Connetive Tissues

Lecturer: Dr MC Selala
Office: Room 336 NSB
Email: callies.selala@smu.ac.za
Types of Epithelial tissues
 Tissues.
• Four primary types: Epithelia,
Muscular, Connective and
Nervous.

• Functions of epithelia tissues:

Protection, while columnar helps
in secretion, absorption, filtration
and also lining of air passages and
lung cavities.
Dr Selala MC
3rd Floor RM336
columnar helps in secretion, absorption, filtration and also lining of air
passages and lung cavities
Characteristics of Epithelia
Tissues.
• Contiguous: Attached to one
another.
• Presence of basement membrane.
• Replacement of tissues by
mitosis.
• Presence of specific polarity.
• They are all avascular: No
penetration of blood vessels.
 Specializations.
• Apical Surface:
– Cilia: Assist to cover the entire apical
surface. They beat in waves, and moves
trapped materials. Ciliated pseudo
stratified columnar (respiratory).
– Flagella: For movement. Spermatozoa.
– Microvilli: Numerous parallel acting
microfilaments. When interact with
cytoplasmic myosin they can contract and
reduce the size of the microvilli.
 Glandular Epithelia
• Prod and secr of specialized substances
e.g. prot, hormones & water
• Classified by mode, type and structure of
the gland secretions.
• Mode:
– Merocrine: Released by exocytosis
– Porcine:. Secretion by pinching off of vesicles
and cytoplasm from cells
– Holocrine: Entire cell burst to release its
secretion.
 Specializations of the lateral
surfaces.
• They attach to each other by intercellular
junctions.
1. Zonula Occludens: Seal off the intercellular
spaces thereby isolating certain body
compartments. Scaf prot/struc for multiprot
2. Zonula adherens: Basal to the tight junctions.
3. Macula: 2 dense granular attachment with
several proteins –desmosome stud like struc.
4. Gap Junction: Disk or patch shaped structure.
• Type: Exocrine glands.
– Serous: secretion of a watery solution
– Mucous: mucin protein and water
– Mixed: both mucous and serous.

Gland Structure:
Unicellular and Multicellular.
Specialization of the Basal Surface.
1. It consists of the basal lamina:
Sheet like structure which helps to bind cells
to the basal shape. It aids in tissue lamina. It
is a sieve like barrier. Helps to maintain cells
organization and cell adhesion.
2. Hemidesmosomes: Located in the inner
surface of basal plasma membranes. Attach
epithelia cells to the basal lamina.
3. Sodium – potassium ATPase: Membrane
bound by enzymes. Transports sodium out
and potassium into the cell.
 Classification of Epithelia.
• Simple Squamous:
Closely packed and flat, several cornered
cells which may be ovoid or flat.
Single layer and resembles tiles on floor.
Allows rapid exchange by diffusion or
filtration.
Find in the lining of blood and lymph
vessels and airsacs of the lungs.
Types of Epithelial tissues
 Classification Contd.
• Stratified Squamous:
More than one layer cells.

Found in areas where mechanical stress

are severe. Mouth, vagina and etc.

The main function is for protection.

 Simple Cuboidal Epithelium.
• Close fitting single layered cells.

They assist in secretion, filtration and

absorption.

Found in many glands, kidney tubules and

bronchioles of the lungs.
 Stratified Cuboidal Epithelium
• More than one layer of cells
• Found in the ducts of sweat glands,
conjunctiva of the eye and the female
urethra.
• Transitional Epithelium.
Cube shaped cells with large surface cells.
Located in the urinary tracts. It assists in
distension.
Simple Columnar Epithelium.
Lining of the most digestive tract.
They helps in protection, secretion and absorption.
. Stratified Columnar Epithelium.
More than one layer of cells. Found in the
pharynx and urethra.
Pseudostratified Columnar Epithelium.
One layer of cells, though it looks so many.
Found in trachea helps to trap and move
pollutants to the mouth.
 Connective Tissues.
• Functions: Binding, Support,
immunologic protection, transporting
fluids and storage.

• Types: Loose and Dense Collagenous

Tissue, Reticular Connective Tissue,
Elastic Connective Tissue.

• Main Components: Cells, Fibres and

Ground Substances.
 Characteristics of Connective
Tissues.
• Composed of fibers and a matrix of
proteins.
• Fibers provide support and flexibility.
• Cellular components provide support
• Intercellular substance appears in solid
and liquid states.
• Regenerates and repairs using new fibres
and matrix.
 Classification of CT.
• Connective Tissue Proper: Cells and
Fibers in a fluid matrix. –areolar &
dense CNT

• Fluid Connective Tissue: Cells in a

watery matrix.

• Supporting Connective Tissue: Fewer

cells in a very fibrous matrix.
 CT PROPER.
Cell Types: Fixed or wander.
• Fibroblast: Fixed cell that secrets fibre.
• Fixed Macrophages: Immune system cells
which phagocytose microorganism.
• Adipocytes: Fixed flat cells which store
lipids
• Mesenchyma Cells: Fixed cells capable of
dividing.
 CT Proper. Cell Types
• Melanocytes: Fixed cells that store
melanin.
• Free Macrophages: Wander cells, helps in
phagocytosin.
• Mast Cells: Small, wandering cells which
store histamine (immune sys releases e.g.
allergy) and heparin (anticoagulant).
• Lymphocytes: wandering immune system
cells.
 CT FIBERS CTD.
• Reticular Fibers: Like collagen fibers but thinner
and more highly glycosylated. They acts as
supportive lattices that allow motile cells to
move. They have mainly type 5 collagen.

• Elastic Fibers: Consist of amorphous protein

called elastin and numerous protein. They are
pliable and elastic found where mechanical
properties are needed for expansion of tissues
 Fibers of CT
Collagen Fibers: Most abundant protein in the
body.
Types:
Type 1: Most abundant and widespread. Occurs in
tendon, ligaments, bone and etc
Type 2: Found in adults only in the cartilage.
Type 3: Similar to 1 but heavily glycosylated and
stain with silver.
Type 4: Occur mostly in basal laminae.
Type 5: Present in placental basement
membranes and blood vessels.
 CT Ground Substance
Consist of water and glycoproteins.
Proteoglycans:Structure include a core protein
and carbohydrate chains.

Glycoprotein: Protein attached to a short

oligosaccharide chains. Smaller than
proteoglycans. Examples include Fibroconectin
which mediates the attachment of cells to the
extra cellular matrix.
 Types of CT.
• Mucous CT: Loose CT found in the umbilical
cord.

• Loose Areolar CT: Contains fibers.

Several cell types
Fluid filled spaces between fibers
Occurs in the subcutaneous layer of skin
Surrounds organs and supports nerves
Provide strength, elasticity and support.
 Types of CT contd.
• ADIPOSE Tissue: Full of adipocytes.
Distributed throughout the body.
Large cells with a single vacuole that
contains fat droplet.
Supply of energy, assist in cushion of joints
and shocks and insulation.
 CT Types ctd
Reticular Tissue: Full of reticular fibers.
Present in the liver and the spleen.
Consist of several interlacing reticular fibers.
Forms part of bone marrow that makes
RBC.
Forms reticular lamina of the basement
membrane.
Bind smooth muscles cells together.
(Killer cells, B cells, T cells)
 CT CONTD.
• Dense Regular CT: Composed of white
collagen fibers and yellow elastic fibers.
They provide strength to tissues.
Tendons: joins muscle to bone.
Ligaments: bone to bone
Elastic tissues: Found in blood vessels
walls.
 CT CONTD.
• Dense Irregular CT: Composed mainly of
irregularly arranged white collagen fibers
and yellow elastic fibers.

• FLUID CT: Blood and Lymph.

• SUPPORTING CT: Cartilage and Bone.

 CARTILAGE.
Hyaline: Tough and flexible. It covers the
end of bones.
Contains fibers and ground substances.

Elastic: Resistant and flexible. Ear

Fibro Cartilage: Durable and tough: Found

between vertebrae
“loose collagen fibers, water and proteins”
 Intervertebral disc and pubic Symphysis

An intervertebral fibrocartilage disc lies between adjacent vertebrae in the

vertebral column
Tough circular exterior of the intervertebral disc that surrounds the soft inner
core, the nucleus pulposus
 BONE
• Osseous connective tissue. Bone cells within a
solid matrix. Collagenous fibers surrounded by
hydroxyapatite.
• Types of bone cells
Osteocytes: mature bone cells, found in areas
called lacunae located btw layers of matrix
called laminae.
Osteoblasts: Cells that give rise to new bones
Osteoclasts: Dissolve bony matrix and released
stored Ca and PO4.
Bone lining cells: repair surfaces of bone
removing nonmineralized collagen fibrils through
matrix metalloproteinases.
 Parts of a Long Bone
• Epiphysis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Epiphyseal plates
• Distal Articular cartilage

• Proximal Spongy bone

Proximal
epiphysis

• Diaphysis Space containing

• Metaphysis red marrow

• Compact bone Endosteum

• Spongy bone
Compact bone

Medullary cavity

• Articular cartilage Yellow marrow

• Periosteum Periosteum Diaphysis

• Endosteum
• Medullary cavity
• Trabeculae
• Bone marrow
• Red marrow and yellow marrow

Distal
epiphysis
50
Femur
 Compact and spongy bone
• Compact Bone: Dense bone, forms the wall of the
shaft or diaphysis of long bones. Carries the wt. The
functional unit is the osteon or Havasian System.

Osteocytes: surround a central canal that has blood

vessels and nerves. Inside lacunae btw rings of
calcified matrix known as lamellae.

Lacunae separated by a matrix of collagen fibers and

mineral deposits primarily calcium and phosphate
salts.

They receive nutrients thru canaliculi, perforated

canals enter the bone from the exterior and connect
vessels and nerves with the central canal.
 Compact Bone
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• Osteon Osteon

aka Haversian System Endosteum

Central canal
containing blood

• Central canal
vessels and nerves

• Perforating canal aka

Periosteum
Nerve

Volkmann’s canal Blood Pores

Central
vessels canal

• Osteocytes
Perforating
canal
Compact Nerve

• Lamellae
bone
Blood
vessels

• Lacunae Nerve

• Bone matrix Trabeculae

Bone matrix

• Canaliculi Canaliculus

Osteocyte

Lacuna
(space)

52
 Spongy bone
• Contain numerous bony bars and plates
separated by irregular spaces.
• Longer than compact bone and can give
strength.
• Solid portion follow lines of stress.
• Spaces filled with red bone marrow
(produces blood cells).
 Parts of a Long Bone
• Epiphysis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Epiphyseal plates
• Distal Articular cartilage

• Proximal Spongy bone

Proximal
epiphysis

• Diaphysis Space containing

• Metaphysis red marrow

• Compact bone Endosteum

• Spongy bone
Compact bone

Medullary cavity

• Articular cartilage Yellow marrow

• Periosteum Periosteum Diaphysis

• Endosteum
• Medullary cavity
• Trabeculae
• Bone marrow
• Red marrow and yellow marrow

Distal
epiphysis
54
Femur
 Microscopic Anatomy of Bone
 Lacunae
 Cavities containing
bone cells
(osteocytes)
 Arranged in
concentric rings
 Lamellae
 Rings around the
central canal
 Sites of lacunae Figure 5.3

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

 Microscopic Anatomy of Bone

 Canaliculi
 Tiny canals
 Radiate from the
central canal to
lacunae
 Form a transport
system
Figure 5.3

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide

 Spongy Bone
• Spongy bone is aka cancellous bone
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Spongy
bone

Compact
bone

(a)
Remnant of Spongy bone Compact bone
epiphyseal plate
(b)

Spongy Compact
57
(c)
bone bone
a: © Ed Reschke; b,c: Courtesy of John W. Hole, Jr.
 Ossification.
• The development of bone.

• Two types: Intramembranous and

Endochondral.
 Intramembranous.
• Development within a fibrous CT.
• Occurs in bones of skull, lower jaw and clavicle.
• Oestoblasts cluster together and secret matrix
• Growth continues from the centre outwards
towards the membrane
• It is possible bcos at birth membrane are still
fibrous and the skull is very plastic during birth
process.
 ENDOCHONDRAL
• Conversion of cartilaginous models to bone.
• Devt within hyaline cartilage
• Occurs in all other bones of the body
• At initial stage skeleton contains hyaline
cartilage
• Blood vessels penetrates the perichondrium and
converts the cartilage cells to osteoblasts. Forms
primary Ossification
 Endo contd
• Blood vessels grows towards the epiphyses and
causes more bone formation and devt of marrow
cavity.

• At birth blood vessels penetrates the epiphyses

and causes secondary devt. And later converted
to bone.

• Cartilage btw the epiphysis and diaphysis

becomes epiphyseal cartilage and continues to
grow.
 Bone Classification
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• Bone Classification: (b)

• Long Bones
• Short Bones
• Sesamoid Bones
• Flat Bones
• Irregular Bones (c)
• Wormian Bones
(sutural)
(d)

63
(a) (e)
 Endochondral Ossification
• Hyaline cartilage model • Epiphyseal plate
• Primary ossification center • Osteoblasts vs. osteoclasts
• Secondary ossification centers
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Articular
Remnants of cartilage
Secondary epiphyseal
ossification plates
Cartilaginous Developing Compact bone center
model periosteum developing Spongy
bone
Epiphyseal
plates

Blood
Medullary Medullary Medullary
vessel
cavity cavity cavity
Compact
bone
Remnant of
Epiphyseal epiphyseal
Calcified Primary plate plate
cartilage ossification Secondary Spongy
center ossification bone
center Articular
cartilage
(a) (b) (c) (d) (e) (f) 64
 Growth at the Epiphyseal Plate
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• First layer of cells Bone tissue

• Closest to the end of

of epiphysis

epiphysis 1 Zone of
resting

• Resting cells
cartilage

2 Zone of

• Anchors epiphyseal plate proliferating

cartilage

to epiphysis 3 Zone of
hypertrophic

• Zone of resting cartilage

cartilage

• Second layer of cells 4 Zone of

calcified

• Many rows of young

cartilage

Ossified
bone of
cells diaphysis

• Undergoing mitosis
• zone of proliferating
cartilage

(a) (b)
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
65
 Growth at the Epiphyseal Plate
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• Third layer of cells Bone tissue

• Older cells of epiphysis

• Left behind when new 1 Zone of

resting
cells appear cartilage

2 Zone of
• Cells enlarging and proliferating
cartilage

becoming calcified 3 Zone of

hypertrophic
• zone of hypertrophic cartilage

cartilage
• Fourth layer of cells 4 Zone of
calcified
cartilage

• Thin Ossified
bone of

• Dead cells diaphysis

• Calcified extracellular
matrix
• zone of calcified
cartilage
(a) (b)
b: © The McGraw-Hill Companies, Inc./Al Telser, photographer
66
 Endo……
• Rate of growth controlled by hormones
and continues until the disks become
ossified and growth stops.
• Bone absorbing cells (osteoclasts) break
down bone, remove worn cells and deposit
calcium in the blood.
• Destruction caused by osteoclasts is
repaired by osteoblasts after 3 wks.
• Osteoblasts takes calcium from blood.
Factors affecting bone formation
• Thickness of bones do change as a result
of replacement of old bone tissue.

• Physical use and hormone balance affects

thickness of bones.

• Adults seem to require more calcium in the

diet than do children in order to promote
the work of osteoblasts.