Vertebrate Origins And The Integumentary System Flashcards
what are the definitions of the terms:
- function
- biological role
- preadaptation
- how a structure interacts with its environment
- selection pressures leading to the function
- features existing before the adaptation pressure
what are the definitions of the terms:
- homology
- analogy
- convergent evolution (homoplasy)
- synapomorphy
- structures with the same origin, regardless of function
- function, not origin
- similar features which evolved independently of one another
- trait that unifies a group-shared derived group
what are the features of chordates?
- pharyngeal slits
- notochord
- dorsal hollow nerve tube (precursor to the CNS)
- endostyle
- post-anal tail
(first two appear at some point in development if absent)
what is a body plan?
a fundamental structural organisation plan which applies to the entire phylum
body plan = body organisational scheme + phylum-specific traits
chordates have bilateral symmetry - what does this mean?
mirroring about the anterior-posterior axis
what are the 3 main axis?
-left/right
-dorso/ventral
-anterior/posterior
what is segmentation?
repetition of tissues, organs or features along the A-P axis
what is serial homology? name some examples of this
2 or more repeated features within the animal that share similar features. eg:
- muscle
- different vertebrae
what is a coelomic space?
a cavity, is a fluid-filled compartment lined by mesodermal epithelium (is closed and empty)
what are some features of the vertebrate subphylum?
- vertebral column
- cranium
- neural crest
- neurogenic placodes (these two = developmental stem cells)
- brain with 3 divisions
-hypothalamus-pituitary system
what did the duplication of the chordate genome allow for? (hypothesis)
expansion and complexity without destruction of key genes; genes for neural crest, 3-part brain and neurogenic placodes already existed but duplication allowed for diversification
what do pharnygeal arches eventually give way to in vertebrates?
- aortic arch
- cranial nerve
- muscle
- skeletal rod
what is contained within the pleuroperitoneal cavity?
lungs and viscera -this becomes sub-divided in mammals by the diaphragm
list the topological structure of the body walls
- integument (skin)
- fascia
- muscle
- fascia
- coelomic membrane
what are:
-epaxial muscles
-hypaxial muscles
- muscles which lie dorsal to the horizontal septum
- muscles which lie ventral to the horizontal septum
what are the three subphyla within chordates?
- cephalochordates
- urochordates
- vertebrates
what was the original function of the notochord?
a rod to stiffen the spine
what is a gnathostome?
term for jawed fish
define synapomorphy
a common trait shared between two or more groups of organisms
define homoplasy
a feature that has been gained or lost independently in separate lineages
sarcopterygians display ‘flashy fins’ - what is this a preadaptation of?
limbs
synapsid skulls became more fenestrated - what does this allow for?
more muscle attachment
what are some key innovations in mammalian evolution
- tribosphenic molars
- middle ear bones
- diaphragm muscle
- hair
-mammary gland
describe the module duplication theory for the development of fore/hindlimbs
Possible T-box module gene (transcription factor) duplication at gnathostome branch, leading to forelimb (Thx5) and hindlimb (Thx4) fin bud development
what are some common evolutionary modifications?
- enlargement/ reduction
- fusion/ subdivision
- elaboration/ simplification
- duplication
- repetition
what is the definition of integument?
a barrier between an organism’s internal and external environment
what are the different layers of the skin in vertebrates?
epidermis, dermis, hypodermis
what are the different cell layers of the cyclostome skin structure?
- cuticle (non-cellular, for mucous)
- epithelial cells
- stratum germinativum
- dermal stratum laxum
- dermal stratum compactum
what is the purpose of the cyclostome dermis being collagen-rich?
for ungilation
what are the different cell layers of the chondrichthyes skin structure?
- vitrodentine
- dentine
- unicellular mucous gland
- stratum spinosum
- stratum germinativum
- dermal stratum laxum
- basal plate
- dermal stratum compactum
what are the different cell layers of the osteichthyes skin structure?
- stratum spongiosum (scale pocket)
- basale membrane
- epithelial cells
- basal layer epithelial cells
- basale membrane
- stratum spongiosum
- stratum spongiosum
- stratum compactum
what is the function of:
- club cells
- sacciform cells
- merkel cells
- ionocytes
- immune defence
- pheromone secretion
- mechanoreceptor
- maintenance of homeostasis + ion loss prevention
what are the three types of osteichthyes scales?
a) ctenoid - apical ends
b) cycloid - smooth, calcified ridges
c) ganoid - rhomboid
what are the different cell layers of the amphibian skin structure?
- mucosal layer
- stratum corneum
- stratum spinosum
- stratum germinativum
- stratum spongiosum
- compact dermis
what is the benefit of the amphibian epidermis being thin? what is a disadvantage to this?
- allows for cutaneous respiration
- prone to water loss
what is the fucntion of leydig cells?
secretion of antimicrobial substance
what are the different cell layers of the reptilian skin structure?
- corneous-layer
- keratinized-layer
- stratum germinativum
- dermal stratum laxum
- dermal stratum compactum
what are the different cell layers of the avian skin structure?
- stratum corneum
- stratum germinativum
- stratum compactum
- stratum spongiosum
- dermal papilla
what are the different cell layers of the mammalian skin structure?
- stratum corneum
- stratum lucidum
- stratum granulosum
- stratum spinosum
- stratum basale
in which locations on the mammalian body is the cell layer stratum lucidum present?
palms/soles/fingertips only
which cell layer (epidermis) is constantly being renewed via proliferation?
stratum basale
which cell layer (epidermis) is responsible for glycolipid production?
stratum granulosum
what is the function of these mammalian gland secretions:
- sebaceous
- eccrine (watery, not hair associated)
- apocrine (viscous, hair associated)
- reduce water loss/ waterproofing, infection defence
- lubrication and cooling
- chemical signalling
