connective tissue Flashcards
where does connective tissue originate
mesenchyme - tissue developing in the middle layer of the embryo ( mesoderm)
describe mesenchymal stem cells
small, spindle- shaped cels with long branching processes that form a network
what are the functions of connective tissue
- binds structures together
- provide support and protection
- fills spaces
- produces blood cells
- stores fat
what are the types of fibrous connective tissue
- loose connective tissue - areolar
- dense connective tissue - regular and irregular
what are the types of connective tissue with special properties
- adipose
- reticular
- mucous
- pigment
what are the supporting types of connective tissue
cartilage and bone
what is the classification of fibrous connective tissue based on
- ratio between fibres and amorphous ground substance
- arrangement of fibres
what are the general characteristics of connective tissue
cells + extracellular matrix
- cells widely separated by extracellular matrix
- solid, semisolid or liquid
- matrix of connective tissue determine properties
what is loose connective tissue characterised by
- low maintenance fibres - <25%
- great volume of ground substance and cells >75%
- always irregular
what is dense connective tissue characterised by
- great maintenance of fibres >75%
- low volume of ground substance and cells
- can be regular and irregular
what is the most abundant connective tissue in an organism
loose areolar connective tissue
what are most cell types in loose connective tissue
transient wondering cells that migrate from local blood vessels to respond to a specific stimulus causing inflammatory and immune reactions
what cells are in loose connective tissue
- Fibroblasts
- Macrophages
- Mast cells,
- Plasma cells,
- Fat cell (adipocytes)
- Pericytes
- Adventitial cells
- Pigment cells
(melanocytes) - Leukocytes migrating
from blood vessels
what is the most dominant cell in connective tissue
fibroblast
what are the functions of fibroblasts
synthesis of fibres and components of ground substance
what are myofibroblasts
involved in wound healing, assist in tooth eruption, pluripotent and develop in new cells
what are macrophages
derived from monocytes and are part of mononuclear phagocyte system
what are macrophages functions
- phagocytosis
- antigen processing and presentation to immune system
- secretion of growth factors and cytokines
where are mast cells abundant in
loose connective tissue
what are the functions of mast cells
secrete heparin and histamine
- involved in inflammatory reactions, allergies and hypersensitivity
what are metachromasia
- granules of mast cells containing heparin and histamine change the blue stain to purple or red
what is the mature form of fibroblasts called
fibrocytes
what are the characteristics of plasma cells
- nucleus contains chromatin clumped in a clock face patter
- cytoplasm is basophilic and filled with rER
- golgi complex displaces nucleus to one side - perinuclear halo
what are Russell’s bodies
when antibodies enter the circulation or stored in a form of inclusions
what is the function of plasma cells
- final stage of development of B-lymphocytes
- production of antibodies (humoral immunity)
how are ring cells/ adipocytes formed
cytoplasm forms a thin peripheral layer around central droplets of fat
what are the functions of adipocytes/ ring cells
- storage of neutral fats
- production of heat
what are adventitial cells
cells accompanying blood vessels and are in blood vessel regeneration
what are pericytes
surround blood capillaries and are part of their wall
they regulate capillary blood flow and growth
where do pigment cells originate from
neural crest cells
what are pigment cells/ melanocytes
- stellate with long branching processes and small round nucleus
- cytoplasm contains melaanin granules
what do melanin granules do
absorb ultra violet that give pigment to cells
what happens when leukocytes migrate
migrate across capillary walls from the blood t connective tissue via diapedesis to increase inflammation
what are reticular cells
similar in appearance to fibocytes
what are the fibres in connective tissue
collagen - strength and forms bundles
elastic - elasticity and thin
what are ground substances
- varies from soft jelly to semisolid consistency
- fills spaces between cells and fibres In connective tissue
what are the functions of ground substances
- determines hardness and viscosity of tissue
- regulates movement of substances between cells
- prevents spread of microorganisms
what are the 3 groups of ground substances
- glycosaminoglycans
- proteoglycans
- multi adhesive glycoproteins
where is regular dense connective tissue found
- tendons and ligaments
where is irregular dense connective tissue foud
reticular layer of dermis
what do tendons consist of
fascicles of parallel collagen fibres
what surrounds individual collagen fibres
fibrocytes which forms endotendineum
what surrounds fascicles
protective layer of loose connective tissue with blood vessels and nerves called peritendineum
what surrounds entire tendon
thicker layer of dense tissue - epitendineum
what is adipose tissue
specialist type of connective tissue
- composed of aggregation of adipocytes and reticular fibres
what is the function of adipose tissue
- store fat
- insults body from head loss
- padding
what is brown fat
mitochondrial protein called uncoupling protein which is involved in the main function of brown fat to generate heat
what is the specific histological staining for reticular tissue
silver impregnation
where is mucous tissue found
- principle component of Whartons jelly of umbilical cord
- ground substance composed of hyaluronic acid, few fibres and fibroblasts
what is the function of pigment tissue
protect organism against damaging effects of non-ionising UV irradiation
what is melanin a determinant of
- skin colour
- iris
- stria vascularis of inner ear
- birthmarks
- some nuclei in brain
what is white/ yellow adipose tissue
1 big droplet of fat found in adults
what is brown adipose tissue
a lot of small droplets with lots of mitochondria
what is reticular tissue made from
reticular cells and reticular fibres
- also called lymphatic tissue
what does reticular tissue produce
stroma of lymph nodes, spleen and red bone marrow
- is part of immune system
