Chapter 4

- 4.1 Basics and Getting Samples: what are tissues, the primary types, microscopy, distortions

- 4.1 Basics and Getting Samples o Tissues are groups of cells in structure and perform a common or related function o 4 primary tissues: § Epithelia- covers § Connective- supports § Muscle- moves § Nervous- controls o Most organs contain all 4 o Microscopy allows us to study tissue structure § It must be fixed- preserved, cut into section (slices) thin enough to shine a light through them or electron, and stained to enhance the contrast between structures · With electron microscopes tissue sections are stained with heavy metal salts § Scanning electron microscopy (SEM) provides 3D pictures of an unsectioned tissue surface § Preserved tissue under a microscope has minor distortions called artifacts

- Blood why is it classified as connective, fibers, function

- Blood o the fluid within blood vessels, is the most atypical connective tissue. o It does not connect things or give mechanical support. o It is classified as a connective tissue because it develops from mesenchyme and consists of blood cells, surrounded by a nonliving fluid matrix called blood plasma o The vast majority of blood cells are red blood cells, or erythrocytes, but scattered white blood cells and platelets (needed for blood clotting) are also seen. o The "fibers" of blood are soluble protein molecules that precipitate, forming visible fiberlike structures during blood clotting. Blood functions as the transport vehicle for the cardiovascular system, carrying nutrients, wastes, respiratory gases, and many other substances throughout the body.

- Bones (Osseous Tissue) what do they do, what do they make and store, cells, osteon, blood supply

- Bones (Osseous Tissue) o has an exceptional ability to support and protect body structures. o Bones of the skeleton also provide cavities for storing fat and synthesizing blood cells. o Bone matrix is similar to that of cartilage but is harder and more rigid because, in addition to its more abundant collagen fibers, bone has an added matrix element—inorganic calcium salts (bone salts). o Osteoblasts produce the organic portion of the matrix, and then bone salts are deposited on and between the fibers. o Mature bone cells, or osteocytes, reside in the lacunae within the matrix they have made § A cross section of bone tissue reveals closely packed structural units called osteons that look like tree rings. § Osteons are concentric rings of bony matrix (lamellae) surrounding central canals containing the blood vessels and nerves serving the bone. · Unlike cartilage, the next firmest connective tissue, bone is well supplied by invading blood vessels.

- Cardiac

- Cardiac o is found only in the walls of the heart. o Its contractions help propel blood through the blood vessels to all parts of the body. o Like skeletal muscle cells, cardiac muscle cells are striated. However, cardiac cells differ structurally in that they are: § Generally uninucleate (one nucleus) with the nucleus situated centrally § Branching cells that fit together tightly at unique junctions called intercalated discs

- Classification of Epithelia Tissue dont forget nucleus

- Classification of Epithelia Tissue o Simple epithelia consist of a single cell layer. They are typically found where absorption, secretion, and filtration occur and a thin epithelial barrier is desirable. § Stratified epithelia, composed of two or more cell layers stacked on top of each other, are common in high-abrasion areas where protection is important- skin surface and lining of the mouth § Squamous cells are flattened and scale-like (squam = scale). § Cuboidal cells are boxlike, approximately as tall as they are wide. § Columnar cells are tall and column shaped. · The nucleus of a squamous cell is a flattened disc; that of a cuboidal cell is spherical; and a columnar cell nucleus is elongated from top to bottom and usually located closer to the cell base.

- Collagen Fibers constructed from where, how do they assemble and what does this allow

- Collagen Fibers o Constructed from the fibrous protein- collagen o Collagen molecules secrete into the extracellular space, where they assemble into cross-link fibrils § These cross-link fibrils are bundled together into thick collagen § The cross-link allows them to be extremely tough and provide high tensile strength- better than steel

- Common Characteristics of Connective Tissue 2 characteristics, blood supply

- Common Characteristics of Connective Tissue o 2 characteristics that together set them apart from other primary tissues: § Extracellular Matrix · Other primary tissues are composed of cells, but connective consists largely of non-living extracellular matric · Because of the matrix, connective tissue can bear weight, withstand great tensions, and endure abuses- physical trauma and abrasions § Common Origin · All connective tissue arises from mesenchyme (embryonic tissue) o Connective tissues differ from each other in their blood supple § Cartilage is avascular § Dense connective is poorly vascularized § Other connective tissues are rich in bloody supply and vessels

- Connective Tissue Cells immature, mature, which ones are active, what can cyte cells do, blood exception, adipocytes, wbc, mast cells- heparin histamine proteases, macrophage

- Connective Tissue Cells o Immature- blast o Mature- cyte o Immature blast cells are actively mitotic o Blast cells secretes the ground substance and fibers characteristics of their particular matrix o Cyte cells are less active and maintains the health of the matrix § If the matrix is damages, cyte cells can revert back to active blast cells to repair and regenerate the matrix o Blood is the exception § Immature cells are called hematopoietic stem cell · It is not located in "its" tissue (blood) and it does not make the fluid matrix (plasma) o Adipocytes- commonly called adipose or fat cells, which store energy as fat. o White blood cells (WBCs or leukocytes, including neutrophils, eosinophils, and lymphocytes) and other cell types that are concerned with tissue response to injury. o Mast cells- which typically cluster along blood vessels. § These oval cells detect foreign microorganisms (e.g., bacteria, fungi) and initiate local inflammatory responses against them. § Mast cell cytoplasm contains secretory granules (mast = stuffed full of granules) with chemicals that mediate inflammation, especially in severe allergies. These chemicals include: · Heparin (hep´ah-rin), an anticoagulant chemical that prevents blood clotting when free in the bloodstream (but in human mast cells it appears to regulate the action of other mast cell chemicals) · Histamine (his´tah-mēn), a substance that makes capillaries leaky · Proteases (protein-degrading enzymes) · Other enzymes o Macrophages- are large, irregularly shaped cells that avidly devour a broad variety of foreign materials, ranging from foreign molecules to entire bacteria to dust particles.

- Connective Tissue Fibers 3 types just names

- Connective Tissue Fibers o Proteins that provide support o 3 types § Collagen- the strongest and abundant § Elastic § Reticular

- Connective Tissue- General 4 types and 5 functions

- Connective Tissue- General o 4 Main Classes § Proper § Cartilage § Bone § blood o Its major functions include (1) binding and supporting, (2) protecting, (3) insulating, (4) storing reserve fuel, and (5) transporting substances within the body.

- Cutaneous Membrane cell type

- Cutaneous Membrane o Your skin o An organ system consisting of keratinized stratified squamous epithelium (epidermis) firmly attached to a thick layer of connective tissue (dermis) o Exposed to the air and is a dry membrane

- Dense Irregular Connective Tissue how is it different, where is it found

- Dense Irregular Connective Tissue o has the same structural elements as the regular variety. o However, the bundles of collagen fibers are much thicker, and they are arranged irregularly; that is, they run in all directions o This type of tissue forms sheets in body areas where tension is exerted from many different directions. o It is found in the skin as the leathery dermis, and it forms fibrous joint capsules and the fibrous coverings that surround some organs (kidneys, bones, cartilages, muscles, and nerves).

- Dense Regular Connective Tissue what is it, what does it do, blood supply, tendons, aponeuroses, ligaments

- Dense Regular Connective Tissue o contains closely packed bundles of collagen fibers running in the same direction, parallel to the direction of pull o This arrangement results in white, flexible structures with great resistance to tension (pulling forces) where the tension is exerted in a single direction. o Crowded between the collagen fibers are rows of fibroblasts that continuously manufacture the fibers and a small amount of ground substance. o Unlike our model (areolar) connective tissue, this tissue has few cells other than fibroblasts and is poorly vascularized. o With its enormous tensile strength, dense regular connective tissue forms: § Tendons- are cords that attach muscles to bones. § Aponeuroses- are flat, sheetlike tendons that attach muscles to other muscles or to bones. § Ligaments- bind bones together at joints. They contain more elastic fibers than tendons and are slightly more stretchy.

- Developmental Aspects of Tissues 3 layers, 2nd month, what tissues are mitotic in adults

- Developmental Aspects of Tissues o One of the first events of embryonic development is the formation of the three primary germ layers, which lie one atop the next like a three-layered pancake. § From superficial to deep, these layers are the ectoderm, mesoderm, and endoderm · These primary germ layers then specialize to form the four primary tissues—epithelium, nervous tissue, muscle, and connective tissues—that make up all body organs. o By the end of the second month of development, the primary tissues have appeared, and all major organs are in place. o In general, tissue cells remain mitotic and produce the rapid growth that occurs before birth. o The division of nerve cells, however, stops or nearly stops during the fetal period. o After birth, the cells of most other tissues continue to divide until adult body size is achieved. o Cellular division then slows greatly, although many tissues retain some ability to regenerate. o In adults, only epithelia and blood-forming tissues are highly mitotic. o Given good nutrition, good circulation, and relatively infrequent wounds and infections, our tissues normally function efficiently through youth and middle age. § But with increasing age, epithelia thin and are more easily breached. § Tissue repair is less efficient, and bone, muscle, and nervous tissues begin to atrophy, particularly when a person is not physically active. § These events are due partly to decreased circulatory efficiency, which reduces delivery of nutrients to the tissues, but in some cases, diet is a contributing factor.

- Elastic Cartilage

- Elastic Cartilage o is nearly identical to hyaline cartilage o However, elastic cartilage has many more elastic fibers. o Found where strength and exceptional stretchability are needed, elastic cartilage forms the "skeletons" of the external ear and the epiglottis (the flap that covers the opening to the respiratory passageway when we swallow).

- Elastic Fibers who protein is in them and what do they do and where are they found

- Elastic Fibers o Fibers containing the protein elastin which allows them to stretch and recoil o Connective tissue can only stretch so much before the collagen fibers become taut § When the tension lets up, elastic fibers snap the connective tissue back to its normal length and shape o Are found where greater elasticity is needed- skin, lungs, blood vessel walls

- Endocrine Glands duct type, what does it produce, cell number,

- Endocrine Glands o No duct o Produce hormones § Secrete hormones through exocytosis into the bloodstream/extracellular space o Endocrine glands are structurally diverse o Most are multicellular, but there are some unicellular ones o Endocrine glands can also secrete modified amino acids, glycoproteins, and steroids Not all endocrine glands arise from epithelial tissue

Epithelial Tissue: 2 types and functions (6)

- Epithelial Tissue o Epithelium is a sheet of cells that covers a body surface or lines a body cavity o 2 Forms § Covering and Lining 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 § Glandular Epithelium · Fashions the glands of the body o Functions of Epithelium § Protection § Absorption § Filtration § Excretion § Secretion § Sensory Reception

- Exocrine Glands where does it secrete, how do unicellular secret, how do multicellular secrete, examples

- Exocrine Glands o Secrete their products onto body surfaces (skin) or into body cavities o The unicellular glands do so directly (by exocytosis) o Multicellular glands do so via an epithelium-walled duct that transports the secretion to the epithelial surface o They are diverse o Includes: § Liver- bile § Pancreas- digestive enzymes § Mucous § Sweat § Oil § Salivary glands § And others

- Fibrocartilage

- Fibrocartilage o is intermediate between hyaline cartilage and dense regular connective tissues. o Its rows of chondrocytes (a cartilage feature) alternate with rows of thick collagen fibers (characteristic of dense regular connective tissue) o Because it resists both compression and tension well, fibrocartilage is found where strong support and the ability to withstand heavy pressure are required: for example, the intervertebral discs (resilient cushions between the bony vertebrae) and the spongy cartilages of the knee.

- Glandular Epithelia what makes up a gland, what do they produce, where they release, cell number

- Glandular Epithelia o Gland consists of one or more cells that make and secrete a product- secretion § Can be a water based with proteins or lipid/steroid rich secretion o Secretion is an active process § Glandular cells obtain needed substances from the blood and transform them chemically into a product that is discharged from the cell o Where the release their product § Exocrine- externally secreting § Endocrine- internally secreting o Number of cells § Unicellular § Multicellular

- Ground Substance what and where is it, 3 components

- Ground Substance o the unstructured material that fills the space between the cells and contains the fibers. It has three components: § Interstitial fluid · The ground substance consists of large amounts of fluid and functions as a molecular sieve through which nutrients and other dissolved substances can diffuse between the blood capillaries and the cells. · The fibers embedded in the ground substance make it less pliable and hinder diffusion somewhat. § Cell adhesion proteins · These proteins serve mainly as a connective tissue glue that allows connective tissue cells to attach to the extracellular matrix. § Proteoglycans · The proteoglycans consist of a protein core to which large polysaccharides called glycosaminoglycans (GAGs) are attached. · The strandlike GAGs stick out from the protein core like the fibers of a bottle brush. o The proteoglycans tend to form huge aggregates in which the GAGs intertwine and trap water, forming a substance that varies from a fluid to a viscous gel. The higher the GAG content, the more viscous the ground substance.

- Hyaline Cartilage what does it contain, appearance, percentage of chondrocytes, where is it

- Hyaline Cartilage o is the most abundant cartilage in the body. o Although it contains large numbers of collagen fibers, they are not apparent and the matrix appears glassy blue-white when viewed by the unaided eye. o Chondrocytes account for only 1-10% of the cartilage volume o Hyaline cartilage provides firm support with some pliability. It is found in a number of key places: § It covers the ends of long bones as articular cartilage, providing springy pads that absorb compression at joints. § It supports the tip of the nose. § It connects the ribs to the sternum. § It supports most of the respiratory system passages (for example, the trachea).

- Loose Connective- Adipose Tissue what is it similar to, cell packing, what does it do, where, brown and white fats

- Loose Connective- Adipose Tissue o Similar to areolar tissue in structure and function, but has a higher nutrient-storing ability o Adipocytes account for 90% of this tissue's mass o Cells are packed closely together o An almost pure triglyceride (oil droplet) occupies most of the adipocyte's volume and displaces the nucleus to one side o Mature adipocytes are among the largest cells in the body o Adipose tissue is richly vascularized, indicating high metabolic activity § We need this tissue to survive § Constitutes 18% of an average person's body weight o May develop anywhere areolar tissue is plentiful § Accumulates in subcutaneous tissue, where it acts as a shock absorber, as insulation, and as energy storage sites · Also prevents heat loss, since it's a poor conductor of heat o The abundant fat beneath the skin serves the general nutrient needs of the entire body, and smaller deposits of fat serve the local nutrient needs of highly active organs o Adipose tissue is sometimes white fat to distinguish it from brown fat § White fat- stores nutrients (for other cells) § Brown fats- contains a lot of mitochondria that use the lipid fuels to generate heat (instead of using ATP) · Bloodstream carries this heat and warms the body o In adults found above the collarbone, neck, abdomen, and spine

- Loose Connective- Areolar Connective Tissue amount, purpose, main functions, main structural feature, reservoir of hat, cell type, other cells, ground substance fluidity

- Loose Connective- Areolar Connective Tissue o Most widely distributed connective tissue in the body o Serves as the universal packing material between other tissues o Binds body parts together while allowing them to move freely over one another o It is the connective tissue that most epithelia rest on and is present in all mucous membranes as the lamina propria o Main functions § Supporting and binding other tissues- fibers § Holding the body fluids- ground substance § Defending against infections- white blood cells and macrophages § Storing nutrients as fat in adipocytes- fat cells o The main structural feature is the loose arrangement of fibers o The rest of the matrix is occupied by ground substance o This connective tissue provides a reservoir of water and salts for surrounding body tissues, always holding more fluid there is in the entire bloodstream o All body cells obtain their nutrients from ad release their wastes into this "tissue fluid" o Fibroblasts- flat branching cells that appear spindle shaped are the predominant cell type o Numerous macrophages are also seen o Adipocytes appear and so do mast cells with their dark stained features o The ground substance of this tissue is viscous- like molasses (because of its high concentration of hyaluronic acid) § This may hinder movement of cells · But some white blood cells secrete enzymes to liquefy this substance

- Loose Connective- Reticular Connective Tissue what does it resemble, where, what cells

- Loose Connective- Reticular Connective Tissue o resembles areolar connective tissue, but the only fibers in its matrix are reticular fibers, which form a delicate network along which fibroblasts called reticular cells are scattered. o Although reticular fibers are widely distributed in the body, reticular tissue is limited to certain sites. It forms a labyrinth-like stroma ("bed" or "mattress"), or internal framework, that can support many free blood cells (mostly lymphocytes) in lymph nodes, the spleen, and bone marrow.

- Membrane Overview and Types what is a membrane, 3 types

- Membrane Overview and Types o Membrane incorporates more than one type of tissue, they are simple organs o 3 Types: § Cutaneous § Mucous § Serous § ***Synovial- some consider this to be one, it only has one tissue type (connective) o They all are continuous multicellular sheets composed of at least 2 primary tissue types: an epithelium bound to an underlying layer of connective tissue proper

- Modes of Secretion 3 types and describe them

- Modes of Secretion o can also be described functionally as merocrine, holocrine, or apocrine glands. o Most are merocrine glands § which secrete their products by exocytosis as they are produced. The secretory cells are not altered in any way (so think "merely secrete" to remember their mode of secretion). The pancreas, most sweat glands, and salivary glands belong to this class o Secretory cells of holocrine glands § in contrast, they accumulate their products within them until they rupture. (They are replaced by the division of underlying cells.) § Because holocrine gland secretions include the synthesized product plus dead cell fragments (holo = whole, all), you could say that their cells "die for their cause." · Sebaceous (oil) glands of the skin are the only true example of holocrine glands o Apocrine glands are present in other animals, there is some controversy over whether humans have this gland type. § Like holocrine glands, apocrine glands accumulate their products, but in this case only just beneath the free surface. Eventually, the apex of the cell pinches off (apo = from, off), releasing the secretory granules and a small amount of cytoplasm. § The cell repairs its damage and the process repeats again and again. § The closest to an example of this process in humans is the release of lipid droplets by lactating mammary glands. · However, most histologists classify mammary glands as merocrine glands because this is the means by which milk proteins are secreted.

- Mucous Membranes what does it line, cell type,

- Mucous Membranes o Line all body cavities that open to the outside of the body, such as the hollow organs of the digestive, respiratory, and urogenital tracts o They are wet or moist membranes bathed by secretions o Most contain either stratified or simple columnar epithelia o The epithelia sheet lies directly over a layer of areolar tissue called the lamina propria o Often adapted for absorption and secretion § Many secretes mucus, but that is not a requirement (the urinary tract does not secrete mucus)

- Multicellular Exocrine Glands 2 parts, how is it supplied, 2 ways of classification

- Multicellular Exocrine Glands o Are structurally more complex o Made up of 2 parts- an epithelium-derived duct and a secretory unit (acinus) consisting of secretory cells o With the exception of the simplest glands, supportive connective tissue surrounds the secretory unit, supplies if with blood and nerve fibers, and forms a fibrous capsule that extends into the gland and divides it into lobes o Can be classified by structure and by mode of secretion

- Nervous Tissue 2 cells

- Nervous Tissue o Main component of the nervous system o 2 main cell types § Neurons § Neuroglia o Neurons- highly specialized cells that generate and conduct nerve impulses o Branching cells with cytoplasmic extensions or processes that enables them to: § Respond to stimuli- dendrites § Transmit electrical impulses over a distance- axons o Supporting cells are non-conducting cells that support, insulate, and protects the delicate neurons

- Pseudostratified Columnar Epithelium definition, nucleus, where

- Pseudostratified Columnar Epithelium o Vary in height, all cells are on the bottom of the basement membrane, only the tallest reach the free surface o The nuclei lie at different levels because of the different heights, thus giving a fake look of multiple layers o The short cells are unspecialized o This epithelium, like columnar, secretes and absorbs substances o A ciliated version containing goblet cells lines most of the respiratory tract § Cilia also moves dust-trapping mucus away from the lungs

- Regenerative Capacity at Different Tissues

- Regenerative Capacity at Different Tissues o Tissues vary widely in their ability to regenerate. § Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, and blood-forming tissue regenerate extremely well. § Smooth muscle and dense regular connective tissue have a moderate capacity for regeneration, but skeletal muscle and cartilage have a weak regenerative capacity. § Cardiac muscle and the nervous tissue in the brain and spinal cord have virtually no functional regenerative capacity, and they are routinely replaced by scar tissue. o In nonregenerating tissues and in exceptionally severe wounds, fibrosis totally replaces the lost tissue. o Over a period of months, the fibrous mass shrinks and becomes more and more compact. The resulting scar appears as a pale, often shiny area composed mostly of collagen fibers. o Scar tissue is strong, but it lacks the flexibility and elasticity of most normal tissues, and cannot perform the functions of the tissue it has replaced.

- Reticular Fibers what are they made up from, what do they do, where

- Reticular Fibers o Short, fine fibers are made of a different type of collagen than the more common ones o They connect coarser collagen fibers o They also form delicate networks that surround small blood vessels and support the soft tissue of organs o Abundant where connective tissue is next to other tissue types § EX: basement membrane of epithelial tissues

- Serous Membrane cell type

- Serous Membrane o Moise membrane found in closed ventral body cavities o Visceral and parietal layers separated by serous fluid o Each layer consists of simple squamous epithelium (a mesothelium) resting on a thin layer of areolar connective tissue o Serous fluid lubricates the facing surfaces of the visceral and parietal, so they slide with ease o Pleurae- lines the thoracic wall o Pericardium- encloses the heart o Peritoneum- encloses the abdominopelvic

- Simple Columnar Epithelium definition, where, whats on them

- Simple Columnar Epithelium o single layer of tall, closely packed cells o It lines the digestive tract from the stomach through the rectum. o Columnar cells are mostly associated with absorption and secretion, and the digestive tract lining has two distinct modifications that make it ideal for that dual function: § Dense microvilli on the apical surface of absorptive cells § Tubular glands made primarily of cells that secrete mucus-containing intestinal juice o Some simple columnar epithelia display cilia on their free surfaces § helps move substances or cells through an internal passageway.

- Simple Cuboidal Epithelium definition, where they are

- Simple Cuboidal Epithelium o consists of a single layer of cells as tall as they are wide o The generally spherical nuclei stain darkly. o Important functions of simple cuboidal epithelium are secretion and absorption. § This epithelium forms the walls of the smallest ducts of glands and of many kidney tubules.

- Simple Squamous Epithelia basic definition, where they are, 2 types

- Simple Squamous Epithelia o Flattened, tile like, cytoplasm is sparse o Thin and often permeable, simple squamous epithelium is found where filtration or the exchange of substances by rapid diffusion is a priority. § In the kidneys, it forms part of the filtration membrane that filters blood to make urine. § In the lungs, it forms the walls of the air sacs across which gas exchange occurs o 2 Special Types § Endothelium ("inner covering") · provides a slick, friction-reducing lining in lymphatic vessels and in all hollow organs of the cardiovascular system (blood vessels and the heart). · Capillaries consist exclusively of endothelium, and its exceptional thinness encourages the efficient exchange of nutrients and wastes between the bloodstream and surrounding tissue cells. § Mesothelium ("middle covering") · is the epithelium found in serous membranes, the membranes lining the ventral body cavity and covering its organs.

- Skeletal

- Skeletal o tissue is packaged by connective tissue sheets into organs called skeletal muscles that are attached to the bones of the skeleton. o These muscles form the flesh of the body, and as they contract, they pull on bones or skin, causing body movements. o Skeletal muscle cells, also called muscle fibers, are long, cylindrical cells that contain many peripherally located nuclei. Their obvious banded, or striated, appearance reflects the precise alignment of their myofilaments

- Smooth

- Smooth o is so named because its cells have no visible striations. o Individual smooth muscle cells are spindle shaped (tapered at both ends) and contain one centrally located nucleus o Smooth muscle is found mainly in the walls of hollow organs other than the heart (digestive and urinary tract organs, uterus, and blood vessels). o It squeezes substances through these organs by alternately contracting and relaxing.

- Special Characteristics of Epithelium o Polarity: 2 surfaces, basal surface- what does it do

- Special Characteristics of Epithelium o Polarity § All epithelia have two surfaces: · Apical surface- not attached to surrounding tissue and is exposed to either outside f the body cavity or the cavity of an internal organ · Basal surface- attached to the underlying connective tissue § We say that epithelia exhibit apical-basal polarity § Most apical surfaces have microvilli, others can be smooth and slick § In epithelia that absorbs or secrete, the microvilli are so dense, it gives off a brushed border appearance § Adjacent to the basal surface is a thin supporting sheet called the basal lamina · The basal lamina is a noncellular, adhesive sheet consisting of glycoproteins secreted from epithelia cells and some fine collagen fibers · It acts as a selective filter that determines which molecules diffusing from the underlying connective tissue are allowed to enter the epithelium

- Stratified Cuboidal Epithelia - Stratified Columnar Epithelia

- Stratified Cuboidal Epithelia o Rare o Mostly found in the ducts of larger glands- sweat, mammary o Normally only 2 layers of cuboidal cells - Stratified Columnar Epithelia o Also limited in the body o Small amounts are found in the pharynx, male urethra, and lining some glandular ducts Only the apical layer is columnar

- Stratified Squamous Epithelium definition, where, division, diffusion, keratinized and non

- Stratified Squamous Epithelium o Most widespread o Several thick layers, protective role o Free surface cells are squamous, as you go deeper you find cuboidal or columnar o Found in areas subject to wear and tear o Surface cells are constantly being rubbed away and replaced by division of its basal cell (they regenerate from the bottom and push cells upward) o Cells farther from the basal membrane are less viable since they don't get as much diffused nutrients as cells closer to the membrane o This epithelium forms the external surface of the skin o The outer layer of the skin, epidermis, is keratinized- contains keratin- though protective protein o Other stratified squamous epithelia are nonkeratinized

- Structural Components of Connective Tissue 3 main compoents just the name, and what does this allow for

- Structural Components of Connective Tissue o Three main components: ground substance, fibers, cells § Ground substance makes up the extracellular matrix o The composition and arrangement of these three components vary greatly, providing for great diversity

- Structure Classification

- Structure Classification o On the basis of their duct structures, multicellular exocrine glands are either simple or compound o Simple glands have an unbranched duct, whereas compound glands have a branched duct. § The glands are further categorized by their secretory units as: · (1) tubular if the secretory cells form tubes; · (2) alveolar if the secretory cells form small, flasklike sacs (alveolus = "small hollow cavity"); · (3) tubuloalveolar if they have both types of secretory units. o Many anatomists use the term acinar interchangeably with alveolar.

- Tissue Repair and Steps what stimulates it, where, what do cells do, 2 ways, initial part of wound healing

- Tissue Repair and Steps o Stimulated by the body's inflammatory response o The battle is waged in the connective tissue o A relatively non-specific reaction, opposed to the immune response which is specific o Tissue repair requires that cells divide and migrate, these activities are initiated by growth factors (wound hormones) o Repair occurs in 2 major ways: § Regeneration- replaces destroyed tissue with the same kind of tissue § Fibrosis- replaces the destroyed tissue with scar tissue, which is dense connective tissue · Which of these occurs depends 1) the type of tissue damaged and 2) the severity § In skin repair involves both activities o In the initial part of wound healing, granulation tissue is form § This is a delicate pink tissue that contains capillaries that grow in from nearby areas and lay down a new capillary bed o (In simple infections (pimple or sore throat) healing is solely by regeneration only severe infections leads to clot formation or scarring)

- Transitional Epithelium where, type of cells, what it does

- Transitional Epithelium o forms the lining of hollow urinary organs, which stretch as they fill with urine o Cells of its basal layer are cuboidal or columnar. o The apical cells vary in appearance, depending on the degree of distension (stretching) of the organ. o When the organ is distended with urine, the transitional epithelium appears to thin from about six cell layers to as few as three, and its domelike apical cells flatten and become squamouslike. § The ability of transitional cells to change their shape (undergo "transitions") allows a greater volume of urine to flow through a tubelike organ. In the bladder, it allows more urine to be stored.

- Unicellular Exocrine Glands the most important, what do they produce

- Unicellular Exocrine Glands o Most important examples of unicellular glands are mucous cells and goblet cells o Unicellular glands are sprinkled in the epithelial lining of the intestinal and respiratory tracts o These glands produce mucin § Mucin is a complex glycoprotein that dissolves in water when secreted § Once it is dissolved, it forms mucus, a slimy coating that protects and lubricates surfaces § Goblets cells- accumulating mucin distends from the top of the cell, distorting the shape of the cell · This distortion does not happen in mucous cells

- Special Characteristics of Epithelium o Avascular but Innervated

o Avascular but Innervated § Although epithelium is avascular (contains no blood vessels), it is innervated (supplied by nerve fibers). § Epithelial cells are nourished by substances diffusing from blood vessels in the underlying connective tissue.

- Special Characteristics of Epithelium o Regeneration

o Regeneration § Epithelium has a high regenerative capacity. · If and when their apical-basal polarity and lateral contacts are destroyed, epithelial cells begin to reproduce themselves rapidly. · As long as epithelial cells receive adequate nutrition, they can replace lost cells by cell division.

- Special Characteristics of Epithelium o Specialized Contacts

o Specialized Contacts § With the exception of glandular epithelia, epithelia cells are fitted closely together to form continuous sheets § They are held together by tight junctions and desmosomes

- Special Characteristics of Epithelium o Supported by Connective Tissue: what is in between them, 2 layers

o Supported by Connective Tissue § All epithelial sheets rest upon and are supported by connective tissue. § In between the epithelial and connective tissues is a basement membrane that reinforces the epithelial sheet, helps it resist stretching and tearing, and defines the epithelial boundary. § The basement membrane consists of two layers: · a basal lamina (described above) · reticular lamina o The reticular lamina is deep to the basal lamina. It consists of a layer of extracellular material containing a fine network of collagen protein fibers that "belongs to" the underlying connective tissue.