Lecture 3 Flashcards
What are some skeletal tissues functions?
Support, protection, feeding, breathing, locomotion, mineral storage, endocrine (hormones), hematopoiesis (blood cells)
Skeletal tissue types
Cartilage, Bone, Bone Marrow
What are mature chondroblasts?
Chondrocytes
What do the mechanical properties of cartilage depend on?
all come down to the relative abundance of these components in the matrix (extracellular matrix)
True or false: cartilage is vascular
false: cartilage is avascular
How do gas & nutrients exchange from chondrocytes?
Diffusion
What is an osteoid
bone extracellular matrix
True or false: bone is vascular
true
What do osteoblasts produce
osteocytes
what do osteoclasts come from
fusion of macrophages
What do osteoclasts do?
secrete enzymes, eat away at extracellular matrix of the bone and take away
What is bone homeostasis regulated by?
osteocytes embedded in the matrix
What is the structural composition of bone dependent on?
bone homeostasis & resorption
How is dermal bone formed
Formed within the dermis through intramembranous ossification
What is dermal bone made of
calcium carbonate
What do crocodilians use osteoderms for?
to regulate blood pH and temperature
What intermembranous ossification
Bone forms on its own within a membrane (Membrane bone, Dermal bone)
What is endochondral ossification
a template made of cartilage is replaced by bone during development
Explain the steps of endochondral ossification
A template for the bone is made out of cartilage, Chondrocytes are now cut off from oxygen and nutrients so they start secreting help signals and the cartilage ECM begins to break down, Blood vessels are attracted to the chondrocyte’s help signals and infiltrate the center of the cartilage
Osteoblasts and osteoclasts hitch a ride on the blood vessels into the center of the cartilage template, Spongy (interior) and compact (exterior) bone replace the cartilage from the inside out.
This leaves a hollow center (medullary cavity) in the bone which is later filled with bone marrow and larger blood vessels
What is bone marrow
fatty (adipose) tissue which sometimes contains hematopoietic and osteogenic stem cells
Describe the skeletal tissue in agnathans
no bone, non-mineralized cartilage
Difference in dermal bone between extinct and extant agnathans
extinct: dermal bone, extant: no dermal bone
Describe the skeletal tissue in gnathostomes
reduction in cartilage, mineralized endo-skeletons
Describe the skeletal tissue in chondrocytes
mineralized cartilage in endoskeleton, no bone
Describe the skeletal tissue in osteichthyes
cartilage, bone (membrane), bone (endochondral ossification) - bone marrow (only hematopoietic in tetrapods)
True or false: Neural crest cells are a vertebrate monophyletic group
false: Neural crest cells are a vertebrate synapomorphy
What has been been hypothesized about neural crest cells
what allowed vertebrates to develop the necessary structures to switch from filter feeding to active predation
Where is the chondrocranium?
surrounds the brain and encloses the sensory organs. Articulates with notochord
Where is the slachnocranium?
supports the gills and contributes to the jaws / inner ear bones. Highly derived.
what is the dermatocranium?
dermal bones that contribute to the jaws, brain case, facial bones. Encloses the chondrocranium and splanchnocranium (made of membranous bone, never cartilage)
What happens in the chondrocranium during embryonic development?
During embryonic development two pairs of cartilaginous bars and 3 pairs of capsules develop, The parachordals associate with the notochord
What happens to the capsules formed during embryonic development?
The capsules, bars and notochord eventually fuse and surround the brain and sensory organs
True or false: In lineages with a dermatocranium the chondrocranium is only the base of the brain case
true
What does the splanchnocranium develop from?
from the pharyngeal arches
What does the splanchonocranium arise from during embryonic development?
pharyngeal arches
What different functions are pharyngeal slits used for in non-vertebrate chordates vs. aquatic gill breathing vertebrates
used for filter feeding vs. some of them develop into the structures that houses the gills
What is each pair of gills supported by?
a visceral arch, alternating with gill slits leading to gill pouches
How many arches are in extant vertebrates?
7
True or false: Chondrichthyes have a dermatocranium
false: Chondrichthyes do not have a dermatocranium
What happens to the first 2 pharyngeal arches in gnathostomes?
develop into two cartilaginous structures that form the beginning of the jaw
what happens to the mandibular and hyoid arch in Chondrichthyes?
the embryonic structures remain in place and form the Jaw
where is the hyomandibular (H)
extends from otic area of chondrocranium
where is the certaohyals (C)
about posterior end of the palatoquadrate and mandibular cartilage
What is the main side of attachment for the jaw to the chondrocranium
the hyoid arch
What form of jaw suspension do sharks have? Describe where it is and its function.
hyostylic ( jaw connects through the hyomandibula) - permits the shark to protact its jaws
What do pharyngeal arches 3-7 do?
forms 5 brachial arches which support the 5 pairs of gills
What happens to the cartilage splanchnocranium in many species?
eventually ossified through endochondral ossification?
What does the operculum do in gill breathing bony fishes?
made of dermal bone that covers the gills and helps with buccal pumping like the spiracle - instead of spiracle
What does the posterior position of the palataquadrate become in Non Mammalian Tetrapods
quadrate bone
what does the posterior portion of Meckyl’s cartilage become in Non Mammalian Tetrapods
articular bone
What does the lower jaw connect by in non mammalian tetrapods?
articular hinge
What do mammals use to attach the mandible (lower jaw) to the rest of the skull
dermal bones
What does a secondary palate do in Mammals, Crocodilians, and some lizards?
separates the mouth from the nasal cavity
What is the advantage of separating the mouth from the nasal cavity?
Can eat and breath at the same time
