Chapter 3 Tissues

Body Tissues Cells are specialized for particular functions Tissues Groups of cells with similar structure and function Four primary types Epithelium - covering Connective tissue - support Nervous tissue - control Muscle tissue - movement

Overview Of Tissues & Functions 1. EPITHELIAL 2. CONNECTIVE 3. MUSCULAR 4. NERVOUS

Overview Of Tissues & Functions 1. Epithelial Tissues Functions Covers exposed surfaces Lines internal passages Forms glands Provide physical protection Control permeability Provide sensation Produce specialized secretions (glandular epithelium)

Overview Of Tissues & Functions 2. Connective Tissues Functions . * Fills internal spaces Supports other tissues Transports materials Stores energy

Overview Of Tissues & Functions 3. Muscular Tissues Functions . Specialized for contraction Skeletal muscle, heart muscle, and walls of hollow organs

Overview Of Tissues & Functions 4. Neural Tissues Functions . Carries electrical signals from 1 part of the body to another

The Epithelial Tissue Epithelia: layers of cells covering internal or external surfaces

Epithelial Tissues Found in different areas Functions: Protection Absorption Filtration Secretion Found in different areas Body coverings Body linings Glandular tissue

Epithelium Characteristics Cells fit closely together Avascular (have no blood supply) Regenerate easily if well nourished

Classification of Epithelium Number of cell layers Simple – one layer Stratified – more than one layer Figure 3.17a

Classification of Epithelium Shape of cells Squamous – flattened, like fish scales Cuboidal – cube-shaped Columnar – column-like Figure 3.17b

Classes of Epithelia

Simple Epithelium Single layer of cells Usually forms membranes or lines tracts Simple Squamous Simple cuboidal Simple columnar Figure 3.18a

Glandular Epithelium Gland – one or more cells that secretes a particular product Fun Fact: Secretion: typically contains protein molecules in an aqueous fluid

Glandular Epithelium Two major gland types Endocrine gland ex: thyroid gland, pituitary gland Ductless Secretions are hormones into interstitial fluid Exocrine gland ex: enzymes entering digestive tract, perspiration on the skin, tears in the eyes, & milk from mammary glands Empty secretions through ducts to the epithelial surface Include sweat and oil glands

Structural classes of exocrine glands You don’t have to know, but it’s fun to be smart! Structure of Multicellular Exocrine Glands Structural classes of exocrine glands Figure 4–7 (1 of 2)

You don’t have to know, but it’s fun to be smart You don’t have to know, but it’s fun to be smart! Structure of Multicellular Exocrine Glands Figure 4–7 (2 of 2)

The Connective Tissue

Connective Tissue Found everywhere in the body Includes the most abundant and widely distributed tissues

Connective Tissue Functions Binds body tissues together Provides protection Have no contact with environment Connect epithelium to the rest of the body Transport materials (blood) Supports the body Provide structure (bone) Store energy (fat)

Connective Tissue Characteristics Variations in blood supply Some tissue types are well vascularized Some have poor blood supply or are avascular

Extracellular Matrix - The extracellular components of connective tissues (fibers and ground substance) majority of cell volume determines specialized function Non-living material that surrounds living cells

Extracellular Matrix 2. Fibers Produced by the cells Three types Two main elements 1. Ground substance – mostly water along with adhesion proteins and polysaccharide molecules 2. Fibers Produced by the cells Three types Collagen fibers Elastic fibers Reticular fibers

*Fibroblasts The most abundant cell type: -secrete proteins and hyaluronan (cellular cement)

Classification of Connective Tissues Connective tissue proper: connect and protect Fluid connective tissues: transport Supportive connective tissues: structural strength

Fibers in Connective Tissue Proper Collagen fibers: most common fibers in CTP long, straight, and unbranched strong and flexible resists force in 1 direction e.g., tendons and ligaments

Fibers in Connective Tissue Proper Reticular fibers: network of interwoven fibers strong and flexible resists force in many directions stabilizes functional cells and structures e.g., sheaths around organs

Fibers in Connective Tissue Proper Elastic fibers: contain elastin branched and wavy return to original length after stretching e.g., elastic ligaments of vertebrae

Connective Tissue Types (1 of 4) Bone (osseous tissue) For weight support Composed of: Bone cells in cavities Hard matrix of calcium salts Large numbers of collagen fibers Function: Used to protect and support the body Figure 3.19a

Connective Tissue Types (2 of 4) CARTILAGE gel-type ground substance for shock absorption and protection Elastic cartilage Example: supports the external ear Support soft tissues and body weight Provides elasticity

Connective Tissue Type (3 of 4) Dense connective tissue Main matrix element is collagen fibers Cells are fibroblasts Examples Tendon – attach muscle to bone Ligaments – attach bone to bone Figure 3.19d

Connective Tissue Types (4 of 4) Blood Blood cells surrounded by fluid matrix Fibers are visible during clotting Functions as the transport vehicle for materials Figure 3.19h

Bones: Bone Cells: Osteocytes Bone Surface: Periosteum: - arranged around central canals within matrix - small channels through matrix (canaliculi) access blood supply Bone Surface: Periosteum: - covers bone surfaces

The Muscle Tissue

Muscle Tissue Function is to produce movement Three types Skeletal muscle (1) Cardiac muscle (2) Smooth muscle (3)

Muscle Tissue Types (1 of 3) 1. Skeletal muscle: Large body muscles responsible for movement Can be controlled voluntarily Cells attach to connective tissue Cells are striated Cells have more than one nucleus Figure 3.20a

Muscle Tissue Types (2 of 3) 2. Cardiac muscle: Found only in the heart Function is to pump blood (involuntary) Cells are striated One nucleus per cell Figure 3.20b

Muscle Tissue Types (3 of 3) 3. Smooth muscle Involuntary muscle Surrounds hollow organs Attached to other smooth muscle cells No visible striations One nucleus per cell Figure 3.20c

Nervous Tissue Neurons and nerve support cells Function is to send impulses to other areas of the body rapidly senses internal or external environment Irritability- ability to respond to stimuli Conductivity – able to conduct impulses Figure 3.21

Nervous Tissue Neural tissue is concentrated in the central nervous system: brain spinal cord Figure 3.21

Tissues Injury and Repair Cells restore homeostasis with 2 processes: 1. Inflammation (1): the tissue’s first response to injury Signs: Swelling, redness, heat, pain, Triggered by: Inflammation or Infection Chemicals released White blood cells clean up

Tissues Injury and Repair When the injury or infection is cleaned up or healing (regeneration (2)) begins Fibroblasts move into necrotic area: lay down collagen fibers to bind the area together (scar tissue) New cells migrate to area

Tissue Repair Determination of method Regeneration Fibrosis Type of tissue damaged Severity of the injury Regeneration Replacement of destroyed tissue by the same kind of cells Fibrosis Repair by dense fibrous connective tissue (scar tissue)

Regeneration of Tissues Tissues that regenerate easily Epithelial tissue Fibrous connective tissue and bone Tissues that regenerate poorly Skeletal muscle Tissues that are replaced largely with scar tissue (*Do not regenerate) Cardiac muscle cells Nervous tissue (neurons) within the brain & spinal cord

Developmental Aspects of Tissue With old age there is a decrease in mass and viabililty in most tissues Speed and efficiency of tissue repair decreases with age, due to: slower rate of energy consumption (metabolism) hormonal alterations reduced physical activity

Developmental Aspects of Tissue Chemical and structural tissue changes: thinning epithelia and connective tissues increased bruising and bone brittleness joint pain and broken bones cardiovascular disease mental deterioration

#1 Let’s Review Real Quick: Tissues Organized into 4 specialized cells: Epithelial tissue Connective tissue Muscular tissue Nervous tissue

#2 Review Division of epithelial tissues into epithelia and glands: epithelia as avascular barriers for protection glands as secretory structures

#3 Review Classification of epithelial cells: by number of cell layers (simple or stratified) by shape of cells (squamous, columnar or cuboidal)

#4 Review The functions of connective tissues: structure transport protection support connections energy storage

#5 Review The structure of connective tissues: matrix ground substance protein fibers

#6 Review The classification of connective tissues: connective tissue proper (cell types, fiber types, and embryonic connective tissues) fluid connective tissues (blood and lymph, fluid transport systems) supporting connective tissues (cartilage and bone)

#7-8 Review The 3 types of muscle tissues (skeletal, cardiac, and smooth) The classification of muscle tissues by striation, nucleation, and voluntary control

#9-10 Review Tissue injuries and repair systems (inflammation and regeneration) The relationship between aging & tissue structure