Histology POM Flashcards
What are Glycosaminoglycans?
Glycosaminoglycans (GAGs) are long, unbranched polysaccharides composed of repeating identical disaccharide units. An amino sugar, either N-acetylglucosamine or Nacetylgalactosamine, is always one of the repeating disaccharides. Because GAGS arecommonly sulfated and usually possess a urionic acid sugar, which has a carboxyl group in the repeating disaccharide unit, they have a strong negative charge. GAGs are generally linked to a core protein.
What are the 4 classes of Glycosaminoglycans?
I. Hyaluronic acid, II. Chondroitin sulfate & Dermatan sulfate, III. Heparin & Heparin sulfate, IV. Keratan sulfate
What are Proteoglycans?
Proteoglycans consist of a core protein from which many GAGs extend. These large molecules are shaped like a bottlebrush. Proteoglycans may attach to hyaluronic acid to form large complex aggregates. Proteoglycans act as binding sites for growth factor (e.g., fibroblast growth factor) and other signaling molecules.
What are glycoproteins?
Glycoproteins are multifunctional molecules whose domains bind to components of the ECM and to receptors on the cell surface, thereby promoting cell adhesion between the cell and the matrix. Examples include fibronectin, laminin, entactin, tenascin, chondronectin, and osteonectin.
What are fibronectin receptors?
Fibronectin receptors are transmembrane proteins consisting of two polypeptide chains. Enable cells to adhere to the ECM. Fibronectin receptors link fibronectin outside the cell to cytoskeletal components (e.g., actin) inside the cell and may activate cell-signaling pathways
What is ground substance?
A component, along with fibers like collagen, that composes the extracellular matrix. Ground substance consists of GAGs, proteoglycan, and glycoproteins.
Type I Collagen:
Synthesized by fibroblasts, osteoblasts, and odontoblasts. Located in dermis of skin, bone, tendons, ligaments, and fibrocartilage. Resists tension.
Type II Collagen:
Synthesized by chondroblasts. Located in the Hyaline cartilage. Resists intermittent pressure.
Type III Collagen:
Synthesized by fibroblasts, reticular cells, smooth muscle, schwawnn cells, and hepatocytes. Found in lymphatic system, CV system, liver, lung, spleen, intestine, uterus, and endouerium. Forms structural framework in expandable organs.
Type IV Collagen:
Synthesized by endothelial cells, epithelial cells, muscle cells, and schwann cells. Found in basal lamina and external lamina. Provides support and filtration, and acts as a scaffold for cell migration.
Type V Collagen:
Synthesized by Mesenchymal cells. Found in placenta and dermal-epidermal junctions. Unknown function.
Type VI Collagen:
Synthesized by keratinocytes. Found at dermal-epidermal junctions. Forms anchoring fibrils that secure lamina densa to underlying connective tissue.
What is connective tissue?
Connective tissue is formed primarily of extracellular matrix, consisting of ground substance and fibers in which various connective tissue cells are embedded. Connective tissue supports organs and cells, acts as a medium for exchange of nutrients and wastes between the blood and tissues, protects against microorganisms, repairs damaged tissues, and stores fat.
What are the 3 types of fibers in connective tissue?
- Collagen fibers, Reticular fibers, and elastic fibers
Collagen fibers in connective tissue:
Most common types are type I and type II collagen. Have great tensile strength, which imparts both flexibility and strength to tissues containing them. Bone, skin, cartilage, tendon, and many other structures contain collagen fibers.
Reticular fibers in connective tissue:
are extremely thin (0.5-2.0 μm) in diameter and are composed primarily of type III collagen. They have higher carbohydrate content than other collagen fibers. Type III collagen fibers constitute the architectural framework of certain organs and glands. Because of their high carbohydrate content, they stain black with silver salts.
What is labeled in this slide?
Elastin fibers.
This slide shows the wall of an elastic artery made of smooth muscle cells and thick sheet of collagen.
What is shown in this slide?
This arrow is pointing to the basement membrane.
What is shown in this slide?
This is type I collagen.
L indicates the longitudinal sections, and T indicates the transverse section
What is being shown in these slides?
These slides show type I collagen, with F indicating fibroblasts.
What is shown in this slide?
This photo shows reticular fibers (type III collagen), which form a delicate supporting framework for many cellular organs.
What is shown in this slide?
This slide shows connective tissue, with the fibroblasts and capillaries labeled. The main component of connective tissue is extracellular matrix material, which is largely composed of organized bundles of fibrous proteins, (wavy pink areas). The ground substance is unstained and is the pale space between the pink fibrous proteins.
What are cells labeled A and B?
A: Plasma cells.
B: fibroblasts.
What is the function of this cell?
Mast cells mediate immediate type I hypersensitivity reactions
Find these:
Lamina propria,
Fibroblast,
Endothelial cell,
Plasma cell,
Epithelial cells,
Basal lamina,
Pericyte.
Lamina propria: the entire lightly-stained region below the epithelial tissue and containing the plasma cell, fibroblast, and blood vessel.
Basal lamina: [wavy line at black arrows]
Remainder are labeled in photo.
What fibers are found in between these cells?
Type I Collagen.
What are the cells (labeled, blue) producing and secreting into the surrounding environment (pink)?
Type I collagen (this is from an achilles tendon)
How would you describe this image of the dermis of the skin?
Dense irregular connective tissue
What is this cell?
Fibroblast (often have an oval-shaped nucleus with two or more nucleoli. Also have lots of golgi and rER)
What is the structure between the arrows made of?
Type IV collagen (the structure is the basement membrane of kidney tubules). The type IV collagen provides support and filtration, and acts as a scaffold.
What is the function of the cell shown with the arrow?
Production of an immunoglobulin (antibody). This is a plasma cell.
What is this cell as shown by an EM?
This is a Mast Cell - The surfaces of mast cells are folded, and their cytoplasm is filled with coarse, deeply stained metachromatic granules with contents are known as primary mediators.
What is this cell/tissue?
Brown fat - Brown adipose tissue is composed of multilocular adipose cells, which contain many large mitochondria (making it brown).
In the EM, which is/are collagen?
1 only
What is the function of this cell?
Production of procollagen (this is a fibroblast)
What type of connective tissue is shown within the yellow box?
Loose connective tissue - (areolar tissue) possesses fewer fibers but more cells than dense connective tissue.
What is the structure between the yellow arrows?
Basal lamina - The basal lamina is an extracellular supportive structure that is visible only by electron microscopy. The basal lamina plus the underlying reticular lamina constitute the basement membrane, which is observable by light microscopy.
What is the function of these structures?
Tensile strength in the extracellular matrix
What cell type is this? What will it develop into?
This is a monocyte. It will develop into a macrophage.
