Chapter 4 - The Tissue Level of Organization Flashcards
(114 cards)
Define tissue
A group of cells that usually have a common origin in an embryo and function together to carry out specialized activities
Define histology
The science of the study of tissues
Epithelial tissue
Covers body surfaces and lines hollow organs, body cavities, and ducts; it also forms glands. Allows body to interact with internal and external environments
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-casuing organisms.
Muscular tissue
is composed of cells specialized for contraction and generation of force. Generates heat.
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.
Cell junction
contact points between the plasma membranes of tissue cells
Tight Junction
weblike strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells. Prevent contents of organs like bladder from leaking into blood
Adherens junction
Contain plaque, a dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and to microfilaments of the cytoskeleton. Transmembrane glycoproteins called cadherins join the cells.
Often form Adhesion belts. Help resist seperation
Desmosome
contain plaque and have transmembrane glycoproteins that attach cells to one another, attaches using elements of the cytoskeleton aka intermediate filaments (made of keratin) preventing seperation
Hemidesmosome
Integrins attach to intermediate filaments, on outside attach to laminin to anchor cells to each other and the basement membrane
Gap junction
connexins connect neighboring cells. Through connexons ions and small molecules can diffuse from the cytosol of one cell to another.
Pathologist
Physician who examines cells and tissues to help other physicians make accurate diagnoses
General features of epithelial tissue
Many cells tightly packed together with little or no extracellular matrix. No blood vessels. Almost always forms surface layers, not covered by another tissue (except lining of blood vessels) Always found immediately adjacent to blood vessel-rich connective tissue.
Apical
Apical (free) surface faces the body surface, cavity, lumen or tubular duct that receives cell secretions. May contain cilia or microvilli.
Basement membrane
thin extracellular layer that consists of two layers, basal lamina and reticular lamina. Attaching to and supporting overlying epithelial tissue. Form a surface along which epithelial cells migrate during growth or healing, restrict passage of large molecules, and filter blood in kidneys.
Covering/Lining epithelium
forms outer covering of skin and some internal organs. Inner lining of blood vessels, ducts, body cavities, and interior of the respiratory, digestive, urinary, and reproductive systems.
Glandular Epithelium
makes up the secreting portion of glands such as the thyroid gland, adrenal glands, and sweat glands.
Lateral surface
may contain tight junctions, adherens junctions, desmosomes, gap junctions.
Basal surface
deepest layer of epithelial cells adhere to extracellular materials such as basement membrane.
Main roles of epithelial tissue
protection, filtration, secretion, absorption, excretion
Structure location and function of simple squamous epithelium
Single layer of flat cells, flattened oval nucleus in centre.
lines cardiovascular and lymphatic system known as endothelium. OR form epithelial layer of serous membranes known as mesothelium. Air sacs of lungs, glomerular capsule of kidneys, inner surface of tympanic membrane.
Sites of filtration, diffusion, secretion
Structure location and function of simple cuboidal epithelium
single layer of cube shaped cells Surface of ovary, anterior surface of capsule lens of eye, pigmented epithelium at posterior surface of retina, lines kidney tubules, secretion and absorption
Structure location and function of simple columnar epithelium
ciliated or nonciliated. single layer contains columnar epithelial cells with microvili at apical surafce and goblet cells.
Lines gastrointestinal tract, ducts of many glands and gullbladder.
Secretiona nd absorption.
Ciliated: lines some bronchioles, uterine tubes, central canal of spinal cord, ventricles of brian, the cilia beat in unison moving mucus and foreign particles toward throat.
