connective tissue I B Flashcards
immigrant blood-derived cells are
white blood cells that are produced from blood cell precursors (hematopoetic cells) in bone marrow, and migrate from blood into connective tissue
immigrant blood derived cells are important for the function of:a
- immune system (defense against virus and infection)
- tissue damage
- allergic hypersensitivites
lymphocytes are important for
acquired immunity to foregin organisms/viruses/material
Macrophages are
are large “engulfing” cells that phagocytose (eat by endocytosis) cells, ECM, and other non-cellular material.
Macrophages are critical regulatory cells that _____
secrete and respond to numerous extracellular signals.
Macrophage-produced signals have numerous functions that include:
- stimulation of enodothelial cells to induce blood vessel growth
- formation (blood vessel formation=angiogenesis)
- immune cell migration and function
- fibroblast activation
- blood vessel permeability
Macrophages have several important physiological functions:
- engulf (phagocytose) invading microorganisms,
- promote blood vessel formation (angiogenesis),
- remodel damaged tissue,
- remodel normal developing tissue and organs as part of their morphogenesis.
Neutrophils and eosinophils, important for ____.
defense against microorganisms
Mast cells are
secretory cells that, when stimulated by immune responses, release various substances, including vasodilators that promote swelling in connective tissue; thus mast cells are important in edema and allergic hypersensitivities.
Osteoclasts are ______.
phagocytic cells that are derived from blood monocytes and are very similar to macrophages
Osteoclast function
bone resorption and remodeling, not general phagocytosis.
precursors or differentiated blood cells must traverse the ____ to enter connective tissues.
endothelium of blood vessels
Macrophages and osteoclasts derive and differentiate from _____.
blood monocytes
Mast cells differentiate from ____.
blood basophils
Lymphocytes, neutrophils and eosinophils come from _____
similar if not identical differentiated cell types in the blood
Fibroblasts make up the components of the
_____
extracellular matrix of most connective tissues
Fibroblasts are _____.
secretory machines that produce the fibrous proteins, proteoglycans, and other components of the extracellular matrix (the ECM)
-Fibroblasts are capable of ____
cell division to produce new fibroblasts, and possibly other connective tissue types.
The _______ of fibroblasts are highly regulated.
secretory activity and proliferation
A common response to a laceration or other tissue injury is a _____
stimulation of proliferation of fibroblasts, and a stimulation of ECM production.
In situations where injury is severe, scarring of tissues results from the _____
hypertrophy (increased growth) of fibroblast-dependent connective tissue.
Fibroblasts are not a ____.
single cell type, but comprise a diverse collection of closely related cell types
fibroblasts in different CT’s express ____.
different sets of markers and regulatory proteins
The different fibroblast states are responsible for the ___
enormous variation in ECM structure and composition
Fibroblasts are developmentally ____
flexible
Fibroblasts can transform (differentiate) into:
other connective tissue cell types such as adipocytes, smooth muscle cells, chondrocytes, and osteoprogenitor cells
Mesenchymal stem cells (MSCs) are
- smaller number in adult connective tissue.
- primary precursors for the different cell types in vivo
- originate in bone marrow
- produce different cell linages from hematopoietic stem cells
- produce CT family cells
the dominant feature of CT is that
most of the tissue components are extracellular.
Organized in an ECM
ECM main components:
- structural fibers which provide mechanical strength and resiliency
- ground substance
- lots of extracellular macromolecules embedded within or diffusing through the ECM
ground substance
a hydrated gelatinous material in which structural fibers are enmeshed
structural fibers of ECM
- collagen
- dense CT
- Loose CT
- elastic fibers
most abundant structural fibers of ECM
collagen
types of collagen
- fibrilar collagen
- fibril associated collagen
- network forming collagen
The collagens are _____ .
fibrous proteins of very similar primary sequence to each other; collagen proteins aggregate to form fibers of varying sizes and organizations.
each collage molecule is composed of
three intertwined polypeptide chains that form a fairly rigid rope-like triple helix.
Each polypeptide is called an α chain
There are at least 25 different α chains encoded by different genes in humans.
Assembly of these α chains in different combination leads to ____.
the formation of multimeric collagens of at least 17 types
Each collagen molecule can be _____
aligned and cross-linked with other collagen molecules to form higher order fibrous structures.
