basic tissue types connective and epithelial Flashcards
Tissue def and 4 types
- groups of cells that perform specific functions
- Epithelial Connective Nervous Muscular
Hierarchical organization of animal body
Organ system -> Organ -> Tissue -> Cell
Epithelial Tissue def, coverages, and function
- continuous sheet of epithelial cells
- covers exterior body surfaces, lines interior body cavities, forms secretory portion of glands
- body Protection, Absorbtion, Secretion
Characteristics of epithelial cells
- adhere to each other by specialized cell junctions
- Exhibit polarity - 3 distinct domains apical (free surface), lateral, basal
- Lowest epithelium always attached by basal surface to basement membrane
Classification of epithelia (number and shape)
Number of layers- simple (one cell layer thick), stratified (more than one cell layer thick), pseudostratified (looks stratified but all cells resting on basement membrane, not all cells will reach free surface) Shape of cells on surface layer- squamous (flat), cuboidal (width, depth, height approximately equal), columnar (height exceeds width)
Apical domain modifications
Microvilli Cilia Stereocilia Primary cilium
Microvilli
which cells have
made of
function
Small finger like cytoplasmic projections of luminal plasma membrane increase surface area of cell
- actin filaments - rigidity
- Cells which transport fluid and absorb metabolites - lots of tall microvilli,
- cells transport less - smaller irregularly shaped microvilli
- Individual not seen in light microscopy but enough closely packed per cell in kidney and small intestine they can be seen as striated or brush border
Cilia
made from
function
Motile hair like extension of apical plasma membrane
- micro tubule-based internal structure associated with motor proteins
- moves fluid and particles across epithelial surface
- Longer than microvilli, give crew-cut appearance to epithelial surface
Primary cillia
location
function
- Solitary, found on almost all eukaryotic cells
- immotile
- signal detectors generate and transmit signals from extracelluar part of cell
Stereocilia
location
function
very long immotile microvilli
- sensory cell of inner ear and male reproductive tract
- visible with light microscopy
types of epithelial tissues
- Endothelium
- Endocardium
- Mesothelium
- Transitional epithelium
- Glands
Endothelium
and cell type
Epithelial lining of blood and lymphatic vessels
- simple squamous
Endocardium and cell type
Epithelial lining of heart, simple squamous
Mesothelium and cell type
Epithelial lining of closed cavities of body, simple squamous
Transitional epithelium
and cell type
Epithelial lining of lower urinary tract, stratified with special characteristics to allow for distention
Connective tissue
function, made from, characteristics, types
- continuous compartment throughout animal body
- structural and functional support for other 3 tissue types
- protein fibers suspended in watery gel (“ground substance”)
- cells do not adhere to each other
types:
-Embryonic connective tissue (mesenchyme)
-Specialized connective tissue (bone, cartilage, blood, hematopoietic tissue, and adipose tissue)
-Connective tissue proper
ECM connective tissue
made from and function
ECM consists of protein fibers and ground substance,
- provides structural, biochemical, and mechanical support for connective tissue
- provides pathway for cell migration and allows for diffusion of small molecules
Fibroblasts and function
staining
main cell type of connective tissue
- synthesize the ECM they reside in
- don’t usually see entire fibroblast in H & E stain but will see fibroblast nuclei as elongated or disk like structure, sometimes with nucleolus
Connective tissue cell types
Primarily fibroblasts, also have resident cell population, wandering cell population
Myofibroblasts characteristics and staining
similar to fibroblasts and smooth muscle - elongated and spindly - contractile proteins - unlike smooth muscle - no external lamina - exist as isolated cell. Do not see in stain.
Fiber types in connective tissue
Collagen, elastic, reticular
Collagen fibers function characteristics
Most abundant in CT
- confer flexibility and tensile strength (resistance to pulling forces)
- in light microscopy -eosinophilic wavy structures - bundles of fine thread-like subunits
Elastic fibers function characteristics and staining
- stretch and distention;
- thinner than collagen fibers
- have branching pattern to form 3d network
- stain with eosin but can be difficult to see with collagen
Reticular fibers function characteristics
- supporting framework for cellular constituents
- form of collagen
- mesh-like pattern
- found at boundary between epithelia and CT
- surround adipocytes, small blood vessels, nerves, and muscle cells
- Do not stain with H&E
Ground substance function characteristics made of staining
Part of ECM
- occupies space between cells and fibers
- clear substance
- glycosaminoglycans, proteoglycans, mutiadhesive glycoproteins, and large amounts of water Lost in H&E
Connective Tissue Proper
types
Loose connective tissue - Dense connective tissue (regular and irregular)
loose CT
characterized
location
areolar tissue-
- loosely arranged fibers
- various cell types
- located beneath epithelia that covers body surfaces and line internal surfaces of body
- epithelium of glands and surrounds smallest blood vessels
- most cells in loose connective tissue are transient wandering cells that migrate in from local blood vessels
dense regular CT
characterized
function
- ordered and densely packed arrays of fibers and cells
- makes up tendons, ligaments, aponeuroses, little ground substance, cells producing fibers packed between fiber bundles
dense irregular CT
characterized
made from
- abundant fibers and few cells
- mostly collagen fibers relatively little ground substance
- fibers in bundles in various direction
- fibroblasts are most abundant cell type