Chp. 6: Classification of Tissues Flashcards
Tissues
Groups of cells that are similar in structure and function
Four Tissue Types
Epithelium, Connective, Nervous, Muscle
Organs
Organized tissues that cumulatively perform body functions. Ex.) Heart, Kidneys, Lungs
Histology
The study of tissues
Epithelial Tissue (epithelium)
A sheet of cells that covers a body surface or lines a body cavity. Occur in the body as 1) covering and lining epithelium and 2) glandular epithelium
Epithelial Functions
Protection, absorption, filtration, excretion, secretion (specialty of glands), and sensory reception.
Apical Surface
The free surface of epithelial tissue
Basal Surface
The attached/bottom surface of epithelial tissue
Basement Membrane
The adhesive membrane that connects the epithelial cells (basal lamina) and connective tissue cells (reticular lamina) via an amorphous material secreted partly by the epithelial cells.
Epithelial tissues are…
Avascular but innervated; supplied by nerves, but have no blood supply of their own. They depend on diffusion of nutrients from underlying connective tissue.
Epithelial Regeneration
If well nourished, epithelial cells can easily divide to regenerate tissue; important because many epithelia are subject to a great deal of friction
Simple Epithelia
One layer of cells attached to the basement membrane
Stratified Epithelia
Consists of two or more layers of cells; named according to the cells at the apical surface of the epithelial sheet.
Squamous Epithelia
Scalelike
Cuboidal
Cubelike
Columnar
Column-like
Pseudostratified Epithelium
Simple columnar epithelium (one layer of cells), but because its cells vary in height and the nuclei lie at different levels above the basement membrane, it gives the false appearance of being stratified; also called ciliated epithelium
Endocrine Glands
Glands that lose their surface connection (duct) as they develop; ductless glands. Secrete hormones into the extracellular fluid, and from the there the hormones enter the blood or the lymphatic vessels that weave through the glands.
Exocrine Glands
Glands that retain their ducts, and their secretions empty through these ducts either to the body surface or into body cavities. A lumen forms in these glands. Includes sweat and oil glands, liver, and pancreas.
Simple Squamous Epithelium
DESCRIPTION: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia.
FXN: Allows materials to pass by diffusion and filtration in sires where protection is not important; secretes lubricating substances in serosae.
LOCATION: Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae).
Simple Cuboidal Epithelium
DESCRIPTION: Single layer of cubelike cells with large, spherical central nuclei.
FXN: Secretion and absorption
LOCATION: Kidney tubules; ducts and secretory portions of small glands; ovary surface
Simple Columnar Epithelium
DESCRIPTION: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells)
FXN: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action.
LOCATION: 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.
Pseudostratified Columnar Epithelium
DESCRIPTION: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting goblet cells and bear cilia.
FXN: Secretes substances, particularly mucus; propulsion of mucus by ciliary action.
LOCATION: Nonciliated type in male’s sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract.
Stratified Squamous Epithelium
DESCRIPTION: 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.
FXN: Protects underlying tissues in areas subjected to abrasion
LOCATION: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane.
Stratified Cuboidal Epithelium
DESCRIPTION: Generally two layers of cubelike cells.
FXN: Protection
LOCATION: Largest ducts of sweat glands, mammary glands, and salivary glands
Stratified Columnar Epithelium
DESCRIPTION: Several cell layers; basal cells usually cuboidal; superficial cells elongated and columnar.
FXN: Protection; secretion
LOCATION: Rare in the body; small amounts in male urethra and in large ducts of some glands.
Transitional Epithelium
DESCRIPTION: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch.
FXN: Stretched readily and permits distension of urinary organ by contained urine.
LOCATION: Lines the ureters, urinary bladder, and part of the urethra
Connective Tissue
Tissue found in all parts of the body as discrete structures or as part of various body organs; most abundant and widely distributed of the tissue types.
4 Main Types of Connective Tissue
Connective Tissue Proper, Cartilage, Bone, Blood
Mesenchyme
Embryonic tissue from which all adult connective tissues are derived from
Connective Tissue Proper
Two subclasses
- Loose Connective Tissues (areolar, adipose, reticular)
- Dense Connective Tissues (dense regular, dense irregular, elastic)
Connective Tissue Functions
Protect, support, insulate, and bind together other tissues of the body. Additionally, serves a vital function on the repair of all body tissues, since many wounds are repaired by connective tissue in the form of scar tissue.
Areolar Connective Tissue
Soft packaging material that cushions and protects body organs.
Adipose (fat) Tissue
Provides insulation for the body tissues and a source of stored energy.
Connective Tissue Characteristics
Connective tissues have a rich supply of blood vessels (except cartilages, tendons, and ligaments). Connective tissues are composed of many types of cells. There is a great deal of noncellular, nonliving material (matrix) between the cells of connective tissue.
Extracellular Matrix
The nonliving material between the cells that is produced by the cells and then extruded. It is primarily responsible for the strength associated with connective tissue, but there is variation in the amount of matrix.
Ground Substance (of matrix)
One component of the extracellular matrix; it is composed chiefly of interstitial fluid, cell adhesion proteins, and proteoglycans. Can be liquid, semisolid, gel-like, or very hard.
Lacunae
Cavities inside the extracellular matrix when it is firm (as in bone) where the connective tissues lie.
Fibers
Collagen (most abundant), Elastic, Reticular
Epithelium Classification
Number of layers and Cell shape
Fibroblasts
Cells that secrete their matrix
Mesenchyme
DESCRIPTION: Embryonic connective tissue; gel-like ground substance containing fibers; star-shaped mesenchymal cells
FXN: Gives rise to all other connective tissue types
LOCATION: Embryo
Loose Connective Tissue, Areolar
DESCRIPTION: Connective Tissue Proper; gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells.
FXN: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid.
LOCATION: Epithelia of body, forms Lamina propria of mucous membranes; packages organs; surrounds capillaries.
Loose Connective Tissue, Adipose
DESCRIPTION: Connective Tissue Proper; Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet.
FXN: Provides reserve fuel; insulates against heat loss; supports and protects organs.
LOCATION: Under skin; around kidneys and eyeballs; within abdomen; in breasts
Loose Connective Tissue, Reticular
DESCRIPTION: Connective Tissue Proper; Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network.
FXN: Fibers form a soft internal skeleton (stroma) that supports other cell types, including white blood cells, mast cells, and macrophages.
LOCATION: Lymphoid organs (lymph nodes, bone marrow, and spleen)
Dense Regular Connective Tissue
DESCRIPTION: Connective Tissue Proper; Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast.
FXN: Attaches muscles to bones or to other muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction.
LOCATION: Tendons, most ligaments, aponeuroses
Elastic Connective Tissue
DESCRIPTION: Connective Tissue Proper; Dense regular connective tissue containing a high proportion of elastic fibers.
FXN: 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 the vertebral column; within the walls of the bronchial tubes.
Dense Irregular Connective Tissue
DESCRIPTION: Connective Tissue Proper; Primarily irregularly arranged collagen fibers; some elastic fibers; major cell type is the fibroblast.
FXN: Able to withstand tension exerted in many direction; provides structural strength.
LOCATION: Fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract.
Hyaline Cartilage
DESCRIPTION: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and, when mature (chondrocytes), lie in lacunae.
FXN: Supports and reinforces; serves as resilient cushion; resists compressive stress.
LOCATION: 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
Elastic Cartilage
DESCRIPTION: Similar to hyaline cartilage, but more elastic fibers in matrix.
FXN: Maintains the shape of a structure while allowing great flexibility.
LOCATION: Supports the external ear (auricle); epiglottis.
Fibrocartilage
DESCRIPTION: Matrix similar to but less firm than matrix in hyaline cartilage; thick collagen fibers predominate.
FXN: Tensile strength with the ability to absorb compressive shock.
LOCATION: Intervertebral discs; pubic symphysis; discs of knee joint.
Bones (Osseous Tissue)
DESCRIPTION: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized.
FXN: Bone supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis).
LOCATION: Bones
Blood
DESCRIPTION: Connective Tissue; Red and white blood cells in a fluid matrix (plasma).
FXN: Transport of respiratory gases, nutrients, wastes, and other substances.
LOCATION: Contained within blood vessels.
Nervous Tissue
Made up of two major cell populations: Neuroglia and Neurons.
Neuroglia
Special supporting cells that protect, support, and insulate the more delicate neurons.
Neurons
Cells that are highly specialized to receive stimuli (excitability) and to generate electrical signals that may be sent to all parts of the body (conductivity).
Structure: Nucleus-containing cell body; cytoplasm is drawn out into long extensions (as long as 1m), allowing a single neuron to conduct an electrical signal over a relatively long distance.
Nervous Tissue
DESCRIPTION: 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.
FXN: Neurons transmit electrical signals from sensory receptors and to effectors (muscles and glands); supporting cells support and protect neurons.
LOCATION: Brain, spinal cord, and nerves.
Muscle Tissue
Highly specialized to contract and produces most types of body movement; tend to be elongated, providing a long axis for contraction.
Skeletal Muscle
DESCRIPTION: Long, cylindrical, multinucleate cells; obvious striations.
FXN: Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control.
LOCATION: In skeletal muscles attached to bones or occasionally skin.
Smooth Muscle
DESCRIPTION: Spindle-shaped cells with central nuclei; no striations; cells arranges closely to form sheets. Has two layers that run at right angles to each other; its contraction can constrict or dilate the lumen of an organ and propel substances along predetermined pathways.
FXN: Propels substances (foodstuffs, urine) or a baby along internal passageways; involuntary control.
LOCATION: Mostly in the walls of hollow organs.
Cardiac Muscle
DESCRIPTION: Branching, striated, generally uninucleate cells that interdigitate at specialized junctions called intercalated discs.
FXN: As it contracts, cardiac muscle propels blood into the circulation; involuntary control.
LOCATION: The walls of the heart.
