Connective Tissue Flashcards
What are the functions of connective tissue (CT)?
- maintains cells/tissues/organs in their correct spatial arrangement when forces are applied
- provides support, binding protection + insulation
What are the 2 types of CT?
- loose
2. dense/fibrous
What are the 4 types of loose CT?
- areolar CT
- adipose tissue
- reticular tissue
- mucous tissue
What is the arrangement + function of areolar CT (LCT)?
ARRANGEMENT:
fibres loosely connected in a meshwork
FUNCTION:
- binds tissue parts
- maintains movement + flexibility
- structural support for organs/glands/vessels/nerves
What is the function of adipose tissue (LCT)?
- provides nutrients
- acts as an energy store
- protection
- insulation
Where can reticular tissue (LCT) be found?
bone marrow, spleen
Where can mucous tissue (LCT) be found?
dental pulp, umbilical cord
What are the 3 types of dense/fibrous CT?
- cartilage
- mineralised
- blood
Properties of dense CT:
- In tendons + ligaments
(a) + closely packed (b) tissue.
(c) fibre bundles running in the (d) direction.
Has (e) cells than loose CT - In the dermis (skin)
(f) collagen fibre bundles
(a) regular/irregular?
(b)
(c)
(d) same/opposite?
(e) more/less?
(f ) regular/irregular?
(a) regular
(b) fibrous
(c) collagen
(d) same
(e) less
(f ) irregular
- In tendons + ligaments
regular + closely packed fibrous tissue.
Collagen fibre bundles running in the same direction.
Has less cells than loose CT - In the dermis (skin)
Irregular collagen fibre bundles
Is cartilage (DCT) innervated?
No
Is cartilage (DCT) vascular or avascular?
Avascular
What is the function of cartilage (DCT)?
provides support
has some pliability/flexibility
What is the function of mineralised CT (DCT)?
provides support + protection
Where can calcified cartilage (DCT) be found?
cartilage
bone
dentine
cementum
What makes up CT?
cells + ECM
What are chondrocytes?
cartilage cells
What are osteoblasts?
bone forming cells
What are osteocytes?
osteoblasts calcified in bone matrix
What are odontoblasts?
dentine forming cells
What are cementoblasts?
cementum froming cells
Which other cells are found in CT?
macrophages mast cells melanocytes adipose cells mesenchymal cells plasma cells leukocytes
What forms the ECM?
- protein fibres
eg, collagen, elastin - ground substance
How are the protein fibres formed?
- protein molecules synthesised by fibroblasts
- fibroblasts secrete protein molecules into ground substance
- the molecule aggregate into fibres
- collagen fibres = mechanical strength
elastin fibres = mechanical strength
What does ground substance consist of?
proteoglycans
glycoproteins
phospholipids
water
Composition + properties of proteoglycans
COMPOSITION:
core protein + long unbranched polysaccharide chain
PROPERTIES:
highly polar
water binding
can act as lubricant/shock absorber
Composition of glycoproteins
conjugated proteins
+ 1 or more short, irregular saccharide side chains
How are collagen fibres formed
- tropocollagen secreted into ECM
2. tropocollagen polymerises to form collagen - forms crosslinks
What is tropocollagen?
3 alpha polypeptide chains bound together to form collagen
Composition of collagen
33% glysine
10% hydroxyproline
0.5% hydroxylysine
66% AA - ie, glysine, alanine, proline
What property does a high proline + hydroxyproline content lead to?
stiffness of the chain
- as there is a loss of free rotation
Properties of collagen
basic
hydrophilic - polar/soluble
more crosslinks = less soluble
How are collagen fibres arranged in areas bearing compressive loads?
in a lattice
- lattice arrangement = tissue can stretch to some extent
= strength + flexibility
How are collagen fibres arranged in areas bearing tensional loads?
longitudinal arrangement
How many types of collagen are there and where would they be found?
Type 1:
in every CT
Type 2:
cartilage
vitreous body of the eye
Type 3:
reticular fibres
healing wounds
smooth muscle
Type 4:
basement membrane
bone + dentine (small amounts)
Type 5:
tendons
bone + dentine + dental pulp (small amounts)
What happens to the bonds in collagen with age?
weak bonds become strong covalent bonds
= mechanical strength increases
= becomes more brittle (eg, skin, bones)
What forms elastin?
4 polypeptide chains
connected by high number of crosslinks
Properties of elastin
stable
elastic (stretch + recoil)
insoluble
Elastin contains a high number of (a) residues
ie, gly, ala, val, leu
Elastin contains little/no (b) residues
ie, low hydroxyproline, no hydroxylysine
Therefore, it is _(c)_philic
(a) non-polar
(b) polar
(c) lipo
Elastin contains a high number of non-polar residues
ie, gly, ala, val, leu
Elastin contains little/no polar residues
ie, low hydroxyproline, no hydroxylysine
Therefore, it is lipophilic
Function of elastin
contributes to elasticity of tissues
Which dental structures can elastin be found in?
dentine
dental pulp
periodontal ligament
bone
Function of ground substance
- provides unstructured filling space between cells + fibres
- plays a role in mineralisation
- holds water
- provides environment for laying down/maturing proteins fibres during tissue development + turnover
- biological function (eg, cell migration)
Which dental structures are CT found in?
oral mucosa PDL alveolar bone cementum dentine dental pulp
