Connective Tissue Flashcards
What is connective tissue?
Tissue which provides general structure, mechanical strength, space filling as well as physical and metabolic support for more specialised tissues
What are examples of connective tissue and what are their functions
Bone -structural integrity
Cartilage - protects joints, structural integrity
Tendons and ligaments - connect muscle to bone and protect joints
Adipose tissue - energy storage
Mesentry - connects the intestine to the abdomen
Layers under skin and around organs - support
What are the main components in connective tissue?
Ground substance, fibre, cells
What are the 3 structural properties of connective tissues and what provides them?
Tensile strength - collagen
Elasticity - elastin
Volume - glycoproteins and complex carbohydrates
What is the extracellular matrix made from?
Ground substance and fibres
What is the ground substance?
It is a clear semi solid gel that provides biochemical support.
It is composed of glycoproteins and complex carbohydrates
It has profound water binding ability
It supports intercellular exchange of substances
What is ground substance made of?
glycosoaminoglycans (GAGs) -hyaluronic acid, chondritin sulphate
proteoglycans - glucosamine
What is the difference in the epithelial tissues and connective tissues?
Cells in epithelial tissues are close together and abundant however in connective tissues, cells are sparse and spread across the ground substance.
What are the main types of fibre and what are their qualities?
Collagen - strongest, most abundant, provide tensile strength
Elastin - long, branched, provide stretch and recoil ability
What are collagen fibres made from?
a tropocollagen helical protein structure made 3 polypeptide alpha chains made from amino acids glycine, proline and hydroxyproline
Describe the first 4 types of collagen
Type 1 - found in fibrous tissues (dermis of skin, tendons, ligaments, bone)
Type 2 - hyaline cartilage
Type 3 - delicate branched ‘reticular’ network found in highly cellular organs (livers and LNs
)Type 4 - collagen is a network/mesh-forming collagen and is an important constituent of basement membranes
Where in the body is elastin fibre found in large amounts?
bladder, lung, skin and blood vessels
What are the 3 cells of connective tissues and what do they do?
**blasts - synthesise and secrete ECM
**cytes - maintain ECM
***clasts - breakdown ECM
What do fibroblasts do?
Most common connective tissue cell type
Secrete fibres and components of ground substance
What do osteoclasts do?
breakdown (recycle) ECM in bones
What do chondrocytes do?
secrete and maintain ECM in cartilage
What do osteoblasts and osteocytes do?
secrete and maintain ECM in bones
Unlike epithelium, connective tissue is highly ______? and why?
vascularised as they contain blood vessels and lymphatics as well as immune cells
What connective tissue is not vascularised?
cartilage, tedons, ligaments
What are the classifications of connective tissue and what do they include?
Connective tissue proper -broad category and loose or dense depending on arrangement of fibres
Skeletal connective tissue -bone, cartilage
Fluid connective tissue -blood, lymph
What does ‘loose’ connective tissue mean?
few fibres, mostly ground substance
What does ‘dense’ connective tissue mean?
many fibres, few ground substance
What are the loose connective tissues and what is their function/location?
Areolar
Universal packing material – supports and binds other tissues and found beneath skin, submucosa, surrounding capillaries
Adipose
Functions include, energy storage, shock absorption, insulation and found deep beneath skin, breasts, in the abdomen, finger and foot pads. Most of the adipocytes (maintain) are made from lipids (fats)
Reticular
Delicate, branched network (type III collagen) providing internal structure to highly cellular organs (liver, lymph nodes, spleen)
What are the dense connective tissues and what is their function/location?
Regular
Closely, packed collagen fibres running in same direction. Provides tensile strength – found in tendons and ligaments
Irregular
Closely, packed interwoven fibres running in different directions. Found in dermis of skin, forms protective capsule around organs
Elastic (dense regular tissue made from mostly elastic fibres)
Allows tissues to recoil after stretching. Found in arteries, skin, lungs and underlying transitional epithelium in bladder
Why does scurvy occur?
lack of vitamin C means proline is not hydroxylated therefore collagen is not correctly formed leading to fragile tissues
What is Systemic Lupus Erythematosis (SLE)?
Autoimmune disease – autoantibodies target host tissues
Target tissues include, skin, bones, tendons, kidneys
Oral symptoms include dryness and soreness
Oral manifestations include buccal and palatal lesions
What is Sjogren’s?
Autoimmune disease – autoantibodies affects glands that produce tears and saliva
Symptoms include dry eyes and mouth
Oral manifestations include increased dental caries and candidiasis
Can occur independently or accompany other disorders, such as, SLE or rheumatoid arthritis
What is the difference between cartilage, tendon and ligament?
A tendon is a band of tissue that connects muscle to bone.
A ligament is an elastic band of tissue that connects bone to bone and provides stability to the joint.
Cartilage is soft, gel-like padding between bones that protects joints and facilitates movement.
How does collagen stain in H&E?
pink as it is acidophilic and stains with eosin
How does elastin stain?
pale staining as it is amorphoras
What are the immune cells of connective tissue?
macrophages
mast cells
plasma cells
lymphocytes
What are the cells of general connective tissue?
adipocytes
fibroblasts
What is the basal lamina?
basement membrane that lies underneath epithelial cells
What are the two types of fat cells?
brown and white fat cells
How do adipocytes look under staining?
empty, white circles
What’s the difference in the function of brown adipose tissue and white adipose tissue?
White - structural fill, shock absorption, energy storage
Brown - insulation
What do myofibroblasts do?
repair in muscle tissue
What embryological orgin do most connective tissues arise from?
mesenchyme
What amino acids is collagen made of?
proline, glycine, hydroxyproline
