Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
20 Cards in this Set
- Front
- Back
|
Continuously Dividing tissues:
|
Here the cells proliferate throughout life, replacing the
ones that get destroyed. Such tissues as: Surface epithelia, Skin epithelia, Oral cavity, Vagina, Cervix, all excretory glands of the body, Columnar epi of the GI, cells of the bone marrow and hematopoietic cells. |
|
|
Quiescent Tissue
|
Normally they replicate at a low level, BUT they can
undergo rapid cell division in response to stimuli. These cells include Parenchymal cells of the Liver, Kidneys, and Pancreas; Mesenchymal cells such as Fibroblasts, and smooth muscle, vascular endothelial cells, lymphocytes and leukocytes. |
|
|
Non diving cells
|
Neurons, Skeletal and Cardiac Muscle cells.
Even though mature skeletal muscle does not divide, it still as regenerative capacity via Satellite cells. |
|
|
Bone Marrow
|
The HSCs generate all of the blood lineages, and are
widely used in the treatment of hematologic diseases. Marrow Stromal Cells (MSCs) These are multipotent and have the potential for therapeutic applications, b/c these cells can generate Chondrocytes, Osteoblasts, Adipocytes, Myoblasts, and endothelial precursor cells depending on the tissue. |
|
|
Liver
|
The liver contains Stem / Progenitor cells located in the canal of Hering. This is located at the Junction b/w the biliary duct system and the hepatocytes.
Cells that are located here can give rise to the precursor cells called as the Oval Cells, which can differentiate into hepatocytes and biliary cells. |
|
|
Skin
|
The Stem cells for the skin are located in 3 different areas of the
epidermis. ---> The Hair follicle bulge, Interfollicular areas of the surface epidermis, and Sebaceous gland. The Bulge cells activation is regulated stimulatory signals via the Wnt pathway and Inhibition signals via the BMP (bone morphogenetic protein) system. |
|
|
Intestinal Epithelium
|
In the small Intestines the stem cells are located at the base of the Crypts.
The Wnt and BMP pathway is important here as well (just like the skin), for the regulation of proliferation and differentiation of the intestinal stem cells. |
|
|
Cornea
|
The corneal Stem cells are located at the Junction b/w the
epithelium of the cornea and the Conjunctiva called as the limbal stem cells (LSCs). Hereditary or acquired conditions of the eye can be treated by Limbal transplantation or by LSC grafting. |
|
|
VEGF
|
Important for Transcytosis
VEGF is a potent inducer for vascular formation during early development called as Vasculogenesis, and also plays a key role in angiogenesis in adults. VEGFR-2 is located in the endothelial cells, and is one of the MAIN receptor for Vasculogenesic and Angiogenesic effects of VEGF. |
|
|
PDGF
|
All PDGF isoforms bind to 2-cell surface receptors PDGFR-α & PDGFR-β and exert their
effects after the binding. o PDGF is stored in the platelet granules and is released once the platelets are activated. o PDGF causes migration and proliferation of fibroblasts, Smooth Muscle cells, and Monocytes to area of inflammation and healing in skin wound (Wound contraction). o Also stimulates production of MMPs. |
|
|
Skin
|
The Stem cells for the skin are located in 3 different areas of the
epidermis. ---> The Hair follicle bulge, Interfollicular areas of the surface epidermis, and Sebaceous gland. The Bulge cells activation is regulated stimulatory signals via the Wnt pathway and Inhibition signals via the BMP (bone morphogenetic protein) system. |
|
|
Intestinal Epithelium
|
In the small Intestines the stem cells are located at the base of the Crypts.
The Wnt and BMP pathway is important here as well (just like the skin), for the regulation of proliferation and differentiation of the intestinal stem cells. |
|
|
Cornea
|
The corneal Stem cells are located at the Junction b/w the
epithelium of the cornea and the Conjunctiva called as the limbal stem cells (LSCs). Hereditary or acquired conditions of the eye can be treated by Limbal transplantation or by LSC grafting. |
|
|
VEGF
|
Important for Transcytosis
VEGF is a potent inducer for vascular formation during early development called as Vasculogenesis, and also plays a key role in angiogenesis in adults. VEGFR-2 is located in the endothelial cells, and is one of the MAIN receptor for Vasculogenesic and Angiogenesic effects of VEGF. |
|
|
PDGF
|
All PDGF isoforms bind to 2-cell surface receptors PDGFR-α & PDGFR-β and exert their
effects after the binding. o PDGF is stored in the platelet granules and is released once the platelets are activated. o PDGF causes migration and proliferation of fibroblasts, Smooth Muscle cells, and Monocytes to area of inflammation and healing in skin wound (Wound contraction). o Also stimulates production of MMPs. |
|
|
FGF
|
o FGFs transduce signals through 4 Tyrosine kinase receptors (FGFRs 1-4).
o FGF-1 binds to all receptors o FGF-7 is also called as keratinocyte GF (KGF). FGFs function in: 1. Wound healing via FGF-2 and FGF-7 (KGF) which contribute to reepithelialization of skin wounds. 2. New blood vessel formation (angiogenesis) specifically via FGF-2 3. Hematopoiesis and Development. |
|
|
TFG-Beta
|
o Is called as a “Pleiotropic agent with a Vengeance”.
o Native TGF-β is synthesized as a precursor protein which is secreted and proteolytically cleaved to give the active growth factor and a 2nd Latent component. o The Active TGF-β binds to 2-cell surface receptors with serine / threonine kinase activity and triggers the phosphorylation of cytoplasmic TFs called as Smads. o The Phosphorylated Smad enters the nucleus and associated with the DNA-binding proteins to either activate or inhibit gene transcription. o TGF-β also inhibits production of MMPs and keratinocyte proliferation. o Growth inhibitor for most epithelial cells via blocking the cell cycle by increasing expression of cell cycle inhibitors Cip/Kip and INK4. o POTENT fibrogenic agent that stimulates fibroblast chemotaxis and enhances production of collagen. |
|
|
Angiogenesis from Preexisting vessels:
|
Consists of Vasodilation in response to NO and VEGF induced increased
permeability of the preexisting vessel. Proteolytic degradation of the Basement Membrane of the parent vessel via MMPs (metalloproteinases). And disruption of the Cell-to-Cell contact by the Plasminogen activator. Migration of endothelial cells towards the angiogenic stimuli. Proliferation of endothelial cells. Maturation which includes inhibition of growth and remodeling into capillary tubes. Recruitment of Pericytes and Vascular smooth muscle cells to form the mature vessel. |
|
|
Angiogenesis from EPCs (endothelial precursor cells):
|
EPCs can be recruited from the Bone Marrow into tissues to initiate angiogenesis.
The EPCs express markers of hematopoietic stem cells as well as VEGFR-2 and VECadherin. EPCs greatly increase in Pts with ischemic conditions, thus EPCs may determine risk for CVDs. |
|
|
Formation of Blood clot
|
Wounds cause rapid activation of coagulation pathway resulting in formation of a blood clot on the sound surface.
GFs, Cytokines and Chemokine’s attract RBCs, Fibrin, Fibronectin and Complement components to the site. VEGF release causes increase in the vascular permeability. Within 24hrs Neutrophils appear at the margin of the incision and release proteolytic enzymes that clean up debris and bacteria. |
