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Lecture 3 Chapter 4: Tissues

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1 Lecture 3 Chapter 4: Tissues
Anatomy & Physiology I Lecture 3 Chapter 4: Tissues

2 Tissues Cells Tissues Histology – the study of tissues
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 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 © 2013 Pearson Education, Inc.

4 H&E Stain Colon tissue sectioned through the crypts

5 Immunohistochemistry
Stained for CD10, a marker for renal carcinoma

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

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

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

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

14 Figure 4.3a Epithelial tissues.
Simple squamous epithelium Description: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia. 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). Photomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (140x). © 2013 Pearson Education, Inc.

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 Figure 4.3c Epithelial tissues.
Simple columnar epithelium Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells). Microvilli Simple columnar epithelial cell Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action. Mucus of goblet cell 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. Basement membrane Photomicrograph: Simple columnar epithelium of the small intestine mucosa (660x). © 2013 Pearson Education, Inc.

17 Figure 4.3d Epithelial tissues.
Pseudostratified columnar epithelium 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. Cilia Pseudo-stratified epithelial layer Function: Secrete substances, particularly mucus; propulsion of mucus by ciliary action. 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. Basement membrane Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (800x). Trachea © 2013 Pearson Education, Inc.

18 Figure 4.3e Epithelial tissues.
Stratified squamous epithelium 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. Stratified squamous epithelium Function: Protects underlying tissues in areas subjected to abrasion. Nuclei Location: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane. Basement membrane Connective tissue Photomicrograph: Stratified squamous epithelium lining the esophagus (285x). © 2013 Pearson Education, Inc.

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 Figure 4.3f Epithelial tissues.
Transitional epithelium 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. Transitional epithelium Function: Stretches readily, permits stored urine to distend urinary organ. Basement membrane Location: Lines the ureters, bladder, and part of the urethra. Connective tissue 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. © 2013 Pearson Education, Inc.

21 Glandular Epithelia Gland Classified by
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 Figure 4.4 Goblet cell (unicellular exocrine gland).
Microvilli Secretory vesicles containing mucin Golgi apparatus Rough ER Nucleus © 2013 Pearson Education, Inc.

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 Figure 4.8a Connective tissues.
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. Elastic fibers Ground substance Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries. Fibroblast nuclei Collagen fibers Epithelium Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (340x). Lamina propria © 2013 Pearson Education, Inc.

35 Figure 4.8b Connective tissues.
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. Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs. Nucleus of adipose (fat) cell Location: Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts. Fat droplet Adipose tissue Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (350x). Mammary glands © 2013 Pearson Education, Inc.

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

37 Figure 4.8d Connective tissues.
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. Collagen fibers Location: Tendons, most ligaments, aponeuroses. Nuclei of fibroblasts Shoulder joint Ligament Photomicrograph: Dense regular connective tissue from a tendon (430x). Tendon © 2013 Pearson Education, Inc.

38 Figure 4.8e Connective tissues.
Connective tissue proper: dense connective tissue, dense irregular Description: Primarily irregularly arranged collagen fibers; some elastic fibers; fibroblast is the major cell type. Nuclei of fibroblasts 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. Collagen fibers Shoulder joint Fibrous joint capsule Photomicrograph: Dense irregular connective tissue from the fibrous capsule of a joint (430x). © 2013 Pearson Education, Inc.

39 Figure 4.8f Connective tissues.
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. Elastic fibers Aorta Heart Photomicrograph: Elastic connective tissue in the wall of the aorta (250x). © 2013 Pearson Education, Inc.

40 Cartilage Cells: Tough yet flexible
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 Figure 4.8g Connective tissues.
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. Chondrocyte in lacuna 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. Matrix Costal cartilages Photomicrograph: Hyaline cartilage from a costal cartilage of a rib (470x). © 2013 Pearson Education, Inc.

43 Figure 4.8h Connective tissues.
Cartilage: elastic Description: Similar to hyaline cartilage, but more elastic fibers in matrix. Function: Maintains the shape of a structure while allowing great flexibility. Chondrocyte in lacuna Matrix Location: Supports the external ear (pinna); epiglottis. Photomicrograph: Elastic cartilage from the human ear pinna; forms the flexible skeleton of the ear (800x). © 2013 Pearson Education, Inc.

44 Figure 4.8i Connective tissues.
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. Chondrocytes in lacunae Intervertebral discs Collagen fiber Photomicrograph: Fibrocartilage of an intervertebral disc (125x). Special staining produced the blue color seen. © 2013 Pearson Education, Inc.

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 Figure 4.8j Connective tissues.
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). Central canal Lacunae Lamella Location: Bones Photomicrograph: Cross-sectional view of bone (125x). © 2013 Pearson Education, Inc.

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

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

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

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

52 Figure 4.9c Muscle tissues.
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. Nuclei Location: Mostly in the walls of hollow organs. Smooth muscle cell Photomicrograph: Sheet of smooth muscle (720x). © 2013 Pearson Education, Inc.

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 Figure 4.10 Nervous tissues.
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. Nuclei of supporting cells Neuron processes Cell body Axon Dendrites Cell body of a neuron Function: Neurons transmit electrical signals from sensory receptors and to effectors (muscles and glands) which control their activity; supporting cells support and protect neurons. Neuron processes Location: Brain, spinal cord, and nerves. Photomicrograph: Neurons (350x). © 2013 Pearson Education, Inc.

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 The only dry membrane
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 Figure 4.11b Classes of membranes.
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 © 2013 Pearson Education, Inc.

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

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


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