Connective Tissue Flashcards
Define tissue:
A group of cells that usually have a common embryonic origin and function together to carry out specialised activities
Explain tissue organisation:
Specialised cell -> Tissue -> Organ -> System -> Organism
Bone is what type of tissue?
Hard
Fat is what type of tissue?
Semisolid
Blood is what type of tissue?
Liquid
What are epithelial tissue cells?
Covers body surface and lines hollow organs, cavities, ducts, glands
Act as first line of immunity
What are connective tissue cells?
Protect, support and bind organs
Store energy as fat
Major transport system
What are muscular tissue cells?
Specialised for contraction and force generation
Generate body heat
What are nervous tissue cells?
Detect change in environmental conditions
Respond to changes through electrical signals (action potentials)
What are the 2 basic elements of connective tissue?
Cells
Extracellular matrix
What is the Extracellular matrix consisted of?
Protein fibres and ground substance
What are the functions of connective tissue?
Binds and supports body tissues
Protects and insulates internal organs
Compartmentalize structures, e.g. skeletal muscles
Major transport system (blood)
Stores energy as adipose tissue
Main source of immune response (platelets/ lymph)
What is the suffix for immature cells?
- Blast
e. g. fibroblasts, chondroblasts, osteoblasts
What are the function of immature connective cells?
Retain the capacity for cell division and secrete extracellular matrix
What produces the extracellular matrix?
Immature connective cells secrete the extracellular matrix
What is the suffix for mature cells?
-Cyte
When do immature cells differentiate into mature cells?
Once the extracellular matrix is secreted
Once an immature connective cell differentiates, what happens to it’s role?
It has a reduced capacity for cell division and is mostly involved in maintenance of the matrix
What are the 6 types of connective tissue cells?
Fibroblasts Adipocytes / Lipocytes Macrophages Lymphocytes Mast cells Plasma cells
What are the resident connective tissue cells?
Fibroblasts
Adipocytes / Lipocytes
What are the fluctuating connective tissue cells?
Macrophages
Lymphocytes
Mast cells
Plasma cells
What is the function of Adipocytes / Lipocytes?
Store and synthesise fats
What is the function of Fibroblasts?
Secrete extracellular matrix and active during wound repair
What is the function of Macrophages?
Immunity, engulf and digest bacteria / foreign bodies through Phagocytosis
What is the function of Lymphocytes?
Immunity, migration to sites of parasitic invasion and allergic response
What is the function of Mast cells?
Produce histamine (vasodilation), also involved in defence mechanism
What is the function of Plasma cells?
Involved in defence mechanism by secreting antibodies
What are the ground substances in the extracellular matrix?
The material between the cells and fibres:
- Fluid
- Semifluid
- Gelatinous
- Calcified
- Water
- Combinations of polysaccharides
- Proteoglycans
What is the role of ground substances in the extracellular matrix?
Support cells and provide a medium for substance exchange
Tissue development, migration and proliferation
Mechanical barrier
Presents adhesion proteins (fibronectin)
What are the three main extracellular matrix fibres embedded in the matrix?
Collagen
Elastic
Reticular
Describe collagen fibres present in the extracellular matrix:
Very strong to resist pulling forces and allow flexibility
Attracts water to give a cushioning effect
Occurs in parralel bundles
Describe elastic fibres present in the extracellular matrix:
Smaller diameter than collagen
Branch together to form a network
Consisted of elastin proteins surrounded by fibrillin
Highly elastic and tensile strength also high
Describe reticular fibres present in the extracellular matrix:
Consists of collagen arranged in branched bundles
Coated in glycoprotein
Supports blood vessel walls and forms network for tissues
Thinner than collagen and immature
Where are the collagen fibres of the extracellular matrix found?
Bones, Cartilage, Tendons and Ligaments
Where are the collagen fibres of the extracellular matrix found?
Bones, Cartilage, Tendons and Ligaments
Where are the reticular fibres of the extracellular matrix found?
Reticular connective tissues of soft tissue organisms, e.g. spleen and lymph nodes
What are the three types of mature connective tissue?
Connective tissue proper (loose / dense)
Supportive connective tissue (cartilage / bone)
Liquid connective tissue
The extra cellular matrix is what type of mature connective tissue?
Liquid connective tissue
What are the 5 classifications of mature connective tissue?
Loose Dense Cartilage Bone Liquid
Give examples of liquid connective tissue?
Blood / Lymph
Give examples of cartilage connective tissue?
Hyaline (end of long bones)
Fibrocartilage (pubic symphysis)
Elastic (larynx)
Give examples of loose connective tissue?
Areolar (basically everywhere)
Adipose (basically everywhere)
Reticular (stroma of organs)
Give examples of dense connective tissue?
Regular (tendons / ligaments / aponeurosis)
Irregular (fascia)
Elastic (lungs / arteries)
What are the differences between connective tissues and other tissues?
Do not appear on body surfaces More vascular (excluding cartilage and tendons) Supplied with nerves (except cartilage) Large supply of extracellular material Widely scattered cells
What is meant by avascular and what connective tissue is avascular?
Cartilage is avascular
Avascular means having few or no blood vessels
What would be considered calcified extracellular matrix?
Bone tissue with usually 25% water, 25% collagen fibres and 50% crystallised mineral salts
What is the structure of cartilage?
A dense network of collagen fibres firmly embedded in chondroitin sulfate.
What is chondroitin sulfate?
A gel like component of the ground substance in cartilage
Explain the strength / resilience of cartilage:
Can endure considerably high amounts of stress, tensile, compressive and shearing forces due to collagen fibres and chondroitin sulfate
Which feature of cartilage gives it resilience and elasticity?
Chondroitin sulfate
What is the role of cartilage?
Support soft tissues
Provide a smooth, lubricated surface for bones articulating
Enable the growth and development of long bones
What are the three types of cartilage?
Hyaline
Fribrocartilage
Elastic
Compare the structure of collagen in the different types of cartilage:
Hyaline = Thin collagen fibres Fribrocartilage = Thick bundles of collagen Elastic = Threadlike network of elastic collagen fibres
Compare the location of cells in the different types of cartilage:
Hyaline = Chondrocytes in lacunae Fribrocartilage = Chondrocytes scattered amongst thicker bundles of collagen Elastic = Chondrocytes located in threadlike network
Compare the presence of perichondrium in the different types of cartilage:
Hyaline = Most surrounded by perichondrium Fribrocartilage = Lacks perichondrium Elastic = Perichondrium present
Compare the characteristics of the different types of cartilage:
Hyaline =
Fribrocartilage =
Elastic =
Compare the relative strength in the different types of cartilage:
Hyaline = Weakest Fribrocartilage = Strongest Elastic = Middle
What are the characteristics of hyaline cartilage?
Most abundant, provides flexibility and support, at joints reduces friction and absorbs shocks
What are the characteristics of fibrocartilage?
Strong and rigid
What are the characteristics of elastic cartilage?
Gives support and maintains shape (elasticity)
Why does cartilage have few blood vessels which form nearby?
They secrete an ant antiangiogenesis, this prevents the formation of new blood vessels
What is the difference between chondroblasts and chondroblasts?
chondroblasts = immature, produce extracellular matrix chondroblasts = mature, maintain extracellular matrix
What are lacunae?
Small spaces in the matrix which are occupied by chondrocytes
Where is proteoglycan found?
Within the ground substance
What are proteogylcans?
Complex macromolecules, a core protein attached to glycosaminoglycans (GAG’s)
What is onloading of articular cartilage?
Fluid pressure rises immediately - Cartilage gradually deforms - Water moves out
What happens after the onloading of articular cartilage?
Fluid pressure drops - Cartilage gradually returns to normal shape Water moves back in
How does articular cartilage receive its nutrition?
Diffusion from underlying subchondral bone, synovial membranes and synovial fluid
Which cartilage type is not covered by perichondrium?
Articular cartilage
What are the two layers of perichondrium?
Outer layer: blood vessels and fibroblasts (which produce collagen)
Inner layer: contains undifferentiated cells
Describe the quality of healing and repair in cartilage:
It is relatively inactive so grows slowly
Has a low ability to regenerate due to avascular nature
In adults, damage to cartilage tissue results in the formation of what tissue?
Fibrous scar tissue
What are the two basic patterns of cartilage growth?
Interstitial growth
Appositional growth
When does Interstitial growth of cartilage occur?
Occurs while the cartilage is young and pliable during childhood and adolescence
When does Appositional growth of cartilage occur?
Starts later than appositional growth and continues through adolescence
Explain the Interstitial growth of cartilage:
A rapid size increase due to the division of chondrocytes and continuous deposition of extracellular matrix
Expands like rising bread as chondrocytes are pushed away from each other as they synthesise the new matrix
Explain the Appositional growth of cartilage:
Growth on the outer surface of the tissue
Cells in the inner cellular layer of the perichondrium differentiate into chondroblasts
Differentiated cells surround themselves with extracellular matrix and become chondrocytes
Matrix accumulates beneath the perichondrium on the outer surface of the of the cartilage causing it to increase width
