Integument 4a Flashcards
The four types of tissues
Epithelial, Connective, Muscle, Nerve
Epithelial Tissue
Covers and Lines body
Supported by connective tissue – reticular and basal laminae
Polarity – apical and basal surfaces
Special contacts – form continuous sheets held
together by tight junctions and desmosomes
Cellularity – composed almost entirely of cells
Avascular but innervated – contains no blood vessels but supplied by nerve fibers
Regenerative – rapidly replaces lost cells by cell
division
Epithelia: Simple Squamous
Single layer of flattened cells with disc-shaped nuclei and sparse cytoplasm
Function: Diffusion and filtration, Provide a slick, friction-reducing lining in lymphatic and cardiovascular systems
Present in the kidney glomeruli, lining of heart, blood vessels, lymphatic vessels, and serosae
Endothelium
A layer of flat cells lining the closed internal spaces of the body such as the inside of blood vessels and lymphatic vessels
Epithelia: Simple Cuboidal
Single layer of cubelike cells with large, spherical central nuclei
Function in secretion and absorption
Present in kidney tubules, ducts and secretory
portions of small glands, and ovary surface
Epithelia: Simple Columnar
Single layer of tall cells with oval nuclei; many contain cilia
Goblet cells are often found in this layer
Function in absorption and secretion
Nonciliated type line digestive tract and gallbladder
Ciliated type line small bronchi, uterine tubes, and some regions of the uterus
Cilia help move substances through internal passageways
Epithelia: Pseudostratified Column
Single layer of cells with different heights; some do not reach the free surface
Nuclei are seen at different layers
Function in secretion and propulsion of mucus
Present in the male sperm-carrying ducts (nonciliated) and trachea (ciliated)
Epithelia: Stratified Squamous
Thick membrane composed of several layers of cells
Function in protection of underlying areas subjected to abrasion
Forms the external part of the skin’s epidermis (keratinized cells), and linings of the esophagus, mouth, and vagina (nonkeratinized cells)
Stratified cuboidal
Quite rare in the body
Found in some sweat and mammary glands
Typically two cell layers thick
Stratified columnar
Limited distribution in the body
Found in the pharynx, male urethra, and lining some glandular ducts
Also occurs at transition areas between two other types of epithelia
Epithelia: Transitional
Several cell layers, basal cells are cuboidal, surface cells are dome shaped
Stretches to permit the distension of the urinary bladder
Lines the urinary bladder, ureters, and part of the urethra
Epithelia: Glandular
A gland is one or more cells that makes and secretes an aqueous fluid
Endocrine Glands
Ductless glands that produce hormones
Secretions include amino acids, proteins,
glycoproteins, and steroids
Exocrine Glands
More numerous than endocrine glands
Secrete their products onto body surfaces (skin) or
into body cavities
Examples include mucous, sweat, oil, and salivary glands
The only important unicellular gland is the goblet cell
Multicellular exocrine glands are composed of
duct and secretory unit
Merocrine
products are secreted by exocytosis (e.g., pancreas, sweat, and salivary
glands)
Holocrine
products are secreted by the
rupture of gland cells (e.g., sebaceous glands)
Apocrine
part of apocrine epithelium comes off with it during secretion, cells are secreted as well leading to smell
Mucous
lines body cavities open to the exterior
e.g., digestive and respiratory tracts
Serous
moist membranes found in closed ventral body cavity
Connective Tissues are
Connective tissue proper
Cartilage
Bone
Blood
Functions of Connective Tissue
Binding and support
Protection
Insulation
Transportation
Connective tissues have
Mesenchyme as their common tissue of
origin
Varying degrees of vascularity
Nonliving extracellular matrix, consisting of ground substance and fibers
Mesenchyme
Stem cells, embryonic connective tissue,
Gel-like ground substance with fibers and star-shaped mesenchymal cells
Gives rise to all other connective tissues
Found in the embryo
