CONNECTIVE TISSUE Flashcards
What does connective tissue do?
connects various issues of the body and gives them support
Where does connective tissue develop from?
mesoderm and mesenchyme
What does connective tissue contain?
cells, fibers, ground substance
What are the cells that makeup the connective tissue?
fibroblast, adipose, macrophages, mast, undifferentiated mesenchyme, plasma, blood, pigment
Describe the fibroblast cells?
What is their role?
spindle shaped, round nucleus, basophilic cytoplasm
also called fibrocytes in resting stage
production and maintenance of fibres and ground substances
Describe adipose cells?
What is their role?
large lipid vacuole, thin cytoplasm, flat & periphery nucleus
cells singly or in groups
specialized for synthesis and storage of fats
Describe macrophages.
What is their role?
Fusiform, stellate or spheroidal in shape
phagocytotic in nature
cytoplasm contains granules and vacuoles
Describe Plasma cells.
What is their role?
cart wheel shaped nucleus
found: lamina propia in digestive and respiratory tract
lymphoid tissue
function: manufacture of antibodies, provides resistance to the body
Describe Mast cells.
What is their role?
connective tissue & along blood vessels
secretes histamine and serotonin
Describe undifferentiated mesenchymal cells
along blood vessels
precursor of all types of cells
Describe pigment cells.
melanocytes
epidermis of skin
protect skin from harmful effects of sun’s rays
Describe blood cells
lymphocytes and neurophils
migrated from blood stream
What are the three types of fibres?
Collagen, elastic, recticular
Where are collagen fibres found?
All types of connective tissue
What is one property of collagen fibres?
inelastic and great tensile strength
Describe the structure of collagen fbres?
made up of collagen
individual fibres are unbranched
fibres run in bundles, split into branches
each fiber contains fine subunits: tropocollagen
What are collagen fibres synthesized by?
fibroblast
What is used in the staining of collagen fibres and what colour are they stained?
fresh fibres- colourless
hematoxylin and eosin- pink stain
What are collagen fibres treated with and what is the result?
dilute acetic acid
swollen = gelatin
Type I collagen fibres?
thickest fibers, seen in bones, tendons, dermis of skin
Type II collagen fibres?
found in the cartilages, vitreous body of eye
Type III collagen fibres?
seen in spleen, lymph nodes, bone marrow, also called reticular fibers
Type IV collagen fibres?
seen the basement membrane
Type V collagen fibres?
fetal tissues, blood vessels
What is one property of elastin fibers?
Highly elastic, can stretch to up to 150% of their resting length
Where are elastin fibers found?
ligamentum nuchae, ligamentum flavum
walls of large arteries
What are elastin fibers synthesized by?
fibroblasts
Describe the structure of elastin fibers
contain protein elastin
can run individually, branched, anastome with each other
yellowish in groups
if broken ends will retract or recoil
What is used in the staining of elastin fibres and what colour are they stained?
hematoxylin and eosin- purple stain
What are collagen fibres treated with and what is the result?
boiled and treated with acetic acid however no change
What are reticular fibres and where are they found?
Type III collagen fibres
Found in spleen, liver, lymph nodes, bone marrow, thymus, endocrine glands
Describe the structure of reticular fibers.
Fine branching fibres form network- reticulum
What is used in the staining of recticular fibres and what colour are they stained?
silver staining methods
What is ground substance?
semisolid gel aka intercellular space
Describe the structure of ground substance.
cells and fibers embedded in it
consists of water, carbohydrates (mucopolysaccharides), proteins (glycoproteins)
What re the classifications of connective tissue?
Loose connective tissue
Dense connective tissue
What are the types of loose connective tissue?
areolar, adipose, myxomatous, reticular
What is areolar tissue?
contains bundles of collagen fibres and scattered individual elastic fibers
fibroblast cells are the most cells present
e.g. superficial fascia
What is adipose tissue?
cells with thin cytoplasm and peripheral nucleus
e.g mesentery
How does adipose tissue appear when stained?
Stained with hematoxylin and eosin fat cells appear empty as fat in lipid vacuole is dissolved during staining
What is myxomatous tissue?
fetal or embryonic type of tissue
contains ground substance, mucosubstances
fine meshwork of collagen fibres with fibroblasts
e.g. umbilical cord, virteous body of eyebal
What is reticular tissue?
type III collage tissue
network of reticular fibres
e.g spleen, liver, lymph node, thymus
What are the two types of dense connective tissue?
- regular dense
2. specialized dense
What is regular dense connective tissue?
tendons of muscles
collagen fibres arranged regularly in bundles of fibroblast cells
What is specialized dense connective tissue?
e.g. bones and cartilages
What are the functions of connective tissue?
- structural support
- compartmentalization
- defense and protection
- site for storage of fat
What is cartilage?
Specialized type of connective tissue
forms skeletal basis of auricle of ear & outer part of nose
can be bent, returns to original form when forced is removed
Composition of cartilage?
extracellular matrix & cells
matrix: ground substance + fibres
covered by perichondrium: 2 layers:
- outer fibrous layer (collagen)
- inner cellular layer (chondroblast)
What are the cells of the cartilage?
chondrocytes found in lacunae
young cells: chondroblast found in perichondrium
What is the ground substance?
semisolid gel containing polysaccharides and proteins
What are the classifications of cartilage?
Hyaline, Elastic, Fibrocartilage
What does the hyaline cartilage contain?
Examples?
cartilage cells, matrix, perichondrium
e.g trachea, thyroid and costal cartilage
What is the function of chondrocytes? How are they found?
located in spaces called lacunae
found in groups of 2-8 cells
produce matrix
What does the matrix contain?
collagen fibres and ground substance
collagen fibres not seen distinctly
What are the two matrices?
- Territorial matrix- around condrocytes, stains dark
2. Interteritorial matrix- everything else, stains light
What is elastic cartilage?
Example?
has elasticity and comes back to its natural state after being stretched
e.g auricle of ear
What does elastic tissue contain?
perichondrium
chondrocytes: singly or in small groups
matrix with branching elastic fibres
What does fibrocartilage contain?
Example?
no perichondrium
chondrocytes: singly arranged in rows
matrix with bundles of collagen fibres
e.g invertebral disc
Characteristics of Bones
- hard form of connective tissue
- highly vascular
- regenerative
- contains calcium phosphate in matrix
What are the functions of bones?
- structural support
- shape
- attachment of muscles
- levers for joints: locomotion
- protection of vital organs
- transmission if body weight
- erythropoiesis
What are the four classifications of bones?
- Position
- Shape, size & consistency
- Development
- Structure
How are bones classified according to position?
- Axial: forming axis e.g. vertebrae
2. Appendicular: bones of limb e.g. femur
How are bones classified according to shape, size and consistency?
- Long bones- 3 parts e.g femur
- Short bones- small and cubodial e.g. carpals
- Flat bones- expanded and flat e.g sternum
- Irregular bones- irregular shape no proper outline e.g vertebrae
- Pneumatic bones- hollow air spaces (sinus) e.g. maxilla
- Sesamoid bones- develop within tendon where it crosses the end of long bones e.g. patella
How are bones classified according to development?
- Membranous: developed from membrane formed by mesenchymal tissue e.g. clavicle, most bones of skull
- Cartilaginous: mesenchymal tissue transformed into cartilage which transforms into a bone e.g femur
How are bones arranged according to structure?
- Compact bones (lamellar): bony plates arranged compactly e.g shaft of long bones
- Spongy bones (cancellous): bony plates arranged irregularly e.g ends of long and flat bones.
What are the four parts of a developing bone?
- Epiphysis- end of bone develops from primary ossification centre
- Physis- cartilage separates epiphysis from diaphysis
- Metaphysis- region of active growth, forms part of the diaphysis and is adjacent to physis
- Diaphysis- develops from secondary ossification centre, form shaft
What are the two types of ossification?
- Membranous ossification formed directly from mesenchyme tissue e.g clavicle, bones of skull
- Cartilaginous ossification: mesenchyme transforms into cartilage first then bone e.g femur
What is ossification of bones?
Process of bone formation
Formed from mesenchyme of embryo
What is involved in the ossification of a long bone?
Begins in one or more areas of future long bone model
areas are called center of ossification
Primary centre of ossification?
diaphysis develops here and later goes on to become shaft
main part of bone
appears before birth
Secondary centre of ossification?
epiphysis develops from this centre
appears at ends of bone after birth
Describe the structure of the bone.
Periosteum
Outer part: Compact bone
Inner part: Spongy bone
Medullary cavity
Describe the periosteum
Double layered membrane covering the surface of the bone
richly supplied with blood vessels, nerves, lymphatic vessels
outer fibrous layer: collagen fibres
inner cellular layer: osteoblasts & osteoprogenitor
Describe the endosteum
membrane lines internal surface of bones
made up a layer of flat cells
What are the two components of bone
- Bone matrix
2. Bone cells
What does the bone matrix consist of?
- organic matter
2. inorganic matter
What does organic matter consist of?
collagen fibres produced by osteoblast
What does inorganic matter consist of?
formed by crystals of calcium phosphate (hydroxypatite)
contains small amounts of Magnesium, flourine and sodium
What contributes to the hardness of bones?
Association of hydroxypatite crystals and collagen fibres
What are the types of bone cells?
- Osteoblast
- Osteocytes
- Osteoclasts
What are osteoblast cells?
Responsible for the synthesis of organic compounds of bone matrix
bone forming cells located on surface of bone and endosteum
What are osteocytes?
Maintain osteoblast cells occupy lacunae in matrix
Maintain bone tissue, provide some nutrition
canaliculi
What are osteoclasts?
large, multinucleated bone removing cells
situated in endosteum
stick to surface of bone and breakdown bone matrix
formed from blood monocytes derived from hemopoietic cells in bone marrow
What is the structure of compact bone?
lamella: plates of bone tissue (three types)
lacunae: spaces between lamella
osteocytes: found in lacunae
canaliculi: extends from lacunae into lamella contains osteocytes processes
What are the three types of lamella?
- concentric 2.interstitial 3.outer and inner circumferential
What is concentric lamella?
Concentric plates of bony tissue around Haversian canal
Describe the Haversian system (osteon)
consists of Haversian canal and concentric lamella surrounding it known as osteon
cylindrical structures that run parallel to long axis of bone
osteons separated from each other by interstitial lamella
Describe the Haversian canal.
run in longitudinal direction
contain blood vessels, lymphatics of bone and nerves
What is interstitial lamella?
Irregular lamellae situated between concentric lamella
What is outer circumferential lamellae?
parallel to periosteum
What is inner circumferential lamellae?
parallel to endosteum
Describe the structure of Spongy bone.
trabeculae- series of interconnecting plates of bones
bone marrow- spaces between trabeculae
lamellae run parallel to one another
osteocytes sit in lacunae
What are the two types of bone marrow?
- red 2. yellow
Describe red bone marrow.
At birth: present throughout skeleton
After 5 years: red bone marrow changes to yellow bone marrow in long bone
Red bone marrow actively involved in the production of blood cells
Describe yellow bone marrow
contains large quantities of fat cells
What is bone marrow?
Vascular connective tissue located in medullary cavity and spaces of spongy bones
Describe the structure of ligaments.
Function?
Dense collagenous tissues
covering: epiligament
contain: bundles of collagen fibres that run parallel
matrix: proteoglycans, elastin
fibroblasts
connect bone to bone
