 3rd and 4th arch
- Right 4th arch = right subclavian artery
- Left 4th arch = the aortic arch
- 5th arch degenerates
- 6th arch associated with the pulmonary system
What are the characteristics of the Necturus lungs?
Their lungs are simple, long narrow sac-like structures w/ very little internal subdivision.
What are the characteristics of anurans lungs?
Their lungs are still small but in most show some level of internal subdivision.
Where does most absorption occur?
In the small intestine
What are the anatomical modifications for absorption?
- Increasing length of intestine
- Spiral valve in the intestine of sharks
- Plicae: folds of the mucosa
- Crypt-villus system: constitute glands of small intestine
- Microvilli
What is heterodonty in mammals?
Incisors, canines, premolars, and molars
What is bunodont?
All teeth on single plain
What are sectorial teeth?
Carnassial: upper premolar and lower molar in carnivores
Describe the function of mammalian teeth.
- Incisors: for cutting (elephant tusks)
- Canines: for piercing (walrus tusks)
- Premolars & Molars: to masticate food
- Diastema: space without teeth
What is mesonephros?
Caudal to the pronephros; functional kidney in all amniote embryos
What is bipotentiality of the reproductive system?
The ability to develop into either male or female; determined by the Sry gene on the Y chromosome.
Describe the Müllerian ducts.
Degenerates in males and form the oviducts in females. Oviducts are open to the coelomic cavity at their cranial end = infundibulum. This receives the eggs when the are released from the ovary.