Ch 4 - The Tissue Level of Organization Flashcards
tissue
a group of cells that usually have a common origin in an embryo and function together to carry out specialized activities
histology
the science that deals with the study of tissues
pathologist
a physician who examines cells and tissues to help other physicians make accurate diagnoses
specialist in the study of diseases
epithelial tissue
AKA Epithelium
Cells are arranged in sheets
Cells are densely packed
Many cell junctions are present
Epithelial cells attach to a basement membrane
Epithelial tissue is avascular but does have a nerve supply
Mitosis occurs frequently
connective tissue
protects and supports the body and its organs. Various types of connective tissues bind organs together, store energy reserves as fat, and help provide the body with immunity to disease-causing organisms.
muscular tissue
composed of cells specialized for contraction and generation of force. In the process, muscular tissue generates hear that warms the body.
nervous tissue
detects changes in a variety of conditions inside and outside the body and responds by generating electrical signals called nerve action potentials (nerve impulses) that activate muscular contractions and glandular secretions.
biopsy
the removal of a sample of living tissue for microscopic examination
cell junctions
contact points between the plasma membranes of tissue cells
tight junctions
web-like strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passage ways between adjacent cells
prevent contents of organs from leaking into blood or surrounding tissue
common in: stomach, intestines, urinary bladder
adherens junctions
contain plaque (dense layer of proteins), cadherins join the cells, usually forms an adhesion belt
Plaque attaches to membrane proteins and microfilaments
Great at resisting separation during contractile activities
Ex. Food moving through intestines
desmosomes
similar to adherens junctions (have plaque and cadherens), plaque attaches to intermediate filaments of cytoskeletol (keratin), spot weld-like junctions, contribute to stability
common in: epidermis, cardiac muscle cells
hemidesmosomes
look like half of a desmosome but DO NOT link adjacent cells, their transmembrane glycoproteins are integrins NOT cadherins, anchor cells NOT to each other but to the basement membrane
gap junctions
connexins form tiny tunnels called connexons, plasma membranes are NOT connected but are separated by a gap
Ions and small molecules diffuse through connexons to the next cell
apical (free) surface
may contain microvilli or cilia
basal surface
opposite the apical surface
basement membrane
a thin extracellular layer that commonly consists of two layers, the basal lamina and reticular lamina
covering and lining epithelium
forms the outer covering of the skin and some internal organs. It also forms the inner lining of blood vessels, ducts, and body cavities, and the interior of the respiratory, digestive, urinary, and reproductive systems.
glandular epithelium
makes up the secreting portion of glands such as the thyroid gland, adrenal galnds, and sweat glands.
Simple
(layer arrangement of epithelial cells)
single layer, for secretion, absorption, diffusion
Pseudostratified
(layer arrangement of epithelial cells)
appears to have multiple layers because NOT all cells reach apical surface
ALL of its cells rest on the basement membrane
nuclei are at different levels
