Chapter 4 Tissue Level of Organization

4-1: Tissue Types u Cells combine to form tissues Histology—the study of tissues u Four types: epithelial, connective, muscle, & nervous 5 - 2

4-1 Checkpoint 1. Define histology. 2. List the four basic types of tissues in the body

4-2: Epithelial Tissue u Epithelial tissues include epithelia & glands Epithelia—layers of cells that cover internal & external surface Glands—secrete cells u Epithelial tissues are tightly bound together, are avascular & regenerate 5 - 4

Functions of Epithelia u Provide protection, control permeability, provide sensation, produce secretions u Exocrine glands release secretions onto surfaces u Endocrine glands release secretions into blood & tissue fluids 5 - 5

The Epithelial Surface u Apical surface is exposed to internal or external environment u Surfaces may have microvilli Increases surface area of cell so more absorption occurs u Ciliated epithelia have cilia to move materials 5 - 6

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The Basement Membrane u Epithelial cells attach to underlying tissues by the basement membrane u Basement membrane provides strength & creates a barrier 5 - 8

4-2 Checkpoint 1. List four essential functions of epithelial tissue. 2. What physiological functions are enhanced by the presence of microvilli or cilia on epithelial cells? 5 - 9

4-3: Classification of Epithelia u Epithelia are classified by cell layers & cell shape Cell Layers u Simple epithelia—single layer of cells (linings, secretion/absorption) u Stratified epithelia—several layers of cells (protection)

Cell Shapes u Squamous epithelia are thin & flat u Cuboidal epithelia appear square u Columnar epithelia appear tall, slender & rectangular

Classification of Epithelia u Simple squamous epithelia Single layer of thin, flattened cells Used in absorption

u Simple cuboidal epithelia Single layer of square cells Release secretions

u Simple columnar epithelia Single layer of column-shaped cells Used in absorption, linings

u Stratified squamous epithelia Several layers of flattened cells Skin surface, mouth

u Stratified cuboidal epithelia Several layers of square cells Rare; found in ducts

u Stratified columnar epithelia Several layers of column-shaped cells Rare; found in the trachea

u Pseudostratified epithelia Appear layered due to positions of nuclei; have cilia Found in nose, trachea & bronchi

u Transitional epithelia Tolerates repeated stretching & recoiling Found in bladder

Glandular Epithelia u Exocrine gland secretions are released through a duct onto a surface u Merocrine secretion releases secretions by exocytosis Ex: mucus, salivary glands

u Apocrine secretions release cytoplasm with secretion Ex: mammary glands u Holocrine secretion causes cell to burst with secretion Ex: sebaceous glands

4-3 Checkpoint 1. Identify the three cell shapes characteristic of epithelial cells. 2. Using a microscope, you examine a tissue and see simple squamous epithelium. Can this be a sample of skin? 3. Name the two primary types of glandular epithelia

4-4: Connective Tissue u Consist of cells suspended in a matrix Matrix consists of protein fibers & fluid ground substance u Functions: Support & protection, transport materials, store energy, defend body

Connective Tissue Proper u Categorized as loose or dense connective tissue u Connective tissue cells Fibroblasts—provide structure Macrophages—consume damaged cells Fat cells (adipocytes)—store lipids Mast cells—immune system

u Connective tissue fibers Collagen fibers—strong & flexible; most common Elastic fibers—stretch & recoil Reticular fibers—framework for organs

Loose Connective Tissues u Areolar tissue Separates skin from other tissues, provides padding

u Adipose tissue Made of adipocytes Provides padding, insulation

Dense Connective Tissues u Tendons & ligaments Cords of dense tissue Attach muscle to bone; bone to bone

Fluid Connective Tissues u Blood Red & white blood cells, platelets suspended in plasma matrix

Cartilage u Hyaline cartilage found on bone ends, sternum u Elastic cartilage found on ears, epiglottis u Fibrocartilage found between vertebrae

Bone u Consist of calcium salts, hard collagen fibers & osteocytes

4-4 Checkpoint 1. Identify several functions of connective tissue. 2. List three types of connective tissues. 3. Why does cartilage heal slower than bone?

4-5: Tissue Membranes u Mucus membranes line cavities exposed to exterior Secrete mucus to keep surfaces moist u Serous membranes line internal cavities & minimize friction Pleura (lungs), peritoneum (abdomen), pericardium (heart)

u Cutaneous membranes cover the surface of the body (skin) u Synovial membranes line bone ends at joints Allows smooth movement of the joint

4-5 Checkpoint 1. Identify the four types of tissue membranes found in the body. 2. What is the function of fluids produced by serous membranes? 3. The lining of the nasal cavity is moist and contains mucous cells. Which type of membrane is this?

4-6: Muscle Tissue u Skeletal muscle tissue Provides movement; fibers are striated and voluntary

u Cardiac muscle tissue Found only in the heart Involuntary, striated fibers with intercalated disks

u Smooth muscle tissue Found in hollow organs & blood vessels Involuntary, spindle-shaped cells

4-6 Checkpoint 1. Identify the three types of muscle tissue in the body. 2. Voluntary control is restricted to which type of muscle tissue? 3. Which type of muscle tissue has small, tapering cells and no striations?

4-7: Nervous Tissue u Conducts impulses Mostly found in brain & spinal cord u Neurons conduct nerve impulses Have a cell body, dendrites, & axons u Neuroglia supply nutrients to neurons

Muscle & Nervous Tissue Comparisons Type Function Location Skeletal MuscleBody movement Attached to bones Smooth MuscleInternal organ Walls of internal movement organs Cardiac MuscleHeart movements Heart muscle Nervous TissueSensory reception Brain, spinal cord, & conduction nerves u Copyright  The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

4-7 Checkpoint 1. A tissue contains irregularly shaped cells with many projections, some several centimeters long. These are probably which type of cell? 2. Why are both skeletal muscle cells and axons called fibers?

4-8: Response to Tissue Injury u Inflammation of injured area occurs first (injured tissue from healthy tissue) Swelling, heat & redness happen due to increased blood flow to area Pain happens due to compression of nerves

u Regeneration of injured area occurs second (injured tissue is replaced) Scar tissue replaces damaged tissue Damaged tissues may be replaced by fibrosis—permanent damage

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4-8 Checkpoint 1. Identify the two phases in response to tissue injury. 2. What signs and symptoms are associated with inflammation? 3. What is fibrosis?

4-9: Tissue Repair & Aging u Speed & effectiveness of tissue healing decreases with age u Tissues are damaged more easily, bones are more brittle Osteoporosis common in women u Cancer rates increase with age

4-9 Checkpoint 1. Identify some age-related factors that affect tissue repair and structure.