4 Tissue: The Living Fabric:

Types of Primary Tissues Epithelial tissue Covers Connective tissue Supports Muscle tissue Produces movement Nerve tissue Controls 4/16/2017 MDufilho

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 4/16/2017 MDufilho

Epithelial Tissue (Epithelium) Form boundaries Two main types (by location) Covering and lining epithelia On external and internal surfaces Glandular epithelia Secretory tissue in glands 4/16/2017 MDufilho

Characteristics of Epithelial Tissue Cells have polarity—apical (upper, free) and basal (lower, attached) surfaces Are composed of closely packed cells Supported by a connective tissue reticular lamina (under the basal lamina) Avascular but innervated High rate of regeneration 4/16/2017 MDufilho

Classification of Epithelia Ask two questions: How many layers? 1 = simple epithelium >1 = stratified epithelium 2. What is the shape of the cell Squamous Cuboidal Columnar 4/16/2017 MDufilho

Figure 4.2a Classification of epithelia. Apical surface Basal surface Simple Apical surface Basal surface Stratified Classification based on number of cell layers. 4/16/2017 MDufilho

Cells of Epithelial Tissues Squamous cells Cuboidal cells Columnar cells (If stratified, name according to apical layer of cells) 4/16/2017 MDufilho

Figure 4.2b Classification of epithelia. Squamous Cuboidal Columnar Classification based on cell shape. 4/16/2017 MDufilho

Overview of Epithelial Tissues For each of the following types of epithelia, note: Description Function Location 4/16/2017 MDufilho

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). 4/16/2017 MDufilho

Simple Squamous Epithelium Two other locations Endothelium The lining of lymphatic vessels, blood vessels, and heart Mesothelium The epithelium of serous membranes in the ventral body cavity 4/16/2017 MDufilho

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). 4/16/2017 MDufilho

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 4/16/2017 MDufilho

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). 4/16/2017 MDufilho

Most abundant and widely distributed of primary tissues Connective Tissue Most abundant and widely distributed of primary tissues Four main classes Connective tissue proper Cartilage Bone Blood 4/16/2017 MDufilho

Table 4.1 Comparison of Classes of Connective Tissues (1 of 2) 4/16/2017 MDufilho

Table 4.1 Comparison of Classes of Connective Tissues (2 of 2) 4/16/2017 MDufilho

Major Functions of Connective Tissue Binding and support Protecting Insulating Storing reserve fuel Transporting substances (blood) 4/16/2017 MDufilho

Characteristics of Connective Tissue Three characteristics make connective tissues different from other primary tissues Have mesenchyme (an embryonic tissue) as their common tissue of origin Have varying degrees of vascularity (blood vessels) Have extracellular matrix Connective tissue not composed mainly of cells Largely nonliving extracellular matrix separates cells So can bear weight, withstand tension, endure abuse 4/16/2017 MDufilho

Connective Tissue Fibers Three types of fibers provide support Collagen Elastic fibers Reticular 4/16/2017 MDufilho

Cells "Blasts" cells "Cyte" cells Immature forum; 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 4/16/2017 MDufilho

Other Cell Types in Connective Tissues Fat cells Store nutrients White blood cells Neutrophils, eosinophils, lymphocytes Tissue response to injury Mast cells Initiate local inflammatory response against foreign microorganisms they detect Macrophages Phagocytic cells that "eat" dead cells, microorganisms; function in immune system 4/16/2017 MDufilho

Cell types Extracellular matrix Ground substance Macrophage Fibers Figure 4.7 Areolar connective tissue: A prototype (model) connective tissue. Cell types Extracellular matrix Ground substance Macrophage Fibers • Collagen fiber • Elastic fiber • Reticular fiber Fibroblast Lymphocyte Fat cell Mast cell Neutrophil Capillary 4/16/2017 MDufilho

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 4/16/2017 MDufilho

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). 4/16/2017 MDufilho

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). 4/16/2017 MDufilho

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. 4/16/2017 MDufilho

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). 4/16/2017 MDufilho

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. 4/16/2017 MDufilho

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. 4/16/2017 MDufilho

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. 4/16/2017 MDufilho

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). 4/16/2017 MDufilho

Nervous Tissue Main component of nervous system Neurons Neuroglia 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 4/16/2017 MDufilho

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). 4/16/2017 MDufilho