IBHS2 Tissues

admin / February 17, 2018
Question Answer
Epithelia Cells covering external or internal surfaces (1. Body surface and lining of involutions 2. Lining of cavities and blood vessels & exocrine glands)
Glands Structures made of cells that produce secretions (derived from epithelia)
Basic functions of epithelial tissue Protection, Transport, Secretion, Provide Sensation
Apical Top (facing the lumen!)
Lateral Sides
Basal Bottom
Basolateral Lower Sides
Characteristics of Epithelia Polarity, Avascular, Regenerative, Cell Attachment (Integrity of epithelium is based on regenerative and attachment properties)
Basement Membrane Layers 1. Lamina Lucida 2. Lamina Densa (these two make up the Basal Lamina) 3. Reticular Lamina
Basal Lamina Extracellular ‘stuff’ that connects the entire epithelium to the rest of the body; limits diffusion
Lamina Lucida Glycoproteins (laminin) and small protein filaments; secreted by epithelial cells
Lamina Densa Larger protein fibers (type IV collagen); secreted by connective tissue cells (fibroblasts)
CAMs transmembrane proteins that tie the cytoskeleton (actin, microtubules) to the cytoskeleton of neighboring cells or proteins in the underlying extracellular matrix. They can also serve as receptors and can contribute to cell junctions.
CAM Classifications Immunoglubulin (Ig) Family, Cahedrins, Integrins, Selectins
Cahedrins Link cytoskeleton of neighboring cells
Integrins Link the cytoskeleton to proteins in matrix
Selectins Transient cell-to-cell binding in bloodstream
Tight Junctions Cell membranes of adjacent cells are tightly stitched together via interlocking proteins (almost no passage of water or solutes between cells and almost no movement of integral proteins)
Tight Junction Location Lateral Surface (i.e. Digestive tract, blood-brain barrier)
Types of Tight Junction Transport Paracellular Transport, Trancellular Transport, Vectoral Transport
Paracellular Transport Limited by tight junctions (permeability varies with location/epithelial function)
Transcellular Transport Occurs via diffusion and/or active transport
Vectoral Transport Membrane transport proteins stay in specific cellular domains
Absorption Apical to Basolateral transport
Secretion Basolateral to Apical transport
Adherens Junctions Usually found in epithelial tissue, below a tight junction (an adhesion belt encircles neighboring cells together)
Adhesion Belt CAM (cahedrin) attached to a web of cytoplasmic actin (terminal web) and also attached to CAM of adjacent cell (which is attached to that cell’s terminal web) The actin of adjacent cells is connected; cells can work together.
Adherens Junction Locations Lateral Surfaces (i.e. Cardiac muscle, digestive tract)
Gap Junctions Allow for movement of small molecules and ions into adjacent cells and between membranes (via the gap)
Connexons Interlocking channel proteins that hold adjacent cells together at gap junctions (open to form a hydrophilic pore and allow passage of ions and small molecules) [flower shapes]
Gap Junction Locations Lateral surfaces of cells that require rapid intercellular communication (i.e. Cardiac and smooth muscle, synapses)
Desmosomes Cells subject to mechanical stress (skin) Stretch, bend, twists, compress
Button Desmosomes Located on the lateral surface; attaches adjacent cells
Hemidesmosomes Located on the basolateral surface; attaches cell to basal lamina
Dense Area Concentration of CAM and intermediate filaments of cytoskeleton
Simple Epithelia Single layer of cells, protection not priority, important for diffusion of “vitals” (located inside body: lungs, blood vessels)
Stratified Epithelia Several layers of cells, protection is priority (body surface)
Simple Squamous Epithelia Most delicate; absorption or excretion (i.e. lining of blood vessel, body cavity)
Stratified Squamous Epithelia Increased mechanical stress; tough but needs to be kept moist (esophagus, anus, vagina); may or may not have keratin (water resistant)
Simple Cuboidal Epithelia Limited protection; absorption, secretion (glands, ducts)
Stratified Cuboidal Epithelia Rare, more protective (where secretions can be rough), absorption, secretion (ducts, sweat glands)
Simple Columnar Epithelia Protection (chemical stress), absorption, secretion, apical side typically has microvilli (intestines)
Pseudostratified Columnar Epithelia Protection and secretion, apical side typically ciliated (bronchi)
Stratified Columnar Epithelia Rare, protection (urethra)
Transitional Epithelia Tolerates repeated cycles of stretching/recoil (bladder) [Empty: looks stratified, Full: looks more simple]
Glandular Epithelia Typically collections of epithelia that produce secretins
Endocrine Glands ’ductless glands.’ Release secretions into interstitial fluid > blood stream [secretions = hormones] (thyroid, pituitary)
Exocrine Glands Release secretions into ducts that open onto epithelial surface (enzymes entering digestive tract, sweat, tears, milk)
Serous Exocrine Glands Watery solution containing enzymes (i.e. parotid salivary glands)
Mucous Exocrine Glands Secrete mucins (i.e. submucosal glands of small intestine)
Mixed Exocrine Glands Contain more than 1 type of gland cell, therefore produce 2 different secretions, such as serous and mucus (i.e. submandibular salivary glands)
Goblet Cells Only unicellular gland. Individual cell producing secretions Goblet Cell Locations
Goblet Cell Functions Secrete mucin glycoproteins (main component of mucus), protect and lubricate
Connective Tissue Functions Structural [F]ramework, [C]onnects different types of tissues, [T]ransports fluids/dissolved material, [P]rotection, Storing [E]nergy, [D]efense
Classic Connective Tissue Connects the epithelium to the rest of the body
Non-Classic Connective Tissue Bone, Blood, Fat, Lymph, Cartilage
Matrix Ground substance + Extracellular protein fibers
Three Basic Components of Connective Tissue Specialized cells, Ground Substance, and Extracellular protein fibers
Cell Components of Connective Tissue Proper Fibroblasts, Mesenchymal cells, Adipocytes, Melanocytes, and Immune Cells
Fibroblasts Most abundant, main source of ground substance and fibers
Mesenchymal Cells C.T. Stem Cells
Adipocytes Energy storage, insulation
Melanocytes Make/store melanin
Immune Cells Lymphocytes, macrophages
Ground Substance Viscous: impedes movement, Water soluble: diffusion of O2, Fills spaces between cells and cells & fibers
Fibers Collagen, Elastic, Reticular
Ground Substance Composition Proteins + Glycosaminoglycans = Proteoglycans; composition of proteoglycans is varied in each CT type
Types of Glycosaminoglycans Hyaluronic Acid, Chondroitin Sulfate, Dermatan Sulfate, Keratan Sulfate
Hyaluronic Acid Aggregates proteins > la brea tar pits for microbes. Intercellular cement
Chondroitin Sulfate Found in cartilage
Dermatan Sulfate Found in Dermis
Keratan Sulfate Found in cornea
Collagen Fibers (Protein) Most abundant protein in the body (35% of all protein in the body) 40 different types of collagen molecules
Collagen Fibers (Fibers) Most abundant fiber. Long, straight, unbranched; Resistant to unidirectional stress; Braided like rope = stronger than steel; Key to ligaments and tendons
Types of Collagen I – Bone, ligaments, tendons, dermins (Fibroblasts) 90%; II – Cartilage (Chondrocytes); III – Blood Vessels (Fibroblasts); IV – Basal Lamina (Epithelia)
Osteogenesis Imperfecta (Type I): Bones break easily; “brittle bone disease”
Ehlers Danlos Syndrome (Type III) Hypermobile joints and hyperextensive skin

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