Histology Connective Tissues Flashcards
Connective Tissues Functions
Physical support, packing material, transports nutrients and oxygen
Supportive connective tissues (also hard CT)
Cartilage and Bone
Loose connective tissue
Filler between cells. Areolar, adipose, hematopoietic (blood forming), and reticular (lymph nodes)
Dense connective tissue
Dense irregular like skin (collagen bundles in multiple directions, strong compressive and shear strength), and dense regular like tendon and ligament (fibers in same direction, strong tensile strength)
All connective tissues have 3 components
Cells, and Extracellular matrix of fibers and ground substance
Collagen formation
Made in fibroblasts, osteoblasts and chondroblasts. Vitamin C adds OH that combine and create pro collagen (3 strands). pro collagen peptidase cuts off ends and creates tropocollagen. Tropocollagen combine to make collagen fibers.
Components of Elastic fibers
Elastin core with fibrillin on outside
Ground substance
Proteoglycans like glysoaminoglycans, with base made of Hyaluronic acid. Linker proteins connect to core proteins with chondroitin and keratin sulfate chains (lots of OH groups attract water). Fills in space to allow cells to migrate through.
Connective Tissue Proper
Loose and dense CT
Principal cell type in dense CT
Fibroblast (dividing cell) and fibrocyte (no longer dividing)
Hematopoietic cells
dendritic reticular cells, lymphocytes, mast cells.
Erythrocytes, monocytes, lymphocytes, granulocytes (neutrophils, basophils, eosinophils)
Most common fibers in CT
Collagen and elastin
Mesenchymal cells
can differentiate into fibroblasts, adipocytes, osteoblasts, and chondroblasts
Adipocyte Brown fat
multilocular, generates heat
Adipocyte White fat
unilocular, storage of triglycerides (energy), provides protection, packing
Chondroblasts
Outer edge of cartilage, make cartilaginous matrix
Chondrocytes
in middle - maintain existing matrix
Perichondrium
Outer surface of cartilage has chondroblasts and fibrous tissues
Vasculature of cartilage matrix
Avascular, gets nutrients by diffusion
How does cartilage change with age?
With age, cartilage dies and can be replaced by bone
Growth of cartilage
Interstitial (within existing matrix) and appositional (on outer surface on the top of the matrix)
Growth of bone
Only appositional (on outer surface)
Ground substance of cartilage
Aggrecan - similar hyaluronic acid core with sulfated glycosaminoglycans (chondroitin and keratin sulfate)
Types of Cartilage
Hyaline cartilage, most common, articular cartilage is a form of hyaline.
Fibrocartilage (thick bundles strong).
Elastic cartilage (Ex. Ear)
Cells of Bone
Osteoblasts (make new bone), Osteocytes (maintain structure), Osteoclasts (remove bone)
Most abundant fiber in bone
Collagen
Bone Ground substance
Glycoaminoglycan with hyaluronic acid and side chains, also has hydroxyapatite which is calcium and phosphate (crystalline shape that makes bone hard)
Roles of collagen and hydroxyapetite
Collagen makes bone strong, while hydroxyapatite makes it hard
Compact bone layout
Haversian arteries travel through small hole called Haversian canals. Layers around this are called Lamella. Inside that are osteocytes. Osteon is unit of all of this.
Cancellous (spongy) bone layout
Lining inside of bone is a layer of osteoblasts called the endosteum. Inside is bone marrow, which can have hematopoietic or fat cells and lots of blood vessels. bone shelves form latticework for strength. Found in vertebra or plates of skulls
Periosteum
Around bones that has fibrous layer and osteoblasts
How is bone made?
Osteoblast connects to osteocyte, lays down osteoid as organic matrix. That gets calcified and becomes bone. It keeps making osteoid until it is covered (can no longer divide) and turns into osteocyte
Can mine bone for what two things?
Calcium and phosphate
