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39 terms

Tissues and Cells: Microscopic Anatomy: Part 1

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How many tissue types are there?
Four- connective tissue, epithelial tissue, muscle cells, and nervous tissue.
Connective Tissue
Composed of cells and their secretory products that fill in the spaces between other cells and tissues.
Muscle Tissue
Composed of cells that contract for movement.
Nervous Tissue
Composed of cells that send electrical signals for communication.
Components of Connective Tissue:
Cells and Extracellular Matrix (ECM).
Cells
Minor component of CT.
Extracellular Matrix (ECM)
Major component of CT.
Major Cell Type
Fibroblasts
Fibroblasts
Secrete "ECM" and scattered cells become embedded in ECM.
Other Cell Types in CT:
For defense and immunity: Permanent residents (always in CT)- Macrophages and Mast Cells, and Transient residents (travel between blood and CT)- Lymphocytes and Eosinophils.
Macrophages
Phagocytose (gobble up) foreign substances; fixed or floating.
Mast Cells
Release histamine and are associated with vasodilation during the inflammatory response.
Lymphocytes
Attack particular antigen.
Eosinophils
Fight allergic and parasitic reactions.
Extracellular Matrix (ECM)
Secreted by fibroblasts and composed of: fiber, ground substance, and glycoproteins.
Fibers
Components of ECM- fibers: collagen and elastic.
Collagen
Strong but flexible, provide framework for the other components of CT, provide support like the beams of a building, about 25% of total body protein, and turner very slowly except during wound healing.
Elastic
Provide elasticity and recoil (so that CT can resume its original shape after being bent, stretched, or compressed).
Ground Substance
The major component of ECM, the space filler, like stuffing material, holds lots of water (provides the medium for transport) through which molecules diffuse, and composed primarily of glycosaminoglycans (long carbohydrate chains).
Glycoproteins
The glue, ex: Laminin and Fibronectin, for cell adhesion and migration, and lots of this is associated with metastasis (spread) of cancer.
Functions of Connective Tissue:
Support, filler, transport, and storage.
Support
Fibers provide framework for the other components (like beams in a building).
Filler
The ground substance fills in spaces between adjacent tissues and organs (like stuffing).
Transport
The ground substance holds a lot of water as medium through which nutrients and wastes dissolved in the water can diffuse, and blood vessels diffuse in CT.
Storage
Water and electrolytes are stored in the ground substance, and fat is stored in adipose tissue, a type of CT.
Connective Tissue Classification:
Connective tissue proper, fluid connective tissue, and supporting connective tissues.
Classification of Connective Tissue Proper:
Loose and dense connective tissue.
Loose Connective Tissue
Contains small collagen fiber bundles, the most cellular: contains all CT cell types, and most vascular: carries blood vessels (nutrients) to other tissue types.
Dense Connective Tissue Irregular
Composed mainly of large collagen fiber bundles which are irregularly arranged, the only cell type contained in this tissue is fibroblast, surrounds and compartmentalizes muscles and nerves into bundles, and lines bones and cartilage.
Dense Connective Tissue Regular
Composed of very large parallel collagen fiber bundles, again, the only cell type contained in this tissue is fibroblast, scant blood supply, and make up tendons and ligaments.
Tendons
If connecting muscle to bone.
Ligaments
If connecting bone to bone or cartilage.
Supporting Connective Tissue:
Cartilage and bones.
The Cartilage Matrix
A stiff gel matrix specialized for resilience to a limited extent, can resume its original shape after begin bent, stretched, and compressed.
Physical Properties of Cartilage:
Depending on the cartilage matrix especially on the type and abundance of fibers.
Three Tissue Types of Cartilage:
Hyaline, Elastic, and Fibrocartilage.
Hyaline Cartilage
The most common type of cartilage, its matrix contains some collagen fibers, making it tough but flexible, provides a smooth support for gliding, so this type of cartilage reduces friction in joints, and found on articular surfaces, between ribs and sternum, and as precursors to long bones.
Elastic Cartilage
Only cartilage that contains elastic fibers, very flexible, tolerates bending and stretched without permanent distortion, and found in ears and larynx (epiglottis).
Fibrocartilage
Only cartilage that contains large collagen fiber bundles, very durable and tough, resists compression, good for shock-absorbing, and weight-beraing surfaces, and found in intervertebral discs, menisci of knee, and pubic symphysis.