Connective Tissue And Fat Flashcards
Types of Connective Tissues
- Loose irregular
- Dense irregular
- Dense regular
- Adipose tissue
1) Structural found in skeleton (cartilage and bone)
2) blood
Composition of Connective Tissue
- Cells: fibrocytes, fibroblasts, blood cells, adipocytes
- Matrix: PGs, GAGs, glycoproteins, tissue fluid
- Fibers: collagen, reticular, elastic
Function of connective tissues
1) supports and connects cells, tissues, and organs, allows blood vessels and nerves to come in proximity to epithelial
2) provides medium for exchange of gasses, nutrients, and metabolites
3) contains cells of the immune system that protect the organism from invasion of foreign material
4) Fibers provide strength and or flexibility depending on the location and type
Fibroblasts
- active in producing fibers and matrix
- spindle shaped with small, dark staining nucleus
Fibrocytes
-inactive, resting fibroblasts
Adipocytes
1) unilocular- one large lipid droplet found in white fat
2) multilocular - many smaller lipid droplets found in brown fat
3) may occur singly or in groups
Mast cells
- oval cells with many dark staining, basophilic granules
- located close to blood vessels
- leukotrienes released from cell membrane ave vasoactive properties (asthma)
- granules contain histamine, heparin, and chemoattractants
- granules released in response to allergens or irritants
Macrophages (Histiocytes)
- phagocytic cells derived from circulating monocytes
- called histiocytes when resident in the connective tissue
- phagocytize foreign material and stimulate immune responses
Leukocytes
- neutrophils, eosinophils, lymphocytes
- defense against infection
Plasma cells
- activated lymphocytes that produce immunoglobulins
- defense against infection
Matrix Function
- in connective tissue, GAGs hold water to make a gel which provides spaces for cells and capillary beds and a diffusion medium for nutrients
- make tissues able to withstand compression, in dermis makes skin supple, in cartilage makes it strong, flexible plastic-like bearing surfaces for joint
Tissue Fluid
-formed by transcytosis of fluid through capillary endothelial cell
Collagen in connective tissue
Type 1 - primary collagen, high tensile strength, stains pink to orange with H&E
Type 2 - found in hyaline and elastic cartilage and the vitreous of the eye, resists pressure
Type 3 - branching collagen that makes reticular fibers, form fine mesh that hold some tissues together (lymphoid organs)
Type 4 - network forming collagen found in basement membranes
Reticular fibers
- made of type 3 collagen
- forms a mesh of fibers that support lymphoid organs, blood vessels, muscle cells and nerves
- requires special stain
Elastic fibers
- made of elastin
- synthesized by fibroblasts in skin and tendons, chondrocytes in cartilage and by smooth muscle cells in large blood vessels
- found in locations where stretching and recoil is necessary ( bladder, large blood vessels, and lungs)
Loose irregular classification
- large amount of matrix
- irregular orientation of fibers
- many cells
Dense irregular Classification
- more fibers more densely packed
- irregular orientation
- fewer cells and less matrix
Dense regular classification
- more densely packed fibers
- regular, parallel orientation
- fewer cells
Loose Irregular
- high in matrix, low in fibers, and cell numbers vary but typically greater than other CTs
- contain capillary beds
- diffusion in matrix provides waste and nutrients exchange with capillaries
- where immune cells guard against bacteria
Loose Irregular Cells
- Lymphocyts - small round cells with dark nucleus
-Macrophagges - differentiated from monocytes, large, pale, oval nucleus, slight indentation with nucleolus
-Eosinophils- large eosinophilic granules, lobed nucleus
Plasma cells - round eccentric nucleus, clock face appearance of chromatin, small amount of pale cytoplasm, differentiate from lymphocyte, secret antibodies
Dense Irregular CT
- similar to loose CT but: Random orientation of thicker fibers provides strength and resists pull in all directions, less matrix, fewer cells
- Found as: fascia and dermis of skin, capsules and septa for all glands and organs, periosteum, perichondrium, epimysium, epineurium, dura, submucosa of GI and respiratory tract
Dense Regular CT
- primarily type 1 collagen
- fibers run in a parallel direction, promotes strength in the long axis of the fibers
- minimal matrix
Tendons
- Regular CT
- attach muscle to bone
- bundles of fibers separated by small amount of dense irregular connective tissue where cells are located and carrying blood vessels
Ligaments
- Dense CT
- attach bone to bone
- similar to tendons but more elastic fibers allow more stretch and flexibility
