Ch. 3 Tissues Flashcards
Connective Tissue
protects and supports the body and its organs;
binds organs together, store energy reserves as fast, and helps provide body with immunity to disease-causing organisms
Muscular Tissue
composed of cells specialized for contraction and generation of force, generates heat that warms the body
Nervous Tissue
detects changes inside and outside the body and responds by generating electrical signals called nerve potentials that activate muscular contractions and glandular secretions
Cell Junctions
contact points between plasma and membranes of tissue cells
Tight Junctions
weblike strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells; impermeable
Ex. Stomach, intestine, urinary bladder
Adherens Junctions
contain plaque; dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and to microfilaments of the cytoskeleton
Permeable, resist separation
Ex. Lining of intestine
Cadherins
transmembrane glycoproteins join the cells; inserts into the plaque from the opposite side of the plasma membrane; crosses intercellular space, and connects to a cadherin of an adjacent cell
Demosomes
contain plaque and have transmembrane glycoproteins that extend into the intercellular space between adjacent cell membranes and attach cells to one another; does not attach to microfilaments instead attached to elements of the cytoskeleton known as intermediate filaments; contributes to stability of the cells and tissue, prevent from separating under tension and cardiac muscle cells from pulling apart; permeable
Ex. Outer layer of skin and heart muscles
Hemidesmosomes
resemble desmosomes but do not link adjacent cells; transmembrane glycoproteins are called intergrins
intergrins attach to intermediate filaments made of protein keratin on the inside of the plasma membrane, on the outside of the plasma membrane, intergrins attach to the protein laminin
anchor to the basement membrane vs one another
Gap Junctions
membrane proteins called connexins form tiny fluid filled tunnels called connexons that connect neighboring cells
separated by a very narrow intercellular gap, ions and small molecules can diffuse from the cytosol of one cell to another but passage of large molecules is prevented
communicate with one another, enable nerve or muscle impulses to spread rapidly among cells
Ex. Lens, cornea, nerves and muscles
Epithelial Tissue
covers body surfaces, and lines hollow organs, body cavities, and ducts; also forms glands
allows body to interact with both internal and external enviroments
Epithelial VS Connective Tissue
tightly packed together with little extracellular matrix- large amount of extracellular matrix separates cells
no blood vessels- networks of blood vessels
always forms surface layers and not covered by another tissue (except within blood vessels)
always found immediately adjacent to blood-vessel-rich connective tissue, enables exchanges with blood
Epithelium
cells in continuous sheets, little intercellular space between adjacent plasma membranes, forms coverings and linings throughout the body
- serves as a selective barrier to limit or aid transfer of substances
- releases products produced by the cells onto its free surfaces
- protects against the abrasive influences of the environment
apical (free) surface
faces the body surface, a body cavity, lumen of an internal organ, or tubular duct; may contain cilia or microvilli
Lateral Surfaces
face adjacent cells on either side, may contain cell junctions
Basal Surface
opposite the apical surface; adhere to extracellular materials such as the basement membrane (hemidesmosomes)
apical layer: superficial layer of cells
basal layer: deepest layer of cells
Basement Membrane
thin extracellular layer that consists of two layers;
basal lamina: closer to and secreted by the epithelial cells, consists of proteins and glycoproteins and proteoglycans (laminin adhere to integrins)
reticular lamina: closer to underlaying connective tissue and contains proteins
form a surface to migrate during growth or wound healing, restrict larger molecules between epithelium and connective tissue, participate in filtration of blood in the kidneys
Avascular
no blood vessels
Covering and Lining Epthelium
forms outer covering of the skin and some internal organs, forms the inner lining of blood vessels, ducts, and body cavities, and interior of the respiratory, digestive, urinary, and reproductive systems
Glandular Epthelium
makes up secreting portion of glands such as the thyroid, adrenal, and sweat glands
Arrangement of Cells in Layers
a) simple (unilaminar) epithelium: single layer of cells that diffuse, osmosis, filtration, secretion, absorption
b) pseudostratified epithelium: appears to have multiple layers of cells because cell nuclei lie at different levels and not all cells reach apical surface, all cells rest on the basement membrane
c) stratified (multilaminar) epithelium: consists of two or more layers of cells that protect underlying tissues in locations of wear and tear
Cell Shapes
a) squamous cells: thin, allow rapid passage of substances through them
b) cuboidal cells: tall as they are wide, shaped like hexagons or cubes, have microvilli at their apical surface and function in secretion or absorption
c) columnar cells: much taller than wide, protect underlying tissues, apical surfaces may have cilia or microvilli, secretion and absorption
d) transitional cells: change shape, squamous to cuboidal and back, as organs stretch to a larger size and then collapse small
Simple Squamous Epithelieum
single layer of flat cells; centrally located nucleus that is flattened and oval
endothelium: lines cardiovascular and lymphatic system
Mesothelium: serous membrane
air sacs of lungs, capsule of kidneys, inner surface of tympanic membrane
present where process of filtration, diffusion, absorption and secretion occur
Simple Cuboidal Epithelium
single layer of cube-shaped cells, round, centrally nucleus
covers surface of ovary, lines anterior surface of capsule of the lens of the eye, forms pigmented epithelium at posterior surface of the retina, lines kidney tubules and smaller ducts of many glands, makes up secretory portion of glands
secretion and absorption
