Chapter 4 Tissue Level of Organization

Unicellular organisms

single celled organisms

Multicellular organisms

Organism made up of many cells

Tissues

Groups of cells with a common structure and function.

Epithelial tissue

Tissue that covers outside of the body and lines organs and cavities.

Epithelium

the specialized epithelial tissue that forms the epidermis of the skin and the surface layer of mucous membranes

Cell Polarity

the cell has a "front" and "back"; the ability of cells to generate functionally distinct regions

Apical surface

an upper free surface exposed to the body exterior or the cavity of an internal organ; opposite side from that binding the basement membrane

Basal Surface

The bottom layer of epithelial tissue that attaches to the basement membrane

Basal lamina

noncellular, adhesive supporting sheet consisting largely of glycoproteins secreted by epithelial cells

Basement membrane

a thin, delicate membrane of protein fibers and glycosaminoglycans separating an epithelium from underlying tissue.

Reticular lamina

a layer of extracellular material containing a fine network of collagen protein fibers that "belongs to" the underlying connective tissue

Avascular

without blood vessels

Innervated

supplied by nerve fibers

Regeneration

replacement of destroyed tissue by the same kind of cells

Fibrosis

Replacement of damaged cells with scar tissue; Repair by dense fibrous connective tissue (scar tissue)

Scar tissue

the connective tissue forming a scar and composed chiefly of fibroblasts in recent scars and largely of dense collagenous fibers in old scars.

Granulation tissue

new tissue that is pink/red in color and composed of fibroblasts and small blood vessels that fill an open wound when it starts to heal

Squamous cells

flattened and scale-like cells

Cuboidal cells

cube shaped cells

Columnar cells

tall and column shaped cells

Simple Epithelia

one layer of epithelial cells

Endothelium

the specialized simple squamous epithelial tissue that lines the blood and lymph vessels

Mesothelium

the simple squamous epithelium found in serous membranes lining the ventral body cavity and covering its organs

Simple cuboidal epithelium

Single layer of cube shaped epithelial cells
Function: secretion and absorption
Location: Kidney tubules; ducts and secretory portions of small glands, ovary surface.

Simple Columnar epithelium

Single layer of column shaped epithelial cells
Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliated action.
Location: nonciliated type lines most of the digestive tract (stomach to anal canal), gallbladder and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus.

Stratified Epithelia

two or more layers of epithelial cells

Pseudostratified Columnar epithelium

epithelial tissue that consists of a single layer of irregularly shaped and sized cells that give the appearance of multiple layers; found in ducts of certain glands and the upper respiratory tract

Stratified Squamous Epithelium

Epithelial tissue that consists of more than one layer. Typically the outer layer is more squamous shaped than the deeper layers which may look more cuboidal.
Function: protects underlying tissues in areas subject to abrasion
Location: nonkeratinized type forms the moist lining of the esophagus, mouth, and vagina; keratinized type forms the epidermis of the skin, a dry membrane.

Stratified Cuboidal epithelium

Cuboidal epithelial cells that consist of more than one layer
Function: protection
Location: Largest ducts of sweat glands, mammary glands, and salivary glands.

Stratified Columnar Epithelium

Columnar epithelial cells that consist of more than one layer
Function: protection and secretion
Location: rare in the body; small amounts in male urethra and in large ducts of some glands

Transitional Epithelium

A type of stratified tissue that consists of squamous, cuboidal and columnar shaped cells.
Function: stretches readily and permits distension of urinary organ by contained urine
Location: lines the ureters, urinary bladder, and part of the urethra

Glandular Epithelia

specialized epithelial tissues that have secretory/excretory functions

Gland

An organ that produces and releases chemicals either through ducts or into the bloodstream. (Prefix for gland is aden-)

Secretion

a process by which substances are produced and discharged from a cell, gland, or organ for a particular function in the organism or for excretion.

Endocrine Glands

Ductless glands that empty their hormonal products directly into the blood

Hormones

Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

Exocrine Glands

Secrete chemical substances into ducts that lead either directly to other organs or out of the body

Unicellular exocrine glands

mucous cells and goblet cells

Multicellular exocrine glands

Multicellular exocrine glands are composed of a duct and a secretory unit
Usually surrounded by supportive connective tissue
Supplied by blood and nerve fibers
Extends into and divides gland into lobes

Simple glands

unbranched duct

Compound glands

have a branched duct

Merocrine glands

Glands that release fluid products by exocytosis

Holocrine glands

accumulate their products within them until they rupture

Apocrine glands

glands that lose small portions of their glandular cell bodies during secretion

Connective tissue

A body tissue that provides support for the body and connects all of its parts

Extracellular matrix (ECM)

The meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesized and secreted by the cells.

Mesenchyme

Embryonic connective tissue from which all connective tissues develop

Ground Substance

unstructured material that fills the space between the cells and contains the fibers; fluid or semi-fluid; mostly water along with adhesion proteins and polysaccharide molecules

Interstitial Fluid

fluid in the spaces between cells

Cell adhesion proteins

perform cell to cell attachments

Proteoglycans

a glycoprotein consisting of a small core protein with many carbohydrate chains covalently attached

Connective tissue fibers

collagen fibers, reticular fibers, elastic fibers

Collagen Fibers

a protein substance found in connective tissues such as bone and cartilage; provides flexibility and strength

Elastic Fibers

Flexible and "stretchy" fibers that add elasticity to tissue

Reticular fibers

Fibers made of collagen fibers that are very thin and branched. Form a tightly woven fabric that joins connective tissue to adjacent tissues.

Connective tissue cells

Cells in Connective Tissue include: fibroblasts, adipocytes, mast cells, melanocytes, red blood cells, white blood cells, macrophages, bone cells, cartilage cells.

Fibroblasts

In connective tissue, spindle-shaped cells that secrete the proteins of the fibers and ground substance.

Chondroblasts

cartilage forming cells

Chondrocytes

mature cartilage cells

Osteoblasts

bone forming cells

Osteocytes

a mature bone cell, formed when an osteoblast becomes embedded in the matrix it has secreted.

Adipocytes

fat cells that make up most of the subcutaneous layer and store triglycerides

White blood cells (WBC)

Leukocyte; fight infection

Mast cells

Cells that are found in connective tissue such as the dermis; release chemicals (such as histamine) that promote inflammation.

Macrophages

Cells with ameboid-like movement that patrol most tissues of the body, and engulf (phagocytose) foreign particles and debris of dead cells.

Lacunae

small cavities in bone that contain osteocytes; small cavities in cartilage that contain chondrocytes

Hematopoietic stem cells

Produce granulocytes and agranulocytes in the bone marrow; precursor cell for all other blood cells including RBCs and WBCs

Connective tissue proper

loose connective tissue and dense connective tissue; serve to connect and protect tissues

Loose connective tissue

areolar, adipose, reticular

Areolar Connective tissue

Composes basement membranes; a soft packaging tissue with a jellylike matrix
Function: wraps and cushions organs
Location: widely distributed under epithelia of body

Adipose tissue

Tissue that stores fat; a collection of fat cells

Reticular connective tissue

Connective tissue that contains reticular fibers and cells; used to make the framework of major organs (e.g. liver and spleen)

Dense connective tissue

dense regular, dense irregular, elastic

Dense Regular connective tissue

Function: attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction
Location: tendons, most ligaments, aponeuroses

Tendons

attach muscle to bone

Aponeuroses

a sheet of pearly-white fibrous tissue that takes the place of a tendon in sheetlike muscles having a wide area of attachment.

Ligaments

Connect bone to bone

Dense Irregular connective tissue

Made of collagen fibers that are irregularly arranged with a few fibroblasts
Function: able to withstand tension exerted in many directions; provides structural strength
Location: fibrous capsules of organs and joints; dermis of the skin; submucosa of digestive tract; fascia; heart valves

Dermis

connective tissue layer of the skin beneath the epidermis

Elastic Connective tissue

Function: allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration

Location: walls of large arteries; within certain ligaments associated with vertebral column, within the walls of the bronchial tubes

Cartilage

strong connective tissue that supports the body and is softer and more flexible than bone

Hyaline Cartilage

Most common type of cartilage; it is found on the ends of long bones, ribs, and nose; Translucent bluish white cartilage consisting of cells embedded in an apparently homogeneous matrix

Elastic Cartilage

cartilage with abundant elastic fibers; more flexible than hyaline cartilage; found in external ear and epiglottis

Fibrocartilage

cartilage that contains fibrous bundles of collagen, such as that of the intervertebral disks in the spinal cord.

Bone (Osseous Tissue)

dense, supportive connective tissue.
contains specialized cells.
produces solid matrix of calcium salt deposits.
around collagen fibers.

Blood

Connective tissue made of plasma, erythrocytes, leukocytes, and platelets.

Muscle tissue

A body tissue that contracts or shortens, making body parts move.

Myofilaments

The contractile proteins, actin and myosin, of muscle cells

Voluntary muscle

A muscle that is under conscious control

Involuntary muscle

muscle that responds automatically to brain signals but cannot be consciously controlled

Skeletal Muscle

A muscle that is attached to the bones of the skeleton and provides the force that moves the bones.

Cardiac Muscle

Muscle of the heart

Smooth Muscle

Involuntary muscle found inside many internal organs of the body

Nervous tissue

A body tissue that carries electrical messages back and forth between the brain and every other part of the body.

Neurons

a nerve cell; the basic building block of the nervous system

Dendrites

Branchlike parts of a neuron that are specialized to receive information.

Axons

a part of a neuron that carries impulses away from the cell body

Cutaneous Membrane

The skin; composed of epidermal and dermal layers

Mucous Membrane

an epithelial tissue that secretes mucus and that lines many body cavities and tubular organs including the gastrointestinal tract and respiratory passages.

Lamina Propria

areolar connective tissue underlying a mucous membrane