Lecture 12- Connective tissue Flashcards
Definition of connective tissue
tissue that :
- connects
- supports
- binds
- separates
other tissues or organs, typically having relatively few cells embedded in an amorphous matrix, often with collagen or other fibres
how many types of connective tissue
6
name the 6 types of connective tissue
1) loose connective tissue (areolar)
2) Dense (fibrous) connective tissue
3) Adipose tissue
4) Cartilage
5) Bone
6) Blood
connective tissue made up of 3 componenets
cells
fibres
ground substance
fibre
collagen, elastin, reticular fibres
extracellular matrix =
ground susbtance nad fibres
ground substance made up of
consists of large molecules called glycosoaminoglycans (GAGs) which link together to form even larger molecules called proteoglycans.
- gel-like substancein the extracellular space that contains all components of the extracellular matrix (ECM) except for fibrous materials such as collagen and elastin
texture of ground susbtance
Viscous clear substance with slippery feel (high water content)
- GAGs attract water to forma. hydrated gel
- GAGs eprmit rapid diffusion but also resists compression

function of connective tissue
Function:
Binds and supports visceral organs in place (holds skin, gut lungs together etc)
Protecting- shock absorber
Insulating (fat underlying skin)
Storing reserve fuel and cells (bone marrow and fat tissue)
Transporting substances within the body (blood and interstitial)
Separation of tissues(fascia and tendons/cartilage)
Interstitial
space between tissues and organs of the body
where is loose connective tissue (areolar) found
beneath epithelia to facilitate diffusion
e. g. Lamina propria beneath mucosal membranes
e. g. located around small blood vessels
loose connective tissue is the
least speciliased connective tissue
loose connective tissue function
Holds vessels that supply fluids e.g. capillaries
Permits cell migration
Involved in inflammation pathways
Located in sites where pathogens may breach epithelial surface
Allows challenge and destruction by cells of the immune system
Acts as packaging around organs
Generally holds everything in place
Cushions and stabilises organs
structure of loose connective tissue
Contains multiple cell types
Contains 2 main fibres
- Collagen
- Elastin
Gel- like Ground substance

fibres in loose connective tissue
Collagen- Flexible with high tensile strength
Elastin- Stretch and recoil
name the cells found in loose connective tissue
- Fibroblasts
- Maxcrophage/ histocytes
- Mast cells
- Adipocytes
fibroblastsw
secrete fibres that lie within ground susbtance (ECM)
fibroblasts important for
Important in wound healing process
Responsible for scar formation
myofibroblasts
are fibroblasts that contain actin and myosin
Responsible for wound contraction when tissue loss has occurred
Have a lot of RER- to make collagen fibres
Macrophages are derived from
monocytes in the blood
- move throguh the gela nd find bacteria
what do amcrophages do
Phagocytose foreign material
Degrade foreign organisms and cell debris
Professional antigen presenting cells
mast cells are a type of
histocyte
- Contain abundant granules
- Histamine- increase blood vessel permeability
- Heparin- anticoagulant
- Cytokines- attracts eosinophils and neutrophils
mast cells ebcome coated with
IgE- bidn to allergens
- When allergen cross links these surface bound IgE molecule, the contents of the granules are all rapidly released front the cell
adipoctes are
fat cells
types of adipocytes
white and brown
structure of white adipocytes
- unilocular- single neromous lipid droplet
- nucleus, cytoplasm and organelles all squeezed to one side of the cells
unilocular
one single enromous lipid droplet

function of white adipose tissue
padding and shock absorber
insulation
energy reserve
brown fat tissue structure
- Multilocular- mutliple small lipids droplets
- nucleus and cytoplasm sques to the centre of the cell
- lots of mitochdonria
*
brown adipose mostly found in…… only a little in….
- Neonates
- adults
function of brown fat
provides insulationa nd energy reserve to neonates
- contains uncoupling proteins UCP
- reduces the proton gradient created int eh mitochiodnria
- less energy released as ATP
- more released as heat energy
give a name of a GAG found in ground susbtance
hyaluronic acid
collagen
flexible with high tensile strength
Looks thicker than elastin on photo

elastin
recoil after stretch or distnesion
reticulin
(absent in areolar tissue)- supporting framework
how many types of collagen
5
type 1 collagen
- most widley distributed type
- fibrils aggrgeate into fibres and fibre bundles
- e.g. tendons, ligaments and dermis
type II collagen
- Fibrils do not form fibres
- E.g hyalien and elastic cartilage
type III collagen also known as reticular
- fibrils form fibres around muscle and nerve cells and within lympathic tissues and lympahtic organs and tendons
Type IV collagen
unique form present in basement membrane (considered part of epithelial tissue)
type V collagen
skin and placenta
elastic fibres
elastin and fibrillin
two types of dense (fibrous) connective tissue
irregular
regular
Dense irregular conenctive tissue
Collagen 1 fibres in all directions- resists stresses in all directions
e. g. skin can resists forces in multiple direction to rpevent tearing
- elastic fibres allow streatch and restoration of shape

Dense Regular Connective Tissue
-
Collagen 1 fibres are parallel – resists stress in one direction
comparision of irregular and regular dense connective tissue

examples of irregular dense
deep laye rof the dermis
submucosa of intestine
examples of regular dense CT
tendons
ligaments
aponeuroses
tendons
fibrous connective tissue that connects muscle to bone and is capable of withstanding tension
what sort fo junction joins muscles to bone
myotendinous junction

Skeletal muscle fibres connecting with tendon collagen bundles
Provides tremendous physiological strength- cross links between
tendon structure
- 30% collagen
- 2% elastin
- 68% water
- dense (fibrous) regular CT
-
whioch collagens found in tendons
70% type 1
30% type 2
ligaments
connect bone to bone
ligaments structure
Similar to tendons
Collagen bundles are densely packed in parallel arrangement
Parallel collagen fibres
Not straight, but undulate
Wrapped in loose connective tissue- fascicles
fascia
is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs

3 types of fascia
1) superfical
2) deep
3) visceral

structure of fascia
Made up of fibrous connective tissue , like ligaments and tendons, containing closely packed bundles of collagen fibres oriented in a wavy pattern parallel to direction of pull.
Flexible
Resist great unidirectional tension
Collagen fibres produced by fibroblasts located within the fascia
production of fibrils
- Fibroblasts secrete procollagen that is converted to collagen molecules outside the cell
- Collagen molecules aggregate to form collagen fibril
- Vitamin C is required for the intracellular production of procollagen
- Hydroxylates proline and lysine
- Without Vit C- collagen formation is disrupted
when is elastin laid down
During fetal development: not replaced in the adult
Main cause of damage of elastin: UV and smoking
E.g. smoking damages lung tissue
- Decreases elasticity of the alveoli
what create eleastins
smooth muscle cells
exampels of where eleastin fibres are prominant
- Artery walls
- aortic walls
- tunica media of the aorta
- demris
name 3 clinical correlates for CT
- scurvy
- marfans
- osteogensis imperfecta
scurvy
Thin collagen fibres aggregate to form thicker collagen fibres
Vitamin C deficiency
Poor wound healing
Impaired bone formation
Gum disease
Bruising of the skin
Bleeding
in Marfans which dibril is affection
-Expression of fibrillin 1 gene affected- such as elastin tissue is abnormal
AUTOSOMAL DOMINANT
Signs of Marfans
Abnormally tall
Exhibit arachnodactlyl- slender and long fingers
Frequent join dislocation
Span longer than height
Risk of aortic rupture
osteogneeiss imperfecta due to
mutated collagen fibres which do not ‘knit together’ or not enough is produced or both
osteognesisi imperfecta
Autosomal dominant
Mild to severe
Due to mutated collagen fibres which do not ‘knit together’ or not enough is produced or both
Signs of osteogensis imperfecta
Weakened bones
Short stature
Presence of blue sclera (in the eye)
Hearing loss
Hyper mobility (loose joins) and flat or arched feet
Poor teeth development
