Tissues Flashcards
groups of cells that are similar in structure and perform a common or related function
Tissue
Four primary tissue types are
epithelial (covering)
connective (support)
muscle (movement)
nervous tissue (control)
a sheet of cells that covers a body surface or lines a body cavity
Epithelial Tissue
Epithelium has many functions including
- protection
- absorption
- filtration
- excretion
- secretion
- sensory reception
Epitielial tissue occurs as
covering and lining epithelium: forms the outer layer of the skin
dips into and lines the open cavities of the cardiovascular, digestive, and respiratory systems
covers the walls and organs of the closed ventral body cavity
2) glandular epithelium: fashions the glands of the body.
All epithelia have two surfaces
apical surface
basal surface
n upper free surface exposed to the exterior or cavity of an internal organ
apical surface
How are Epithelia tissue named
Indicates the number of cell layers present.
The shape of its cells.
Named by the cells at the apical layer
T or F. Epithelial tissue is avascular but innervated (contains no blood vessels)
T
Three common shapes of epithelial cells:
squamous, cuboidal, and columnar.
Concerned with absorption, secretion, and filtration.
Thin and often permeable.
Found where filtration or the exchange of substances by rapid diffusion is a priority
Simple Epithelia
Boxlike
About as tall as they are wide
Spherical nucleus
Forms the walls of the smallest ducts of glands and many kidney tubules
Simple Cuboidal Epithelium
Tall and column shaped
Elongated nuclei (from top to bottom)
Located close to the cell base
Lines the digestive tract from the stomach through the rectum.
Mostly associated with absorption and secretion
Simple Columnar Epithelium
Varies in height
All cells rest on the basement membrane, but only the tallest reach the free surface of the epithelium
Cell nuclei lay at different levels, gives the false impression that there are several layers.
This epithelium secretes or absorbs substances
Pseudostratified Columnar Epithelium
Contains two or more cell layers.
Regenerate from below - they divide and push apically to replace the older surface cells.
More durable than the simple epithelial.
Typically found in high-abrasion areas where protection is important, such as skin surface
Stratified Epithelia
most widespread of the stratified epithelia.
Made of several layers, it’s thick and well suited for protection.
Free surface cells are squamous, deeper cells are cuboidal or columnar.
Found in areas with wear and tear.
Surface cells are constantly rubbed away and replaced.
Forms the external part of the skin and extends a short distance into every body opening that’s directly continuous with the skin
Stratified Squamous Epithelium
rare in the body, mostly found in ducts of some of the larger glands (sweat, mammary).
Stratified Cuboidal Epithelia
small amounts are found in the pharynx, male urethra, and lining some glandular ducts
Stratified columnar epithelium
Forms the lining of hollow urinary organs, which stretch as they fill with urine
Transitional Epithelium
one or more cells that make and secrete (export) a particular product.
The product is called a secretion.
Classified as endocrine (internally secreting) or exocrine (externally secreting), depending on where they release their product.
Also classified as unicellular (one-celled) or multicellular (many-celled) depending on how many cells make up the gland.
Gland (glandular epithelia)
called ductless glands because they eventually lose their ducts. Produce hormones (regulatory chemicals) secreted directly into the extracellular space.
Endocrine Glands
glands that have ducts.
Secrete their products onto body surfaces (skin) or into body cavities.
Ex. mucous, sweat, oil, and salivary glands, the liver, and the pancreas.
Exocrine Glands
only important example is the goblet cell.
Scattered in the epithelial linings of the intestinal and respiratory tracts.
All of these glands produce mucin, which when dissolved, forms mucus
Unicellular Exocrine Glands
The most abundant and widely distributed of the primary tissues
Connective Tissue
four main classes of connective tissue
Connective tissue proper (includes fat and fibrous tissue of ligaments)
Cartilage
Bone tissue
Blood
Aside from connecting body parts, connective tissue has many functions
binding and support
protection
insulation
and as blood, transportation
Common characteristics of connective tissue
Common origin – arises from mesenchyme (an embryonic tissue).
2. Degrees of vascularity:
cartilage is avascular
dense connective tissue is poorly vascularized
other varieties have rich vascularization.
3. Extracellular matrix – composed mainly of nonliving extracellular matrix (made of ground substance and fibers).
what are the 3 structural elements of connective tissue
Ground substance, fibers, cells
unstructured material that fills space between cells and contains fibers.
Ground substance
Connective tissue fibers do what
provides support
Three types of connective tissue fibers
Collagen
Elastic fibers
Reticular fibers
Extremely tough and provide high tensile strength to the matrix.
Also referred to as white fibers
Collagen
long, thick fibers which form branching networks in the extracellular matrix.
Contain a rubber-like protein-elastin, which allows them to stretch and recoil; Sometimes called yellow fibers
Elastic fibers
fine collagenous fibers continuous with collagen fibers.
Branch extensively.
Form delicate networks which surround small blood vessels and support the soft tissue organs.
Abundant where connective tissue abuts other tissue types.
Ex. the basement membrane of epithelial tissues and around capillaries.
Reticular fibers
undifferentiated cells which are actively mitotic and secrete the ground substance and the fibers characteristic of their particular matrix.
suffix “blast”
The primary blast cell types by connective tissue class are
fibroblast – connective tissue proper
chondroblast – cartilage
osteoblast – bone
hematopoietic stem cell - blood (always actively mitotic)
What are the two subclasses of connective tissue proper?
loose connective tissues
dense connective tissues
Examples of loose connective tissues
areolar, adipose, and reticular
Examples of dense connective tissues
dense regular, dense irregular, and elastic
- supporting and binding other tissues.
- holding body fluids (ground substance role).
- defending against infection (activity of white blood cells and macrophages).
- storing nutrients as fats (in fat cells)
Areolar Connective Tissue (shared by other connective tissue)
flat, branching cells
fibroblast
Provides a reservoir of water and salt for surrounding body tissues
Areolar connective tissue
The most widely distributed connective tissue in the body and serves as a kind of universal packing material between other tissues
Areolar connective tissue
Binds body parts together while allowing them to move freely over one another
Wraps small blood vessels and nerves
Areolar connective tissue
Surrounds glands
Forms the subcutaneous tissue, which cushions and attaches the skin to underlying structures.
Present in all mucous membranes as the lamina propria
Areolar connective tissue
The matrix is scanty and the cells are packed closely together, giving a chicken wire appearance to this tissue
Adipose (Fat) Tissue
Adipocytes predominate and account for 90% of this tissues mass
Adipose (Fat) Tissue
Usually accumulates in subcutaneous tissue, where it acts as a shock absorber and as insulation.
Helps prevent heat loss from the body
Richly vascularized and highly metabolic
Adipose (Fat) Tissue
____ fat stores nutrients
white
_____ fat consumes its nutrient stores to generate heat to warm the body
brown
Forms a delicate network along which fibroblasts, called reticular cells, lie scattered.
Limited to certain sites.
Can support many free blood cells in lymph nodes, the spleen, and bone marrow
Reticular Connective Tissue
Contains loosely packed bundles of collagen fibers running in the same direction, parallel to the direction of pull
Dense Regular Connective Tissue aka fibrous connective tissue
It is a white, flexible structure with great resistance to tension (pulling forces) where the tension is exerted in a single direction
Dense Regular Connective Tissue
It’s poorly vascularized
Forms tendons, cords which attach muscle to bone, and flat, sheetlike tendons called aponeuroses, which attaches muscle to other muscles or to bones.
Forms ligaments, binds bones together as joints
Dense Regular Connective Tissue
Found in the skin as the dermis.
Forms fibrous joint capsules and the fibrous coverings that surround some organs (testes, kidneys, bones, cartilages, muscles, and nerves).
Dense Regular Connective Tissue
