Connective Tissues II Flashcards
Types of immigrant blood-derived cells
a. lymphocytes
b. macrophages
c. neutrophils and eosinophils
d. mast cells
e. osteoclasts
Lymphocytes are
central to acquired immunity to foreign organisms/viruses/ materials
Macrophages are _______ cells that _______ cells, ECM, and other non-cellular material. Macrophages are also critical regulatory cells that _______
- large “engulfing”
- phagocytose (eat by endocytosis)
- secrete and respond to numerous extracellular signals
Macrophage-produced signals have numerous functions that include:
- stimulation of enodothelial cells to induce blood vessel growth and formation (blood vessel formation = angiogenesis)
- immune cell migration and function
- fibroblast activation
- blood vessel permeability
Macrophages have several important physiological functions:
(i) engulf (phagocytose) invading microorganisms
(ii) promote blood vessel formation (angiogenesis)
(iii) remodel damaged tissue
(iv) 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, _______; thus mast cells are important in _______ and _______
- release various substances, including vasodilators that promote swelling in connective tissue
- edema
- allergic hypersensitivities
Osteoclasts are _______ cells that appear to be derived from _______ and are very similar to macrophages. However they specifically function in _______
- phagocytic
- blood monocytes
- 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
_______ are the central CT cell type that makes the components of the extracellular matrix of most connective tissues
Fibroblasts
Fibroblasts are secretory machines that produce the
fibrous proteins, proteoglycans, and other components of the extracellular matrix (the ECM)
Fibroblasts are capable of _______ to produce new fibroblasts, and possibly _______
- cell division
- new fibroblasts
- other connective tissue types.
The _______ and _______ of fibroblasts are highly regulated. A common response to a laceration or other tissue injury is a stimulation of _______, and a stimulation of _______. In situations where injury is severe, scarring of tissues results from the _______
- secretory activity
- proliferation
- proliferation of fibroblasts
- ECM production
- hypertrophy (increased growth) of fibroblast-dependent connective tissue.
Recent evidence shows that fibroblasts in different CT’s express _______. Even within a single CT region,_______
- different sets of markers and regulatory proteins
- several fibroblast “types” have been observed
_______ methods are required to detect fibroblast differences; by _______ most fibroblasts look _______. The different fibroblast states are likely responsible for the enormous variation in ECM structure and composition.
- Immunohistological
- standard histological staining (e.g. H&E)
- very similar throughout the body
fibroblasts are developmentally flexible: They can transform (differentiate) into other connective tissue cell types such as
adipocytes, smooth muscle cells, chondrocytes, and osteoprogenitor cells
small numbers “less determined” _______ remain in many adult connective tissues, and these cells may be the primary precursors for these different cell types in vivo. These may originate in the _______, like blood cells, but they produce different cell lineages from the _______
- mesenchymal stem cells (MSCs)
- bone marrow
- hematopoietic stem cells
MSCs produce _______, at least under normal conditions. At a minimum, it seems likely that fibroblasts or MSCs differ in their _______, given the apparent diversity of fibroblasts.
- CT family cells
- developmental potential
