connective tissue functions
support and framework, medium of exchange, defense, protection, storage
connective tissue components
extracellular matrix and cells
extracellular matrix
ground substance (glycans) and fibers (collagen or elastic)
connective tissue is derived from _
mesoderm
connective tissue proper
located in stroma and capsules of organs, dermis of skin, tendons and ligaments, surrounding blood vessels, fascia
collagen
provides tensile strength, most abundant protein of ECM
elastic fibers
provide stretch and recoil
type I collagen
most abundant; in tendons, ligaments, dermis, bone
type I collagen provides _
tensile strength and stiffness
type I collagen is synthesized by
fibroblasts and osteoblasts
type II collagen
found in hyaline cartilage for structure and strength; made by chondroblasts
type III collagen (reticular fibers)
found in the liver, bone marrow, and lymphoid tissue
type III collagen is synthesized by _
fibroblasts
type III collagen provides _
an architectural framework in organs
type IV collagens
synthesized by epithelial cells to make basal lamina
type IV collagen function
support of delicate structures
collagen formation
procollagen is produced intracellularly –> forms a helix of 3 –> extracellularly cleaved to tropcollagen –> fibrils –> fibers
scruvy
lack of vitamin C will cause defect in collagen synthesis; vitamin C is ruined if boiled
keloid
collagen fiber tumors at sites of injury
elastic fibers
found in skin, lung, blood vessels, and elastic cartilage
Marfan syndrome
defects in fibrillin synthesis causes elastic laminae to be replaced with proteoglycans, weakening aorta
fibrillin
incorporate around elastin
fixed (resident) cells
fibroblasts, adipocytes, pericytes, mast cells (bone marrow derived)
fibroblasts
most common cell type of CT proper; produce procollagen and other component of ECM
