Connective Tissue Proper And Supporting Ct

Front 1

Connective Tissue Proper: Dense CT

Back 1

2a) Dense CT: Dense Regular CT

2b) Dense CT: Dense Irregular CT

2c) Dense CT: Elastic Tissue

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2a) Dense CT: Dense Regular CT

Back 2

largely collagen type I fibres arranged in parallel arrays

thus imparts tensile strength in one direction as long as force is applied in direction of fibres

eg: tendons, aponeuroses, ligaments

tendon and aponeuroses both attach muscle to bone

ligament attaches bone to bone so they experience tensile force along one axis

Front 3

2b) Dense CT: Dense Irregular CT

Back 3

largely collagen type I fibres arranged in a meshwork sheet thus imparts tensile strength in >1 direction

eg: reticular layer of dermis, periosteum, perichondrium, organ capsules, joint capsules, submucosa of GI tract

needed anywhere a sheet that is very strong and tough and capsulated as well

Front 4

2c) Dense CT: Elastic tissue

Back 4

high [] of elastic fibres increase resiliency (bounce and twist back)

found in structures that must stretch and recoil (change shape)

certain ligaments eg: ligamentum flavum, supporting transitional epithelium, BVs

BVs: aorta

elastic fibres are much finer compared to size of cell

Front 5

Supporting Tissue Proprer: 3. Cartilage

Back 5

Characteristics & Fxns:

* EC matrix abundant, firm, gel-like, resilient and smooth ( like rubber)

* gives structure to soft tissues

eg: trachea, gives flexibility to airway but holds flap open with cartilage rings

*fxn in development and growth of long bones (covered under bone)

*most cartilages surrounded by perichondrium (dense irregular)

* all types: avascular, no lymphatic vessels, no nerves

(gets nutrients and oxygen by diffusion like epithelia and repair is slow)

thus chondrocytes metabolize glucose mainly by anaerobic glycolysis

nourished by diffusion thru GS from vessels in surrounding perichondrium and/or ordinary CT

Front 6

Matrix defines the cartilage

Back 6

composition of the matrix determines the physical properties of a cartilage

GS:

*rich in proteoglycans linked to hyaluronic acid forming aggrecan (bottle brush where bristles are GAGs and linked to protein core to get proteoglycans)

*high water content resists compression (binds water tightly thus flexible)

*adhesive glycoproteins binds cells with components of the matrix

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Matrix defines the cartilage

Back 7

fibres:

most cartilage rich in collagen type II

*componentes and proportions vary btw cartilage types, determine characteristics

Front 8

Matrix defines the cartilage

Back 8

cells

chondrocytes in lacunae within the matrix

fxn: to produce , maintain fibres, and organic components of the GS (will produce adhesive glycoproteins, the PGs, collagen fibres or elastic fibres)

if chondrocytes die than matrix will degenerate and cartilage will die as well

Front 9

Perichondrium and Cartilage

Back 9

perichondrium

is dense irregular CT, has collagen type I, forms sheet

has BVs, Ns, Ls (if you rip cartilage, it will hurt as it has nerves)

*fxn: in cartilage growth and attachment (attach cartilage to bone)

consists of 2 layers:

1. outer fibrous layer

2. inner cellular layer

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Perichondrium and Cartilage

Back 10

1.Outer fibrous layer:

contains mainly collagen fibres and fibroblasts

*fibroblasts produce collagen and when they mature they are fibrocytes

Front 11

Perichondrium and Cartilage

Back 11

2.inner cellular layer:

contains chondroblasts: synthesize the organic components of the matrix

(synthesize collagen type II on surfaceof cartilage and synthesize HAs and PGs)

also contributes to cartilage growth thus decreases prominence with maturity

Front 12

Layout of perichondrium and cartilage

Back 12

Outer: perichondrium

chondrocytes in lacunae of matrix

cartilage

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Formation of Cartilage

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A. Cartilage develops from condensations of embryonic mesenchyme

B. mesenchymal cells differentiate into chondroblasts, which secrete the organic components of the matrix

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Formation of cartilage

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C. chondroblasts ultimately surround themselves with matrix thus becoming isolated in their lacunae

D. these chondroblasts may divide, thus causing the cartilage to grow from within in a process called interstitial growth (4 per lacunae)

isolated chondroblasts become quiescent, maintain matrix as chondrocytes (mature)

Front 15

Interstitial growth of Cartilage

Back 15

chondrocyte undergoes division within a lacuna surrounded by cartilage matrix

As daughter cells secrete additional matrix, they move apart, expanding cartilage from within

*The cartilage expands from within as chondrocytes in the matrix divide, grow and produce new matrix

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Appositional growth of cartilage

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1. mesenchymal cells at the surface of the newly formed cartilage differentiate into fibroblasts, which form the fibrous layer of the perichondrium

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appositional growth of cartilage

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2. mesenchymal cells deep to this fibrous layer differentiate into chondroblasts forming the cellular layer of the perichondrium (cellular layer below fibrous layer)

These cells secrete matrix onto the surface of the newly cartilage in a process called appositional growth (relating to thickness of cartilage)

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Types of Cartilage

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3a) Hyaline cartilage

3b) elastic cartilage

3c)Fibrocartilage

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3a) Hyaline cartilage

Back 19

* most common and weakest cartilage

closely packed collagen type II fibrils in a firm gel-like GS

Front 20

Hyaline cartilage

Back 20

articular cartilage (found on ends of bonds of joint)-->there is no perichondrium for this type as two surfaces are rubbing against each other so you don't want BVs, Ns or lymph to rub against each other

tracheal rings, costal cartilage, immature skeleton, nasal cartilage

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Hyaline cartilage

Back 21

fxn: resists compression; provides tough, flexible support; reduces friction btw bony surfaces in articulations ( smooth surface as 2 surfaces are moving together so two articulating ends of knees can move in friction free manner)

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3b) Elastic Cartilage

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like hyaline, but with higher proportion of elastic fibres (going to snap back to original shape)

pinna of external ear, epiglottis, pharyngotympanic tube

epiglottis= flap that covers trachea when swalloing and then snaps back

fxn: provides greater flexibility and resiliency e.g.: it bounces back

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3c) Fibrocartilage

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little GS; high proportion of densely interwoven collagen type I fibres arranged in perpendicular arrays

* intermediate in strength btw hyaline C and dense regular CT (flexible like cartilage but also able to resist tensile forces)

* chondrocytes arranged in rows btw bundles of collagen type I fibres (like fibrocytes but rounder and less oval)

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Fibrocartilage

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*anulus fibrosis of intervertbral disks, pubic symphysis , intra-articular disks, tendon & ligament insertions (resist pull like tendon, and compression like cartilage)

intra-articular disks= inside knee

fxn: resists both compression & tension