Chapter 4 Flashcards
What is tissue and what are 4 major types of tissue
Tissue is a group of cells that have a common origin and function Epithelial, connective, muscle and nervous tissue are the 4 types present in the body
Histology and pathologist
Histology is the study of tissue A pathologist examines and studies tissue and cells
Epithelial tissue
Covers body surfaces and lines hollow organs, cavities and ducts Forms glands, Allows body to interact with both internal and external environments
Connective tissue
Protects and supports body and organs Bonds organs together, stores energy reserves as fat, helps provide immunity against disease causing organisms
Muscular tissue
Composed of cells specialized for contraction and generation of force Generates heat
Nervous tissue
Detects changes inside and outside body, responds to changes by generating nerve action potentials (nerve impulses) to activate muscle contractions and glandular secretions
Glands
Cells that secrete substances Endocrine glands excrete hormones into interstitial fluid and directly into bloodstream Exocrine glands excrete products into ducts that empty on to skin and hollow organs, products can be harmful in bloodstream
Glandular epithelium
Glands made of epithelial tissue that secrete hormones and other products
Connective tissue cells
Fibroblasts, macrophage, plasma cells, mast cell, andipocyte, and leucocytes
Extracellular matrix of connective tissue
Material between widely spread apart cells in connective tissue Consists of protein fibres and ground substance Secreted by connective cells Determines tissues qualities
Fibroblast
Large flat cells with branching processes Most numerous cells present in connective tissue Secrete fibres and ground substance
Macrophages
Develop from monocytes Type of white blood cell Irregular shape with short branching projections Engulf bacteria and debris produced by phagocytosis Fixed macrophages reside in specific areas such as alveolar macrophages in lungs. Wandering macrophages move through tissue and gather at infection sites to carry out phagocytosis.
Plasma cells
Small cells developed from small white blood cells called B lymphocytes. Secrete antibodies and proteins that attack or neutralize foreign substances. Important to immune system
Mast cells
Abundant along blood vessels Produce histamine which dial antes small blood vessels as inflammatory response Binds to, ingests, and kills bacteria
Adipocytes
Fat cells or adipose cells Store fats Found around deep organs such as heart and kidneys
Tight Cell Junctions
Made of web like strands of membrane protiens that fuse together outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells.
Present in tissue lining stomach, intestines, and urinary bladder,
Inhibit passage of substances between cells and prevent contents of organs from leaking into surrounding tissue
Adherens Junctions
Contain plaque- dense layer of proteins on inside of plasma membrane that attach to both membrane proteins and cytoskeleton of cells. Joined by transmembrane glycoproteins called cadherins.
form extensive zones called adherens belts.
help epitheleal surfaces resist seperation during contractile activities.
Desmosomes
contain plaque and transmembrane glycoproteins.
plaque of desmosomes does not attatch to microfilaments, instead attaches to intermediate filaments.
contributes to stability of cells and tissue, common among cells in epidermis and cardiac muscle cells.
prevent epidermal cells from seperating under tension and prevent muscle cells from pulling apart during contraction.
Hemidesmosomes
have transmembrane protiens called integrins, look like half of a desmosome.
attach to intermediate filaments made of keratin on inside, on ouutside attatch to laminin.
Do not anchor to other cells.
Gap junctions
connexins protiens form fluid filled tunnels called connexons that connect neighboring cells.
cells seperated thrugh intracellular gaps, allowing diffusion of particles between cells.
allow for communication between cells by allowing nerve impulses to travel quickly between cells.
basement membrane
lowest part of membrane,
thin layer of epithelial tissue made up of mostly protein fibers, made up of basal lamina and reticular lamina.
function-to protect epithelial tissue and help with injury
Cell layers
Simple epithelium-single layer of cells, function in diffusion, osmosis, filtration, secretion or absorption.
Pseudostatified-appears to have multiple layers because nuclei lay at different levels, all cells rest on basement membrane. secrete mucus.
Stratified- consists of two or more layers of cells that protect underlying tissue in ocations where there is considerable wear and tear.
Cell shapes
Squamous cells-thin, allow for rapid passage of substances
Cuboidal-wide, shaped like cubes and hexagons. function in secretion or absorption.
Columnar-taller and thinner, like columns, protect underlying tissue. specialized for secretion or absorption.
Transitional-change shape, such as urinary bladdar stretching and collapsing.
structural classification of exocrine glands
unicellular
multicellular
simple
compound
acinar
tubuloacinar
unicellular-single cell glands, ex-goblet cells are inportant in unicellular glands that secrete mucus, found in epitheleal lining of respiratory
multicellular-multi cell layer, ex-sweat glands
simple-duct does not branch out
compound-duct branches out
acinar-rounded secretatory glands
tubuloacinar-tubular secretatory glands
functional classifications of glands
merocrine
apocrine
holocrine
merocrine-secretory product is expelled out of cell into lumen,
apocrine-responsible for accumalation in apex in secreatory cells, cells pinch and cut off.
holocrine-secratory product accumulated, cells die and are released into lumen, rupture and secretory cells released.
