Connective tissue

Proper connective tissue

LCT

DICT

DRCT

Specialized Connective tissue

DRECT

Reiticular

Adipose

Fluid CT

Blood

Lymph

Supportive CT

Bone

Cartilage

Fascia

influences mechanical functions it connects supports tissues

glides, stretches, lubricates, and is resilient in movement

Collagen type 1

CT proper, bone, fibrocartilage

Collagen type 2

only in cartilage

Collage type 3

LCT, DICT, lymphatic organs, and blood vessel walls

also known as reticular fibers

Collagen type 4

only in basement fibers

Elastic fibers

Found in LCT, DICT, Elastic CT

Ground substance

Non-fibrous componsents of ECM produced by fibroblasts

Glycosaminoglycans (GAGs)

help draw water into CT and bind cells to ECM fibers

Ground Substance functions

route of communication and transport

provides barrier against bacterial penetration and migration

cell adhesion and stabilization

Cell differentiation via intercellular signaling

Ground substance barrier and diffusion

Prevents movement of largemolecules and fast moving-liquid

viscosity changes during infection to let germs spread or to let immune cells in

Ground substance immune and inflammation

contains proteins that actively fight off bacteria

prevents runaway inflammation by holding onto the inflammatory signals via its negative charge

Principal cell types

fibroblasts

adipocytes

osteocytes

chondrocytes

tenocytes

Wandering cells types

Predominately WBC

plasma cells

lymphocytes

neutrophils

eosinophils

basophils

macrophages

potentially mast cells

Fixed cells

stem cells

scattered adipocytes

mast cells

resident macrophages

Collagen synthesis intracellular

Translation: rER sythesizes protein chain

Hydroxylation: Prolyl and lysyl hydroxylases modify chains; VITAMIN C is needed

Triple helix assembly: Three chains twist into stable structure

Collagen Synthesis extracellular

Cleavage: Procollagen peptidases remove terminal extension to tropocollagen

Fibrillogenesis: Tropocollagen self-assembles into collagen fibrils

Cross-linking: lysyl oxidase catalyzes covalent cross-links in the tropocollagen creating tensile strength of these wovven fibrils

Mast cells

release histamine which dilates capillaries and increase permeability causing plasma leakage

Fibroblasts

creates extracellular fibers and ground substance

Plasma cells

create antibodies

Lymphocytes

various immune/defense functions

Eosinophilic leukocytes

moderate allergic/vasoactive reactions and defense against parasites

Neutrophilic leukocytes

phagocytosis of bacteria

Macrophages

Phagocytosis of ECM componenets and debris

also present antigents to immune cells

Adipocytes

storage of neutral fats and provide protection

CT and aging

Over time, the enzymes for breakdown increase and the enzymes for synthesis decrease, leading to more rigid blood vessels, ligament/tendon flexibility loss, and wrinkles in skin

Wound healing stages

Inflammation

Proliferation

remodeling

Inflmmation phase

Hemostasis/blood clotting

inflamation/vasodilation for 1-3 days allowing white blood cells to clean up and signal CT tissue to start repair

Proliferation phase

about 2 weeks

granulation tissue (well vascularized with new blood tissue)

stimulates regeneration and synthesis of CT fibers nad epithelium

Remodeling phase

Up to 2 years

maturation of granulation CT to form a scar

final healing involves scar formation

Adult vs fetal healing

different signaling means that fetal healing ends in a scarless result because the healing matches the previous tissue so well, but adult healing results in a scar