Anatomy Chapter 4: Histology

Epithelial Tissue Classification

1. By the number of layers present (that lie on basement membrane): a. Simple-single cell layer (areas that need quick absorption, secretion, and filtration) b. Stratified-2 or more cell layers (areas that need more protection 2. By cell shape (looking at the apical cell layer): a. Squamous-flattened and scale like -flat nucleus b. Cuboidal-boxlike (approx. as tall as they are wide) -spherical nucleus c. Columnar-tall and column shaped -elongated nucleus, located closer to cell base

Types of Connective Tissue

1. Connective Tissue Proper -all mature c.t. is c.t. proper (except bone, cartilage, and blood) a. Loose Connective -Areolar -Adipose -Reticular b. Dense Connective -Dense Regular -Dense Irregular -Elastic? 3. Cartilage a. Hyaline Cartilage b. Fibrocartilage c. Elastic Cartilage 4. Bone a. Spongy b. Compact 5. Blood a. White Blood Cells b. Red Blood Cells

Characteristics Common to Connective Tissue

1. Highly vascular -rich supply of blood vessels -except mature cartilage (avascular) and dense c.t (poorly vascular) 2. Extracellular matrix -connective tissue is composed primarily of extracellular matrix (non-living) (except adipose tissue) -all other tissue types are composed mainly of cells -separates the living cells of the tissue -allows the tissue to bear weight, withstand tension, and endure abuses (trauma and abrasion) that no other tissue can tolerate 3. Common origin -derived from mesoderm (fetal tissue) only 4. Able to undergo mitosis -mitosis is the result of immature c.t. cells called -blast that mature into -cyte cells

Epithelium Characteristics *look at figure in PPT

1. Polarity: -All epithelia have an apical and basal surface -Surfaces differ in both structure and function a. apical (upper free) surface exposed to the body exterior/cavity of an internal organ -some apical surfaces are smooth -most apical surfaces have microvilli: fingerlike extensions of the plasma membrane that increase exposed surface area (i.e. lining the intestines or kidney tubules) (brushed border) -some apical surfaces have cilia: hairlike projections that propel substances along the free surface (i.e. Lining the trachea) b. basal (lower attached) surface 2. Supported by connective tissue: Epithelial tissue lies on basement membrane surface: Function: -reinforces epithelial sheer, resists stretching and tearing, defines epithelial boundary Basement surface consists of 2 laminae: a. Basal lamina: -noncellular, adhesive sheet consisting of glycoproteins and collagen fibers -acts as selective filter: determines which substances diffusing from the underlying connective tissue are allowed to enter the epithelium -also acts as scaffolding along which epithelial cells can migrate to repair a wound b. Reticular lamina: -layer of extracellular material of collagen protein fibers that "belongs to" the underlying c.t 2. Avascularity -contains no blood vessels, but contain nerve endings (innervated) -because they are avascular, epithelial cells are nourished by substances diffusing from blood cells in underlying c.t. 3. Regeneration -high regenerative rate as long as they are well nourished -mitosis (asexual reproduction) 4. Cellularity (specialized contacts) -no extracellular matrix -cells are packed closely together, held together by tight junctions, gap junctions, and desmosomes -these lateral contacts bind cells together at many points -tight junctions maintain epithelial polarity by keeping proteins in apical surface from diffusing into basal surface 5. Develop from any of the 3 fetal tissue types

Types of Epithelium

1. Simple Squamous 2. Simple Cuboidal 3. Simple Columnar 4. Pseudostratified Columnar 5. Stratified Squamous 6. Stratified Cuboidal 7. Stratified Columnar 8. Transitional

Observation of Gross Histology

1. Skin 2. Hypodermis 3. Skeletal muscle (located in biceps brachi muscle) 4. Smooth muscle (located in stomach wall) 5. Cardiac muscle 6. Dense regular c.t. (located in a tendon) 7. Hyaline cartilage (located in a knee joint) 8. Fibrocartilage (located in a knee joint) 9. Serous membranes a. visceral peritoneum b. parietal peritoneum 10. Adipose tissue (located in hypodermis) 11. Loose areolar c.t.

Bone (Osseous) Tissue

2 types: 1. Compact bone 2. Spongy bone Description: -hard, calcified extracellular matrix -matrix consists of inorganic salts (calcium phosphate) and collagen fibers -matrix is organized in lamellae (layers, like thoseof an onion) -bone tissue is produced by osteoblasts (mobile bone cells) -osteocytes are immobile, mature cone cells that are cemented into lacunae -osteocytes receive nourishing interstitial fluid by way of diffusion through canaliculi: tiny canals that penetrate the lamellae -very well vascularized Function: -salts provide a hard quality to matrix -collagen fibers provide strength and some flexibility -supports and protects -marrow inside bones is site for hematopoiesis (blood cell formation) -stores calcium and other minerals, fat Location: -bomes (i.e. femur) ID Characteristics: -composed of osteocytes (small black ovals) arranged into rings around a central canal in each "tube" of bone -bone tissue looks like a tree trunk -1st ring is the central canal -2nd ring has osteocytes -cannaliculi connect one ring to another Be able to ID: -osteocyte in lacuna -osteonic canal -canaliculi -lamella

Structural Elements of Connective Tissue

3 main elements: 1. Ground substance 2. Fibers 3. Cells Ground substance and fibers make-up the extracellular matrix Density of protein fibers and ground substances in c.t. varies from one type to another -loose c.t. consists of low density of protein fibers within semifluid ground substance -dense c.t. has a much higher density of protein fibers that allow a sparse amount of semifluid ground substance -cartilage has a relatively dense protein matrix, and its ground substance is gelatinous due to presence of many large protein-sugar molecules -bone has very hard ground substance, due to the abundance of minerals -blood is very different, with a population of cells carried in a fluid ground substance, know as plasma Composition and arrangement of elements varies in different connective tissue -allows each c.t. to perform a specific function Areolar Prototype model: common structural plan

Tissue

A group of cells similar in structure that perform common or related functions -such as protection, secretion, or contraction

Dense Connective Tissue

Characterized by a high concentration of collagen fibers, allowing realtively little ground substance and few cells a.k.a Fibrous connective tissue Cells are fibroblasts -produce the collagen fibers and ground substance 3 types of Dense Connective Tissue 1. Dense Regular 2. Dense irregular 3. Elastic All 3 forms provide strenth with some flexibility

Loose Connective Tissue

Characterized by the presence of protein fibers that are loosely arranged and in low abundance Primary cell type: fibroblast -large cell capable of movement throughout the semifluid ground substance

Multicellular Exocrine Gland Classification

Classified by: 1. Structure a. Duct structure -simple glands: unbranched duct -compound glands: branched duct b. Secretory unit structure: -tubular: tube forming (secretory cells form tubes) -alveolar (acinar): form flask like sacs -tubuloalveolar: form both types of secretory units 2. Type/Mode of secretion: -Merocrine -Apocrine -Holocrine

Exocrine Gland Classification

Classified by: 1. Number of cells: -Unicellular -Multicellular

Stratified Columnar Epithelium

Description: Function: Location:

Hyaline Cartilage

Description: -Amorphous but firm matrix -collagen fibers form an imperceptible network (unable to see them) -chondroblasts produce the matrix -once mature, chondrocytes lie in lacunaue -ground substance is filled with chondroitin sulfate: large protein-sugar molecules Function: -serves as smooth surface to support bone movement at many of the body's joints -in trachea, forms the rings that keep the trachea open -supports and reinforces -serves as resilient cushion -resists compressive stress Location: -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 alrynx ID Characteristics: -chondrocytes tend to cluster into groups of 2-4 -chondrocytes shrink away from the pocket (lacuna): they sit within the semisolid intracellular matrix, leaving a small space next to the cell -typically cannot see collagen fibers in matrix (matrix is smoother than in fibrocartilage) Be able to ID: -chondrocyte (embedded within lacunae) -lacuna -extracellular matrix

Dense Regular Connective Tissue

Description: -a.k.a fibrous c.t. -primarily parallel arrangement of tighly packed collagen fibers -few elastic fibers -major cell type is the fibroblast (they secrete the collagen fibers) -less ground substance than other c.t. -poorly cascularized Function: -attaches muscle to bone or to muscles -attaches bone to bones -withstands great tensile stress when pulling force is applied in one direction Location: -tendons -most ligaments -aponeuroses ID Characteristics: -fibroblasts/cytes are found in between protein strands -nuclei of cells appeared to be lined up in rows between strands -collagen protein fibers run parallel to one another -be able to distinguish from smooth muscle tissue . -when looking at dense c.t. tissue, you are looking for patterns Be able to ID: -collagen fibers -nuclei of fibroblasts: visible as the small, purple-stained nuclei between thick collagen strands

Transitional Epithelium *Do not have to ID

Description: -ability to contract and expand -cells are in the process of changing between a relaxed, plump state and a compressed, flattened state (allowing tissue to stretch) -resembles both stratified squamous and stratified cuboidal -surface cells are dome shaped or squamous like, depending on degree of organ stretch -basal cells are cuboidal or columnar Function: -stretches readily; permits stored urine to distend urinary organ Location: -forms lining of hollow urinary organs: ureters, bladder, and part of urethra

Cardiac Muscle Tissue

Description: -branching, striated cells -centrally located single nucleus -cells interdigitate at specialized junctions: itnercalated discs (y-shaped connections) Function: -involuntary contraction that propels blood forward as it contracts Location: -forms the walls of the heart ID Characteristics: -myocytes are short and branched -myocytes are connected by intercalated disks, which may show up as dark bands between cells -myocytes have striations in cytoplasm -nuclei are large, round, and centrally located -typically single nucleus (may be bi-nucleated) Be able to ID: -cardiac muscle cells (quadangular) -nucleus -intercalated disc -striations

Elastic Connective Tissue *Do not have to ID

Description: -dense arrangement of collagen fibers -dominated by large numer of branching elastic fibers Function: -provides a firm, but elastic, structure -allows recoil after stretching -aids passive recoil of lungs following inspiration -maintains pulsatile flow of blood through arteries Location: -walls of large arteries -within walls of the bronchial tubes

Fibrocartilage

Description: -dense, slightly slightly flexible cartilage that contains bundles of collagen fibers in the extracellular matrix -matrix similar to but less firm than in hyaline cartilage -collagen fibers predominate, present as thin wavy lines Function: -tensile strength allows it to absorb compressive shock Location: -intervertebral discs -pubic symphysis -discs of knee joint ID Characteristics: -chondrocytes tend to line up in rows (and lie within lacunae) -collagen fibers in intracellular matrix are visible and run parallel to one another -chondrocytes shrink away from the lacuna they sit in Be able to ID: -chondrocyte -lacuna -collagen fibers in ground susbtance

Dense Irregular Connective Tissue *Do not have to ID

Description: -fibers are packed tighyl together and are organized into smaller bundles that are randomly arranged (appears randomized because it is withstanding tension in many directions) -collagen fibers dominate the tissue -some elastic fibers -main cell type: fibroblast (for all dense c.t.) Function: -withstands tension exerted in many directions -provides structural strength Location: -found in deep layers of the skin (dermis) -sclera of the eyes -in the fascia in and around muscles -fibrous capsules surround many organs and joints -submucosa of digestive tract -valves and pericardium of the heart

Smooth Muscle Tissue

Description: -forms sheets that contribute to the walls of hollow organs -cells are spindle shaped (elongated) with single, centrally located nucleus -lack striations Function: -propels substances (foodstuffs, urine, a baby, etc) through hollow organs (along internal passageways -involuntary control Location: -walls of hollow organs: blood vessels, stomach, small intestine ID Characteristics: -myocytes are spindle-shaped -myocytes run parallel to one another -each myocyte contains one centrally located nucleus -no striations (stripes) in muscle cells -single cigar-shaped nucleus centrally located in myocyte Be able to ID: -smooth muscle cell -nuclei

Loose Connective Areolar Tissue

Description: -gel like matrix with all three fiber types: fibroblasts, macrophages, mast cells, and some WBC's -considered the prototype of the connective tissues because it is the best representative of the common structural plan of all the c.t.'s -fibers randomly arranged -well vascularized -lots of ground substance Function: -wraps and cushions organs (acts as soft packing tissue) -its macrophages phagocytize bacteria -plays important role in inflammations -holds and conveys tissue fluid -forms the lamina proprietary of mucous membranes -surrounds capilarries Location: -found between skin and muscles and between other organs of the body -widely distributed epithelia of body ID Characteristics: -you will see a lot of protein fibers (collagen, reticular, and elastic) running in many directions-randomly arranged -between the fibers: fibroblasts, fibrocytes, WBC's, etc -abundance of ground substance Be able to ID: -Fibroblast: cell type that secretes the matrix in areolar tissue -mast cells (may be present): have large, darkly stained granules in their cytoplasm -collagen fibers: thick bands -elastic fiber: thinner black strands -ground substance

Loose Reticular Connective Tissue *Do not have to ID

Description: -loose network of thin, branching reticular fibers and loose ground substance -reticular cells (specialized type of fibroblast) produce the fibers and ground substance Function: -fibers form a soft internal skeleton (stroma) (scaffolding) that supports other cell types including WBC's, mast cells, and macrophages Location: -lymphoid organs (lymph nodes, bone marrow, and spleen)

Loose Connective Adipose Tissue

Description: -matrix as in areolar, but very sparse -closely packed adipocytes (fat cells) that make up 90 % of the tissue -nucleus pushed to the side by large fat droplet -highly vascular Function: -provides reserve food fuel (energy storage) -supports and protects organ (cushions from injury) -insulates against heat loss Location: -under the skin in subcutaneous tissue -around some visceral organs: kidney, heart, and spleen -around eyes -within abdomen -in breast ID Characteristics: -cell are large and round -lipids stain clear unless a special stain is used: entire cell is clear except for nucleus and cell membrane -nucleus is usually pushed off to the side Be able to ID: -Adipose cell -lipid vacuole -plamsa membrane -nucleus Be able to ID:

Blood

Description: -most fluid of the connective tissues -Cells: red and white blood cells, platelets, lymph in a fluid matrix (plasma), -plasma is the groun substance (slightly thicker than water) Function: -performs the vital function of transporting O2 and CO2 (respiratory gases) to and from the body cells -transports waste materials, hormones, enzymes, nutrients, and other vital materials throughout the body Location: -contained within blood vessels -seen in a blood smear ID Characteristics: Be able to ID: -WBC (lymphocyte) (neutrophil?) -RBC (erythrocyte) -platelets

Skeletal Muscle Tissue

Description: -primary tissue of muscular system -skeletal muscle cells (muscle fibers) are long and cylindrical in shape -multinucleate cells (nuclei are peripherally located) -many obvious striations: relflects alignment of their myofilaments Function: -attaches to bone -voluntary movement: locomotion -manipulation of envrionment -facial expression -voluntary control Location: -in skeletal muscles attached to bones -occasionally to skin ID Characteristics: -myocytes are very long -myocytes are parallel to one another -myocytes are multinucleate -nuclei tend to be pushed to periphery of cell -myocytes are striated Be able to ID: -skeletal muscle cell -nuclei -striations -connective tissue -sarcolemma

Pseudostratified Columnar Epithelium

Description: -single layer of cells of differing heights; some not reaching the free surface (appears to have many layers) (all cells contact the basement membrane, giving it classification of single layer) -nuclei seen at different levels -may contain mucus secreting cells (goblet cells) -ciliated or nonciliated Function: a. Nonciliated: -lacks cilia and goblet cells b. Ciliated: -secretion, particularly of mucous -propulsion of mucous by ciliary action (upward and out toward the mouth and nasal cavity) Location: a. Nonciliated (PSCC)lines: -large ducts of certain glands -epididymis -part of male urethra b. Ciliated lines: -trachea -bronchi ID Characteristics: -goblet cells: mucous will either stain clear or purplish/blue -all cells touch basement membrane, but not all cells reach space, so nuclei are at different levels -contains cilia on apices of cells Be able to ID: -cilia -goblet cell -PSCC cell -connective tissue -nucleus of goblet cell and of basal cell -basement membrane

Simple Squamous Epithelium

Description: -single layer of flattened cells with a central disc-shaped nucleus and sparse cytoplasm Function: -very thin structure allows for rapid movement of substances across it during diffusion, flirtation, and secretion Location: -kidney glomeruli -air sacs of lungs -linings of heart (endocardium), blood vessels (endothelium), and lymphatic vessels -lining of ventral body cavity (serous membranes) (mesothelium) ID characteristics: a. cells tend to be very long and thin, so nuclei will bulge out into space b. you will not see much of the cytoplasm Be able to ID: -a squamous cell -nucleus -cell membrane

Simple Columnar Epithelium

Description: -single layer of tall, usually cylindrical cells -round to oval nuclei near basal surface of each cell -many have microvilli (brushborder) -can be ciliated or nonciliated (conciliated is more common) -may contain goblet cells (mucus secreting unicellular exocrine glands) between the cylindrical cells -many mitochondria Function: a. Nonciliated -absorption -secretion of mucus and enzymes, and other substances b. Ciliated -propels mucus, cerebrospinal fluid, and reproductive cells via ciliary action Location: a. Nonciliated forms inner lining of: -digestive tract (stomach to anal canal)(small intestine) -reproductive tract (excluding fallopian tubes and portions of the uterus) -urinary tracts -excretory ducts of many glands -often contains microvilli at the apical surface of cells b. Ciliated-lines: -portions of respiratory tract (smaller bronchi) -fallopian tubes -parts of uterus -paranasal sinuses -central canal of spinal cord ID Characteristics: -cells are tall, column shaped -nuclei are elongated and nuclei of cells tend to be in the same plane -may or may not have cilia, microvilli, or goblet cells Be able to ID: -nonciliated columnar epithelium -columnar cell -connective tissue -microvilli (brush border) -nucleus -lumen -connective tissue

Stratified Squamous Epithelium

Description: -thick membrane composed of several cell layers -surface cells are flattened (squamous) -basal cells are cuboidal or columnar and are metabolically active -between the basal and apical layers, the cells transition from columnar/cuboidal to squamous -in keratinized type, surface cells contain keratin and are dead Function: -protects underlying tissues in areas subjected to abrasion Location: a. Nonkeratinized forms linings of: -esophagus -mouth (i.e. buccal surgace) -vagina b. Keratinized: -epidermis of skin (dry membrane) ID characteristics: a. top cell flyers may or may not have nuclei (depends if tissue is keratinized or nonkeratinized) -keratinized tissues will not have nuclei in the superficial (apical) cell layers and look as though they are flaking off b. Cells change shape as they extend from basement membrane to the superficial cell layers -*when id'ing a cell shape for epithelium id, always look at the top cell layer Be able to ID: -basal cell (deep)layer -apical layer -squamous cell -connective tissue

Stratified Cuboidal Epithelium *Do not have to ID

Description: -two layers of tubelike cells Function: -protection -function reflects location (i.e. sweat glands release sweat, salivary glands release saliva) Location: -mammary glands -salivary glands -largest ducts of sweat glands

Elastic Cartilage

Description: -yellowish cartilage characterized by presence of elastic fibers that dominate the protein matrix (*Requires a special stain to see the elastic fibers in the matrix) -similar to hyaline cartilage, but more elastic fibers in matrix Function: -maintains the shape of a structure while allowing great flexibility Location: -supports the external ear (pinna) -epiglottis ID Characteristics: -requires special stain to see elastic protein fibers in extracellular matrix -fibers will stain dark purple to black and are randomly arranged -chondrocytes shrink away from the pocket they sit in within the semisolid intracellular matrix -less intracellular matrix that hyaline cartilage Be able to ID: -chondrocyte -lacuna -elastic fibers in ground substance

Nervous Tissue

Description: a.k.a neraul tissues -presence of cells that are highly specialized to communicate to other cells by electrochemical signals (conductivity) -cells are neurons: highly specialized nerve cells that generate and conduct nerve impulses -neurons are found in many different shapes, most of which contain a long process: axon (conducts signal to other cell) and smaller processes: dendrites (receive signals from other cells) -neuralgia: cells that support, insulate, and protect neurons Location: -brain -spinal cord -nerves Function: -regulates and controls body function -internal communication ID Characteristics: -main visible component is the neuron cell body, containing the nucleus -you will see the beginning of the extensions coming off the cell body: axons and dendrites Be able to ID: -neurons -neuralgia

Mesenchyme (Embryonic Connective Tissue) *Do not have to ID

Description: -gel like ground substance containing fibers and start-shaped mesenchymal cells Function: -gives rise to all other c.t. types Location: -embryo

Simple Cuboidal Epithelium

Description: -single layer of cube-shaped cells with large, spherical centrally located nuclei Function: -secretion and absorption -often contains cilia or microvilli to assist in these functions Location: -kidney tubules -duct and secretory portions of small glands -ovary surface ID characteristics: a. cells are roughly cube shaped b. nuclei are large and round; nuclei of cells tend to be in the same place c. cytosol typical s evenly distributed around nucleus d. may or may not see cell membranes between individual cells Be able to ID: -cuboidal cell -plasma membrane -nucleus -lumen -apical surface -basal surface -connective tissue in viewing area

Connective Tissue Cells

Each major class of c.t. has a resident cell type that exists in immature (-blast) and mature (-cyte) forms Immature (-blast) cells: -are actively mitotic -secrete ground substance and fibers characteristic of their particular matrix: a. fibroblast-connective tissue proper (dense and loose c.t.) b. chondroblast-cartilage c. osteoblast-bone (*hemapoietic stem cell produces blood, but it is not considered because it is not location in its tissue) Mature (-cyte) cells: -maintain health of matrix -can easily revert to active state to repair and regenerate Other cell types found in c.t.: a. Adipose(fat) cells: -nutrient storage b. WBC's: -response to tissue injury -neutrophils, eosinophils, lymphocytes, etc. c. Mast cells: -detect foreign microbes and initiate local inflammatory response against them -cytoplasms contain secretory granules with chemicals that mediate inflammation (heparin, histamines, proteases, etc) -typically cluster around blood vessels d. Macrophages: -irregularly shaped cells that devour foreign material and dead tissue cells -central actors in the immune system e. Permanent cells: Cells are: a. Permanent -macrophages -adipocytes -fibroblasts b. Migrating (wandering): -macrophages -lymphocytes (WBC's)

Major Types of Tissue

Epithelial Tissue Connective Tissue Muscle Tissue Nervous Tissue

Epithelial Tissue

Epithelium is a sheet of cells that covers a body surface or lines a body cavity -forms boundaries between different environments -nearly all substances received or given off by the body must pass through and epithelium Function: -protection -absorption -secretion -excretion -filtration -sensory reception 2 forms of epithelium: 1. Covering and lining epithelium: external and internal surfaces 2. Glandular epithelium: secretory tissue in glands Arrangement: sheets or clumps of cells

Epitheleal Membranes

Epithelium is eventually organized into membranes -composed of one or more layers of epitheleal cells bound to an underlying layer of c.t. 3 types of epithelial mebranes: 1. Cutaneous membranes -the skin (integument) (covers body surface (epidermis)) -"dry": does not secrete a lubricating fluid -keratinized stratified squamous 2. Mucous membranes(a.k.a mucosae) -lines the body cavities open to the exterior: digestive tract, respiratory tract, and urogenital tract (mucosa of nasal cavity, mouth, esophagus lining, and lung bronchi -"wet": secretes mucous -stratified squamous or simple columnar 3. Serous membranes (a.k.a. serosae) -lines serous body cavities: parietal layer - covers surfaces of many internal organs: visceral layer (parietal/visceral peritoneum, pericardium, and pleurae) -"wet": produce serous fluid (lubricating fluid) -simple squamous epithelium -endothelium: serous membranes taht line blood vessels -endocardium: serous membranes that line the inside of the hear

Covering and Lining Epithelium

External and internal surfaces -Forms the outer layer of the skin (covers the body) -Lines body cavities: open cavities (hollow structures) of urogenital, digestive, and respiratory systems -Covers walls and organs of the closed ventral body cavity Examples: -Body surface is covered by epithelium that protects the body from UV rays - Respiratory tract epithelium is lined with cilia to sweep foreign particles away from the lungs -Small intestine is lined by epithelium that functions in absorption -Kidney tubules contain epithelia that functions in absorption, filtration, and excretion

Exocrine glands

Externally secreting Composed of folds of epithelial tissue Synthesize and secrete product through a duct into a body surface or cavity Location: -skin (sweat glands): secrete sweat -head (salivary glands): secrete saliva, tears -stomach: secretes -mammary glands: -prostate gland: secretes sperm -liver: secretes bile -pancreas: secretes pancreatic fluid Secretions: saliva, tears, sweat, oil, bile, pancreatic fluid, sperm, eggs, etc

Connective Tissue Fibers

Fibers are proteins that provide support Synthesized and secreted by blast cells that are specific to the tissue that the fibers are located in -i.e. osteoblasts, fibroblasts, chondroblasts 3 types of c.t. fibers: 1. Collagen (white) fibers -primarily composed of collagen (fibrous protein) -assemble into cross linked fibrils -extremely tough, yet flexible, providing high tensile strength -provides resistance to the matrix from tension, stretch, and pressure 2. Elastic (yellow) fibers -long and thin fibers, forming branching networks in the extracellular matrix -contain elastin: allows fibers to stretch and recoil -found where great elasticity is needed: skin, lungs, blood vessel walls 3. Reticular (fine collagen) fibers ("retic" = network) -short, fine, collagenous fibers that branch from collagen fibers into networks -networks provide support for small blood vessels and organs -found where c.t. is next to other types types i.e. around capillaries, in basement membranes of epithelial tissue

Exocrine glands-Multicellular

Form by invagination of epithelial sheet into underlying connective tissue More complex structure (than exocrine glands) containing 2 parts: 1. Duct-derived from epithelium 2. Secretory Unit (acinus)-consist of secretory cells -supportive connective tissue surrounds glands and supplies them with blood vessels and nerve fibers and forms fibrous capsule that divides the gland into lobes Classified by: 1. Structure a. Duct structure -simple glands: unbranched duct -compound glands: branched duct b. Secretory unit structure: -tubular: tube forming (secretory cells form tubes) -alveolar (acinar): form flask like sacs -tubuloalveolar: form both types of secretory units 2. Type/Mode of secretion: -Merocrine -Apocrine -Holocrine

***Johnwiley.net.au Tissue level of organization Name that tissue game

Game

Glandular Epithelium

Glandular epithelium fashions the glands of the body Glands are specialized structures arising from epithelium and are formed by localized proliferation and penetration of epithelial cells into the connective tissue beneath the epithelium Gland: one or more cells that makes and secretes an aqueous fluid called a secretion (containing proteins, lipids, or steroids) Gland Classification: 1. Where they release their products (2 Major categories of glands) a. Exocrine glands b. Endocrine glands 2. Number of cells: a. Unicellular b. Multicellular

Differentiate between selected exocrine glands according to size, shape, and secretory product

Goblet cell Sweat glands Sebaceous glands Ceruminous glands Mammary glands Salivary glands

Organ

Groups of tissue combine to perform specific body functions

Endocrine glands

Internally secreting Composed of folds of epithelial tissue Lack a duct Synthesize and secrete hormones that are released for diffusion into the blood (for their transport throughout the body -via exocytosis into extracellular fluid Include: -pituitary gland (brain) -pineal body (brain) -thymus -thyroid gland -parathyroid gland -pancreas -adrenal glands -gonads (ovaries/testes) Products of endocrine glands: hormones

Membranes

Membranes of the body form protective sheets that transmit blood vessels, lymphatic vessels, and nerves -they cover surfaces and line cavities throughout the body 2 categories of membranes: 1. Epithelial membranes a. Cutaneous membranes b. Mucosa membranes c. Serous membranes 2. Synovial membranes

Connective Tissue

Most abundant and widely distributed tissue in the body All classes of c.t. consist of living cells surrounded by a matrix -their major differences reflect cell type and the types and relative amounts of fibers Major Functions: 1. Binding -binds and connects other tissues together 2. Support -nutritional and structural support -maintains form and shape -provides continuity of form 3. Protection and Insulation -for the body i.e. fat 4. Storage -storing reserve fuel i.e. fat 5. Transportation -transporting substances within the body i.e. blood

Muscle Tissue

Muscle tissue is composed of myocytes -specialized cells containing molecular filaments of protein -main proteins: myosin and actin, which are arranged in parallel bundles -protein filaments enable cells to shorten in length, or contract (enabling movement) Derived from mesoderm 3 types: 1. Skeletal muscle tissue 2. Smooth muscle tissue 3. Cardia muscle tissue Function: produces movement (through contraction)

Types of Nervous Tissue

Neurons Neuralgia

Cartilage

Primarily composed of chondrocytres Extracellular matrix contains adhesiona called chondroitin sulfates Cartilage has a gelatinous ground substance (unlike other forms of c.t.) -ground substance is strengthened by presence of protein fibers, including collagen fibers and elastic fibers -gives cartilage some flexibility and resistance to stress Center of cartilage is avascular, due to the density of ground substance and protein matrix Surrounded by perichondrium -a dense irregular capsule with an underlying layer of chondroblasts (region of protein fibers and blood vessels) -servse as norusing interstitial fluid for the embedded chondrocytes (main cell type) Cartialge is prominent tissue in joints throughout the body 3 basic types: 1. Hylaine cartilage 2. Fibrocartilage 3. Elastic cartilage

Fetal Tissue (Primary Germ Layers)

Primary tissues are derived from at least 1 of the 3 types of fetal tissues (superficial to deep): 1. Ectoderm 2. Mesoderm 3. Endoderm Formed early in embryonic development Specialize to for the 4 primary tissues that make-up all body organs -Nerve tissue arises from ectoderm -Muscle and connective tissue arise from mesoderm -Epithelial tissues arise from all 3 germ layers -inner lining of digestive system (from endoderm)

Apocrine secretion

Releases product by pinching off a piece of the cell -release secretory granules and small amount of cytoplasm Cell repairs its damage and the process is repeated *Present in animals, but debate as whether they are present in humans -release of lipid droplet in mammary glands is the best example, BUT mammary glands are considered merocrine glands

Exocrine glands-Unicellular

Scattered within epithelial sheets Produce mucin: complex glycoprotein that dissolves in water when secreted -forms a slimy coating for lubricating and protection services (once dissolved) Examples: -Mucous cells: mucous contains mucin, water, WBC's, salts, and exfoliated cells -Goblet cells: accumulation of mucin distends the top of cell

Merocrine secretion

Secretes products by exocytosis (hormones?) -secreted cells are not altered Most multicellular exocrine glands are merocrine glands Examples: -most sweat glands -pancreas -salivary glands

Synovial Membranes

Synovial membranes -differ from epithelial membranes because they are composed entirely of connective tissue -contain no epithelial cells -line the cavities surrounding the goints -form a smooth surface and lubricating fluid (synovial fluid) -line tendon sheahs and bursae (small sacs that provide cushioning)

Holocrine secretion

The entire secretory cell ruptures, which release the secretions -the cell is dead, so not only do you get secretions relesed, but also dead cell fragments Example: -Only sebaceous (oil) glands do this Figure: Mature cell dies and becomes secretory product -cell division replaces lost cell

Histology

The study of tissues -vital in diagnostics (pathology)

Why study tissues?

They provide the structural and functional basis of an organ

Connective Tissue Ground Substance

Unstructured material that fills space between cells and contains the fibers Function: -molecular sieve through which nutrients and other dissolved substances can diffuse between blood capillaries and the cells Composition: a. Interstitial fluid -tissue fluid b. Cell adhesion proteins -c.t. glue that allows c.t. cells to attach to matrix elements -i.e. fibronectin, laminin, etc. c. Proteoglycans -protein core with attached GAG's -GAG (glycosaminoglycans): chondroitin sulfate and hyualronic acid -form aggregates that form substances into viscous gel Depending on the relative amounts of those components, the ground substance is fluid, semifluid, gelatinous, or hard