Flashcards in 1.03 - Connective Tissue Deck (35):
A group of similar cells specialised in a particular way for the performance of a common function
Define: Connective Tissue
Supports the various organs and fills the spaces between different tissue types. Binds tissue systems together.
What does connective tissue do?
Structural (binds together, protects and support other tissues)
Mediate exchange of nutrients, metabolites and waste products between cells and the circulatory system
What two components form connective tissue?
Extracellular matrix (made up of ground substance & fibres)
Cells: Indigenous (fibroblasts, adipocytes & reticulocytes) & Migratory (cells of the immune system)
What are the two different types of connective tissue in the body and their respective subtypes?
Connective tissue proper
Special: vascular connective tissue, cartilage, bone
What are the types of indigenous cells that form part of connective tissue?
The active form of the cell
Responsible for maintenance and synthesis of extracellular matrix
Contain large amounts of organelles
Easily found in healing wounds
What is a Fibrocyte and how is it different to a Fibroblast?
Fibrocytes are the mature inactive form of fibroblasts. They are larger than fibroblasts and their nuclei typically stains lighter
They also have irregular cytoplasms
Adapted for storage of fat
Immature form in known as lipoblast
Very long lived cells
Large in size due to fat accumulation
Nucleus pushed to periphery
Describe the differences between White Adipose and Brown Adipose Tissue
White: 20-25% of total body weight in humans. Important for energy storage. Thermal insulator. Cushion against mechanical shock for deep organs.
Brown: Typically found in newborns. Temperature regulation
Name the Migratory cells of the immune system
Originate in bone marrow and enter blood stream. Enter tissue and differentiate into macrophages
Life span: months to years
Main function is defence: act as tissue scavengers as they phagocytose foreign materials
Antigen presenting cell to lymphocytes and other cells
Describe Mast Cells
Derived from basophils in the bone marrow
Migrate to peripheral tissues such as the skin and GIT and develop and differentiate.
Cytoplasm filled with numerous large vesicles
Present in healthy connective tissue - they stand guard and monitor local situation
Function: defence against protein containing foreign material like bacterium or allergens
Discharge contents of vesicles (heparin and histamine) on contact which causes capillaries to leak, vasodilation and improve blood flow to the area
Describe plasma cells
main function: defence
Produce antibodies. cytoplasm increases when producing antibodies
Originate in bone marrow
Rounded or oval cells with a bilobed nucleus
Contain large amounts of bright red granules in the cytoplasm.
Found in healthy connective tissue
8-12 day life span
Main Function: Defence against parasites and in some allergic disorders - either phagocytose or release their granule content
Derived from the bone marrow
Circulate in blood between various lymphoid tissues in various amounts
Their nuclei are round and stain very dark. The cytoplasm forms a narrow rim around the nucleus and may be difficult to see.
What are the three subtypes of fibre that make up the extracellular matrix?
Describe Collagen Fibres
Dominant type seen on most connective tissues
Main function: Strength & Support
Elongated and arranged in a regular manner
Forms capsules of several organs (liver, spleen, kidney)
Wavy, pink appearance in H&E stain
Composed of thinner collagen fibrils which is composed of microfibrils.
What are the types of collagen fibres?
Describe the location and cells of origin of Type 1 Collagen
Found in Loose & Dense ordinary connective tissue as well as bone.
Produced by fibroblasts and osteoblasts
Describe Reticular Fibres
Collagen Type III
Tiny collagen fibres
Form delicate networks instead of thick bundles
Main function: supporting framework for cells in organs like the liver, lymph node and adrenals
Describe Elastic Fibres
Elastin molecules are cross-linked to each other and form a random coil
Can be stretched to 150% of their original length
Can resist severe chemical conditions (extreme of alkalinity, acidity and heat that destroys collage)
Main Function: Confer elasticity
Found in the skin, blood vessels, lung, urinary bladder, ligaments and cartilage
Consists of individual microfibrils, which are embedded in an amorphous matrix
Produced by fibroblasts and smooth muscle cells
Describe Ground Substance
Semi-fluid gel-like material composed of: glycoaminoglycan, proteoglycans, glycoproteins
Main Function: act as a medium for passage of molecules and exchange of metabolites.
Functions: contributes to physical consistency, an adhesive substance for collagen fibres, transport and regulation of water and electrolytes, barrier to spread of bacteria, absorb compressive loads
Describe the basement membrane
Sheet of extracellular matrix proteins between epithelial cells and the parenchyma
Provides structural support
Involved in control of growth of epithelial cells
Permits the passage of nutrients and metabolites
May regulate permeability (kidney)
What are the types of connective tissue?
Loose (Mucoid, Reticular, Adipose)
Describe Dense Connective Tissue
Lots more fibres, less cells, less ground substance
Divided into two subcategories based on the spatial arrangement of the fibres: Regular and Irregular
Describe Irregular Dense Connective Tissue
Densely woven 3D network that resists deformation. Moderately packed thick fibre bundles arranged in a meshwork. Fibrocytes scattered amongst fibres.
Examples: Dermis layer of the skin, capsule sheaths around organs
Describe Regular Dense Connective Tissue
Tightly packed bundle fibres run parallel to each other - stress only in one direction so fibres are arranged to resist deformation in that direction
Fibrocytes squeezed in-between fibre bundles
Examples: tendons, ligaments, cornea of the eye
Describe Loose Connective Tissue
Permits mobility between structures.
Present in all parts of the body
Also called areolar connective tissue
Special Variants: Mucoid, Reticular, Adipose
Describe Mucoid Connective Tissue
More space between the cells
Large amount of ground substance leading to decreased cohesiveness
Examples: umbilical cord, dental pulp
Descrive Reticular Connective Tissue
Consists of reticular cells and the network of fibres formed by them.
Forms the structural framework in which the cells of the organ are suspended
Useful in tissues and organs in which diffusion and or cell movements are functionally important
Examples: liver, lymph nodes, spleen
Describe Adipose Tissue
Connective tissue containing large number of adipocytes
Two types: Brown & White
Describe White Adipose Tissue
Unilocular adipose tissue containing one large lipid droplet
Functions: storage of lipids, structural, cushioning (palms of hand, soles of feet, gluteal region
Describe Brown Adipose Tissue
Multilocular Adipose Tissue containing many lipid droplets
Functions: fetal development, cells generate heat by decoupling of oxidation of fatty acids.
Most brown differentiates into white fat in adults
Contain large number of mitochondria
Located in axilla, between shoulder blades, neck region and around large blood vessels