*Chapter 5-- Histology (microscopic anatomy)

Ch. 5 Study Guide Read Chapter 5 up to page 170 right before 5.4 Nervous and Muscular TissueComprehend Terminology (those in bold in the textbook)Study-- Figure questions, Think About It questions, and Before You Go On (section-ending) questionsDo end-of-chapter questions Testing Your Recall 1-4, 6-10, 13, 17, 18, 20True or False 1, 2, 5, 6, 10Testing Your Comprehension-- #4, #5*

5.1--The study of tissues*

* The Study of TissuesWhole body contains only 200 different types of cellsFour tissue classes (Def. of tissue--?) See Table 5.1.

Histology (microscopic anatomy)study of tissues and how they form organsOrgan = structure with discrete boundariescomposed of 2 or more tissue typesExamples:

* Differences among 4 Tissue ClassesTypes and functions of cells-- For example: Epithelial, CT, Nervous, MuscularCharacteristics of the matrix (extracellular material)Rubbery, stony, or gelatinousRelative amount of space occupied by cells versus matrixCT vs. muscle and epithelium

* Embryonic TissuesEmbryo begins as a single celldivides into many cells that form layers (strata)Three primary germ layersectoderm (outer) gives rise to: epidermis + nervous system endoderm (inner): mucous membranes: GI tract and respiratory linings; digestive glands. mesoderm (middle) forms mesenchyme (gelatinuous tissue) and then give rise to muscle, bone, and blood

* Tissue Sectioning (1)1. Preparation of histological specimensfixationsectionsmounted on slides & stained

2. Sectioning (slicing) an organ or tissue reduces a 3-dimensional structure to a 2-dimensional slice (see the next 3 slides)

1 2 3 4 512345Slices 1 & 5 miss the yolk / cell nucleus

Cell nucleus is smaller in sections 2 & 4Tissue Sectioning (2)*

*Tissue Sectioning (3)Image A is a cross section of elbow macaroni, resembling a blood vessel, piece of gut, or other tubular organ.Image B is a longitudinal section of a sweat gland. Notice what a single slice could look likeA B

* Types of Tissue Sections (1)Longitudinal sectiontissue cut along the longest direction of an organCross sectiontissue cut perpendicular to the length of an organOblique sectiontissue cut at an angle between a cross & longitudinal section

*Types of Tissue Sections (2)Would you classify the egg sections as longitudinal, cross, or oblique sections? How would the egg look if sectioned in the other two planes? (Fig. 5.2 question)Practice at home.

5.2--Epithelial tissue*

* Epithelial Tissue Introduction (1)One or more layers of closely adhering cells(Top) Forms a flat sheet with the upper (______) surface exposed to the environment or an internal body cavity(Bottom) Sits on basement membrane (basal surface of cells); Fig. Xanchors epithelium to underlying connective tissue(Nourishment) No room for blood vessels; . . .CT

*What are the functions of the basement membrane?

* Epithelial Tissue Introduction (2)Arrangement and Cell ShapeSimple epitheliumcontains one layer of cellsnamed by shape of cells

Stratified epitheliumcontains more than one layernamed by shape of apical cells

Fig. 5.3

*

1.Simple Squamous Epithelium*

*(Structure) Single row of flat cells (scaly)(Functions) Allows rapid diffusion of substances; secretes serous fluid(Locations) in alveoli, glomerular capsule, endothelium (blood vessels and heart), and serosa (external surface) such as stomach & intestines

* 2. Simple Cuboidal Epithelium (Structure) Single row of cube-shaped cells, often with microvilli(Functions) Absorption & secretion; produces mucus(Locations) Liver, thyroid, mammary, salivary and other glands, bronchioles, and most kidney tubules

Fig. 5.5

*

* 3.Simple Columnar Epithelium(Structure) Single row of tall, narrow cellsvertically oriented, oval nuclei in basal half of cell(Functions) Absorption & secretion; secretion of mucus(Locations) Inner lining of GI tract from stomach to the anus; ducts of gallbladder; uterus, and uterine tubes; some kidney tubes; a few portions of upper respiratory tract

*

* 4. Pseudostratified Epithelium(Structure) Single row of cells not all of which reach the free surface; nuclei at different levels.(Functions) secretes propels mucus(Locations) most of the upper respiratory system from nasal cavity to bronchi; part of male urethraFig. 5.7

*

* Stratified EpitheliaComposed of more than one layer of cells & named for shape of __________ cells

Deepest cells sit on basement membrane

* 5A. Keratinized Stratified SquamousLayers of epithelium covered with compact, ______ squamous cells (no nuclei) packed with protein keratinRetards water loss, prevents entrance of organismsForms epidermal layer of skin (esp. soles and palms)Fig. 5.8 Skin from the sole of the foot

* 5B.Nonkeratinized Stratified SquamousMultilayered epithelium that lacks surface layer of dead cells forming moist, slippery layerLocations: tongue, oral mucosa, esophagus & vaginaEpithelial layerFig. 5.9 Mucosa of the vagina

Pap smear/testWhat? Examination of exfoliated cells Where? The cervix Why? How? Loose cells are examined microscopically for abnormal cellsWho? Between 30-50 years old

Fig. 28.5*

Fig. 28.5Pap smearsWhich one is normal cells?*

* 6. Stratified Cuboidal Epithelium(Structure) Two or more layers of cells; surface cells square or round (Functions) Secretion and production(Locations) Sweat glands, mammary glands, salivary glands, ovarian follicles, seminiferous tubulesFig. 5.10Sweat gland ducts

* 7. Transitional Epithelium(Structure) Multilayered epithelium with rounded (not flattened) surface cells(Functions) Allow stretches and distension(Locations) Urinary tract--part of kidney, ureter, urinary bladder, part of the urethra

Fig. X

*

Qs from Before You Go On (p. 162)Distinguish between simple and stratified epithelia. Explain why pseudostratified columnar epithelium belongs in the former category?Distinguish a stratified squamous epithelium from a transitional epithelium.How do the epithelia of the esophagus and stomach differ? Respective functions?*

5.3--Connective tissue*

* Connective Tissue (CT) OverviewMost abundant and variable tissue type3 structural elements Consists mostly of (a) G________; (b) F_______ (c) with widely spaced cellsFunctions of CT:Binding of organs --Ex. a tendon connects muscle to boneSupport, protection, movement -- Ex. bonesStorage (energy, electrolytes) Ex. Fats/bonesTransport -- Ex. Blood

* 1. Ground Substance of C.T.Gelatinous or rubbery material found in between cells Function? Consists of 3 classes of large moleculesGlycosaminoglycans (GAGs) Polysacharides that attract sodium & hold waterEx.--Proteoglycan is bottlebrush-shaped molecule Forms thick gel that slows the spread of pathogens

Cell adhesive glycoproteinsAllow themselves bind to matrix elements

* 2. Fibers of C.T.Collagen fibers--called white fibers (Fig. 5.13)Most abundant protein of the body Thick, tough, resist stretch yet flexibleEx. tendons, ligaments & dermisElastic fibers--called yellow fibersmade of E______; recoil like rubberband (elasticity)Ex. skin, lungs & arteries; ability to recoilReticular fibersThin collagen fibers coated with glycoproteinEx. form framework for spleen & lymph nodes

Figure 5.13Tendons (collagen)Collagen

* 3. Cells of C.T.Fibroblasts -- produce fibers & ground substanceWBCs -- wander (mostly in CT) in search of bacteriaMacrophages large phagocytic cells-- arise from monocytes (WBC); function? phagocytosis

Plasma cells -- arise from lymphocytes; antibody-producing cellsMast cells oval shaped; clustered along blood vessels; secrete heparin and histamine

Adipocytes or fat cells --store triglycerides

5.3--Connective tissueA. Fibrous CT*

* Five Types of Fibrous C.T.Divided into 2 broad categories:Loose CT (3 slides followed)contains MORE gel-like ground substance between cells3 types: A--areolar, B--reticular, C--adipose tissue

Dense CT (2 slides followed)FIBERS fill the spaces between cells2 types varying in fiber orientation: D--dense regular, E--dense irregular

* A-- Areolar TissueLoose arrangement of collagenous and elastic fibers; scattered cell types; abundant ground substanceLocations-- Underlying all epithelia; surrounding nerves, blood vessels, esophagus, tracheaFig. Mesentery

* B-- Reticular TissueLoose network of R_________ and cells

Forms structural supportive stroma for lymphatic organs

Locations-- lymph nodes, spleen, thymus & bone marrowFig. Spleen

* C-- Adipose Tissue (Fat)Large, empty-looking cells dominate with thin margins; nucleus pressed against cell membrane; often very paleFunctions-- Energy storage, insulation, space filled as cushioning

Locations-- Subcutaneous fat beneath skin, breast, heart surface, surrounding organsFig. 5.18

Figure 5.16bFig. Adipose tissue*

* D-- Dense Regular CTStructure-- Mainly densely, PACKED, PARALLEL C__________FIBERS; compressed fibroblast nuclei; scanty open space and blood vesselsLocations-- Tendons & ligaments

Figure 5.16

*D-- Dense Regular CTFig. Tendon

* E-- Dense Irregular CTDensely packed collagen fibers running in ________ directions; scanty open space; few visible cells and blood vesselsFunction-- Withstands stresses applied in MANY DIFFERENT DIRECTIONS Locations-- Deeper portion of skin; capsules around organs (ex. Liver, kidney etc); sheaths around cartilages and bones

Figure 5.17

*E-- Dense Irregular CTFig. Dermis of the skin

5.3--Connective tissueB. Cartilage, Bone, Blood*

* CartilageSupportive CT with rubbery matrixChondroblasts produce matrix, surround themselves, and become ChondrocytesNo blood vessels; so diffusion must bring in nutrients & remove wastes; healing . . .3 types of cartilage depend upon FIBER TYPESA--hyaline, B--elastic, and C--fibrocartilage

* A-- Hyaline CartilageClear, glassy matrix; invisible fine dispersed collagen fibers; chondrocytes in small clusters enclosed in lacunaeSupports airway, eases joint movements

Locations-- Over ends of bones at movable joints; sternal ends of ribs; supportive material in larynx, trachea, bronchi and fetal skeletonFig. 5.19

Figure 5.19bFig. Fetal skeleton*

* B-- Elastic CartilageHyaline cartilage with weblike mesh of elastic fibers amid the lacunae; always has perichondrium (a sheath of C.T.)

Provides flexible, elastic support

Locations Ear + EpiglottisFig. 5.20

Figure 5.20bFig. External ear*

* C-- FibrocartilageCartilage containing extensive parallel Collagen fibers; never has perichondrium; row of chondrocytes in lacunaeResists compression and absorbs shock in some jointsLocations-- Pubic symphysis, menisci (pads) in knee joint, & intervertebral discsFig. 5.21

Figure 5.21bFig. Intervertebral disc*

* Bone (osseous tissue) Spongy bone looks spongy in appearancefills heads of long bonesdelicate struts of boneALWAYS COVERED BY COMPACT BONECompact (dense) bone looks solid No space visible to the naked eyeExternal surfaces of ALL bones

* Compact boneCalcified matrix in concentric lamellae around central (haversian) canal containing blood vesselsosteocytes in lacunae between lamellae connected by canaliculi delicate narrowing canals . . .

Physical support; leverage for muscles; mineral storageLocations-- in skeleton (Fig. 5.22)

Fig. Compact bone*Canaliculi ?

* BloodVariety of cells and cell fragments; some with nuclei & some without

RBC, WBC, platelets

Found in heart and blood vessels

Fig. 5.23

Fig. Blood smear*

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