Cells and tissues
classification of epithelium
Classification on the basis of arrangement (layers)
stratified epithelium
Stratified epithelia consist of two or more cell layers. considerably more durable than the simple epithelia these epithelia function primarily to protect (skin)
where are stratified squamous cells found?
Stratified squamous epithelium is found in sites that receive a good deal of abuse or friction, such as the esophagus, the mouth, and the outer portion of the skin
simple epithelia
concerned with absorption, secretion, and filtration. Because simple epithelia are usually very thin, protection is not one of their specialties. ex: in the gut; lumen of small intestine; alveoli of lung
support
connective
chlorine
in ionic form, a makor extracellular anion
potassium
in its ionic form, the major intracellular cation necessary for the conduction of nerve impulses and for muscles contraction
cells
the smallest structural and functional unit of an organism typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane
pseudostratified columnar epithelium
All of the cells of pseudo stratified columnar epithelium rest on a basement membrane. However, some of its cells are shorter than others, and their nuclei appear at different heights above the basement membrane
glandular epithelium
Composed of cells that are specialized to produce and secrete substances.
epithelial absorption
Epithelium specialized to absorb substances lines some digestive system organs such as the stomach and small intestine, which absorb food nutrients into the body.
Special Characteristics of Epithelium
Except for glandular epithelium (described), epithelial cells fit closely together to form continuous sheets. Neighboring cells are bound together at many points by specialized cell junctions, including desmosomes and tight junctions. The membranes always have one free (unattached) surface or edge. This so-called apical surface is exposed to the body's exterior or to the cavity of an internal organ. The exposed surfaces of some epithelia are slick and smooth, but others exhibit cell surface modifications, such as microvilli or cilia. The lower surface of an epithelium rests on a basement membrane, a structureless material secreted by both the epithelial cells and the connective tissue cells that abut the epithelium. Epithelial tissues have no blood supply of their own (that is, they are avascular) and depend on diffusion from the capillaries in the underlying connective tissue for food and oxygen If well nourished, epithelial cells regenerate themselves easily
simple columnar
Forms the lining of the stomach and small intestine functions in absorption and secretion
Pseudostratified Columnar Epithelium
Like simple columnar epithelium, this variety mainly functions in absorption and secretion.
pseudostratified ciliated columnar
Lines much of the respiratory tract The mucus produced by the goblet cells in this epithelium traps dust and other debris, and the cilia propel the mucus upward and away from the lungs.
epithelial secretion
Secretion is a specialty of the glands, which produce such substances as perspiration, oil, digestive enzymes, and mucus.
fibroblast
The elongated shape of this cell lies along the cable-like fibers that it secretes
Fibroblasts
The elongated shape of this cell lies along the cable-like fibers that it secretes. It has an abundant rough ER and a large Golgi apparatus to make and secrete the protein building blocks of these fibers; a cell in connective tissue which produces collagen and other fibers.
epithelial filtration
The epithelium lining the respiratory tract has cilia, which sweep dust and other debris away from the lungs. In the kidneys, epithelium both absorbs and filters.
epthelial cells
The hexagonal shape of this cell is exactly like a "cell" in a honeycomb of a beehive. This shape allows epithelial cells to pack together in sheets. An epithelial cell has abundant intermediate filaments that resist tearing when the epithelium is rubbed or pulled. behaves like wallpaper that covers surfaces
skeletal muscle and smooth muscle cells
These cells are elongated and filled with abundant contractile filaments, so they can shorten forcefully and move the bones or change the size of internal organs
why is it called transitional epithelium?
This ability to slide past one another and change their shape (undergo "transitions") allows the ureter wall to stretch as a greater volume of urine flows through that tubelike organ. In the bladder, it allows more urine to be stored.
Erythrocyte (red blood cell)
This cell carries oxygen in the bloodstream. Its concave disk shape provides extra surface area for the uptake of oxygen and streamlines the cell so it flows easily through the bloodstream. So much oxygen-carrying pigment is packed in here than all other organelles have been shed to make room.
nerve cell (neuron)
This cell has long processes for receiving messages and transmitting them to other structures in the body. The processes are covered with an extensive plasma membrane, and a plentiful rough ER is present to synthesize membrane components
hydrogen
a component of most organic molecules; in ionic form, influences the pH of body fluids
nitrogen
a component of proteins and nucleic acids (genetic material)
sulfur
a component of proteins, particularly contractile proteins of muscle
iron
a component of the functional hemoglobin molecule (which transports oxygen within red blood cells) and some enzymes
transitional epithelium
a highly modified, stratified squamous epithelium that forms the lining of only a few organs—the urinary bladder, the ureters, and part of the urethra All these organs are part of the urinary system and are subject to considerable stretching Cells of the basal layer are cuboidal or columnar; those at the free surface vary in appearance When the organ is not stretched, the membrane is many-layered, and the superficial cells are rounded and domelike. When the organ is distended with urine, the epithelium thins, and the surface cells flatten and become squamous like
oxygen
a major component of both organic and inorganic molecules; as a gas, essential to the oxidation of glucose and other food fuels, during which cellular energy (ATP) is produced
Macrophages
a phagocytic cell This cell extends long pseudopods ("false feet") to crawl through tissue to reach infection sites The many lysosomes within the cell digest the infectious microorganisms it takes up
secretory portion of exocrine gland
acinar or tubular may be branched produce secretory product
parts of a cell
all cells have 3 main parts: nucleus, cytoplasm and plasma membrane
sodium
as an ion, the major extracellular cation important for water balance, conduction of nerve impulses and muscle contraction
conducting portion of exocrine gland
branched or unbranched modifies secretory product by absorption contributes to secretion in some glands
gland
consists of one or more cells that make and secrete a particular product, a secretion
which cell covers and lines body organs?
epithelial cells
covering
epithelium
the 4 primary tissue types MENC
epithelium connective tissue nervous tissue muscle all interweave to form the fabric of the body
epithelial protection
epithelium of the skin protects against bacterial and chemical damage
2 types of glandular epithelium
exocrine and endocrine
what cells store nutrients?
fat cells
oocyte
female The largest cell in the body this egg cell contains several copies of all organelles, for distribution to the daughter cells that arise when the fertilized egg divides to become an embryo
which cells connect body parts?
fibroblasts and erythrocytes
calcium
found as a salt in bones and teeth in ionic form, required for muscle contraction , neutral transmission and blood clotting
body tissues
groups of cells that are similar in structure and function
Function of fibroblasts
has an abundant rough ER and large golgi apparatus to make and secrete the protein building blocks of fibers a cell in connective tissue which produces collagen and other fibers
neutron
in the nucleus neutral charge mass 1 amu
proton
in the nucleus positive charge mass 1 amu
examples of pH
lemon juice; gastric juice= 2 saliva; milk= 6.5 distilled water= 7 human blood; semen= 7.4 household bleach= 12
endocrine
lose their connection to the surface (duct); thus they are often called ductless glands Their secretions (all hormones) diffuse directly into the blood vessels that weave through the glands
what cells that fight disease?
macrophages
sperm
male This cell is long and streamlined, built for swimming to the egg for fertilization. Its flagellum acts as a motile whip to propel the sperm.
movement
muscle
iodine
needed to make functional thyroid hormones
what cells gather info and control body functions?
nerve cell
control
nervous
what are the cells of reproduction?
oocyte and sperm
electron
orbitals outside the nucleus negative charge 1/1800 amu
common elements that make up the human body
oxygen (65%) carbon (18.5%) hydrogen (9.5%) nitrogen (3.2%) calcium (1.5%) phosphorus (1%) potassium (0.4%) sulfur (0.3%) sodium (0.2%) chlorine (0.2%) magnesium (0.1%) iodine (0.1%) iron (0.1%)
Phosphorus
present as a salt, in combination with calcium in bones and teeth also present in nucleic acids and many proteins; forms part of the high-energy compound ATP
magnesium
present in bone important cofactor for enzyme activity in metabolic reactions
epithelial functions (FAPS)
protection, absorption, filtration, and secretion
what are the subatomic particles?
protons, neutrons, electrons
Erythrocyte
red blood cell this cell carries oxygen in the bloodstream its concave disk shape provides extra surface area for the uptake of oxygen and streamlines the cell so it flows easily through the bloodstream
exocrine glands
retain their ducts, and their secretions empty through the ducts to the epithelial surface include the sweat and oil glands, liver, and pancreas, are both internal and external.
simple cuboidal
secretion and absorption
epithelium
simple stratified squamous cuboidal columnar
simple squamous epithelium
single layer of thin squamous cells resting on a basement membrane the cells fit closely together, like floor tiles ex: form part of the alveolar walls
which cells move organs and body parts?
skeletal muscle and smooth muscle cells
fat cells (adipocytes)
store nutrients The huge spherical shape of a fat cell is produced by a large lipid droplet in its cytoplasm.
epithelial tissue
the lining, covering, and glandular tissue of the body Glandular epithelium forms various glands in the body. Covering and lining epithelium covers all free body surfaces and contains versatile cells. One type forms the outer layer of the skin. Others dip into the body to line its cavities. Because epithelium forms the boundaries that separate us from the outside world, nearly all substances that the body gives off or receives must pass through epithelium
Stratified Squamous Epithelium
the most common stratified epithelium in the body It usually consists of several layers of cells. The cells at the free edge are squamous cells, whereas those close to the basement membrane are cuboidal or columnar
carbon
the primary elemental component of all organic molecules, including carbohydrates, lipids, proteins, and nucleic acids
what are examples of endocrine glands
thyroid, adrenals, and pituitary
secretion
typically contains protein molecules in an aqueous (water-based) fluid.
Stratified Cuboidal and Stratified Columnar Epithelia
typically has just two cell layers with (at least) the surface cells being cuboidal in shape The surface cells of stratified columnar epithelium are columnar cells, but its basal cells vary in size and shape Both of these epithelia are fairly rare in the body, found mainly in the ducts of large glands.