Connective Tissue Morphology Flashcards
connective tissue definition
Tissue that is found between other tissues elsewhere in the body
three components in all connective tissue
ground substance, fibers and cells
what does the ground substance and fibers combine to form?
extracellular matrix
what is the ground substance?
a complex of proteoglycans, GAGs and multiadhesive glycoproteins such as laminin and fibronectin
function of connective tissue
supporting matrix, transmission of forces, facilitation of movement, fat storage, insulation, cushioning, infection repair, growth factor gradients
GAGs examples
uronic acidm, hyaluronic acid, glucosamine, galactosamine
function of GAGs
form viscous pericellular network which binds to water and ensures that ECM is hydrated
small, highly sulphated GAGs bind to proteins, prevent them from diffusing out
high negative charge sequester cations
multiadhesive glycoprotein functions
multiple binding sites for integrins
large molecules allow adhesion of cells to substrate
laminin, binding sites for integrins
fibronectin, binding sites for collagen, GAGs and integrins
different fibres in connective tissue
collagen, reticular fibres and elastic fibres
what are reticular fibres?
collagen type 3- form an extensive network of thin fibers that can support cells
heavily glycosylated
what do the reticular fibres support?
adipocytes, smooth muscle, nerve fibres and small blood vessels
elastic fibres structure
thinner than type 1 collagen
composite of fibrillin to form microfibrils
lysine rich areas interspersed with hydrophic lysine and proline regions
elastic fiber function
important for stretch and recoil
what produces the different fibres?
all produced by fibroblasts
cells in connective tissue?
fibroblasts, mast cells, adipocytes, macrophages,
fibroblast function
produce and maintain the majority of ECM components
synthesise and secrete collagen and elastin, GAGs, proteoglycans,
mast cell functions
localised release of bioactive substances involved in local inflammatory response
where are mast cells located?
near blood cells, mesenteries and tissues that line the digestive and respiratory tracts
what molecules are released from mast cells + function?
heparin- GAG- anticoagulant
histamine- promote vascular permeability and contraction of smooth muscle
serine proteases- mediators of inflammation
eosinophil- attract leukocytes
cytokines
phospholipid precursors that become prostaglandins
adipocyte function
store lipids as neutral fats in cytoplasm
produce heat
two different types of adipose tissue
white and brown adipose
white adipose structure
mature adipocytes with one large triglyceride droplet
nucleus on periphery
white adipose function
stores fats from chylomicrons and VLDLs
free fatty acids and glycerol synthesis
insulation, padding
brown adipose structure
more cytoplasm
many smaller fat droplets
more centrally located nucleus
brown adipose function
heat generation- non shivering thermogenesis
where is brown adipose mainly located?
young children
mainly lost in adults but found around kidneys adrenal glands, aorta and mediastinum
macrophage structure
irregular surface of pleats, protrusions and indentations
well developed golgi, many lysosomes
macrophage function
phagocytes, abundant at sites of inflammation
break down ECM and debris
three different connective tissue diseases
Ehlers Danlos, Marfans and osteogenesis imperfecta
explain ehlers-danlos
set of diseases caused by a mutation in collagen, leading to its poor strength
causes loose skin, problems with wound healing, hypermobile joints and fragile blood vessels
explain Marfan’s
mutation in FBN1 gene, encoding fibrillin 1, essential in the formation of elastic fibres
results in tall individuals with long and thin limbs
flexible joints and scoliosis
increased risk of aortic aneurysms
explain osteogenesis imperfecta
brittle bone disease
lack of collagen 1, mutations in COL1A1 or COL1A2
results in amino acid substitution of glycine to bulkier amino acid which results in steric hindrance
changes the interactions between collagen and hydroxyapatite crystals which makes bones brittles
four different types of tissue/
epithelial, connective, muscle and nervous
6 types of connective tissue
loose connective tissue
dense connective tissue
bone
cartilage
blood
lymph
