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Anatomy & Physiology I Lecture 3 Chapter 4: Tissues.

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1 Anatomy & Physiology I Lecture 3 Chapter 4: Tissues

2 Tissues Cells – Individual body cells specialized – Each type performs specific functions that maintain homeostasis Tissues – Groups of cells similar in structure that perform common or related function Histology – the study of tissues

3 © 2013 Pearson Education, Inc. Studying Human Tissue: Microscopy Tissue is fixed – Preserved – FFPE or Fresh/Frozen Cut – Sliced thin enough to transmit photons or electrons Stained to enhance contrast – H&E – Hematoxylin and eosin stain – Immunohistochemisty – Specific dye to highlight cells or structures

4 H&E Stain Colon tissue sectioned through the crypts

5 Immunohistochemistry Stained for CD10, a marker for renal carcinoma

6 © 2013 Pearson Education, Inc. Brain Spinal cord Nerves Nervous tissue: Internal communication Muscles attached to bones (skeletal) Muscles of heart (cardiac) Muscles of walls of hollow organs (smooth) Muscle tissue: Contracts to cause movement Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters Lining of digestive tract organs and other hollow organs Skin surface (epidermis) Bones Tendons Fat and other soft padding tissue Connective tissue: Supports, protects, binds other tissues together Figure 4.1 Overview of four basic tissue types: epithelial, connective, muscle, and nervous tissues.

7 Epithelial Tissue Sheet of cells tht covers a body surface or lines a body cavity Two main types (by location) Covering and lining epithelia – On external and internal surfaces Glandular epithelia – Secretory tissue in glands

8 Epithelial Tissue Forms boundaries – Protection – Absorption – Filtration – Excretion – Secretion – Sensory reception

9 Five Characteristics Polarity – apical vs basal surface Specialized contacts – tight junctions, desmosomes Supported by connective tissues – for reinforcement Avascular, but innervated Can regenerate

10 Classification of Epithelia All epithelial tissues have two names First indicates number of cell layers – Simple epithelia = single layer of cells – Stratified epithelia = two or more layers of cells Second indicates shape of cells – Squamous – Cuboidal – Columnar

11 © 2013 Pearson Education, Inc. Figure 4.2a Classification of epithelia. Basal surface Stratified Classification based on number of cell layers. Basal surface Simple Apical surface

12 © 2013 Pearson Education, Inc. Cuboidal Squamous Columnar Classification based on cell shape. Figure 4.2b Classification of epithelia.

13 Simple Epithelia Functions limited due to their thickness, but nonetheless important – Absorption – Secretion – Filtration

14 © 2013 Pearson Education, Inc. Air sacs of lung tissue Nuclei of squamous epithelial cells Function: Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae. Location: Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae). Description: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia. Photomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (140x). Simple squamous epithelium Figure 4.3a Epithelial tissues.

15 Simple Squamous Some have specialized names based on location: Endothelium – The lining of lymphatic vessels, blood vessels, and heart Mesothelium – The epithelium of serous membranes in the ventral body cavity

16 © 2013 Pearson Education, Inc. Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action. Location: Nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus. Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus- secreting unicellular glands (goblet cells). Simple columnar epithelium Basement membrane Photomicrograph: Simple columnar epithelium of the small intestine mucosa (660x). Mucus of goblet cell Simple columnar epithelial cell Microvilli Figure 4.3c Epithelial tissues.

17 © 2013 Pearson Education, Inc. Pseudostratified columnar epithelium Function: Secrete substances, particularly mucus; propulsion of mucus by ciliary action. Description: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus- secreting cells and bear cilia. Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (800x). Cilia Basement membrane Pseudo- stratified epithelial layer Location: Nonciliated type in male’s sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract. Trachea Figure 4.3d Epithelial tissues.

18 © 2013 Pearson Education, Inc. Stratified squamous epithelium Function: Protects underlying tissues in areas subjected to abrasion. Description: Thick membrane composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers. Basement membrane Location: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane. Nuclei Connective tissue Stratified squamous epithelium Photomicrograph: Stratified squamous epithelium lining the esophagus (285x). Figure 4.3e Epithelial tissues.

19 Other Stratified Epithelia Stratified cuboidal and stratified columnar are rare and limited to specialized parts of body – pharynx, male urethra, some glandular ducts, sweat and mammary glands

20 © 2013 Pearson Education, Inc. Transitional epithelium Function: Stretches readily, permits stored urine to distend urinary organ. Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch. Location: Lines the ureters, bladder, and part of the urethra. Transitional epithelium Photomicrograph: Transitional epithelium lining the bladder, relaxed state (360x); note the bulbous, or rounded, appearance of the cells at the surface; these cells flatten and elongate when the bladder fills with urine. Basement membrane Connective tissue Figure 4.3f Epithelial tissues.

21 Glandular Epithelia Gland – One or more cells that makes and secretes an aqueous fluid called a secretion Classified by – Site of product release—endocrine or exocrine – Relative number of cells forming the gland – Unicellular or multicellular

22 Endocrine Glands Ductless glands – Secretions not released into a duct, but via exocytosis Secrete hormones that travel through lymph or blood to their specific target organs – every hormone has a specific target cell for a specific physiological response

23 Exocrine Glands Secretions released onto body surfaces (skin) or into body cavities – mucous, sweat, oil, and salivary glands, digestive juices More numerous than endocrine glands Secrete products into ducts

24 Unicellular Glands Mucous cells and Goblet cells Found in epithelial linings of intestinal and respiratory tracts – All produce mucin – Dissolves in water to form mucus – Slimy protective, lubricating coating

25 © 2013 Pearson Education, Inc. Microvilli Golgi apparatus Rough ER Nucleus Secretory vesicles containing mucin Figure 4.4 Goblet cell (unicellular exocrine gland).

26 Multicellular Exocrine Glands Multicellular exocrine glands are more complex and specialized for the function Pancreas and Liver have exocrine functions despite their other roles

27 Connective Tissue Most abundant and widely distributed of primary tissues Four main classes – Connective tissue proper – Cartilage – Bone – Blood

28 Major Functions Binding and support Protecting Insulating Storing reserve fuel Transporting substances (blood)

29 Connective Tissue Elements Ground Substance Tissue Fibers

30 Ground Substance Extracellular maxtix Unstructured material that fills space between cells – white blood cells and immune cells migrate Components – Interstitial fluid – Cell adhesion proteins ("glue" for attachment) – Proteoglycans Protein core + large polysaccharides that trap water in varying amounts, affecting viscosity of ground substance

31 Connective Tissue Fibers Collagen – Strongest and most abundant type Elastic fibers – Networks of long, thin, elastin fibers that allow for stretch and recoil Reticular – Short, fine, highly branched collagenous-like fibers – Form networks that offer support and elasticity

32 Connective Tissue Cells "Blast" cells – Immature form; mitotically active; secrete ground substance and fibers – Fibroblasts in connective tissue proper – Chondroblasts in cartilage – Osteoblasts in bone – Hematopoietic stem cells in bone marrow "Cyte" cells – Mature form; maintain matrix – Chondrocytes in cartilage – Osteocytes in bone

33 Connective Tissue Proper Loose Connective Tissue – Areolar – Adipose – Reticular Dense Connective Tissue – Regular – Irregular – Elastic

34 © 2013 Pearson Education, Inc. Connective tissue proper: loose connective tissue, areolar Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells. Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid. Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries. Epithelium Lamina propria Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (340x). Elastic fibers Ground substance Fibroblast nuclei Collagen fibers Figure 4.8a Connective tissues.

35 © 2013 Pearson Education, Inc. Connective tissue proper: loose connective tissue, adipose Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet. Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (350x). Nucleus of adipose (fat) cell Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs. Location: Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts. Fat droplet Adipose tissue Mammary glands Figure 4.8b Connective tissues.

36 © 2013 Pearson Education, Inc. Connective tissue proper: loose connective tissue, reticular Description: Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network. Photomicrograph: Dark-staining network of reticular connective tissue fibers forming the internal skeleton of the spleen (350x). White blood cell (lymphocyte) Location: Lymphoid organs (lymph nodes, bone marrow, and spleen). Spleen Reticular fibers Function: Fibers form a soft internal skeleton (stroma) that supports other cell types including white blood cells, mast cells, and macrophages. Figure 4.8c Connective tissues.

37 © 2013 Pearson Education, Inc. Connective tissue proper: dense connective tissue, dense regular Description: Primarily parallel collagen fibers; a few elastic fibers; major cell type is the fibroblast. Function: Attaches muscles to bones or to muscles; attaches bones to bones; withstands great tensile stress when pulling force is applied in one direction. Location: Tendons, most ligaments, aponeuroses. Shoulder joint Ligament Tendon Collagen fibers Nuclei of fibroblasts Photomicrograph: Dense regular connective tissue from a tendon (430x). Figure 4.8d Connective tissues.

38 © 2013 Pearson Education, Inc. Connective tissue proper: dense connective tissue, dense irregular Description: Primarily irregularly arranged collagen fibers; some elastic fibers; fibroblast is the major cell type. Function: Withstands tension exerted in many directions; provides structural strength. Location: Fibrous capsules of organs and of joints; dermis of the skin; submucosa of digestive tract. Shoulder joint Fibrous joint capsule Photomicrograph: Dense irregular connective tissue from the fibrous capsule of a joint (430x). Collagen fibers Nuclei of fibroblasts Figure 4.8e Connective tissues.

39 © 2013 Pearson Education, Inc. Connective tissue proper: dense connective tissue, elastic Description: Dense regular connective tissue containing a high proportion of elastic fibers. Function: Allows tissue to recoil after stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs following inspiration. Location: Walls of large arteries; within certain ligaments associated with the vertebral column; within the walls of the bronchial tubes. Photomicrograph: Elastic connective tissue in the wall of the aorta (250x). Aorta Heart Elastic fibers Figure 4.8f Connective tissues.

40 Cartilage Cells: – Chondroblasts and chondrocytes Tough yet flexible – Up to 80% water - can rebound after compression Lacks nerve fibers and blood vessels (avascular)

41 Cartilage Hyaline Elastic Fibrocartilage

42 © 2013 Pearson Education, Inc. Cartilage: hyaline Description: Amorphous but firm matrix; collagen fibers form an imperceptible network; chondroblasts produce the matrix and when mature (chondrocytes) lie in lacunae. Function: Supports and reinforces; serves as resilient cushion; resists compressive stress. Location: Forms most of the embryonic skeleton; covers the ends of long bones in joint cavities; forms costal cartilages of the ribs; cartilages of the nose, trachea, and larynx. Costal cartilages Photomicrograph: Hyaline cartilage from a costal cartilage of a rib (470x). Matrix Chondrocyte in lacuna Figure 4.8g Connective tissues.

43 © 2013 Pearson Education, Inc. Cartilage: elastic Description: 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. Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (800x). Chondrocyte in lacuna Matrix Figure 4.8h Connective tissues.

44 © 2013 Pearson Education, Inc. Cartilage: fibrocartilage Description: Matrix similar to but less firm than that in hyaline cartilage; thick collagen fibers predominate. Function: Tensile strength allows it to absorb compressive shock. Location: Intervertebral discs; pubic symphysis; discs of knee joint. Photomicrograph: Fibrocartilage of an intervertebral disc (125x). Special staining produced the blue color seen. Collagen fiber Chondrocytes in lacunae Intervertebral discs Figure 4.8i Connective tissues.

45 Bone – Osseous Tissue Supports and protects body structures – Stores fat and synthesizes blood cells in cavities – More collagen than cartilage – Has inorganic calcium salts Osteoblasts produce matrix Osteocytes maintain the matrix Richly vascularized

46 © 2013 Pearson Education, Inc. Others: bone (osseous tissue) Description: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized. Function: Supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis). Location: Bones Photomicrograph: Cross-sectional view of bone (125x). Lamella Central canal Lacunae Figure 4.8j Connective tissues.

47 Blood Atypical connective tissue – is a fluid Red blood cells most common cell type that function in transport – Also contains white blood cells and platelets Fibers are soluble proteins that precipitate during blood clotting

48 © 2013 Pearson Education, Inc. Connective tissue: blood Description: Red and white blood cells in a fluid matrix (plasma). Function: Transport respiratory gases, nutrients, wastes, and other substances. Location: Contained within blood vessels. Photomicrograph: Smear of human blood (1670x); shows two white blood cells surrounded by red blood cells. Plasma White blood cells: Lymphocyte Neutrophil Red blood cells (erythrocytes) Figure 4.8k Connective tissues.

49 Muscle Responsible for most types of movement – Highly vascularized Skeletal muscle tissue – Voluntary Cardiac muscle tissue – Involuntary Smooth muscle tissue – Involuntary

50 © 2013 Pearson Education, Inc. Skeletal muscle Description: Long, cylindrical, multinucleate cells; obvious striations. Function: Voluntary movement; locomotion; manipulation of the environment; facial expression; voluntary control. Location: In skeletal muscles attached to bones or occasionally to skin. Photomicrograph: Skeletal muscle (approx. 440x). Notice the obvious banding pattern and the fact that these large cells are multinucleate. Striations Nuclei Part of muscle fiber (cell) Figure 4.9a Muscle tissues.

51 © 2013 Pearson Education, Inc. Cardiac muscle Description: Branching, striated, generally uninucleate cells that interdigitate at specialized junctions (intercalated discs). Function: As it contracts, it propels blood into the circulation; involuntary control. Location: The walls of the heart. Photomicrograph: Cardiac muscle (900x); notice the striations, branching of cells, and the intercalated discs. Striations Nucleus Intercalated discs Figure 4.9b Muscle tissues.

52 © 2013 Pearson Education, Inc. Smooth muscle Description: Spindle-shaped cells with central nuclei; no striations; cells arranged closely to form sheets. Function: Propels substances or objects (foodstuffs, urine, a baby) along internal passageways; involuntary control. Location: Mostly in the walls of hollow organs. Photomicrograph: Sheet of smooth muscle (720x). Smooth muscle cell Nuclei Figure 4.9c Muscle tissues.

53 Nervous Tissue Main component of nervous system Brain, spinal cord, nerves – Regulates and controls body functions Neurons – Specialized nerve cells that generate and conduct nerve impulses Neuroglia – Supporting cells that support, insulate, and protect neurons

54 © 2013 Pearson Education, Inc. Nervous tissue Description: Neurons are branching cells; cell processes that may be quite long extend from the nucleus-containing cell body; also contributing to nervous tissue are nonexcitable supporting cells. Function: Neurons transmit electrical signals from sensory receptors and to effectors (muscles and glands) which control their activity; supporting cells support and protect neurons. Location: Brain, spinal cord, and nerves. Photomicrograph: Neurons (350x). Neuron processes Nuclei of supporting cells Cell body of a neuron Neuron processesCell body Axon Dendrites Figure 4.10 Nervous tissues.

55 Lining Membranes Composed of at least two primary tissue types – An epithelium bound to underlying connective tissue proper Three types – Cutaneous membranes – Mucous membranes – Serous membranes – Synovial membrane (connective tissue only, Ch. 8)

56 Cutaneous Membrane Skin – Keratinized stratified squamous epithelium (epidermis) attached to a thick layer of connective tissue (dermis) The only dry membrane

57 Mucous Membranes Epithelial sheet lies over layer of connective tissue called lamina propria Line body cavities open to the exterior – Digestive, respiratory, urogenital tracts Mucosa indicates location not cell composition – All called mucosae

58 © 2013 Pearson Education, Inc. Mucous membranes Mucous membranes line body cavities that are open to the exterior. Mucosa of nasal cavity Mucosa of mouth Esophagus lining Mucosa of lung bronchi Figure 4.11b Classes of membranes.

59 Serous Membranes Serosae—found in closed ventral body cavity Simple squamous epithelium (mesothelium) resting on thin areolar connective tissue Parietal serosae line internal body cavity walls Visceral serosae cover internal organs Serous fluid between layers

60 © 2013 Pearson Education, Inc. Visceral peritoneum Parietal peritoneum Parietal pericardium Visceral pericardium Visceral pleura Parietal pleura Serous membranes line body cavities that are closed to the exterior. Serous membranes Figure 4.11c Classes of membranes.

61 Today’s Lab Lab Exercise 6 Learn to identify tissue under the microscope and understand their general functions


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