Transcript Connective Tissue

WHERE AM I?
Online Anatomy Module 1
INTRO & TERMS
CELL
EPITHELIUM
CONNECTIVE TISSUE
MUSCLE
NERVOUS SYSTEM
AXIAL SKELETON
APPENDICULAR SKELETON
MUSCLES
EMBRYOLOGY
SOFT CONNECTIVE TISSUES
The ‘soft’ distinction being made here is between cartilage and bone
as firm connective tissues and the softer ones, such as fatty tissue,
ligament, dermis of skin, etc.
Articular cartilage
Dermis
Marrow
Hypodermis
Bone
Joint capsule
Ligament &
Periosteum
Tendon
Text reading in Marieb is pp. 79-82
Muscle
SMALL-GUT CONNECTIVE TISSUE ROLES
VILLI covered with simple
columnar epithelium on a core
of very loose-textured CT
Extensive area of fairly loosetextured CT holding the lining
to the muscle of the wall
Another layer of connective tissue
outside and assisting the muscle
by carrying vessels, nerves, and
just holding things together
GUT VILLUS
transport
Simple Columnar Epithelium
absorbing ENTEROCYTES
mucus-secreting
GOBLET CELLS
BASAL LAMINA
{
VILLUS CORE of:
loose connective tissue
C T cells
lymphatic capillary
capillaries
CONNECTIVE TISSUE ROLES I
Connect/Support
Transport/Nourish
EPITHELIUM
}
Connective tissue
VESSEL
The connective tissue under an epithelium is termed the
LAMINA PROPRIA (adjacent layer). Where it is more
intermingled with epithelial cells, as in a gland, it
becomes the STROMA.
THE CELL: Some basics IV
Cells do not operate in isolation. They have surroundings
and attachments - to other cells and materials outside them
Surface specializations of the plasmalemma
to interact with tube content
Cell-cell attachments more specializations of
the plasmalemma or
‘cell membrane’
Attachments to
materials outside the
cell in the EXTRACELLULAR MATRIX
THE CELL: Some basics V
The cells shown here form a single layer. It holds this form in part
by the cells’ fastening at the base to a sticky porous membrane
named a BASAL LAMINA or a BASEMENT MEMBRANE
Basement membrane
Basement membrane
itself attaches to
connective tssue
below it
THE CELL: Some basics VI
Cell are soft and squishy. Think jellyfish - it needs water to
support it. To holds us together & for life on land and the
ability to move and manipulate things, we need a strong , in
place rigid, extracellular matrix.
Cells of the soft
connective tissues ,
cartilage, and bone
make materials that
interact outside the
cells to provide
strength and support
via
EXTRA-CELLULAR
MATRIX (ECM)
CONNECTIVE TISSUE MATERIALS
Cells of the soft connective tissues make materials that
interact outside the cells to provide strength and support
One very special product is the
basement membrane to
support epithelial cells
The bulk of the connective-tissue matrix comprises:
bound water, meaning that it does not slosh as you move
molecules to bind the water and hold other components together
long fibers to give strength and elasticity to the tissue
other sticky molecules - glycoproteins - to hold the fibers in place
CONNECTIVE TISSUE MATERIALS: Details
bound water
molecules to bind the water - PROTEOGLYCANS
long fibers - COLLAGEN (strength) & ELASTIC
other sticky molecules - GLYCOPROTEINS
MORE CONNECTIVE TISSUE ROLES
While the matrix properties allow the tissue to support
& connect , other things are going on.
The matrix offers an ideal place for microorganisms
to grow, so that connective tissues have a range of
defensive cells and are a battle-ground of great
medical significance
The matrix stores a number of useful materials,
including ones to help control defensive reactions and
adjacent tissues. And a special cell - the fat cell/
adipocyte - stores fats/lipids for energy & growth
Connective tissue readily repair themselves &
react to damage to other tissues
CONNECTIVE TISSUE ROLES
Connect/Support
Transport/Nourish
Defend
Storage
Control
EPITHELIUM
}
Connective tissue
VESSEL
Repair
CONNECTIVE TISSUE COMPONENTS
Synthetic cells
signals
for structural
macromolecules, e.g.
for building
fibers
collagen
elastic
Defensive cells
Cells lie in, attach to, & are supported
by the EXTRACELLULAR MATRIX
(ECM) of fibers & ‘ground substances’
DEFENSIVE CONNECTIVE TISSUE CELLS
The matrix offers an ideal place for microorganisms
to grow (food, warmth) so connective tissues have a
range of defensive cells, and are a battle-ground of
great medical significance
MACROPHAGE (MF) eats dead & bad stuff;
coordinates defense
PLASMA CELL (from B Lymphocyte)
makes & secretes antibodies (Igs)
MAST CELL triggers defensive reaction/
inflammation (degranulates)
MACROPHAGE (MF)
lysosomes
PLASMA CELL
MAST CELL
Golgi
much GER
Cartwheel
nucleus [Peripheral clumps of
heterochromatin]
Big
granules
MACROPHAGE Mf
POD
Macrophage can:
attach to fibers;
release & crawl around;
extend projections - podia;
recognize bad things;
wrap its podia around them;
eat the stuff (phagocytosis);
digest it with lysosomes
MACROPHAGE MF
Collagen
fiber
FOCAL ADHESION - attachment
lysosome
-POD
Actin monomers & filaments
in controlled flux for crawling,
podia-extension, & phagocytosis
MACROPHAGE /MF receptors
Pathway for phagocytosis & lysosomal digestion
lysosome
POD
Membrane scavenger
receptors to recognize targets
CONTEXT FOR MAST CELL ACTIONS
Invader
EPITHELIUM
}
CT
VESSEL
Defensive white blood cells
& chemicals in vessel need
to get out to counteract the
invader
MAST CELL
Triggered by invader
Releases granules
Granule agents act on
vessels & white blood
cells to encourage exit
MAST CELL
MAST-CELL ACTIVATION
IgE antibody molecules
Fce Receptor for a region of
the Ig molecule
Invader
IgE binding triggers
degranulation
IgE binding triggers
degranulation
MAST-CELL ACTIONS I
Granules contain many agents (&
proteoglycans), e.g.
HISTAMINE to increase
permeability & loosen wall
MAST CELL
CHEMOKINES to attract
leukocytes out into CT
of Vessel
MAST-CELL ACTIONS II
Heparin & proteoglycans
influence signaling
MAST CELL
Chemokine receptors
White
blood cell
Vessel
Defensive blood chemicals,
e.g., Complement
CONNECTIVE-TISSUE CELLS: TWO MORE TYPES
MACROPHAGE (MF)
lysosomes
PLASMA CELL
MAST CELL
Fibroblast is an elongated cell
amidst the fibers etc it has made
Golgi
much GER
Cartwheel
nucleus [Peripheral clumps of
heterochromatin]
ADIPOCYTE
FIBROBLAST
Big
granules
Adipocyte/ fat cell grows to be very large, with a
thin shell of cytoplasm around a huge fat droplet
fat droplet
COLLAGEN - Molecule to Fiber
Collagen I trimer
Three intertwined
helices
Last of the spinning.
Hereafter, strength comes
from cross-linking &
glueing
“Glueing” & control of fibril &
fiber width are done by high-#
collagens, glycoproteins, and
proteoglycans
Assembly of trimers end-to-end,
side-by-side, but staggered to
build a cross-banded fibril
Further glueing of
fibrils to make a FIBER
CONNECTIVE TISSUES
ROLES
CELLS
EC MATRIX
WORKING
CONTEXTS
TYPES
CONNECTIVE-TISSUE CELLS
FIBROBLAST
MACROPHAGE (MF)
lysosomes
PLASMA CELL
MAST CELL
Golgi
much GER
Cartwheel
nucleus [Peripheral clumps of
heterochromatin]
ADIPOCYTE
One huge fat droplet
Big
granules
ROLES OF CONNECTIVE-TISSUE CELLS
FIBROBLAST makes ECM; destroys ECM
MACROPHAGE (MF) eats dead & bad stuff;
coordinates defense
PLASMA CELL (from B Lymphocyte)
makes & secretes antibodies (Igs)
MAST CELL triggers defensive reaction/
inflammation (degranulates)
ADIPOCYTE stores & releases ‘energy’ (&
brown adipocytes can make heat)
ROLES OF CONNECTIVE-TISSUE CELLS
FIBROBLAST
MACROPHAGE (MF)
PLASMA CELL)
MAST CELL
ADIPOCYTE
CONNECTIVE TISSUE COMPONENTS: Cells & ECM
Fibroblast
Osteoblast
Chondroblast
synthetic
Macrophage
Plasma cell
Lymphocyte
Mast cell
defensive
Fat cell or
Adipocyte
storage
Structural &
other ECM
molecules
What are these?
CONNECTIVE TISSUE COMPONENTS: Cells & ECM
Collagen
Fibroblast
synthetic
FIBERS Reticular
Structural &
other ECM
molecules
Fibroblasts rework the matrix
that they have formed by
carefully breaking it down, while
synthesizing new materials to
adapt to greater or otherwise
changed loads
Elastic
BINDERS &
CONTROLLERS:
Sticky glycoproteins
Water-binding
proteoglycans
Destructive enzymes
Enzyme inhibitors
Signaling Molecules
CONNECTIVE TISSUE ‘GROUND SUBSTANCE’
Collagen
FIBERS Reticular
Fibroblast
Structural &
other ECM
molecules
‘Ground substance’ is
the old-fashioned name
for the non-fiber
extracellular part of
connective tissue
Elastic
BINDERS &
CONTROLLERS:
Sticky glycoproteins
Water-binding
proteoglycans
Destructive enzymes
Enzyme inhibitors
Signaling Molecules
CONNECTIVE T. COMPONENTS: Reticular fibers
Fibroblast
synthetic
Structural &
other ECM
molecules
Collagen
FIBERS Reticular
Elastic
Reticular fibers are a delicate version of collagen
fibers, used so as to support cells, but not
interfere with blood-cell interactions, e.g., in liver
Reticular fibers
HEPATOCYTES
Endothelial cells
lining vessel
blood vessel
blood
TYPES OF CONNECTIVE TISSUE
Around the body different combinations of these
cells, fibers, and other ECM materials are needed
The starting embryonic tissue is mesenchyme - jellylike, with a few thin fibers and unspecialized
mesenchymal cells
As the mesenchymal cells become fibroblasts, these
can make the tissue, by fiber packing, loose or dense
The fibroblasts may align the fibers parallel to make a
regular tissue ,or arrange them in different
orientations - an irregular tissue
Elsewhere, mesenchymal cells may become fat cells
making an adipose tissue
The tissue requirements also vary when the tissue is
somatic (in body wall or limb) rather than visceral
TYPES OF CONNECTIVE TISSUE
SOMATIC
VISCERAL
Loose irregular
Loose irregular
Dense irregular
Dense irregular
Reticular
Reticular
Adipose
Adipose
Elastic
Elastic
Dense regular
In the beginning was Mesenchyme
MESENCHYME
Mesenchymal cells,
mostly synthetic for
signals
structural
macromolecules, e.g. for
building
fibers immature
collagen
Much ground substance
e.g., hyaluronan (a GAG)
Mesenchymal cells - precursors/ progenitors of
some differentiated CT cells, e.g., fibroblasts
Mesenchyme takes up & commits space to be a
future connective tissue, and has modest jellylike mechanical properties of its own
CONNECTIVE TISSUES: Contexts
Tube Man
Head modification of
body wall +
brain & special
senses + start
of two tubes
Worm Woman
re
Al
Soma - body
wall & the limbs - - - Viscera
tubes, modified
o
tubes, &
accessory
organs
cvl
- -
u
diaphragm
SOMATIC STRUCTURES
Articular cartilage
Dermis
Marrow
Hypodermis
Bone
Joint capsule
Ligament &
Tendon
Periosteum
Muscle
SOMATIC CONNECTIVE TISSUES: Dense regular
Ligament &
Tendon dense regular
Muscle
DENSE REGULAR CONNECTIVE TISSUE
{
Bundles of
thick collagen I
fibers
{
Elongated fibroblasts
Looser vascular CT
between the bundles
DENSE REGULAR CONNECTIVE TISSUE: Tendon
{
Bundles of
thick collagen I
fibers
{
Elongated fibroblasts - tenocytes
Looser vascular CT
between the bundles endotendinuem
If the tissue is in a tendon, some special names
(not to be learned) are used
SOMATIC CONNECTIVE TISSUES: Reticular & Adipose
Marrow reticular
Hypodermis
adipose
Muscle
WHITE ADIPOSE TISSUE
Capillary
Adipocyte
Reticular
fibers
Fat cell
CONNECTIVE TISSUE - Mechanical functions
The stringy strength of collagen allows a
variety of mechanical actions
Supporting - ligament
Binding - ligament
Restraining - ligament
Directing - tendon
Separating - fascia
For firmer support something has to be added to the
collagen to make cartilage or bone
The large soft cells of adipose tissue can be confined in
sheets of collagenous tissue for
Padding - fat pad
SOMATIC CONNECTIVE TISSUES: Dense irregular
The collagen fibers are arranged
in various directions for different
pulls on the tissue
Dermis dense irregular
Periosteum
dense irregular
Joint capsule dense irregular
Muscle
SOMATIC CONNECTIVE TISSUES: Loose irregular
marks loose irregular filling in between more solid
structures & allowing them
freedom of movement
Muscle
TYPES OF CONNECTIVE TISSUE
SOMATIC
Loose irregular (Areolar)
between more solid structures
Dense irregular
joint capsule, periosteum, dermis
Dense regular
tendon, ligament
Adipose
hypodermis
Elastic
elastic ligament
(inconspicuous in man)
SOMATIC CONNECTIVE TISSUES
Articular cartilage (hyaline)
loose irregular
Dermis dense irregular
Marrow reticular
Hypodermis
adipose
Bone
Joint capsule dense irregular
Ligament &
Tendon dense regular
Muscle
Periosteum
dense irregular
TYPES OF CONNECTIVE TISSUE
VISCERAL
Loose irregular
Dense irregular
Reticular
Adipose
Elastic
In the beginning was Mesenchyme
Tube Man
Worm Woman
re
Al
Liver
processes blood
drained from the
GI tract
- - - -
cvl
- -
u
diaphragm
Visceral Connective Tissue 1 re
Al
Liver
- - - -
Reticular
cvl
- - u
e.g., in liver, spleen, kidney
diaphragm
processes
blood drained
from the GI
tract
Reticular fibers
HEPATOCYTES
blood vessel
Macrophage
Endothelial
cells lining
vessel
Reticular fibers + Macrophages = Reticular
tissue
TYPICAL TUBULAR ORGAN
Visceral Connective Tissue 2 - Loose irregular
main working tissue Epithelium
inner service tissue Connective tissue
lumen
motility tissue Muscle
loose irregular ct with
vessels & nerves
outer service tissue Connective tissue
VISCERAL CONNECTIVE TISSUE
TYPES
AORTA
Elastic
re
ESOPHAGUS
Lamina propria
lumen
Al
Loose irregular
Adventitia
- - - -
LIVER
Reticular
cvl
- -
-
diaphragm
u
Kidney
CAPSULE
Dense
irregular
MESENTERY
Adipose
TYPES OF CONNECTIVE TISSUE
Loose irregular
lamina propria, tunica adventitia
VISCERAL
Dense irregular
organ capsules
Reticular
liver, spleen
Adipose
mesentery, pericardium
Elastic
lung, elastic arteries
have collagen fibers for strength, but
need much elasticity
CONNECTIVE TISSUE COMPONENTS: Cells & ECM
Fibroblast
Osteoblast
Chondroblast
synthetic
Collagen
Structural &
other
molecules
Macrophage
Plasma cell
Lymphocyte
Mast cell
defensive
Fat cell or
Adipocyte
storage
FIBERS Reticular
Elastic
BINDERS &
CONTROLLERS:
Sticky
glycoproteins
Water-binding
proteoglycans
Destructive
enzymes
Enzyme
inhibitors Signaling
Molecules
CONNECTIVE TISSUE ROLES
Connect/Support
COMPARTMENTS
Transport/Nourish
Defend
Storage
LUMINAL
}
(EPITHELIAL)
}
INTERSTITIAL
connective tissue
VASCULAR
Control
nervous,
paracrine (local),
biochemical
Repair
EXTRACELLULAR MATRIX ECM
What cells produce and organize outside theselves
allows them to construct huge organisms, with complex
repertoires of movements & behaviors, and multiple
physiologies based on separate compartments
Tight junctions
}
LUMINAL
} (EPITHELIAL)
}
INTERSTITIAL
connective tissue
VASCULAR
EXTRACELLULAR MATRIX ECM 2
Cells create and achieve control over their environment by
synthesizing combinations of types of macromolecule which
interact outside the cells
Learn the requirement, not the particular molecules meeting it
Over water (why you don’t slosh as you
walk)
Why you can swallow, wink, spit, etc
Hyaluronan
Large
proteoglycans
Mucin glycoproteins
(epithelial products)
Creation of barriers
- Basal laminae Laminin, Collagen IV
Perlecan (a heparan
sulfate proteoglycan)
- Connective tissue ground substance Fibronectin Tenascin
Attachment & support
Collagen fibrils & fibers (I &
III) + associated molecules
BASAL LAMINA CONSTRUCTION a sticky hedge
Learn the requirement, not the particular molecules meeting it
Epithelial-cell attachments to laminin
Interwoven networks of LAMININ & COLLAGEN IV
attached by Nidogen/Entactin
Basal-lamina Proteoglycan molecules attached to
the lattice , e.g., Perlecan
Generally
LAMININ
PERLECAN
‘IN’ ending - glycoprotein
‘AN’ ending - proteoglycan
Heparin - a glycosaminoglycan - is an exception
EXTRACELLULAR MATRIX ECM 3
Cells create and achieve control over their environment by
synthesizing combinations of types of macromolecule which
interact outside the cells
Elastic fibers &
Elastic recovery of shape & elastic
laminae
storage of the work of the heart &
Elastin & fibrillin
respiratory muscles
Resilient firmness in joint, airway,
& fetal-skeletal cartilages
Resilient hardness of bone
Cartilage collagens II & IX
aggregated proteoglycans
link proteins & hyaluronan
cartilage glycoproteins
Collagens I & XII
bone proteoglycans
bone glycoproteins
mineral crystals
Again, learn the requirement, not the particular molecules meeting it
EXTRACELLULAR MOLECULAR INTERACTIONS 1
Further assembly of the molecules to make larger &
eventually ‘visible’ structures, such as fibrils
Modification of the molecules, e.g., cross-linking, to make
them resistant to digestion
Deliberate breakdown of the molecules by the forming cells
for turnover and renewal, by proteases & other enzymes
Controlled breakdown, with more synthesis & assembly,
provides for remodeling & adaptation of ECM, e.g., to a
heavier load in tendon or cartilage
Some of these enzymes, e.g. collagenase, include a zinc atom
& require Ca2+ to work - hence Matrix Metalloproteinases, e.g.
MMP-3
Some of these enzymes, e.g. collagenase, include a zinc
atom & require Ca2+ to work - hence Matrix
Metalloproteinases, e.g. MMP-3
The inhibitors of these enzymes go under the abbreviation
TIMPs - Tissue Inhibitors of MMPs; & are also made by
fibroblasts & other matrix-influencing cells
ECM MOLECULAR INTERACTIONS - Pathology 1
Unintended degradation by enzymes released from cells,
e.g., leukocytes, engaged in defensive reactions.
ECM is the battleground for defenses initially targeted at
microorganisms.
“--itises” occur throughout the body, & are real hazards to
comfort & life, e.g., endocarditis weakens & distorts heart
valves & thus can kill
ECM MOLECULAR INTERACTIONS - Pathology 2
Unwanted degradation by bystander inclusion in cytokine
signaling pathways of defensive cells
IL-1
MF
IL-1
Articular
chondrocytes
Lymphocytes of inner joint synovium
Joint cartilage cells also
respond to the signal:
enzymes
enzyme inhibitors
proteoglycans
= an inappropriate response causing cartilage matrix
destruction - ARTHRITIS
IL-1 Interleukin-1 a typical cytokine
ECM MOLECULAR INTERACTIONS - Pathology 3
Unwanted degradation by:
microbes trying to colonize, e.g., using bacterial hyaluronidase
to liquify ground substance
metastasizing cancer cells breaking through basal laminae
& connective tissues to get into the blood or lymph streams
Unwanted synthesis - the formation of excess collagen,
clogging organs with delicate blood-cell relations.
Cytokines released by activated macrophages trigger
synthesis in fibroblasts, causing cirrhosis in the liver and
fibrosis in kidney, lung, marrow, etc
Bad assembly - genetically defective fibrillin makes an
inadequate scaffold for elastin deposition
weak aorta,
slack connective tissues, etc, of Marfan’s syndrome
This balance is
significant
matrix
cells
Thus, loose connective tissues have less matrix
materials (except for water) and more cells than
dense ones, because the looser textured matrix
is more favorable to the growth of
microorganisms, and hence needs more
defensive cells: dense tendon needs far fewer.
Adipose tissue is mostly the very large fat cells.
WHERE AM I?
Online Anatomy Module 1
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