1.24k likes | 1.6k Views
Tissue Level of Organization. Dr. Michael P. Gillespie. Tissue Types. Four basic tissue types exist in the body. 1. Epithelial tissue 2. Connective tissue 3. Muscle tissue 4. Nervous tissue. Epithelial Tissue.
E N D
Tissue Level of Organization Dr. Michael P. Gillespie
Tissue Types • Four basic tissue types exist in the body. • 1. Epithelial tissue • 2. Connective tissue • 3. Muscle tissue • 4. Nervous tissue Dr. Michael P. Gillespie
Epithelial Tissue • Epithelial tissue covers body surfaces and lines hollow organs, body cavities, and ducts. It also forms glands. Dr. Michael P. Gillespie
Connective Tissue • Connective tissue protects and supports the body and its organs. Various types of connective tissue bind organs together, store energy reserves as fat, and help provide immunity to disease-causing organisms. Dr. Michael P. Gillespie
Muscle Tissue • Muscle tissue generates the physical force needed to make body structures move. Dr. Michael P. Gillespie
Nervous Tissue • Nervous tissue detects changes in a variety of conditions inside and outside the body and responds by generating nerve impulses and help maintain homeostasis. Dr. Michael P. Gillespie
Biopsy • A biopsy (bio = life, -opsy = to view) is the removal of a sample of living tissue for microscopic examination. • Used to diagnose disorders. • Compared to normal tissue. • Removed surgically or through needle and syringe. Dr. Michael P. Gillespie
Cell Junctions • Cell junctions are contact points between the plasma membranes of tissue cells. • Functions • Forming seals between cells. • Anchoring cells to one another or to extracellular material. • Channels between cells in a tissue (passage of ions and molecules). Dr. Michael P. Gillespie
Major Types of Cell Junctions • Tight junctions • Adherens junctions • Desmosomes • Hemidesmosomes • Gap junctions Dr. Michael P. Gillespie
Adherens Junctions • Help epithelial cells resist separation. • Located in epithelial cells. Dr. Michael P. Gillespie
Desmosomes • Attach cells to one another. • Contribute to the stability of the cells and tissue. • Found in the epidermis and between cardiac muscle cells. Dr. Michael P. Gillespie
Hemidesmosomes • Hemi – half. Hemidesmosomes lack links to adjacent cells. • Anchor cells to the basement membrane. Dr. Michael P. Gillespie
Gap Junctions • Form fluid filled channels that connect adjacent cells. • Ions and small molecules can diffuse from the cytosol of one cell to the next. • Enable nerve impulses to travel more rapidly among cells. Dr. Michael P. Gillespie
Epithelial Tissue • Cells arranged in continuous sheets. • Avascular – without blood vessels. • Exchange of substances occurs by diffusion. Dr. Michael P. Gillespie
Apical Surface • Apical (free) surface – faces the body surface, a body cavity, the lumen (interior space) of an internal organ, or a tubular duct that receives secretions from cells. Dr. Michael P. Gillespie
Lateral Surfaces • The lateral surfaces of an epithelial cell face adjacent cells. • The lateral surfaces may contain tight junctions, adherens junctions, desmosomes, and gap junctions. Dr. Michael P. Gillespie
Basal Surface • Opposite the apical surface. • Anchored to the basement membrane. Dr. Michael P. Gillespie
Basement Membrane • Attaches to and supports the epithelial layer. • Restricts the passage of larger molecules between the epithelial layer and connective tissue. Dr. Michael P. Gillespie
Types of Epithelium • Covering and lining epithelium • Forms the outer covering of skin and some internal organs. • Forms the lining of blood vessels, ducts, body cavities, and the interior of the respiratory, digestive, urinary, and reproductive systems. • Glandular epithelium • Forms the secreting portion of glands (I.e. thyroid, adrenal and sweat glands). Dr. Michael P. Gillespie
Classification of Epithelium • Classified by the # of layers. • Classified by the shapes of cells. Dr. Michael P. Gillespie
Arrangement of Cells in Layers • Simple epithelium - single layer of cells • Functions in secretion and absorption • Stratified epithelium – 2 or more layers of cells • Protects underlying tissues • Pseudostratified epithelium – contains a single layer of cells, but the nuclei lie at different levels. • Some cells are ciliated or secrete mucus. Dr. Michael P. Gillespie
Cell Shapes • Squamous cells • Flat, thin cells that allow for rapid movement of substances through them. • Cuboidal cells • As tall as they are wide. Function in secretion or absorption. May have microvilli. • Columnar cells • Taller than they are wide. Specialized for secretion or absorption. • Transitional cells • Change shape as organs stretch and collapse. Dr. Michael P. Gillespie
Types of Simple Epithelium • Simple squamous epithelium • Simple cuboidal epithelium • Simple columnar epithelium • Nonciliated • Ciliated Dr. Michael P. Gillespie
Types of Stratified Epithelium • Stratified squamous epithelium • Keratinized • Nonkeratinized • Stratified cuboidal epithelium • Stratified columnar epithelium • Transitional epithelium Dr. Michael P. Gillespie
Pseudostratified Columnar Epithelium • Nonciliated • Ciliated Dr. Michael P. Gillespie
Simple Squamous Epithelium • Single layer cells. • Flat cells. • Location • Bowman’s capsule of kidneys • Air sacs of lungs • Lining of the heart • Lining of blood vessels • Lining of lymphatic vessels • Inner surface of the tympanic membrane Dr. Michael P. Gillespie
Simple Cuboidal Epithelium • Single layer of cells. • Cells have an equal height and width. • Functions of secretion and absorption. • Location • Surface of ovary • Kidney tubules • Ducts of many glands • Secreting portions of some glands Dr. Michael P. Gillespie
Simple Columnar Epithelium • Single layer of cells. • Cells are taller than they are wide. • Location • Ciliated • Upper respiratory tract • Uterine (Fallopian) tubes • Paranasal sinuses • Central canal of spinal cord • Nonciliated • GI tract from stomach to anus • Ducts of many galnds • Gallbladder Dr. Michael P. Gillespie
Stratified Squamous Epithelium • 2 or more layers of cells • Apical layers of cells are flat • Deep layers vary in shape from cuboidal to columnar • Keratinized and nonkeratinized forms • Location • Keratinized lines the surface of the skin • Nonkeratinized lines wet surfaces such as the mouth, esophagus, epiglottis, vagina and tongue Dr. Michael P. Gillespie
Stratified Cuboidal Epithelium • 2 or more layers of cells • Equal in height and width • Location • Ducts of adult sweat glands and esophageal glands • Part of male urethra Dr. Michael P. Gillespie
Stratified Columnar Epithelium • 2 or more layers of cells • Taller than they are wide • Basal layer contains shortened, irregularly shaped cells • Only the apical layer has columnar cells • Location • Part of urethra • Excretory ducts of some glands (I.e. esophageal) • Anal mucous membrane • Conjunctiva of the eye Dr. Michael P. Gillespie
Transitional Epithelium • 2 or more layers of cells • Variable in appearance • Present in the urinary system • Un-stretched it looks similar to stratified cuboidal epithelium • Stretched it looks similar to stratified squamous epithelium • Location • Urinary bladder • Portions of the ureters and urethra Dr. Michael P. Gillespie
Pseudostratified Columnar Epithelium • Single layer of cells – appears to be more than one layer due to uneven nuclei • Some cells do not extend to the surface • The cells that extend to the surface either secrete mucous (goblet cells) or bear cilia • Location • Airways of the upper respiratory tract • Larger ducts of many glands • Epididymis • Part of male urethra Dr. Michael P. Gillespie
Glandular Epithelium • Function – secretion • Gland – a single cell or group of cells that secrete substances into ducts, onto a surface, or into the blood. • 2 types • Endocrine • Exocrine Dr. Michael P. Gillespie
Endocrine Glands • The secretions of endocrine glands enter the interstitial fluid and then diffuse directly into the bloodstream. • These secretions do NOT flow through a duct. • These secretions are called hormones. • Examples • Pituitary, thyroid, and adrenal glands Dr. Michael P. Gillespie
Exocrine Glands • Exocrine glands secrete their products into ducts that empty onto the surface of a covering and lining epithelium. • Types of secretions • Mucus, sweat, oil, earwax, sailva, digestive enzymes • Examples • Sudoriferous (sweat) and salivary glands Dr. Michael P. Gillespie
Structural Classification of Glands • Unicellular – single celled • Multicellular – many celled – distinct organ • Simple - unbranched • Compound - branched • Tubular – tubular secretory parts • Acinar – rounded secretory portions • Tubular Acinar Dr. Michael P. Gillespie
Simple Glands • Simple tubular • Glands in Large Intestine • Simple branched tubular • Gastric glands • Simple coiled tubular • Sweat glands • Simple acinar • Glands of penile urethra • Simple branched acinar • Sebaceous glands Dr. Michael P. Gillespie
Compound Glands • Compound tubular • Bulbourethral (Cowper’s) glands • Compound acinar • Mammary glands • Compound tubuloacinar • Acinar glands of the pancreas Dr. Michael P. Gillespie