BIOL 207 Lecture Notes - Lecture 19: Loose Connective Tissue, Precursor Cell, Elastic Fiber
CONNECTIVE TISSUE (pgs 126-136 (overall) pg 126, table 4.1, pg 127 figure 4.7)
• mesenchyme - gives rise to CT and muscle tissue. all CT arises from this
• CT is most abundant tissue in the body.
• a wide range of vascularization. some will be highly vascularized, some will be poorly
vascularized. all CT is characterized by having widely scattered cells. the cells then proceed to produce
stuff that fills space between the widely scattered cells; which is called matrix. material that surrounds
the cell that encloses the cell.
• basement membrane is the very specialized, narrow, thin base upon which the basal part of the
cell will be attached to, and that basement membrane itself is attached to an underlying, thicker CT.
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Connective tissue (pg 127, figure 4.7)
• the atri is a geeral ter to desrie the stuff i etwee the widel sattered ells that
make up CT. it consists of 2 components; one is the GS (ground substance). GS is a homogenous product
of the CT cells that it surrounds. // The GS varies in terms of consistency, from a fluid to a semi solid gel.
the other component is the Fibers (both GS and fibers are produced by cells of CT; the immature (blast)
cells). These fibers will be found imbedded to various degrees in the GS. This is what determines loose
CT and dense CT, it depends on the extent and thickness/density of fibers, as well as the number of
fibers, the size of them and the number of them in the matrix.
• there are 4 types of connective tissue (pg 126, table 4.1; pg 129, table 4.8; 129-136 there are
figures/diagrams)
• CTP (Connective Tissue Proper) - ** many of these elements are also found in cartilage, bone,
and just throughout the body **
• LCT (Loose Connective Tissue) - (a) areola (b) adipose (c) reticular
• DCT (Dense Connective Tissue) - (a) dense collagenous regular **fibers are arranged in a very
long, parallel regular fibers** (b) dense collagenous irregular **an irregular arrangement of the fibers**
(c) elastic tissue
• Cartilage (cartilagenous)
• Bone (osseous)
• Blood
• CT Stem Cell types
• each major type has a special stem cell that gives rise to them (mesenchyme can give rise to
these other stem cells, which give rise to the basic 4 divisions of CT)
• all have the suffi last - bud, forming, sprout; refers to something just beginning
• blast cells are very active, they secrete both the ground substance and the fibers of the matrix,
therefore they essentially secrete the matrix.
• blast cells both secrete GS and fibers of the matrix. blast cells produce the matrix. they go from
the blast to the cyte of the cell. when they mature they play a maintaining role, they sustain the
integrity of the CT they gave rise to.
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• CTP Blast Cells - fibroblast **they produce the fibers within the CT proper**
• Cartilage - chondroblasts
• Bone - osteoblast
• blood - hemocytoblast/hematopoietic
Connective Tissue Proper (pg. 129)
• most abundant type of connective tissue.
• 2 categories of CTP; Loose connective tissue and dense connective tissue (LCT and DCT)
• Loose Connective tissue (pg. 127 figure 4.7)
• the most widely distributed connective tissue in the body.
• it surrounds blood vessels and nerves
• it is within the fabric of mucous membranes (mucosa)
• also found in the papillary region of the dermis
• LCT as well as other CT consists of a number of cell and fiber types.
• The GS for CTP is a fluid type of substance known as hyaluronic acid; not only does it serve as
the GS for CTP, but also a contributing GS for other CT. in addition to this GS (produced by cells of that
CT), there are also 3 fiber types - (a) collagenous fibers (made of protein called collagen - a tough and
white protein that is flexible and can be bent and returned to shape - never stretch. can flex but never
stretch. it is flexible, not stiff) (b) elastic fibers - smaller and finer than collagenous, made up of protein
called elastin (it is a finer type, building block, a yellowish color. it can stretch and return back to normal
shape. (c) reticular - these fibers are very important. they basically form an extensive network
interconnecting fine fibers that form an internal flexible skeleton. they are found off in structures that
aren't all that protective. they make up framework for liver, spleen, lymph nodes and several other
delicate structures. they give internal support. this skeleton has a general term
• (c) stroma - basic structural framework of an organ as distinguished from the functional cells
(parenchyma) of that organ.
• Stroma - that portion of a tissue that forms the foundation or framework of an organ as
opposed to its functional parts (its cells - parenchyma)
• these soft tissues remain, they keep their shape.
• stroma - found in liver, spleen, dermis, lymph nodes, and bone marrow
• Parenchyma - the cells of a tissue or organ that are responsible for fulfilling its functional role -
as distinguished from the stroma of that tissue.
• Parenchyma - the functional parts (cells) of an organ
• Cell types (pgs 127-128)
• fibroblast - these are the predominant cell types in CT. they keep the tissue going (indigenous)
• macrophages - cells that are phagocytes (cells that can engulf items). develop from a white
blood cell known as a monocyte (white blood cells that are manufactured in bone marrow. travel in
blood (as monocytes) and when they reach capillary, the cells wiggle out of blood and into tissue. as
soon as this happens they undergo a metamorphosis of sorts). they help recycle cells, and they help to
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Document Summary
Mesenchyme - gives rise to ct and muscle tissue. all ct arises from this. Connective tissue (pg 127, figure 4. 7) make up ct. it consists of 2 components; one is the gs (ground substance). Gs is a homogenous product the (cid:373)atri(cid:454) is a ge(cid:374)eral ter(cid:373) to des(cid:272)ri(cid:271)e the (cid:862)stuff(cid:863) i(cid:374) (cid:271)etwee(cid:374) the widel(cid:455) s(cid:272)attered (cid:272)ells that of the ct cells that it surrounds. // the gs varies in terms of consistency, from a fluid to a semi solid gel. the other component is the fibers (both gs and fibers are produced by cells of ct; the immature (blast) cells). These fibers will be found imbedded to various degrees in the gs. Ctp (connective tissue proper) - ** many of these elements are also found in cartilage, bone, figures/diagrams) and just throughout the body ** long, parallel regular fibers** (b) dense collagenous irregular **an irregular arrangement of the fibers**
