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87 Cards in this Set
- Front
- Back
General Considerations
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Composed of closely aggregated polyhedral cells w/very little extracellular substance
Avascular, nourished by diffusion from adjacent CT, rich supply of sensory nerve endings |
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Cell Structure
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Columnar, Cuboidal, Squamous w/nucleus formed corresponding to cell shape
Single (simple) or multiple (stratified) layers |
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Specialized Cells
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Neuroepithelial cells have sensory function (i.e. taste buds)
Myoepithelial cells have contractile function (i.e. glands) |
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Intercellular Junctions - Structure
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Structures on lateral membranes of cells that contribute to cohesion and communication between cells.
Present in most tissues, prominent in epithelia Located from apex towards the base of the cell |
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Types of Intercellular Junctions
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Tight
Adhering Gap |
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Tight Junctions (Zonula Occludens)
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A plasmalemmal fusion of adjacent cells. Prevents the flow of substances between cells
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Adhering Junctions
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Attachment of cytoskeletal elements of adjacent cells, through link proteins.
Provide firm adhesion, but space between cells is maintained |
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Parts of Adhering Junctions
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Zonula Adherens
Desmosomes |
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Zonula Adherens
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Encircles a cell and provides adhesion from one cell to its neighbor
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Desmosomes
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Macula Adherens - Disk-shaped structure at the surface of the adjacent cell
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Gap Junctions
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Communicating - Channels between adjacent cells. Allow metabolic and ionic coupling between cells (epithelial, cardiac muscle, smooth muscle)
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Surface Specializations of Epithelial Tissue
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Located on the free surface of some epithelial cells. Allow a specialized function
(microvilli, stereocilia, cilia) |
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Microvilli
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Short, nonmotile, cytoplasmic projections or folds.
Composed of actin filaments. May be none, few, or many per cell. Increase surface area for absorption (i.e., small intestine) |
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Stereocilia
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Long, branched, microvilli
Increase surface area for absorption (i.e., male reproductive system) |
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Cilia
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Long, motile, cytoplasmic projections.
Composed of microtubules. May be none, few, or many per cell Transport substances (i.e., fallopian tubes, trachea) |
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Functions of Epithelial Tissue (5)
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Protection
Absorption Secretion Sensation (neuroepithelium) Contraction (myoepithelium) |
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How Epithelial Tissue is Classified
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Number of cell layers
Shape of most superficial cells |
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Simple Squamous - Function
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Absorption
Lines surfaces across which metabolites or gases must move rapidly |
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Simple Squamous - Distribution
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Endothelium - inner lining of the blood vessels, Lymphatics, and Heart.
Mesothelium - Lining of the body cavities Kidneys |
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Simple Cuboidal - Function
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Protection, Secretion
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Simple Cuboidal - Distribution
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Covering of the ovary, thyroid.
Lines small ducts. Kidney |
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Simple Columnar - Function
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Protection, Absorption, Secretion
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Simple Columnar - Distribution
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Lining of the stomach, intestine, uterine cervix.
Lines ducts |
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Simple Pseudostratified - Function
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Protection, Secretion
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Simple Pseudostratified - Distribution
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Lining of the upper respiratory tract, male reproductive tract
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Stratified Squamous Keratinized - Function
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Protection
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Stratified Squamous Keratinized - Distribution
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Epidermis of skin
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Stratified Squamous non-keratinized - Function
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Protection, Secretion
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Stratified Squamous non-keratinized - Distribution
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Mouth, esophagus, larynx, vagina, anal canal.
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Stratified Cuboidal - Function
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Protection, secretion
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Stratified Transitional - Function
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Protection, distensibility
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Stratified Transitional - Distribution
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Lining of the urinary tract
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Stratified Columnar - Function
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Protection
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Stratified Columnar - Distribution
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Conjunctiva
Lines large ducts |
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Keratin
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Cytoskeletal intermediate filament that accumulates in epithelial cells during maturation.
Remains adherent to underlying layers of living cells |
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Definition of Gland
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Individual cell, group of cells, or organ which is specialized to 'synthesize and release (secrete) a product used by other elements of the organism.
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Definition of Secretion
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Synthesis and release of cell products for further use outside the secreting cell(s)
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Product Distribution Classification (Glandular Epithelia)
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Exocrine, Endocrine
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Type of Secretion Classification (Glandular Epithelia)
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Exocrine (Mucous, Serous, Lipid)
Endocrine (Polypeptide, Steroid) |
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Structure Classification (Glandular Epithelia)
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Unicellular (isolated cells)
Multicellular (clusters of cells) |
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Mode of Secretion Classification (Glandular Epithelia)
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Merocrine (exocytosis), Apocrine (cell cytoplasm and secretory product), Holocrine (entire cell and secretory product), Diffusion
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Exocrine Glands
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Secretory products are released on to an epithelial surface either directly or via a duct or duct system
Polarized distribution of organelles (Goblet Cells, Sheet Glands, Sweat Glands) |
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Endocrine Glands
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Secretory products are released directly into the extracellular fluid and eventually into the blood or lymph (no duct system)
Do not display a polarized distribution (Enteroendocrine Cells, Islets of Langerhans, Adrenal Glands) |
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Composition of Epidermis
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Keratinized Stratified Squamous Epithelium
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Organization of Epidermis - Superficial Layer
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15-20 layers of flattened, non-nucleated, keratinized cells
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Organization of Epidermis - Deep Layer
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Single layer of columnar or cuboidal "keratinocyte" stem cells, which are mitotically active and produce keratin.
Cells differentiate as they move outwards, turnover from deep to superficial ranges from 25-50 days. |
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Epidermis Specializations (3 types)
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Melanocytes, Merkel Cells, Langerhans Cells
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Malanocytes
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Produce pigment, melanin, which is essentially "injected" into keratinocytes
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Merkel Cells
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May serve as sensory mechanoreceptors or neuroendocrine cells
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Langerhands Cells
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Immune function
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Dermis - Composition and Organization
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Loose CT (Superficial Layer)
Dense Irregular CT (Deep Layer) |
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Dermis Specializations (3)
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Dermal Papillae
Nonencapsulated Receptors Encapsulated Receptors |
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Dermal Papillae
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Projections of the dermis that interdigitate with evaginations of the epidermis, called epidermal ridges
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Nonencapsulated Receptors
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Sensitive to touch, pressure, pain, temperature
Extend into epidermis |
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Encapsulated Receptors
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Function as mechanoreceptors, include Ruffini, Pacinian, Meissner, and Krause
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Hypodermis
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Subcutaneous Tissue, Superficial Fascia
Not part of skin Loose CT w/variable number of adipose cells |
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Surface Specializations Derived From Epidermis
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Hair, Nails, Glands
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Sebaceous Glands
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Produce and release sebum (complex lipid mixture)
Located in skin of most body regions except palms and soles |
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Sweat Glands
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Produce and release sweat.
Eccrine - widely distributed Apocrine - Distributed in axilla, areola, and circumanal regions |
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Regional Variations - Thick Skin
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No hairs and sepaceous glands
Palms, Finger Tips, Soles |
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Regional Variations - Thin Skin
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Contains hairs and sebaceous glands
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Function of Skin
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Protection, Sensation, Thermoregulation, Metabolic (vitamin D)
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Basic Organization of the Circulatory System
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Tunica Intima, Tunica Media, Tunica Adventitia
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Tunica Intima
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Layer closest to body
Commonly includes an endothelium, basement membrane, and subendothelial loose CT |
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Tunica Media
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Middle Layer
Commonly includes smooth muscle and elastic lamellae |
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Tunica Adventitia
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Layer furthest from blood
Commonly includes loose CT Continuous w/CT of organ through which vessel runs |
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Composition of Circulatory System - Endothelium
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Simple Squamous Epithelium
In tunica intima Rests on basement membrane: carries a negative charge that repels circulating blood cells. Underlying basement membrane carries a positive charge that encourages platelet clotting |
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Composition of Circulatory System - Smooth Muscle
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In all 3 tunics, most prominent in tunica media
Organized circularly - media Organized longitudinally - intiima and adventitia |
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Composition of Circulatory System - Connective Tissue
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In all 3 tunics, most prominent in tunica adventitia
Loose CT, but can be Dense irregular in larger vessels Vessels contain concentric fenestrated (lamellae) or continuous (laminae) sheets of elastic fibers |
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Layers of the Heart
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Endocardium
Myocardium Epicardium |
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Endocardium
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Inner layer composed of endothelium and basement membrane
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Cardiac Valves
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Folds of endocardium with central flat sheet of dense irregular CT
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Myocardium
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Middle layer composed of cardiac muscle tissue. Fibers insert on componenets of cardiac skeleton
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Epicardium
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Outer layer composed of simple squamous epithelium (mesothelium) supported by a thin later of dense irregular CT
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Supporting Structure of the Heart
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Cardiac Skeleton
Pericardium |
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Cardiac Skeleton
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Composed of dense irregular CT: annuli fibrosi, fibrous trigones, septum membranaceum
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Annuli Fibrosi
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Rings surrounding each valve
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Fibrous Trigones
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Two triangular zones between annuli fibrosi
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Septum Membranaceum
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Superior portion of interventricular septum
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Pericardium
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Composed of inner visceral layer of simple squamous epithelium and outer layer of dense irregular CT
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Covering Epithelium of Larynx -> Terminal Bronchiole
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Ciliated pseudostratified columnar epithelium (Respiratory Epithelium)
Contains goblet cells that secrete mucous |
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Lamina Propria - Respiratory System
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Loose CT underlying the covering epithelium
Includes elastic and reticular fibers, lymph tissue, smooth muscle, and/or glands (except at level of bronchiole) Smooth muscle becomes more prominent towards the respiratory portion |
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Submucosa - Respiratory System
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Middle layer of loose CT, contains glands (except at level of bronchiole)
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Adventitia - Respiratory System
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Outer layer. Commonly includes loose CT, but may be dense irregular CT in larger airways (i.e. trachea, bronchi)
Contains cartilaginous rings and plates (hyaline cartilage) |
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Interalveolar Septum
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Consists of 2 layers of alveolar simple squamous epithelium, btw which lie capillaries, elastic and reticular fibers, and CT matrix.
Contains lung macrophages, called dust cells |
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Epithelial Lining Cells - Type I
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97% of alveolar cells, squamous "lining" cells
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Epithelial Lining Cells - Type II
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Interspersed btw Type I cells, produce pulmonary surfactant which lowers the alveolar surface tension
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