Chapter 4 Flashcards
are collections of specialized cells and the extracellular substances surrounding them. Body tissues are classified into four types, based on the structure of the cells, the composition of the noncellular substances surrounding the cells (called the extracellular matrix)
Tissues
is the microscopic study of tissues. Much information about a person’s health can be gained by examining tissues.
Histology
is the process of removing tissue samples from patients surgically or with a needle for diagnostic purposes. Examining tissue samples can distinguish various disorders.
biopsy
is an examination of the organs of a dead body to determine the cause of death or to study the changes caused by a disease. Microscopic examination of tissue is often part of an autopsy.
autopsy
the inner layer, forms the lining of the digestive tract and its derivatives.
endoderm
the middle layer, forms tissues such as muscle, bone, and blood vessels.
mesoderm
the outer layer, forms the skin
ectoderm
becomes the nervous system
neuroectoderm
give rise to parts of the peripheral nerves, skin pigment, the medulla of the adrenal gland, and many tissues of the face.
neural crest cells
covers and protects surfaces, both outside and inside the body.
Epithelial tissue
consists of a single layer of cells, with each cell extending from the basement membrane to the free surface.
Simple epithelium
consists of more than one layer of cells, but only the basal layer attaches the deepest layer to the basement membrane.
Stratified epithelium
is a special type of simple epithelium. The prefix pseudo- means false, so this type of epithelium appears to be stratified but is not. It consists of one layer of cells, with all the cells attached 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 and do not extend to the free surface.
Pseudostratified columnar epithelium
cells are flat or scalelike.
Squamous
cells are cube-shaped—about as wide as they are tall.
Cuboidal
(tall and thin, similar to a column) cells tend to be taller than they are wide
Columnar
Found in areas such as the mouth, esophagus, rectum, and vagina, consists of living cells in the deepest and outermost layers. A layer of fluid covers the outermost layers of cells, which makes them moist.
Nonkeratinized (moist) stratified squamous epithelium
found in the skin, consists of living cells in the deepest layers, and the outer layers are composed of dead cells containing the protein keratin. The dead, keratinized cells give the tissue a dry, durable, moisture-resistant character. In addition to the skin, keratinized stratified squamous epithelium is also found in the gums and hard palate of the mouth.
keratinized stratified squamous epithelium
lines the urinary bladder, ureters, pelvis of the kidney, and superior part of the urethra
transitional epithelium
which are specialized columnar epithelial cells. The goblet cells are responsible for synthesizing and secreting mucus
goblet cells
consist of adhesive glycoproteins that bind cells together and intracellular proteins attached to intermediate filaments that extend into the cytoplasm of the cells
desmosomes
similar to one-half of a desmosome, attach epithelial cells to the basement membrane.
Hemidesmosomes
hold cells together and form a permeability barrier. Tight junctions are formed by proteins in the plasma membranes of adjacent cells that join one another to make a very tight seal.
Tight junctions
of glycoproteins is found just below the tight junction. It is located between the plasma membranes of adjacent cells and acts as a weak glue that holds cells together
adhesion belt
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
gap junction
are secretory organs. Glands are composed primarily of epithelium, with a supporting network of connective tissue. These glands develop from an infolding or outfolding of epithelium in the embryo.
Glands
Glands with ducts, Both the glands and their ducts are lined with epithelium.
exocrine glands
Alternatively, some glands become separated from the epithelium of their origin and have no ducts, have extensive blood vessels.
endocrine glands
The cellular products of endocrine glands, are secreted into the bloodstream and carried throughout the body.
hormones
have a single, nonbranched duct. If there are multiple secretory regions that branch off the duct, then the gland is called branched.
Simple glands
have multiple, branched ducts. For both simple and compound glands, the shape of the secretory regions further defines the gland.
Compound glands
Glands with secretory regions shaped as tubules (small tubes)
tubular
whereas those shaped in saclike structures
acinar or alveolar
involves the release of secretory products by exocytosis, is used by water-producing sweat glands and the exocrine portion of the pancreas.
Merocrine secretion
involves the release of secretory products as pinched-off fragments of the gland cells. The milk-producing mammary glands release milk by a combination of apocrine and mostly merocrine secretion.
Apocrine secretion
involves the shedding of entire cells. Products accumulate in the cytoplasm of each epithelial cell, the cell ruptures and dies, and the entire cell becomes part of the secretion.
Holocrine secretion
create the matrix
Blasts
maintain it
cytes
break it down for remodeling
clasts
are cells that form fibrous connective tissue
Fibroblasts
maintain it.
fibrocytes
form cartilage; maintain it
Chondroblasts; chondrocytes
also called adipose (fat) cells, contain large amounts of lipid. The lipid pushes the rest of the cell contents to the periphery, so that each cell appears to contain a large, centrally located lipid droplet with a thin layer of cytoplasm around it.
Adipocytes
play important roles in inflammation. They contain chemicals, such as heparin, histamine, and proteolytic enzymes, that are released in response to injury, such as trauma and infection.
Mast cells
continuously move from blood vessels into connective tissues. The rate of movement increases dramatically in response to injury or infection.
White blood cells, or leukocytes
are large, phagocytic cells found in some connective tissue types. They are derived from monocytes, a type of white blood cell.
Macrophages
are fragments of hemopoetic cells containing enzymes and special proteins that function in the clotting process to reduce bleeding from a wound.
Platelets
are a type of adult stem cell, that persist in connective tissue. They have the potential to form multiple cell types, such as fibroblasts or smooth muscle cells, in response to injury.
Undifferentiated mesenchymal cells
consist the protein of collagen. Collagen is the most abundant protein in the body. It accounts for one-fourth to one-third of total body protein and 6% of total body weight. Collagen is synthesized within fibroblasts and secreted into the extracellular space.
Collagen (kol′a-jen) fibers
are very fine collagen fibers and therefore not a chemically distinct category of fibers. However, reticular fibers are very different from collagen fibers.
Reticular fibers
consist of the protein elastin (e-las′tin). As the name suggests, this protein has the ability to return to its original shape after being stretched or compressed, giving tissue an elastic quality.
Elastic fibers
consists of nonfibrous molecules. It is the “shapeless” background against which the collagen fibers are seen through the microscope. The two major components are hyaluronic acid and proteoglycans.
ground substance
is a long, unbranched polysaccharide chain composed of repeating disaccharide units. It gives a very slippery quality to the fluids that contain it; for that reason, it is a good lubricant for joint cavities
Hyaluronic (glassy appearance) acid
Elastic fibers consist of
the protein elastin (e-las′tin). As the name suggests, this protein has the ability to return to its original shape after being stretched or compressed, giving tissue an elastic quality.
The ground substance consists of
nonfibrous molecules. It is the “shapeless” background against which the collagen fibers are seen through the microscope. The two major components are hyaluronic acid and proteoglycans.
Two major categories of connective tissue are embryonic and adult. Embryonic connective tissue is called
mesenchyme (mez′en-kīm). It forms in the embryo during the third and fourth weeks of development from mesoderm and neural crest cells (see chapter 29), and all adult connective tissue types develop from it. By 8weeks of development,
Adipose tissue
Adipose tissue functions as an insulator, a protective tissue, and a site of energy storage. Lipids take up less space per calorie than either carbohydrates or proteins and therefore are well adapted for energy storage.
