Special Connective Tissue Flashcards
What are the components of the Extracellular Matrix?
(MEG C.) Collagen, Tropoelastin–> Elastin (elastic fibers), Mircrofibrils, Ground Substance
What is the precursor to collagen?
Tropocollagen
What is the function of collagen?
provide tensile strength to tissue
What are the major types if collagen and where are they found?
Type 1: Dermis, ligaments, bone, cornea
Type 2: Hyaline cartilage (i.e., Articulating surfaces of bones, nose, trachea)
Type 3: Reticular collagen; Meshwork in highly cellular organs (i.e,. liver, spleen, kidney)
What is the most abundant protein in the human body?
collagen
What are the two components of mircofibrils?
fibrillin and fibronectin
What is fibrillin?
Elastic fiber component (scaffold for elastin deposition)
What is fibronectin?
deposition and orientation of collagen as well as binding of CT cells to extracellular matrix, including linking actin cytoskeleton to matrix
Describe ground substance?
transparent, viscous, semi-fluid gel
What is the function of ground substance?
influence fluid transport and metabolic exchange
What are proteoglycans? What part of the extracellular matrix are they a part of?
GAG + core protein (binds to GAG) +linker protein (binds core protein and GAG to hyaluronic acid backbone
Ground Substance
What is proteoglycan aggregate composed of?
proteoglycan + hyaluronic acid + some collagen
Name 2 types of specialized Connective Tissues.
Cartilage and bone
Where is cartilage developed from?
paraxial mesoderm
Cartilage: what is perichondrium; what are the layers?
Fibrous layer- fibroblasts, vasculature
Chondrogenic layer- chondroblasts and chondrocytes
What is lucunae?
space occupied by a cell (in cartilage- a chondrocyte as it has walled itself by extreting ECM
What is the first type of cartilage?
1st type: Hyaline Cartilage
What is the second type of cartilage?
2nd type: Elastic Cartilage
What is the third type of cartilage?
3rd type: Fibrous Cartilage
Does Hyaline Cartilage have perichondrium?
YES, but not found in articulating surface joints to keep growth at a minimum
Does Elastic Cartilage have perichondrium?
YES
Does Fibrous Cartilage have perichondrium?
NO
What is the only difference between elastic and hyaline cartilage?
there are elastic fibers in elastic cartilage but NOT in hyaline
Where is hyaline cartilage located?
tracheal bands, bronchi, nasal septum, joints, growth plates of long bones, site of initial bone repair following a fracture, embryonic template for the formation of long bones
Where is elastic cartilage located?
external ear lobe, epiglottis, pharyngotympanic tube (Eustachian tube)
Where is firbous cartilage located?
intervertebral discs (annulus fibrosis) and symphyses (joints between bones of breastbone and joint b/w left and right pubic bones in the hip)
What type of collagen is found in hyaline and elastic cartilage?
Type 2 (elastic cartilage) predominantly
[Type 1 in outer fibrous layer of perichondrium]
Where is bone derived from?
paraxial mesoderm
Are bone and cartilage derived from the same thing? If so, from what?
paraxial mesoderm
Name the outer and inner layers on the most EXTERNAL portion of bone. What do these layers contain?
fibrous (fibroblasts) and osteogenic periosteum (osteoblasts mostly but also can have osteocytes)
extensions of periosteum into compact bone:
Sharpey’s fibers (allow for better adherence of periosteum to underlying bone given that periosteum serves as attachment site for muscle tendons)
What cells are in bone? (hint: 3)
Osteoblasts, osteocytes, osteoclasts
What are osteoblasts?
main builder of bone
What are osteocytes?
secondary builder of bone; bone maintenance
What are osteoclasts?
maintenance–> dissolve bone
Name the seven structures of bone?
lamellae, cancliculi, lacunae, Haversian system/osteon, Haversian canal, Volkmann canal, Howship’s lacunae
Name two steps of bone development:
intramembraneous ossification and endochondral ossification
What is intramembraneous ossification?
formation of FLAT bones (like in the skull, face)
What are the two steps of intramembraneous ossification?
- CT replaced with bone matrix
2. Mesenchymal cells differentiate into bone cells (osteoblasts)
What is endochondral ossification?
formation of LONG bones (like arm and legs)
Where is endochondral ossification derived from?
miniature hyaline cartilage template
What are the three steps of endochondral ossification?
Epiphysis, Metaphysis, Diaphysis
What is epiphysis?
Secondary ossification site (contains the RED BONE MARROW–important for hemopoesis)
What is metaphysis?
location of the GROWTH PLATE; closes at adolescence
What are the zones of metaphysis?
Reserve cartilage (R) Proliferation (P) Maturation (M) Hypertrophy/calcification (H) Degeneration (D) Ossification (O)
RPMH DO- Run past my house DO it
What is reserve cartilage (R)?
typical hyaline cartilage with chondrocytes in small clusters
What is proliferation?
mitotic activity of chondrocytes increases, ECM rich in proteoglycans
What is maturation?
mitosis has STOPPED and chondrocytes have INCREASED in size
What is Hypertrophy/calcification (H) ?
chondrocytes continue to INCREASE in size; Matrix becomes calcified–trapped chondrocytes in lacunae
What is degeneration?
chondrocytes DEGENERATE and are invaded by osteogenic cells and capillaries that will FORM bone marrow of the shafts of long bone, the diaphyses
What is ossification?
bone becomes CALCIFIED in increase strength–allowed to maintain a small amount of flexibility
What is diaphysis?
bone shaft; primary ossification site
What type of bone tissue is present during bone repair and during bone development?
Primary bone tissue
what is primary bone tissue?
has a random organization of collagen fibers–not as dense as mature bone
Describe the first bone of development/after fracture:
unorganized or woven
Why is bone after a fracture unorganized or woven?
because a fracture causes destruction of bone matrix and death of bone cells. Damaged blood vessels form a clot and the clot, cells and damaged matrix removed by macrophages
What is the role of periosteum and endosteum in bone fracture?
it responds with intense proliferation, surrounding the fracture and penetrating the fracture
What two things are formed at the same time? (hint: a bone and a cartilage)
primary bone and hyaline cartilage
What do primary bone and hyaline do during a fracture?
they are replaced with bone as well as CT is formed and replaced. They form irregular trabeculae or bone calluses
What replaces Callus?
Secondary bone tissue
