Ch. 4: Tissue - The Living Fabric Flashcards
Define Tissues
Groups of cells similar in structure that perform common or related function
Define Histology
Study of tissues; diagnose disease
Define Epithelial Tissue (epithelium)
Sheet of cells that covers body surfaces or cavities; forms boundaries between different environments
What are the 2 main forms of Epithelial Tissue?
- Covering & lining epithelia: external & internal surfaces (i.e. skin)
- Glandular epithelia: secretory tissue in glands (i.e. salivary glands)
What are the main functions of Epithelial Tissue?
Protection, absorption, filtration, excretion, secretion, & sensory reception
How are cells arranged in Epithelial Tissue?
Arranged in sheets, densely packed
What membrane are Epithelial Cells attached to?
Basement membrane
Describe the Polarity of Epithelial Tissue
- Apical surface exposed to surface or cavity; has microvilli
- Basal surface faces inwards toward body; attaches to basal lamina to hold underlying cells
What are the 5 distinguishing characteristics of Epithelial Tissues?
- Polarity
- Specialized contacts
- Supported by connective tissues
- Avascular, but innervated
- Regeneration
What does the first name of epithelial tissues indicate?
Number of cell layers
- SIMPLE epithelia = single layer thick
- STRATIFIED epithelia = 2 or more layers thick (involved in protection)
What does the second name of epithelial tissues indicate?
Shape of cells (cell named according to the shape in apical surface)
- Squamous = flattened & scale-like
- Cuboidal = box-like, cube
- Columnar = tall, column-like
How are covering and lining epithelia classified?
According to the shape of the cells & how many layers thick they are
Describe Simple Squamous Epithelium
- Single layer of flattened cells (simplest of epithelia), disc shaped nuclei
- Allows materials to pass by diffusion & filtration in sites where protection is not important
- Secretes lubricating substances in linings of ventral body cavity (serosae)
- Located in lung air sacs, heart lining, blood vessels, lymphatic vessels, serosae, & kidney glomeruli
Describe Simple Cuboidal Epithelium
- Single layer of cube like cells, large spherical nuclei
- Secretes & absorbs
- Located in kidney tubules, ducts & secretory portions of small glands, ovary surface
Describe Simple Columnar Epithelium
- Single layer of tall cells, round/oval nuclei, may contain cilia, microvilli, or goblet cells
- Absorbs, secretes mucus, enzymes, & other substance (ciliated type propels mucus or reproductive cells)
- Located in digestive tract (stomach to rectum), gallbladder, excretory ducts of some glands, small bronchi, uterine tubes, some regions of uterus
Describe Pseudostratified Columnar Epithelium
- Cells vary in height and appear to be multi-layered and stratified, but tissue is in fact single-layered simple epithelium
- Involved in secretion (of mucus) & in movement of mucus (ciliary sweeping)
- Located mostly in upper respiratory tract, ducts of large glands, tubules in testes
Describe Stratified Squamous Epithelium
- Basal cells are active in mitosis, produce cells of the more superficial layers
- Protects underlying tissues in areas subjected to abrasion
- Nonkeratinized forms moist linings of esophagus, mouth, vagina; keratinized forms epidermis of skin (dry epithelium)
Describe Transitional Epithelium (Stratified)
- Forms lining of hollow urinary organs (bladder, ureters, urethra)
- Basal layer cells are cuboidal or columnar
- Ability of cells to change shape when stretched allows for increased flow of urine & more storage (bladder)
Define a Gland (Glandular Epithelia)
One or more cells that makes & secretes an aqueous fluid (secretion)
How is Glandular Epithelia classified?
- Site of product release: endocrine - ductless, secreting into body fluids-blood (ex. hormones); exocrine - secreting through ducts (ex. sweat)
- Relative number of cells forming the gland (unicellular/goblet cells or multicellular)
What are the modes of secretion in multicellular exocrine glands
- Merocrine: secrete products by exocytosis as secretions are produced (sweat, pancreas)
- Holocrine: accumulate products within, then rupture (sebaceous oil glands)
- Apocrine: accumulate products within, but only apex ruptures
What type of epithelium is the epidermis made of?
Stratified squamous
What type of epithelium is found in the urinary bladder?
Transitional epithelium
Describe Connective Tissue
Most abundant & widely distributed of primary tissues
What are the major functions of Connective Tissue?
Binding & support, protecting, insulating, storing reserve fuel, transporting substances (blood)
What are the 4 main classes of Connective Tissue?
- Connective tissue proper
- Cartilage
- Bone
- Blood
What are the 3 characteristics that make connective tissues different from other primary tissues?
- All have common embryonic origin: arise from mesenchyme tissue as their tissue of origin
- Have varying degrees of vascularity (cartilage is avascular, bone is vascularized)
- Have 3 main elements: ground substance, fibers, & cells
What elements make up the extracellular matrix in connective tissue?
Ground substance & Fibers
Describe the 3 types of connective tissue fibers that provide support
- Collagen: strongest, most abundant, high tensile strength
- Elastic fibers: long, thin, elastin fibers that allow for stretch & recoil
- Reticular: short, fine, highly branched fibers, forms networks (from collagen fibers)
Describe Reticular Fibers
Made of collagen & glycoproteins, provide support in blood vessel walls, form branching networks around cells
Describe Collagen Fibers
Strong, flexible bundles of the protein collagen, most abundant protein in body
Describe Elastic fibers
Stretchy, strong, made of proteins, elastin, & fibrillin, found in skin, blood vessels & lung tissue
Describe “Blast” cells
Immature form of cell that actively secrets ground substance & ECM fibers
Describe Fibroblasts
Large, flat cells, move through connective tissue and secrete fibers & ground substance, found in connective tissue proper
Describe Chondroblasts
Found in cartilage
Describe Osteoblasts
Found in bone (hematopoietic stem cells in bone marrow)
Describe “Cyte” Cells
Mature, less active form of “blast” cell that now becomes part of and helps maintain health of matrix
Describe Connective Tissue Proper
Consists of all connective tissues except bone, cartilage, & blood
Describe Areolar Loose Connective Tissues
- Gel-like matrix with 3 fiber types; cells: fibroblasts, macrophages, mast cells, some WBC
- Wraps/cushions organs, macrophages ear bacteria, role in inflammation, holds & conveys tissue fluid
- Widely distributed under epithelia of bound, packages organs, surrounds capillaries
Describe Adipose Loose Connective Tissues
- Sparse gel-like matrix, closely packed adipocytes (fat cells), nucleus pushed to the side by large fat droplet
- Provides reserve food fuel, insulates, supports & protects organs
- Under skin in subcutaneous tissue; around kidneys & eyeballs, within abdomen & breasts
Describe Reticular Loose Connective Tissue
- Loose network of reticular fibers in a gel-like ground substance; reticular cells lie on fibers
- Fibers form a soft internal skeleton (stroma) that supports other cell types including WBC, mast cells, macrophages
Describe Regular Dense Connective Tissues
- Parallel collagen fibers, few elastic fibers, major cell type = fibroblast
- Attaches muscles to bones or to muscles; attaches bones to bones; withstands tensile stress when pulling is applied in 1 direction
- Found in tendons, most ligaments, aponeuroses
Describe Irregular Dense Connective Tissues
- Primarily irregularly arranged collagen fibers; some elastic fibers; fibroblast (major cell type)
- Withstands tension exerted in many directions; provides structural strength
- Fibrous capsules of organs & joints, dermis of skin, submucosa of digestive tract
Describe Elastic Dense Connective Tissues
- Dense regular connective tissue containing a high proportion of elastic fibers
- Allows tissue to recoil after stretching; maintain pulsating flow of blood through arteries; aids passive recoil of lungs following inspiration
- Walls of large arteries; within certain ligaments associated with the vertebral column; within walls of bronchial tubes
Describe Cartilage
- Matrix secreted from chondroblasts (during growth) & chondrocytes (adults)
- Avascular: receives nutrients from membrane surrounding it (perichondrium)
Describe Chondrocytes
- Found in cavities called lacunae; mature cell of cartilage
- 80% water with packed collagen fibers & sugar proteins (chondroitin & hyaluronic acid)
- Periochondrium gives rise to chondrocytes
Describe Hyaline Cartilage
- Most abundant
- Appears shiny bluish glass
- Supports & reinforces; serves as resilient cushion; resists compressive stress
- Found at tips of long bones, nose, trachea, larynx, & cartilage of the ribs
Describe Elastic Cartilage
- Similar to hyaline but with more elastic fibers
- Maintains the shape of a structure while allowing great flexibility
- Found in ears & epiglottis
Describe Fibrocartilage
- Properties between hyaline & dense regular tissue
- Tensile strength allows it to absorb compressive shock
- Strong, found in areas such as intervertebral discs & knee
Describe Bone Tissue (osseous tissue)
- Supports & protects body structures, levers for the muscles to act on, store calcium, other minerals, & fat; marrow is site for hematopoiesis (blood cell formation)
- Stores fat & synthesizes blood cells in cavities
- More collagen than cartilage
- Inorganic calcium salts
- Osteoblasts (bone forming cells) produce matrix
- Osteocytes (mature bone cells) maintain matrix (reside in lacunae)
- Osteons: individual structural units
- Vascularized
Describe Blood Tissue
- Most atypical connective tissue (it’s fluid)
- Cells surrounded by matrix (plasma)
- RBC most common type
- WBC & platelets
- Fibers are soluble proteins that precipitate during blood clotting
- Functions in transport & in carrying nutrients, wastes, gases, other substances
- Located in blood vessels
Describe Muscle Tissue
- Highly vascularized
- Responsible for most types of movement: muscle cells have myofilaments (actin & myosin) that bring about contraction
Describe Skeletal Muscle Tissue
- Attached to & causes movement of bones (voluntary muscle)
- Cells are called muscle fibers (multiple nuclei, striated/banded)
- Long, cylindrical; consciously controlled
Describe Cardiac Muscle Tissue
- Found in walls of heart
- Involuntary muscle (not consciously controlled); as it contracts blood is propelled into circulation
- Contains striations, only 1 nucleus
- Cells can can have many branches that join branches of other cardiac cells
- Intercalated discs: special joint where cardiac cells are joined
Describe Smooth Muscle
- Cells are spindle shaped (tapered on ends), central nuclei, no striations; cells arranged closely to form sheets
- Propels substances or objects along internal passageways (involuntary control)
- Mostly in the walls of hollow organs
Describe Nervous Tissue
- Main component of nervous system (brain, spinal cord, nerves); regulates/controls body functions
- Made neurons (cells that conduct nerve impulses) & supporting cells (support, insulate, protect neurons)
- Transmit electrical signals from sensory receptors & to effectors (muscles & glands)
What are covering & lining membranes composed of?
At least 2 primary tissue types: epithelium bound to underlying connective tissue proper layer
Describe Cutaneous membranes
Another name for skin, dry membrane
Describe Mucous membranes (mucosae)
Line body cavities that are open to exterior (digestive, respiratory, urogenital tracts)
Describe Serous membranes (serosae)
- Found in closed ventral body cavities
- Parietal serosae line internal body cavity walls; visceral serosae cover internal organs (pleurae - lungs; pericardium - heart, peritoneum - abdomen)
