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A&P Ch 4 Tissues
Tissues
Question | Answer |
---|---|
Tissues | are collections of specialized cells and the extracellular substances surrounding them |
Four primary tissue types | epithelial tissue, connective tissue, muscle tissue, and nervous tissue |
______________ are called germ layers because the beginning of all adult structures can be traced back to one of them and they give rise to all the tissues of the body | ectoderm, mesoderm, and endoderm |
endoderm | inner layer, forms the lining of the digestive tract and its derivatives |
mesoderm | middle layer, forms tissues such as muscle, bone, and blood vessels |
ectoderm | outermost layer (skin) |
Epithelial tissue, or epithelium | covers and protects surfaces, both outside and inside the body |
The characteristics common to most types of epithelial tissue are ____________ | Mostly composed of cells Covers body surfaces Distinct cell surfaces Cell and matrix connections Nonvascular Capable of regeneration |
The major functions of epithelial tissue are ________ | Protecting underlying structures Acting as a barrier Permitting the passage of substances Secreting substances Absorbing substances |
Classification of Epithelial Tissues | Simple epithelium, Stratified epithelium, Pseudostratified columnar epithelium Squamous,Columnar, Cuboidal |
Simple epithelium | consists of a single layer of cells, with each cell extending from the basement membrane to the free surface |
Stratified epithelium | consists of more than one layer of cells, but only the basal layer attaches the deepest layer to the basement membrane |
Pseudostratified columnar epithelium | consists of one layer of cells w/ all the cells attachd to the basement membrane. There appear to be two or more layers of cells because some of the cells are tall and extend to the free surface, whereas others are shorter & dnt extend to the free surface |
Squamous | cells are flat or scalelike |
Cuboidal | (cubelike) cells are cube-shaped—about as wide as they are tall |
Columnar | (tall and thin, similar to a column) cells are taller than they are wide. |
Goblet Cells | specialized columnar epithelial cells --- contain abundant organelles, such as ribosomes, endoplasmic reticulum, Golgi apparatuses, and secretory vesicles, that are responsible for synthesizing and secreting mucus |
Transitional Epithelium | is specialized to expand. It is found in the urinary bladder, ureters, kidneys, and superior part of the urethra |
desmosomes | disk-shaped structures with especially adhesive glycoproteins that bind cells to one another and intermediate filaments that extend into the cytoplasm of the cells - found in areas of stress (skin) |
Hemidesmosomes | similar to one-half of a desmosome, attach epithelial cells to the basement membrane |
Tight junctions | hold cells together and form a permeability barrier |
gap junction | is a small, specialized contact region between cells containing protein channels that aid intercellular communication by allowing ions and small molecules to pass from one cell to another |
intercalated disks | The gap junctions between cardiac muscle cells are found in specialized cell-to-cell connections |
glands | secretory organs- Many composed primarily of epithelium, with connective tissue - develop from an infolding or outfolding of epithelium in the embryo. If the gland maintains an open contact with the epithelium from which it developed, a duct is present |
exocrine glands | with ducts- their ducts are lined with epithelium |
endocrine glands | some glands become separated from the epithelium of their origin and have no ducts - have extensive blood vessels in the connective tissue of the glands ... hormones are secreted into the bloodstream and carried throughout the body |
multicellular glands | Most exocrine glands are composed of many cells |
unicellular glands | composed of a single cell |
simple gland | single duct |
compound gland | ducts that branch |
tubular gland | Glands with secretory regions shaped as tubules (small tubes) |
acinar/alveolar gland | saclike |
merocrine secretion | most common type of secretion - products are released, but no actual cellular material is lost - used by water-producing sweat glands and the exocrine portion of the pancreas |
apocrine secretion | the secretory products are released as fragments of the gland cells |
holocrine secretion | involves the shedding of entire cells |
Adipose cells/adipocytes | or fat cells, contain large amounts of lipid |
blasts | create matrix |
cytes | maintain |
clasts | break it down for remodeling - consists of cells separated from each other by abundant extracellular matrix |
connective tissue | it makes up part of every organ in the body - |
Functions of Connective Tissue | Enclosing and separating other tissues - Connecting tissues to one another - Supporting and moving parts of the body - Storing compounds - Cushioning and insulating - Transporting - Protection |
Mast cells | commonly lie beneath membranes in loose connective tissue and along small blood vessels of organs. They contain chemicals, such as heparin, histamine, and proteolytic enzymes, that are released in response to injury |
White blood cells/leukocytes | continuously move from blood vessels into connective tissues. The rate of movement increases dramatically in response to injury or infection. |
Macrophages | are found in some connective tissue types. |
Platelets | are fragments of hemopoetic cells containing enzymes and special proteins that function in the clotting process to reduce bleeding from a wound. |
The extracellular matrix of connective tissue has three major components: | (1) protein fibers, (2) ground substance consisting of nonfibrous protein and other molecules, and (3) fluid. |
Three types of protein fibers | collagen, reticular, and elastic |
Collagen fibers | consist of collagen, which accounts for one-fourth to one-third of total body protein, or 6% of total body weight. |
Reticular fibers | are very fine collagen fibers - very short, thin fibers that branch to form a network and appear different -- are not as strong as most collagen fibers, but networks of reticular fibers fill spaces between tissues and organs |
Elastic fibers | consist of a protein called elastin |
Connective Tissue Proper | Loose Connective Tissue - Dense Connective Tissue |
Loose Connective Tissue | onsists of relatively few protein fibers that form a lacy network, with numerous spaces filled with ground substance and fluid ... areolar, adipose, and reticular |
Dense Connective Tissue | has a large number of protein fibers that form thick bundles and fill nearly all of the extracellular space. Most of the cells are spindle-shaped fibroblasts |
Dense regular connective tissue | protein fibers in the extracellular matrix that go in one direction |
Dense regular collagenous connective tissue | abundant collagen fibers, which give this tissue a white appearance -- (tendons, and most ligaments) |
Dense regular elastic connective tissue | parallel bundles of collagen fibers and abundant elastic fibers. The elastin in elastic ligaments gives them a slightly yellow color |
Dense irregular connective tissue | has protein fibers arranged as a meshwork of randomly oriented fibers |
Dense irregular collagenous connective tissue | forms most of the dermis, which is the tough, inner portion of the skin, as well as the connective tissue capsules that surround organs (kidney and spleen) |
Dense irregular elastic connective tissue | is found in the walls of elastic arteries -- the layers of this tissue contain abundant elastic fibers. |