Body Plan 06: Connective Tissue and Cartilage Flashcards
Mesenchyme
Embryonic connective tissue with lots of ECM and migrating cells; derives from mesoderm
What can mesenchyme cells differentiate into?
Mesothelial cells, Endothelial cells, smooth muscles, osteoblasts, osteoclasts, chondroblasts, adipocyte, fibroblast
Fibroblasts
Secrete fibril ECM and ground substances
Fibrocytes
Inactive fibroblast
Collagen
A main structural protein found in many connective tissues
What are the main reasons for variation in collagen?
1) Genetic differences in amino acid sequence
2) Whether they form fibrils, fibers, or bundles
3) Differences in amounts of carbohydrate linked to hydroxylysine
Collagen Type 1
A bundle of collagen, consists of a bunch of type 3 collagen. Found in bone, tendon, skin, dentin
Collagen Type 2
A fibril of collagen. Found in hyaline cartilage
Collagen Type 3
A fiber of collagen, consists of a bunch of type 2 collagen. Flexible network in organs that change size
Reticular fibers
Collagen type 3 fibers. Only visible through silver staining
Collagen Types 4 and 7
Molecular forms of collagen that assemble into sheets. Type 4 becomes basal membrane and type 7 becomes anchoring fibrils
Scurvy
Vitamin C deficiency, results in decreased assembly of type 1 collagen
Osteoporosis imperfecta
A point mutation changing one nucleotide in the genetic coding for type 1 collagen
Elastic Fibers
ECM fibers in structures that deform then recover shape. Found in the dermis, lungs, arteries, elastic ligaments of the spinal cord, and the bladder
What are the components of elastic fibers?
Microfibrils and tropoelastin
Marfan Syndrome
Mutation in fibrilin gene that prevents scaffoling of the elastic fibers, leading to dilation of the root of the aortic artery and aortic aneurysms
What immune cells are found in connective tissue?
Macrophages, dendritic cells, mast cells, leukocytes (specifically, neutrophils, eosinophils, lymphocytes)
Mast cells
Connective tissue counterpart of basophils
Plasma cells
Terminally differentiated B lymphocytes. Can be found in lamina propria of mucosa
Macrophages
Develop from monocytes after migrating into tissue; phagocytotic; antigen-presenting cells
Adipocytes
Lipid storages that develop from lipoblasts from mesenchyme
White adipose tissue
Store energy and are about 20-25% of body weight
Brown adipose tissue
Non-shivering heat production, not found much in adults
What are the four types of connective tissue?
Loose connective tissue, elastic connective tissue, dense connective tissue, cartillage
Loose connective tissue
Allows for movement and houses immune defense cells. It is loose to accommodate for moving things and smooth muscle contraction
Mucosa
The mucous membrane, consisting of epithelial lining, underlying connective tissue, and muscularis mucosae
Serosa
Single layer of squamous mesothelial cells with underlying loose connective tissue that lines celomic cavities
Dense connective tissue
Transmit tensile forces from muscles to bones; includes tendons and ligaments
Elastic connective tissue
Consists of elastic fibers, stores and returns energy
Cartilate tissue
Avascular connective tissue that can bear stress without permanent distortion. Comes in three types (1, 2, and elastic fibers)
How is cartilage molecularly organized?
The chondroitin sulfate side chains of the proteoglycan electrostatically bind to the collagen fibrils, forming a cross-linked matrix
Hyaline cartialge
Most prominent type of cartilage in body, mostly type 2 cartilage
Elastic cartilage
Maintains shape after deformation, consists of type 2 cartilage and elastic fibrils. Found in ear and larynx
Fibrocartilage
Dense regular connective tissue with cells in lacunae, consisting mainly of type 1 cartilage. Found in places where hyaline cartilage is not available
Perichondrium
Layer of dense irregular connective tissue that surrounds the cartilage of developing bone
Chondroblast
Immature cartilage producing cell
Where do chondrocytes usually reside?
In lacunae inside the Territorial/capsular matrix
Interstitial cartilage growth
Chondrocytes secrete ECM and become confined to their lacunae. Only viable in young, smaller bones
Appositional cartilage growth
Perichondrium cells secrete fiborous element around cartilage. Chondrocytes in perichondrium secrete ECM , sealing themselves off
Ground substance
a fluid, gelatinous component of extracellular matrix that is rich in glycosaminoglycans, proteoglycans, and glycoproteins
