Chapter 4 Study Skills: Key Terms
Groups of cells that are similar in structure and perform a common or related function
What are the four primary tissue types?
Epithelial, connective, muscle, nervous
What are the roles of the four tissue types?
Epithelial tissue COVERS, connective tissue SUPPORTS, muscle tissue PROVIDES MOVEMENT, and nervous tissue CONTROLS
What three things must occur before a specimen can be viewed through a microscope?
Fixation (preserved), Sectioning (cut into slices thin enough to transmit light/electrons), and Staining (dyed with colored synthetic dyes to enhance contrast)
Minor distortions in microscope specimens that are the result of their exposure to many procedures that alter their original condition
Study of tissues
Brain, spinal cord, nerves
Contracts to cause movement
Muscles attached to bones (skeletal), muscles of the heart (cardiac), muscles of walls or hollow organs (smooth)
A sheet of cells that covers a body surface or lines a body cavity; Forms boundaries between different environments, protects, secretes, absorbs, filters
Lining of the digestive tract organs/other hollow organs, skin surface (epidermis)
Supports, protects, binds other tissues together
Bones, tendons, fat and other soft padding tissue
What are the two forms of epithelial tissue that occur in the body?
Covering/lining epithelium and Glandular epithelium
Forms the outer layer of the skin; dips into and lines the open cavities of the urogenital, digestive, and respiratory systems; covers the walls and organs of the closed ventral body cavity
Fashions the glands of the body
What are the main functions of the epithelium?
Protection, absorption, filtration, excretion, secretion and sensory reception
On an epithelium: an upper free surface exposed to the body exterior or the cavity of an internal organ; most are smooth, but some have microvilli
On an epithelium: lower attached surface to the apical surface, faces inward toward the body, attaches to the connective tissue
Why do we say that the apical and basal surfaces exhibit apical-basal polarity?
Because the two surfaces differ in both structure and function
Fingerlike extensions of the plasma membrane; greatly increase the exposed surface area
Tiny, hairlike projections that propel substances along their free surface
Noncellular, adhesive sheet adjacent to the basal surface of an epithelium that consists largely of glycoproteins secreted by the epithelial cells plus some fine collagen fibers; acts as a selective filter that determines which molecules diffusing from the underlying connective tissue are allowed to enter the epithelium; acts as scaffolding along which epithelial cells can migrate to repair wounds
What is the purpose of tight junctions in epithelial tissues?
To help keep proteins in the apical region of the plasma membrane from diffusing into the basal region, thus helping maintain epithelial polarity
Deep to the basal lamina; a layer of extracellular material containing a fine network of collagen protein fibers
Formed by the basal and reticular laminae; reinforces the epithelial sheet and helps it resist stretching and tearing, defines the epithelial boundary
What are the special characteristics of epithelial tissues?
Polarity, specialized contacts, supported by connective tissues, avascular but innervated, high regenerative capacity
Epithelium is ____ (vascular/avascular) but ______ (innervated/not innervated)
Does epithelium have a high or low regenerative capacity?
How is epithelium classified?
Two names: first indicates the number of cell layers present, the second describes the shape of the cells
Consists of a single cell layer; typically found where absorption, secretion, and filtration occur and a thin epithelial barrier is desirable
Composed of two or more cell layers stacked on top of each other; common in high-abrasion areas where protection is important (i.e.: skin surface, lining of the mouth)
Flattened and scale-like
Nucleus is a flattened disc
Boxlike, approximately as tall as they are wide
Nucleus is spherical
Tall and column-shaped
Nucleus is elongated from top to bottom, located closer to the cell base
According to what layer are stratified epithelia named and why?
They're named according to the shape of the cells in the APICAL layer because cell shape differs in the different layers
Simple Squamous Epithelium
Single layer of flattened cells wit disc-shaped central nuclei, sparse cytoplasm; simplest of the epithelia
Where is Simple Squamous Epithelium located?
Kidney glomeruli; air sacs of lungs; lining of the heart, blood vessels, and lymphatic vessels; lining of the ventral body cavity (serosae)
What is/are the function(s) of Simple Squamous Epithelium?
Allows materials to pass by diffusion and filtration in sites where protection is not important; secrets lubricating substances in serosae
A type of Simple Squamous Epithelium; provides a slick, friction-reducing lining in lymphatic vessels and in all hollow organs of the cardiovascular system (blood vessels, heart, and capillaries); exceptional thinness encourages the efficient exchange of nutrients and wastes between the bloodstream and surrounding tissue cells
A type of Simple Squamous Epithelium; found in serous membranes (the membranes lining the ventral body cavity and covering its organs)
Simple Cuboidal Epithelium
Single layer of cuboidal cells with large, spherical central nuclei
What is/are the location(s) of Simple Cuboidal Epithelium?
Kidney tubules; ducts and secretory portions of small glands; ovary surface
What is/are the function(s) of Simple Cuboidal Epithelium?
Secretion and absorption
Simple Columnar Epithelium
Single layer of tall cells with round to oval nuclei; many cells bear microilli, some bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells)
What is/are the location(s) of Simple Columnar Epithelium?
Nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus
What is/are the function(s) of Simple Columnar Epithelium?
Absorption, secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action
What two distinct modifications make the digestive tract lining ideal for the dual function of absorption and secretion?
Dense microvilli on the apical surface of absorptive cells and tubular glands that are made primarily of cells that secrete mucus-containing intestinal juice
Pseudostratified Columnar Epithelium
Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia
Location(s) of Psuedostratified Columnar Epithelium
Nonciliated type in sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract
Function(s) of Psuedostratified Columnar Epithelium
Secret substances, particularly mucus; propulsion of mucus by ciliary action
Stratified Squamous Epithelium
Thick membrane composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers
Location(s) of Stratified Squamous Epithelium
Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane
Function(s) of Stratified Squamous Epithelium
Protects underlying tissues in areas subjected to abrasion
Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnal; surface cells dome shaped or squamous-like, depending on degree of organ stretch
Location(s) of Transitional Epithelium
Lines the ureters, bladder, and part of the urethra
Function(s) of Transitional Epithelium
Stretches readily, permits stored urine to distend urinary organ
Consists of one or more cells that make and secrete a particular product
Aqueous fluid that usually contains proteins, but can be lipid- or steroid-rich
According to what two traits are glands classified?
Where they release their product, and the number of cells they have
"internally excreting"; often called ductless glands; produce hormones that are secreted by exocytosis directly into the extracellular space; most are compact multicellular organs, some individual hormone-producing cells are scattered in the digestive tract lining and in the brain
Messenger chemicals secreted by endocrine glands
"externally excreting"; secrete products onto body surfaces or into body cavities; unicellular glands use exocytosis, multicellular glands use an epithelium-walled duct that transports the secretion to the epithelial surface
complex glycoprotein produced by unicellular exocrine glands that dissolves in water when secreted to produce mucus
Mucus-secreting unicellular exocrine glands
What are the two basic parts of multicellular exocrine glands?
An epithelium-derived duct and a secretory unit (acinus) consisting of secretory cells
How are multicellular exocrine glands classified?
Simple or compound
have an unbranched duct
have a branched duct
Secretory units are tubular if the secretory cells form tubes
Secretory units are alveolar if the secretory cells form small, flask-like sacs
Secretory units are tubuloalveolar if they are both tubular and alveolar
Glands that secret their products by exocytosis as they are produced
Glands that accumulate their products within secretory cells until they rupture
What are the four main classes of connective tissue?
Connective Tissue Proper, Cartilage, Bone, and Blood
What are the three characteristics that set connective tissues apart from other primary tissues?
Common origin, degrees of vascularity, and extracellular matrix
What is the common origin of connective tissues?
All connective tissues arise from mesenchyme (an embryonic tissue)
What are the different degrees of vascularity in connective tissues?
Cartilage is avascular, dense connective tissue is poorly vascularized, and other types of connective tissue are richly vascularized
Non-living material that composes connective tissues
What are the benefits of the extracellular matrix in connective tissues?
Connective tissues can bear weight, withstand great tension and endure abuses such as physical trauma and abrasion that no other tissue can tolerate
What are the three main structural elements of connective tissues?
ground substance, fibers, and cells
Unstructured material that fills the space between the cells and contains the fibers of connective tissues; consists of large amounts of fluid and functions as a molecular medium through which nutrients and other dissolved substances can diffuse between the blood capillaries and the cells
What are the three types of connective tissue fibers and what are they composed of, respectively?
Collagen fibers, collagen; Elastic fibers, elastin; Reticular fibers, collagen
What type of connective tissue fibers are strongest and most abundant?
Cells of the connective tissue proper
Cells of the cartilage
Cells of the bones
Typically cluster along blood vessels; detect foreign organisms and initiate the local inflammatory responses against them
Large, irregularly shaped cells that avidly devour a broad variety of foreign materials and dispose of dead tissue cells
What are the two subclasses of connective tissue proper?
Loose connective tissues and dense connective tissues
What are the three types of loose connective tissue?
Areolar, Adipose, Reticular
Gel-like matrix with all three fiber types
Cells: fibroblasts, macrophages, mast cells, and some white blood cells
Function(s) of Areolar Tissue
Wraps and cushions organs; macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid; storing nutrients as fat in adipocytes (fat cells)
Location(s) of Areolar Tissue
Widely distributed under epithelia of the body (e.g. forms lamina propria of mucous membranes; packages organs; surrounds capillaries
Matrix as in areolar, but very sparse; closely packed adipocytes (fat cells), have nucleus pushed to the side by large fat droplet; richly vascularized
Function(s) of Adipose Tissue
Provides reserve food fuel; insulates against heat loss; supports and protects organs
Location(s) of Adipose Tissue
Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts
What are the two types of adipose tissue?
White adipose tissue and Brown adipose tissue
White Adipose Tissue
Brown Adipose Tissue
Rich in mitochondria that use the lipid fuels to heat the bloodstream to warm the body
Loose network of reticular fibers in a gel-like ground substance; reticular cells lie on the network
Function(s) of Reticular Tissue
Fibers form a soft internal skeleton (stroma) that supports other cell types including white blood cells, mast cells, and macrophages
What are the three types of dense connective tissue?
Dense Regular, Dense Irregular, and Elastic
Dense Regular Connective Tissue
Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast
Function(s) of Dense Regular Connective Tissue
Attaches muscles to bones or to muscles; attaches bones to bones; withsands great tensile stress when pulling force is applied in one direction
Location(s) of Dense Regular Connective Tissue
Tendons, most ligaments, aponeuroses
Flat, sheetlike tendons that attach muscles to other muscles or to bones
Dense Irregular Connective Tissue
Primarily irregularly arranged collagen fibers; some elastic fibers; fibroblast is the major cell type
Function(s) of Dense Irregular Connective Tissue
Withstands tension exerted in many directions; provides structural strength
Location(s) of Dense Irregular Connective Tissue
Fibrous capsules of organs and of joints; dermis of the skin; submucosa of the digestive tract
Elastic Connective Tissue
Dense regular connective tissue containing a high proportion of elastic fibers
Function(s) of Elastic Connective Tissue
Allows tissue to recoil after stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration
Location(s) of Elastic Connective Tissue
Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes
Connective tissue that stands up to both tension and compression; has qualities that are between those of dense connective tissue and bone; tough but flexible, lacks nerve fibers and is avascular; main cell type is chondrocytes
How does cartilage receive its nutrients?
Diffusion from blood vessels located in the connective tissue layer (perichondrium) surrounding it
Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae
Function(s) of Hyaline Cartilage
Supports and reinforces; serves as resilient cushion; resists compressive stress
Location(s) of Hyaline Cartilage
Forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx
Similar to hyaline cartilage, but more elastic fibers in matrix
Function(s) of Elastic Cartilage
Maintains the shape of a structure while allowing great flexibility
Location(s) of Elastic Cartilage
Supports the external ear (pinna); epiglottis; found where strength and exceptional stretchability are needed
Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate
Function(s) of Fibrocartilage
Tensile strength allows it to absorb compressive shock
Location(s) of Fibrocartilage
Intervertebral discs; pubic symphysis; discs of knee joint; where strong support and the ability to withstand heavy pressure are required
Bone (Osseous Tissue)
Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae; very well vascularized; has an exceptional ability to support and protect body structures
Function(s) of Bone (Osseous Tissue)
Supports and protects (by enclosing); provides levesr for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis)
Blood cell formation
Red and white blood cells in a fluid matrix (plasma)
Function(s) of Blood
Transport respiratory gases, nutrients, wastes, and other substances
Location of Blood
Contained within the blood vessels
Highly cellular, well-vascularized tissues that are responsible for most types of body movement
Elaborate networks of the actin and myosin filaments that bring about movement or contraction in all cell types
What are the two classifications of muscle tissue?
Voluntary muscle and involuntary muscle
Muscle whose contraction is under our conscious control
Muscle whose contraction is not under our conscious control
What are the three types of muscle tissue?
Skeletal, Cardiac, and Smooth
Skeletal Muscle Tissue
Long, cylindrical, multinucleate cells; obvious striations; form the flesh of the body
Function(s) of Skeletal Muscle Tissue
Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control
Location(s) of Skeletal Muscle Tissue
In skeletal muscles attached to bones or occasionally to skin
Cardiac Muscle Tissue
Branching, striated, generally uninucleate cells that interdigitate at specialized junctions (intercalated discs)
Function(s) of Cardiac Muscle Tissue
As it contracts, it propels blood into the circulation, through the blood vessels to all parts of the body; involuntary control
Location of Cardiac Muscle Tissue
The walls of the heart
Smooth Muscle Tissue
Spindle-shaped (elongated) cells with central nuclei; no striations; cells arranged closely to form sheets
Function(s) of Smooth Muscle Tissue
Propels substances or objects (foodstuffs, urine, a baby) along internal passageways; involuntary control
Location(s) of Smooth Muscle Tissue
Mostly in the walls of hollow organs other than the heart
Neurons are branching cells; cell processes that may be quite long extend from the nucleus-containing cell body; also contributing to nervous tissue are non-excitable supporting cells
Function(s) of Nervous Tissue
Neurons transmit electrical signals from sensory receptors and to effectors (muscles and glands); supporting cells support and protect neurons
Location(s) of Nervous Tissue
Brain, spinal cord, and nerves
Highly specialized nerve cells that generate and conduct nerve impulses
What are the functions of neurons?
Respond to stimuli, transmit electrical impulses over substantial distances within the body
Mucous Membranes (Mucosae)
Membranes that line all of the body cavities that open to the outside of the body
i.e.: the hollow organs of the digestive, respiratory, and urogenital tracts
Layer of loose connective tissue over which the simple columnar epithelial sheet of the mucosae lies
Serous Membranes (Serosae)
Moist membranes found in closed ventral cavities; consists of simple squamous epithelium resting on a thin layer of loose connective (areolar) tissue, which results in the thin clear serous fluid that lubricates the facing surfaces of the parietal and visceral layers so they slide across each other easily
Serosae that lines the thoracic wall and covers the lungs
Serosae that encloses the heart
Serosae that encloses the abdominopelvic viscera
Relatively nonspecific reaction that develops quickly wherever tissues are injured
Extremely specific reactions that take longer to swing into action than inflammatory responses
What are the two ways in which tissue repair occurs?
Regeneration and Fibrosis
Form of tissue repair in which destroyed tissue is replaced with the same kind of tissue
Form of tissue repair in which dense connective tissue proliferates to form scar tissue
What are the stages of Tissue Repair?
1) Inflammation sets the stage, 2) Organization restores the blood supply, 3) Regeneration and fibrosis effect permanent repair
What is the first step of Tissue Repair?
Inflammation sets the stage; tissue trauma causes capillaries to dilate, white blood cells and other inflammatory substances seep into the injured area
What is the second step of Tissue Repair?
organization restores the blood supply; blood clot is replaced by granulation tissue, which produce growth factors and new collagen fibers and later becomes scar tissue
What is the third step of Tissue Repair?
Regeneration and fibrosis effect permanent repair; surface epithelium begins to regenerate until it finally resembles the adjacent skin tissue; end result is a fully regenerated epithelium and an underlying area of scar tissue
What kinds of tissues have high regenerative capacity?
Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, and blood-forming tissue
What kinds of tissues have moderate regenerative capacity?
Smooth muscle, dense regular connective tissue
What kinds of tissues have a weak regenerative capacity?
Skeletal muscle, cartilage
What kinds of tissues have no regenerative capacity?
Cardiac muscle, nervous tissue