The Tissue Level of Organization - Chapter 4
simple columnar epithelium
A _____ _____ ____ is typically found where absorption or secretion occurs, such as in the small intestine. In the stomach and large intestine, the secretions of _____ _____ _____ protect against chemical stresses.
simple cuboidal epithelium
A _____ ______ _____ provides limited protection and occurs where secretion or absorption takes place. Such an epithelium lines portions of the kidney tubules
stratified squamous epithelium
A ______ ______ _____ is generally located where mechanical stresses are severe. The cells form a series of layers, like the layers in a sheet of plywood.
glandular epithelial
A ______ _______ cell releases its secretions by: (1) merocrine secretion, (2) apocrine secretion, or (3) holocrine secretion.
avascular
Epithelia are ________; that is, they lack blood vessels. Epithelial cells must therefore obtain nutrients by diffusion or absorption across either the exposed or the attached epithelial surface.
produce specialized secretions
Epithelia perform four essential functions: 1. Provide Physical Protection. 2. Control Permeability. 3. Provide Sensation. 4. _______ _________ _______
provide sensation.
Epithelia perform four essential functions: 1. Provide Physical Protection. 2. Control Permeability. 3. ______ ________ 4. Produce Specialized Secretions
control permeability.
Epithelia perform four essential functions: 1. Provide Physical Protection. 2. _________ ________ 3. Provide Sensation. 4. Produce Specialized Secretions
provide physical protection.
Epithelia perform four essential functions: 1. ________ _______ ______ 2. Control Permeability. 3. Provide Sensation. 4. Produce Specialized Secretions
gland cells
Epithelial cells that produce secretions are called _____ _____(s).
epithelia
Epithelial tissue includes ______ and glands.
ductless glands
Examples of endocrine glands include the thyroid gland and the pituitary gland. Because their secretions are not released intoducts, endocrine glands are often called ______ _____(s).
exocrine glands
Glandular Epithelia: Produce secretions: - onto epithelial surfaces - through ducts
endocrine glands
Glandular Epithelia: Release hormones: - into interstitial fluid - no ducts
simple epithelium
If only one layer of cells covers the basal lamina, that layer is a _______ _______. _____ ______ are necessarily thin. All the cells have the same polarity, so the distance from the nucleus to the basal lamina does not change from one cell to the next. Because they are so thin, _____ _____are also fragile. A single layer of cells cannot provide much mechanical protection, so ______ ______ are located only in protected areas inside the body.
glandular epithelium
In a ______ _______, most or all of the epithelial cells produce secretions, which are either discharged onto the surface of the epithelium (to provide physical protection or temperature regulation) or released into the surrounding interstitial fluid and blood (to act as chemical messengers).
stratified epithelium
In a _______ _______, several layers of cells cover the basal lamina. _____ ______are generally located in areas that need protection from mechanical or chemical stresses, such as the surface of the skin and the lining of the mouth.
columnar epithelial
In a typical sectional view, _____ ______ cells appear rectangular. In reality, the densely packed cells are hexagonal, but they are taller and more slender than cells in a cuboidal epithelium
adhesion belt
Inferior to the occluding junctions, a continuous ________ _______ forms a band that encircles cells and binds them to their neighbors. The bands are attached to the micro filaments of the terminal web.
simple cuboidal epithelium
LOCATIONS: Glands; ducts; portions of kidney tubules; thyroid gland FUNCTIONS: Limited protection, secretion, absorption
pseudostratified ciliated columnar epithelium
LOCATIONS: Lining of nasal cavity, trachea, and bronchi; portions of male reproductive tract FUNCTIONS: Protection, secretion
stratified cuboidal epithelium
LOCATIONS: Lining of some ducts, sweat glands and mammary glands (rare) FUNCTIONS: Protection, secretion, absorption
simple columnar epithelium
LOCATIONS: Lining of stomach, intestine, gallbladder, uterine tubes, and collecting ducts of kidneys FUNCTIONS: Protection, secretion, absorption
simple squamous epithelium
LOCATIONS: Mesothelia lining ventral body cavities; endothelia lining heart and blood vessels; portions of kidney tubules (thinsections of nephron loops); inner lining of cornea;alveoli of lungs FUNCTIONS: Reduces friction; controls vessel permeability; performs absorption and secretion
stratified columnar epithelium
LOCATIONS: Small areas of the pharynx, epiglottis, anus, mammary gland, salivary gland ducts, and urethra FUNCTION: Protection
stratified squamous epithelium
LOCATIONS: Surface of skin; lining of mouth, throat, esophagus, rectum, anus, and vagina FUNCTIONS: Provides physical protection against abrasion, pathogens, and chemical attack
transitional epithelium
LOCATIONS: Urinary bladder; renal pelvis of kidneys; ureters FUNCTIONS: Permits expansion and recoil after stretching
adhesion molecules
Large areas of opposing plasma membranes are interconnected by transmembrane proteins called cell ______ ________(s) (CAMs), which bind to each other and to extracellular materials.
endocrine glands
Some of these glands, called ______ _____(s), release their secretions into the interstitial fluid.
mesothelium
Special names have been given to the simple squamous ep ithelia that line chambers and passageways that do not communicate with the outside world. The simple squamous epithelium that lines the ventral body cavities is a ______.
keratinized
Superficial layers are both tough and water resistant; the epithelium is said to be ________.
basal lamina
The base of an epithelium is bound to a thin ______ _______, or basement membrane.
squamous epithelium
The cells in a _______ ______ are thin, flat, and somewhat irregular in shape, like pieces of a jigsaw puzzle. From the surface, the cells resemble fried eggs laid side by side.
cuboidal epithelium
The cells of a _____ ______ resemble hexagonal boxes. (In typical sectional views they appear square )
intercellular cement
The membranes of adjacent cells may also be bonded by _______ _______, a thin layer of proteoglycans that contain polysaccharide derivatives known as glycosaminoglycans, most notably hyaluronan (hyaluronic acid).
endothelium
The simple squamous epithelium lining the inner surface of the heart and all blood vessels is an _________.
histology
The study of tissues.
macula adherens
There are two types of _______ ______(s): -Spot desmosomes -Hemidesmosomes
basolateral
the __________ surface, which include both the base, where the cell attaches to underlying epithelial cells or deeper tissues, and the sides, where the cell contacts its neighbors.
apical
the _______surface, where the cell is exposed to an internal or external environment
lumen
When the epithelium lines a tube, such as the intestinal tract, the apical surfaces of the epithelial cells are exposed to the space inside the tube, a passageway called the ______.
exocrine glands
______ _____(s), release their secretions into passageways called ducts that open onto an epithelial surface
stratified cuboidal epithelia
______ ______ _____ are relatively rare; they are located along the ducts of sweat glands, and in the larger ducts of the mammary glands
spot desmosomes
______ _______(s) are small discs connected to bands of intermediate filaments. The intermediate filaments function to stabilize the shape of the cell.
neural tissue
______ _______, which carries information from one part of the body to another in the form of electrical impulses.
epithelial tissue
______ _______, which covers exposed surfaces, lines internal passageways and chambers, and forms glands.
connective tissue
______ _______, which fills internal spaces, provides structural support for other tissues, transports materials within the body, and stores energy reserves.
muscle tissue
______ _______, which is specialized for contraction and includes the skeletal muscles of the body, the muscle of the heart, and the muscular walls of hollow organs.
stratified columnar epithelium
_______ ______ _____ are relatively rare, providing protection along portions of the pharynx, epiglottis, anus, and urethra, as well as along a few large excretory ducts. The epithelium has either two layers or multiple layers.
cell junctions
_______ _______(s) are specialized areas of the plasma membrane that attach a cell to another cell or to extracellular materials. The three most common types of cell junctions are (1) occluding (tight) junctions, (2) gap junctions, and (3) macula adherens (desmosomes).
epithelia
_______ are layers of cells that cover internal or external surfaces.
glands
_______ are structures that produce fluid secretions; they are either attached to or derived from epithelia.
epithelial tissue
________ ______ covers body surfaces, lines cavities and tubular structures, and serves essential functions
epithelia
________ cover every exposed surface of the body.
epithelia
________ form the surface of the skin and line the digestive, respiratory, reproductive, and urinary tracts—in fact, they line all passageways that communicate with the outside world.
epithelia
________ have several important characteristics: 1. Cellularity 2. Polarity 3. Attachment 4. Avascularity
hemidesmosomes
_________(s) resemble half of a spot desmosome. Rather than attaching one cell to another, a hemidesmosome attaches a cell to extracellular filaments in the basal lamina. This attachment helps stabilize the position of the epithelial cell and anchors it to underlying tissue.
stem cells
An epithelial cell may last just a day or two before it is shed or destroyed. The only way the epithelium can maintain its structure over time is by the continual division of ____ ____(s).
transitional epithelium
A ______ _______ is an unusual stratified epithelium because, unlike most epithelia, it tolerates repeated cycles of stretching and recoiling (returning to its previous shape) without damage.
simple squamous epithelium
A _______ _______ _______is the body's most delicate type of epithelium. This type of epithelium is located in protected regions where absorption or diffusion takes place, or where a slick, slippery surface reduces friction. Examples are the respiratory exchange surfaces (alveoli) of the lungs, the lining of the ventral body cavities, and the lining of the heart and blood vessels.
nonkeratinized
A _______ stratified squamous epithelium resists abrasion, but will dry out and deteriorate unless kept moist. _________ stratified squamous epithelia are situated in the oral cavity, pharynx, esophagus, anus, and vagina.
dense area
A typical macula adherens is formed by two cells. Within each cell is a complex known as a _____ _____, which is connected to the cytoskeleton. It is this connection to the cytoskeleton that gives the macula adherens—and the epithelium—its strength.
tissues
A variety of cell types arranged in various combinations form ______, structures with discrete structural and functional properties. The four ______ types are epithelial, connective, muscle, and neural.
gap junction
At a ___ _____, two cells are held together by interlocking junctional proteins called connexons.
tight junction
At an occluding or _______ _______, the lipid portions of the two plasma membranes are tightly bound together by inter- locking membrane proteins
tissues
Cells organized into layers create ______.
cell junctions
Cellularity: Epithelia are composed almost entirely of cells bound closely together by interconnections known as ____ _______(s).
merocrine secretion
Modes of Glandular Secretion: In ______ _______, secretory vesicles are discharged at the apical surface of the gland cell by exocytosis. This is the most common mode of secretion. One type of merocrine secretion, mucin, mixes with water to orm mucus, an effective lubricant, a protective barrier, and a sticky trap for foreign particles and microorganisms.
apocrine secretion
Modes of Glandular Secretion: _______ _______ involves the loss of apical cytoplasm. Inclusions, secretory vesicles, and other cytoplasmic components are shed in the process. The gland cell then undergoes growth and repair before it releases additional secretions, Milk production in the mammary glands involves a combination of merocrine and _______ ______.
holocrine secretion
Modes of Glandular Secretion: _______ _______ occurs as superficial gland cells burst. Continued secretion involves the replacement of these cells through the mitotic division of underlying stem cells.
apocrine secretion
Modes of Secretion in Glandular Epithelia: - Is produced in Golgi apparatus - Is released by shedding cytoplasm - For example, mammary gland
merocrine secretion
Modes of Secretion in Glandular Epithelia: - Is produced in Golgi apparatus - Is released by vesicles (exocytosis) - For example, sweat glands
holocrine secretion
Modes of Secretion in Glandular Epithelia: - Is released by cells bursting, killing gland cells - Gland cells replaced by stem cells - For example, sebaceous gland
macula adherens
Most epithelial cells are subject to mechanical stresses— stretching, bending, twisting, or compression—so they must have durable interconnections. At a _______ ______(s) or desmosome (DEZ-mo-som; desmos, ligament + soma, body), CAMs and proteoglycans link the opposing plasma membranes. _______ ______(s) are very strong and can resist stretching and twisting.
germinative cells
Most stem cells, also called _________ _____(s), are located near the basal lamina, in a relatively protected location.
keratin
On exposed body surfaces, where mechanical stress and dehydration are potential problems, apical layers of epithelial cells are packed with filaments of the protein _______.
pseudostratified columnar epithelium
Portions of the respiratory tract contain a ____ _____ _____, a columnar epithelium that includes several types of cells with varying shapes and functions. The distances between the cell nuclei and the exposed surface vary, so the epithelium appears to be layered, or stratified. It is not truly stratified, though, because every epithelial cell contacts the basal lamina. _____ _____ _____ cells typically possess cilia. Epithelia of this type line most of the nasal cavity, the trachea (windpipe), the bronchi (branches of the trachea leading to the lungs), and portions of the male reproductive tract
avascular
a-, without + vas, vessel
