THE TISSUE LEVEL OF ORGANIZATION PART I: EPITHELIAL TISSUE

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1 THE TISSUE LEVEL OF ORGANIZATION PART I: EPITHELIAL TISSUE 4 Main Tissue Types Epithelium Covers surfaces, lines cavities, forms glands Connective Tissue Support and protects body Muscular Tissue Movement - contains contractile elements Nervous Tissue Communication transmits impulses Epithelial Tissue Cells are close together (no gaps) Cells sit on a basement membrane Cells have exposed or free surface Avascular without blood vessels Regenerate well Can tolerate damage well Frequent cell division to form new cells Suffers under conditions of chemo- or radiation therapy Epithelial Tissue Functions Absorption lining of intestine Secretion glands (saliva) Excretion glands (sweat) Transport kidney tubules Protection - skin Sensory Perception taste buds

2 Epithelial Tissue Classification Layer Simple One layer of cells Ideal for passive diffusion if squamous (alveoli) Stratified Several layers of cells Ideal for protection, and abrasion resistance (epidermis) Pseudostratified One layer of cells that appear to be more than one layer Contains short, immature cells. (airway lining) Shape Squamous Flat and thin Ideal for passive diffusion if 1-layer (alveoli) Cuboidal Square - cube Ideal for pumping, secretion (glands), and active transport (kidney) Columnar Rectangular Ideal for protection and absorption (lining of gut)

3 Naming of Epithelial Tissue Layer + Shape + Epithelial Tissue first name + middle name + last name: epithelial tissue Examples: Simple squamous epithelial tissue Stratified squamous epithelial tissue Simple columnar epithelial tissue Stratified cuboidal epithelial tissue Transitional epithelial tissue Simple Epithelium Simple squamous Lining of blood vessels, alveoli Simple cuboidal Glands, kidney Simple columnar Intestines Pseudostratified columnar Respiratory tract Stratified Epithelium Stratified squamous Many layers start round but flatten closer to surface Epidermis, vagina, esophagus, mouth, rectum Transitional ~dozen layers round when relaxed, flat when stretched: bladder

4 Glands Epithelial Tissue Some have ducts EXOcrine glands Sweat, odor, oil (acne), etc. Some don t have ducts ENDOcrine glands Send product to the blood: hormones, etc. Exocrine Glands Sudoriferous (Sweat) Glands Merocrine (eccrine) sudoriferous glands (sweat) Only the substance is released from cells Apocrine sudoriferous glands (pheromones) Armpit & genital areas, mammary glands Substance is released with some cytoplasm and proteins Sebaceous Glands Holocrine glands (oil) Cells rupture and DIE to release their product Whole cell falls apart Hair & Nails Epithelial Tissue Formed with Keratin Hair Follicle Arrector pili muscle Nerve ending Pore Nails Matrix nail growth area Cuticle

5 THE TISSUE LEVEL OF ORGANIZATION PART II: CONNECTIVE TISSUE Connective Tissue Loose Connective Tissue Dense Connective Tissue Cartilage Bone Blood All contain an intercellular matrix stuff between cells Intercellular Matrix The matrix determines what the tissue is like: Ground Substance gel-like substance, mostly water and sugar proteins Proteoglycan filaments, allows diffusion (chondroitin sulfate & glucosamine target this part of connective tissue) Fibers Collagen Fibers rope for strength Elastin Fibers spring to our skin Reticular Fibers net found in lymph nodes net found in lymph nodes Cells Cells that form the Matrix -cytes cells that are in the matrix Chondrocytes cartilage cells Osteocytes bone cells -blasts makers of the matrix Chondroblasts Osteoblasts Fibroblasts Hemocytoblasts -clasts cells that remove or breakdown Osteoclast

6 Loose Connective Tissue Areolar Connective Tissue Holds blood vessels, found under hypodermis, over dense regular connective tissue that surrounds muscle, surrounding some organs Adipose Connective Tissue Yellow fat, energy storage, insulation, protection Reticular Connective Tissue Net-like tissue used as an anchor to keep cells from being washed away (lymph) Dense Connective Tissue Regular Dense Connective Tissue Collagen lined up in the same direction (strongest) Tendons, ligaments, aponeuroses Irregular Dense Connective Tissue Collagen fibers in different directions Dermis of the skin (leather is tanned dermis) Elastic Dense Connective Tissue Similar to regular dense connective tissue but more elastin fibers found in vocal cords

7 Cartilage Hyaline Cartilage glassy cartilage Lines joints, part of rib cage, much of the nose Most common type of cartilage Fibrocartilage More collagen for strength Disks between vertebrae Elastic Cartilage More elastin fibers Ears and epiglottis Fasciae Layers and wrappings that support or surround organs Superficial Deep Subserous Bone Blood In detail in BIO 202 during CV portion

8 THE TISSUE LEVEL OF ORGANIZATION PART III: MUSCLE & NERVOUS TISSUE Muscle Tissue Skeletal Muscle Attached to bone, responsible for movement Striated, voluntary, and multinucleated Are long and thin Do not divide (replicate) Are usually called muscle fibers Cardiac Muscle Found only in the heart Striated, involuntary, and single nucleus Form branching networks connected at intercalated disks Can conduct electricity Smooth Muscle Found in the walls of hollow, contracting organs (blood vessels, urinary bladder, respiratory, digestive, and reproductive tracts) Nonstriated, involuntary, and single nucleus Are small and tapered Can divide and regenerate Organs, vessels, etc. Nervous Tissue Our body s communication lines will be discussed in detail in a few weeks starting with Ch. 11