CONNECTIVE TISSUES. LOOSE IRREGULAR connective tissue.
All
CONNECTIVE tissues are: 1) Developed from MESENCHYME,
and 2) Composed of
2 c o m p o n e nts:
1)
CELLs and 2)
EXTRA
CELLULAR
MATRYX (=
ECM) between cells.
ECM is composed of
2 components: A) FIBRES and b) GROUND substance.
3 types of
fibres: 1) Collagen fs, 2) Elastic fs, 3) Reticular fs .
GROUND substance is composed of : a)
Glycos
Amino
Glycans (=
GAGs), b) Proteoglycans,
c) Glycoproteins.
GAGs are 2 types: 1) Sulfated GAGs, such as chondroitin sulfate, heparan sulfate,
dermatan sulfate; 2) NONsulfated GAGs, such as HYALURONIC acid.
If amount of cells and ground substance more, than number of fibres – connective tissue is
LOOSE.
If amount of fibres more, than number of cells and ground substance- connective tissue is
DENSE.
If
fibres arranged PARALLELLY – con. tis. is
REGULAR; if it form mashwork -
IRREGULAR.
LOOSE IRREGULAR connect. tis. (=
LICT). It
locates in all inner organs
around nerves and
around
blood vessels. Main c e l l t y p e s of
LICT :
1) DIFFERENTIATED (or, MATURE)
FIBROBLAST. Has abundance of rER and Golgi apparatus.
Funct.: Secretion of
ALL components of
ECM. It means, secretion of : a) GAGs and proteoglycans
for formation of
GROUND substance, b)protein COLLAGEN and protein ELASTIN for formation of collagen FIBRES and elastic FIBRES. After necrosis (in skin, in myocardium) it secrets TOO MUCH
of
collagen, resulting in formation of
COLLAGEN SCAR (connective tissue
scar), replacing of necrotic zone. SCAR is composed of
100% thick bundles of
collagen fibres.
2)
MAST cell. It contains
basophilic metachromatic GRANULES. Granules contain
HEPARIN and HISTAMINE. Funct.:
mast cell PREVENTS blood coagulation (by heparin) and INCREASES allergic reactions and inflammation (by histamine).
3) Tissue
MACROPHAGE (=MP). It is developed from blood MONOCYTE. Monocyte is developed from
PHSC of red bone marrow.
Macrophage has cytoplasmic PROCESSES (pseudopodia), a lot of LYSOSOMES. Funct.: PHAGOCYTOSIS of bacteria and it killing by LYTIC enzymes.
Macrophages of
all inner organs form
SYSTEM of
mononuclear phagocytes, because ALL of it
originate from MONOCYTE and function of it ALL is - P H A G O C Y T O S I S.
MP of liver is KUPFFER cell; MP of nervous tissue is MICROGLIA; MP of bones is OSTEOCLAST;
MP of lungs is ALVEOLAR macrophage ( or dust cell).
4)
PLASMA cell. It originates from B-LYMPHOCYTE. B-lymphocyte originates from PHSC. Funct.: secretes 5 classes of
immunoglobulins (or
antibodies):
Ig A,
Ig D,
Ig E,
Ig G,
Ig M.
5)
PERICYTES. It
surround endothelial cells of
capillary wall and regulate it diameter.
6)
MYOFIBROBLASTS. Locate in
wounded surfaces during it healing. Funct.:contract area of wound.
7)
BROWN adipocytes (or
multilocular fat cells). It contain
many small-sized lipid droplets in cytoplasm periphery, nucleus is in
centre. Funct. of brown adipose cs – is
HEAT production.
8)
WHITE adipocites (or
unilocular fat cs
). It contain ONE
big-sized lipid droplet in centre; nucleus –is in cytoplasm
periphery. Funct.- is fat storage and origin of energy.
DENSE REGULAR connective tiss. locates in
TENDON and ligaments. Is composed of a) thick
bundles of
collagen fibres, arranged
PARALLELLY; b) thin layers of LICT between bundles, named
endotendineum and peritendineum.
DENSE IRregular connective tiss. Locates in reticular layer of
skin dermis. Is composed of:
a) Thick
bundles of
collagen fibres, arranged into MESHWORK (not parallelly), b) a
little number of fibroblasts and ground substance.
SPECIAL connective tissues:
1)
Brown adipose tis. It situates in
newborn between scapulas. It is composed of BROWN ADIPOCYTES. Funct.: it regulates body temperature due to
HEAT production.
2)
White adipose tis. It locates in
adults skin
hypodermis. It is composed of WHITE ADIPOCYTES.
3)
MUCUOUS connective tiss (or Whartons jelly). It locates in umbilical cord. It is composed of fibroblasts and too MUCH
HYALURONIC acid. Funct.: prevents compression of umb. vessels.
4)
RETICULAR connective tissue. It locates in
red bone marrow and forms it
stroma. Is composed
of anastomosing RETICULAR cells and reticular FIBRES, forming MESHWORK. Funct.: reticular cells secrete factors,
stimulating hemopoiesis. Such as: ILs (interleukins) and CSFs.
Составитель – доцент В.В. Бондаренко.