Connective Tissue Flashcards
What can occur after a sheet of cells has formed
Compartment formation
Cell specialisation
Organ development
What do organs require
They need a scaffold/mesh work for support
Protection and padding may also be required
What is connective tissue’s role
Form the scaffold/mesh work or protection organs req
Parenchyma
Cells and tissues of the organ that perform the actual function of the organ
Make up the bulk of the organ
Stroma
Structures surrounding and supporting the parenchyma eg nerves, blood vessels, CT
What are the parenchyma and stroma of the liver
P: hepatocytes
S: nerves ducts blood vessels CT
Four basic tissue types making up a multicellular organism
Connective
Muscular
Nervous
Epithelial
Types of CT
Proper
Specialised
Types of proper CT
Loose
Dense
Types of specialised CT
Bone
Cartilage
Blood
What type of specialised CT is blood
Fluid
What type of specialised CT are bone and cartilage
Structural
Types of loose proper CT
Areolar
Adipose
Reticular
Types of dense proper CT
Regular
Elastic
Irregular
Main cell of origin (stem cell)
Mesenchymal cell
Cell types that mesenchymal stem cell differentiate into
Chondrocytes Osteocytes Adipocytes Defence cells Fibroblast Myofibroblasts
Function of brown fat
Heat regulation in the new born (under nervous control)
Functions of white fat
Storage of fat reserve Metabolic fx Endocrine fx Insulation Shock absorption Protection
Types of defence cells
Mast cells
Tissue Macrophages
WBC
Fx of defence cells
Part of the immune system
Fx of fibroblasts
Synthesis and maintenance and recycling of ECM
What are the ECM fibres
Collagen
Elastin
Ground substance
Collagen synthesis process
Pro collagen (made of 3 pp chains) is secreted into ECM by fibroblast where it gets made into tropocollagen which polymerises to form fibrils which join to form fibres (tendons), meshes(liver), networks(BM)
General fx of collagen
Confer tensile strength as it resists pulling stretching and tearing
Collagen type 1
Follows normal production pattern
Main structural collagen type in body
Found in skin tendon bone and joint cartilage
Confers tensile strength
Collagen type 2
Forms fibrils not fibres
Main structural collagen in hyaline cartilage
Collagen type 3
Aka reticulin
Forms support mesh work of organs (eg liver bone marrow lymphoid organs)
Poor staining with H&E but good with silver stains
Collagen type 4
Mesho timing and cell membrane associating protein
Form part of BM
Helps anchor BM to epithelial cells above
Collagen type 7
Forms special fibrils anchoring the BM to the ECM
What is the most abundant protein in the body
Collagen
How many members of the collagen family
Superfamily with 28 members
Elastin
Forms fibres or discontinuous sheets
Confer elasticity and stretch to the tissue
Found in lungs skin urinary bladder blood vessel walls and anywhere where elasticity is important for fx
Secreted by fibroblasts as tropoelastin
What is ground substance made of
A range of glycoproteins, mostly proteoglycans
What are proteoglycans
Proteins bound to long complex carbohydrate chains called glycosaminoglycans
They form large aggregates
What is Ehlers Danlos Syndrome
Extra stretchy skin (can be quite severe) due to mutation in collagen synthesis)
What is arteriosclerosis
Thickening/hardening of elastin
Describe the 2 different GAG types
Sulphated (form proteoglycans)
Non-sulphated (form the backbone of the large aggregates formed by the proteoglycans and hyaluronate)
Describe the structure of the large aggregates found in ground substance
Proteoglycans form a large aggregate which bind to hyaluronate (an even larger molecule) and a non sulphites GAG forms the backbone
Fx of ground substance
Confers: Compression resistance Shock absorption Space filling To the tissues Allows for metabolic exchange of molecules
Why does GS allow for metabolic exchange
Molecules can easily diffuse through
What binding abilities do the large aggregates have
Profound water binding ability
How does the GS become a gel
The water binding ability of the aggregates attract sodium and water which when bound produce a gel
What can GS bind to
Other fibres in the ECM eg collagen
Fx of myoglobin lasts
Contractile fx similar to a muscle cell so are good for wound healing/closing and assist with repair and scar formation
What does CT consist of
Cells of a mesenchymal origin sitting in an ECM produced and secreted by themselves
Where are fibroblast found
Everywhere in the body
What ECM do fibroblasts produce
Depending where they are it is specific to that tissue eg in tendons will mainly be Collagen type 1, but in the dermis will be some C 1 but a lot more ground substance this allows for different tissue properties
What are myofibroblasts
Activated forms of fibroblasts
Blast v cyte
Blast has just been formed
Cyte is older
What do adobo cures form from
Mesenchymal immature cells called lipoblasts
What do adipocytes look like
Start off flat like fibroblasts but then their cytoplasm starts to fill with triglycerides so they become very large round and fat filled
Their cell organelles are pushed flat to the cell periphery
How are adipocytes metabolically active
Convert excess glucose from the blood into TGs for storage
How have adipocytes got an endocrine fx
Produce cytokines (protein messengers) and other hormones like leptin (key in appetite regulation)
Eg of adipocytes as shock absorbers
Foot pad of dog
Surrounding organs
What CT types are adipocytes found in
White fat (adipose tissue) mainly but also found scattered throughout other types (loose CT eg areolar)
Who has brown fat reserves
Newborns
Hibernation animals
Why are adipocytes of brown fat different
They have unique mitochondria with a different e- transport system than other cells
They don’t use the E in fat to make ATP, they use it to make heat (no atp is made)
How do brown fat adipocytes maintain a newborns body temp
The heat gen from the adipocytes is dissipated through the body by the bloodstream for the first crucial period of life until they have suckered
What is the process that brown fat adipocytes do
Non shivering thermogenesis
Categories of defence cells
Fixed (intrinsic) cells
Wandering (extrinsic) cells
Type of fixed defence cell
Tissue specific macrophages (different names in different parts of the body) eg dendritic cells (aka langerhans cells in the skin)
Mast cells
What are dendritic cells and what is their fx
Large, with long branched dendrites
They phagocytise and digest and present the antigen on their surface to T cells (aka antigen presenting cells)
When stimulated they migrate to the lymph nodes and are an important part of the immune response
Where are mast cells found, what is their fx and what do they look like
Found in most CT, prevalent in the skin GI tract thoracic and abdominal linings
Near blood vessels
Densely packed with histamine containing granules
They release the granules in response to a threat
Toes of wandering defence cells
WBC of a different origin to macrophages eg neutrophils eosinophils lymphocytes
How do wandering cells enter tissues
Via the blood
Mesenchyme
Make up
Found in
Fx
Embryonic CT
Gel like GS with fibres and stellate cells
Give rise to ALL CT
Loose CT
Relatively unspecialised so can differentiate into any CT type. Also act as stem cells in more mature CT
Areolar
Make up
Found in
Fx
Gel like matrix with both CT fibres
Fibroblasts macrophages adipocytes mast cells some WBCs
Wrap and cushion organs
Widely distributed
Adipose
Make up
Found in
Fx
Food store insulation support protection
Under skin, around kidneys and other organs , in abdomen and mammary glands
Local fat deposits serve nutrient needs of highly active organs
Adipocytes
Reticular
Make up
Found in
Fx
Loose GS reticular fibres
Reticular cells lie in a fibre network
Form soft internal skeleton/stroma supporting other cells types
Found in Lymph nodes liver bone marrow spleen
Regular
Make up
Found in
Fx
Mainly parallel collagen fibres, elastic fibres, little fluid
Fibroblasts
Attach muscle to bone and other muscles and bone to bone
Tendons ligaments aponeuroses
Irregular
Make up
Found in
Fx
Irregularly arranged collagen fibres with some elastic fibres little fluid
Fibroblasts
Withstand tension in many directions so gives structural strength
Dermis
Au mucosa of digestive tract fibrous organ capsules
Elastic
Make up
Found in
Fx
Abundant elastic fibres
Some collagen
Fibroblasts
Walls of arteries airways heart urinary bladder skin pleura
What allows for sheets of cells to form
Cells developed attachments between themselves
