Connective Tissue Flashcards
Functions of connective tissue
Connects/binds cells and tissues
Provides structural support for tissues and organs in the body
Aids in defense, protection, and repair of the body
One of the four basic tissues
General composition of CT
Cells (resident and transient cells)
Extracellular matrix - ground substance (resists compression) with fibers (provides tensile strength and elasticity) in it
Resident CT cells
Fibroblasts/fibrocytes
Macrophages
Mast cells
Adipose cells
Pericytes
Fibroblasts
Most abundant CT cells
Oval nucleus with cytoplasm
Synthesize extracellular matrix
Turns into a fibrocyte when inactive
Fibrocytes
Inactive forms of fibroblasts
Small, dense nucleus - appears flat
Macrophages
Shape varies when cells are active - usually round with dense, round-oval nucleus
Phagocytic for many different materials
Also called histiocytes
Mast cells
Common in loose CT
Contain many membrane-bound granules (difficult to see without specific stains)
Granules contain inflammatory mediators
Adipose cells
Fat cells derived from mesenchyme
Synthesize and store triglycerides
Two types - unilocular (white adipose) and multilocular (brown adipose)
Unilocular adipose cells
Large cells - cytoplasm and nucleus are forced to cell periphery (signet ring shaped)
Store lipid as a single droplet in the cytoplasm
Multilocular adipose cells
Smaller than unilocular - nucleus is not pushed to the edge and is more circular
Lipid is stored in multiple droplets in each cell
Contain more mitochondria
Pericytes
Partially surround endothelial cells of capillaries and small venules
Surrounded by their own basal lamina
Multipotent - can differentiate into other cells (endothelium, fibroblasts, vascular smooth muscle cells)
Transient CT cells
Plasma cells
Leukocytes (lymphocytes, eosinophils, neutrophils, basophils)
Plasma cells
Most abundant in CT in respiratory and digestive systems
Manufacture antibodies
Nucleus is eccentrically placed and appears as a “clock face”
Leukocytes
White blood cells in the blood circulatory system that enter into CT, especially during inflammation (lymphocytes, eosinophils, neutrophils, basophils)
Lymphocytes
T cells, B cells, natural killer cells
Eosinophils
Attack parasites; moderate allergic reactions
Neutrophils
Phagocytic especially bacteria; have lobed nuclei
First to migrate to an inflammatory site
Basophils
Release components that control the inflammatory process (rare)
Extracellular matrix
Hydrated gel-like ground substance with fibers embedded in it
Fibers - provide tensile strength and elasticity
Ground substance - resists compression
Types of fibers
Collagen, reticular, and elastic
Collagen fibers
Composed of collagen
Tough, nonelastic fibers
Secreted by fibroblasts in CT proper
5 types of collagen
Reticular fibers
Type III collagen
Often visualized with silver stains
Form fine network of fibers closely associated with individual cells of certain organs (lymphs, spleen, liver, kidney, bone marrow)
Elastic fibers
Slender, long, and branching in loose CT
Found in bundles (ligaments) and sheets (walls of large blood vessels)
Embryonic connective tissue
Mesenchymal CT and Mucous CT
Mesenchymal CT
Present in developing embryo
Pale cytoplasm and oval nucleus
Mucous CT
Loose, amorphous CT
Fibers are Type I and Type III collagen fibers
Fibroblasts present
Found in umbilical cord and embryonic subdermal CT
Loose (areolar) CT
Loose arrangement of fibers and cells
Contains collagen, reticular, and elastic fibers. Also contains nerves and blood vessels
Dense irregular CT
More fibers, fewer cells, and less ground substance than loose CT
Collagen fiber bundles are arranged randomly
Fibroblasts between collagen fibers
Dense regular collagenous CT
Densely packed coarse collagen fibers that are arranged in parallel
Little ground substance and few cells interspersed in fibers
Dense regular elastic CT
Densely packed coarse (large) branching elastic fibers
Fibroblasts present between fibers
Few collagen fibers are present
Reticular CT
Consists of reticular fibers (Type III collagen)
Delicate meshwork with interspersed fibroblasts and other cells
