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
Nonciliated simple columnar epthelium
single layer nonciliated column like cells with oval nuclei near base of cells;
mircovilli: fingerlike cytoplasmic projections, increase surface area of plasma membrane, increase rate of absorption by cell
goblet cells: modified columnar epithelial cells, mucus
lines the gastrointestinal tract, ducts of glands and gallbladder
secretion and absorption, lubricant, prevent destruction of stomach lining; capable of higher level of secretion/absorption
Ciliated Simple Columnar Epithelium
single layer ciliated column cells with oval nuclei near base; upper resp. tract, goblet cells are interspersed
lines some bronchioles of resp tract, uterine tubes, uterus, paranasal sinuses, central canal of spinal cord, ventricles of the brain
cilia beat in unison, moving mucus toward throat, coughing/sneezing speeds up movement, help move oocytes expelled from ovaries through tube
Pseudostratified Columnar Epithelium
nuclei of cells are at various layers, all attached to basement membrane
ciliated= contains cells that extend to surface and either secrete mucus or bear cilia
unciliated= contains cells without cilia and lack goblet cells
lines airways of upper resp. tract vs lines larger ducts of many glands, epididymis and male urethra
secrete mucus that traps foreign particles, sweep away mucus vs absorption and protection
Stratified Squamous Epithelium
two or more layers of cells; apical layer are squamous; at apical layer, dead cells lose cell junction
Keratinized SSE develop tough layer of keratin in apical layer; more keratin farther away from blood supply
Nonkeratinized constantly moistened by mucus (organelles not replaced)
keratinized form superficial layer of skin; non lines wet surfaces
protects against abrasion, water loss, ultraviolet radiation, foreign invasion, form the first line of defense against microbes
Stratified Cuboidal Epithelium
two or more layers of cells, apical layer are cube-shaped (rare type)
ducts of adult sweat glands and esophageal glands and part of male urethra
protection and limited secretion and absorption
Stratified Columnar Epithelium
basal layers consist of shortened shaped cells; only apical layers have columnar in shape (uncommon)
lines part of urethra, large excretory glands, small area in anal mucous membrane, part of conjunctive of eye
protection and secretion
Transitional Epithelium
relaxed- stratified cubodial ( apical layer are large and rounded)
stretched- cells become flatter, stratified squamous
ideal for lining hollow structures that are subject to expansion
lines urinary bladder and portions of ureter and urethra
allows organs to strech to hold a variable amount of fluid without rupturing
Gland
single or group of cells that secrete substances via ducts onto a surface, or into the blood in the absence of ducts
Endocrine Glands
enter ICF and diffuse directly into the bloodstream without flowing through a duct; hormones regulate activities to maintain homeostasis; far-reaching effects because distributed throughout the body
Exocrine Glands
secrete their products into ducts that empty onto the surface of a covering or lining epithelium; limited effects, harmful if entered bloodstream