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HAP Lab: Classifications of tissues.

Human Anatomy Lab: Classifications of tissues.Nicole Burdick Simple squamous epithelium

Single layer of flattened cells with disc shaped central nuclei and sparse cytoplasm, the simplest of epithelia .allows materials to pass by diffusion and filtration in sites where protection is not important, secretes lubricating substances in serosaeKidney glomeruli, air sacs of lungs, lining of heart, blood vessels and lymphatic vessels, lining of ventral body cavity

Simple cuboidal epithelium

Single layer of cube-like cells with large, spherical central nucleus Secretion and absorptionKidney tubules, ducts and secretory portions of small glands, ovary surfaces

Simple columnar epithelium

Single layer of tall cells with round to oval nuclei, some cells bear cilia, layer may contain mucous-secreting unicellular glandsAbsorption, secretion of mucus, enzymes and other substances. Ciliated type propels mucus by ciliary actionNonciliated type lines most of the digestive tract(stomach to anal canal), gallbladder, and excretory ducts of some glands. Ciliated type lines small bronchi, uterine tubes and some regions of the uterus

4Pseudostratified columnar epithelium

single layer of cells of differing heights, some not reacing the free surface, nuclei seen at different levels; may contain mucus-secreting cells and bear cilia Secretion, particularly of mucus; propulsion of mucus by ciliary action. Nonciliated type in males sperm carrying ducts and ducts of large glands. Ciliated variety lines the trachea, most of the upper respiratory tract

Stratified squamous epithelium

Thick membrane composed of several cell layers, basal cells are cuboidal or columnar and metabolically active, surface cells are flattened, in the keratinized type, the surface cells are active in mitosis and produce the cells of the more superficial layers Protects underlying tissues in areas subjected to abrasion Nonkeratinized type forms the moist linings of the esophagus, mouth and vagina. Keratinized variety forms the epidermis of the skin, a dry membrane.

Transitional epithelium Resembles both stratified squamous and stratified cuboidal, basal cells cuboidal or columnar, surface cells dome shaped and squamouslike, depending on degree of organ stretch Stretches readily and permits distension of urinary organ by contained urine Lines the ureters, urinary bladder and part of the urethra

Connective, Muscle & Nervous Tissue:Embryonic Connective Tissue:MesenchymeGel-like ground substance contains fibers; star-shaped mesenchymal cells.Gives rise to all other connective tissue types.Primarily in embryo

Areolar (loose c.t.)wraps and cushions organs, macrophages phagocytize bacteria; plays important role in inflammation: holds and conveys tissue fluid.Widely distributed under epithelia of body.

Adipose (loose c.t.)Provides reserve fuel; insulates against heat loss; supports/protects organs.Under skin; around kidneys and eyeballs; within abdomen; in breasts.

Reticular (loose c.t.)Fibers form soft internal skeleton that supports other cell types, including white blood cells, mast cells, and macrophages.Lymph nodes, bone marrow, and spleen.

Dense regular (dense c.t.)Attaches muscle to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction.Tendons, most ligaments, aponeuroses.

Elastic (dense c.t.)Allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration.Dense regular connective tissue containing a high proportion of elastic fibers.Walls of large arteries; within certain ligaments associated with the vertebral column; within walls of bronchial tubes.

Dense irregular (dense c.t.)Able to withstand tension exerted in many directions; provides structural strength.Fibrous capusules of organs and of joints; dermis of the skin; submucosa of digestive tract.

Hyaline (cartilage)Supports & reinforces; has resilient cushioning properties; resists compressive stress.Amorphous but firm matrix: collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae.Forms most of embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larnyx.

Elastic (cartilage)Maintains the shape of a structure while allowing great flexibility.Supports the external ear; epiglottis.

fibrocartilageTensile strength with the ability to absorb compressive shock.Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate.Intervertebral discs; pubic symphysis; discs of knee joint.

Osseous tissue (bone)Bone supports and protects; provides levers for the muscle to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formationBones


Transport of respiratory gases, nutrients, wastes, and other substances.Contained within blood vessels.

Nervous tissueTransmit electrical signals from sensory receptors and to effectors (muscles and glands) which control their activity.Brain, spinal cord, and nerves.

Skeletal muscleVoluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control.Long, cylindrical, multinucleate cells; obvious striations.In skeletal muscles attached to bones or occasionally to skin.

Cardiac muscleAs it contracts, it propels blood into the circulation; involuntary controlThe walls of the heart.Branching, striated, generally uninucleate cells that interdigitate at specialized junctions (intercalated discs).

Smooth musclePropels substances or objects (food, urine, baby) along internal passageways; involuntary controlMostly in the walls of hollow organs.Spindle-shaped cells with central nuclei; no striations, cells arranged closely to form sheets.

Integumentary system:Meissners corpuscle:they are light touch receptors in the skin, which are prone to touch sensitivity. They are hairless areas which have flattened cells and encapsulated nerve endings, such as fingertips, soles of feet, palms, eyelids, nipples, and the tip of the tongue.

Pacinian corpuscle:Deep pressure receptors;a specialized bulblike nerve ending located in the subcutaneous tissue of the skin; occurs abundantly in the skin of palms and soles and joints and genitals

Blood vesselBlood vessels are intricate networks of hollow tubes that transport blood throughout the entire body.Epidermis

Avascular epidermis is a keratinized stratified squamos epithelium consisting of four distinct cell types and four or five distinct layers.

Stratum Corneum

Most superficial layer; 20-30 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space.is the outermost layer of the epidermis, consisting of dead cells (corneocytes) that lack nuclei and organelles.

Stratum basale Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers.

Dermis:[ papillary & reticular]Papillary: the more superficial dermal region composed of areolar connective tissue. Very uneven and has fingerlike projection from its superior surface.Reticular level: the deepest skin layer. It is compsed of dense irregular connective tissue and conains many arteries and veins, sweat and sebaceious glands, and pressure receptors (pacinian corpuscles)

Hair follicle:A structure formed from both epidermal and dermal cells. Its inner epithelial root sheath, with two parts (internal/external), is enclosed by a thickened basement membrane, the glassy membrane, and connective tissue root sheath, which is essentially dermal tissue.

Hair shaftThe portion of the hair projecting from the scalp surface.

Sweat glands/eccrineThese exocrine glands are widely distributed all over skin. Outlets for the glands are epithelial openings are called pores. Sweat glands are categorized by composition of their secretions:Eccrine glands (merocrine sweat glands): produce clear perspiration consisting of water, salts, and urea. Important part of the bodys heat regulating apparatus.

Sebaceous glandsFound nearly all over skin except palms of hands and soles of the feet. Ducts usually empty into a hair follicle, but some open directly on the skin surface. Produces sebum (mixture of oily substances and fragmented cells that acts as a lubricant to keep skin soft and moist /keeps hair from becoming brittle). Tend to become oiler in duration of puberty.