Histology Notes BIOL 214
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This 10 page Bundle was uploaded by kgrunwaldt on Monday January 25, 2016. The Bundle belongs to BIOL 214 at Truman State University taught by Dr. Guffey in Spring 2016. Since its upload, it has received 23 views. For similar materials see Anatomy and Physiology I in Science at Truman State University.
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Date Created: 01/25/16
Histology TISSUE DESCRIPTION Histology study of tissues Groups of cells similar in structure and function Four major types 0 Epithelial lining and covering 0 Connective support padding energy storage etc o Muscular contractile for movement 0 Nervous responds to environment and conducts impulses BODY FLUIDS For the body39s cells to survive the composition of the surrounding fluids must be precisely maintained at all times Fluid inside body cells is called intracellular fluid Fluid outside body cells is called extracellular fluid ECF and is found in two principal places 0 ECF filling the narrow spaces between cells of tissues is called interstitial fluid intercellular fluid or tissue fluid 0 ECF in blood vessels is termed plasma Since ECF is in constant motion throughout the body and also surrounds all body cells it is often called the body39s internal environment EPITHELIAL TISSUES General Characteristics 1 Always have a free surface 1 cover organs and the body 2 line body cavities 3 line hollow organs 2 Cellularity composed almost entirely of cells 3 Special contacts form continuous sheets held together by tight junctions and desmosomes 4 Polarity apical free surface and basal basement membrane surfaces 5 Supported by connective tissue reticular and basal laminae 6 Avascular but innervated contains no blood vessels but supplied by nerve fibers 7 Regenerative rapidly replaces lost cells by cell division Basement membrane opposite the free surface 0 Basal lamina o Reticular lamina 0 Func ons I guide for cell migration during development I may become thickened due to increased collagen and laminin production I Example In diabetes mellitus the basement membrane of small blood vessels especially those in the retina and kidney thickens Classification of Epithelial Tissue based on shape of cell and number of cell layers 0 Simple squamous Epithelial I Single layer of flattened cells with discshaped nuclei and sparse cytoplasm I Func ons I Diffusion and filtration I Provide a slick frictionreducing lining in lymphatic amp cardiovascular systems I Present in kidney glomeruli endothelium lymphatic vessels and serosae 0 Simple Cuboidal Epithelial I Single layer of cubelike cells with large spherical central nuclei I Function in secretion and absorption I Present in kidney tubules ducts andsecretory portions of small glands and ovary surface 0 Simple columnar Epithelial I Single layer of tall cells with oval nuclei many contain cilia I Goblet cells are often found in this layer I Function in absorption and secretion I Nonciliated type with microvilli line digestive tract and gallbladder I Ciliated type line small bronchi uterine tubes and some regions of the uterus o Pseudostratified Columnar Epithelial I Single layer of cells with different heights some do not reach the free surface I Nuclei are seen at different layers I Function in secretion andpropulsion ofmucus I Present in the male spermcarrying ducts nonciliated and trachea ciliated 0 Stratified Squamous Epithelial I Thick membrane composed of several layers of cells I Function in protection of underlying areas subjected to abrasion I Forms the external part of the skin39s epidermis keratinized cells and linings of the esophagus mouth and vagina nonkeratinized cells I PAP Smear I Collect sloughed off cells of uterus and vaginal walls 0 Stratified Cuboidal and Stratified Columnar I Stratified cuboidal I Quite rare in the body I Found in some sweat and mammary glands I Typically two cell layers thick I Stratified columnar I Limited distribution in the body I Found in the pharynx male urethra and lining some glandular ducts I Also occurs at transition areas between two other types of epithelia o Transitional Epithelial I Several cell layers basal cells are cuboidal surface cells are dome shaped I Stretches to permit the distension of the urinary bladder I Lines the urinary bladder ureters and part of the urethra Glandular Epithelium o Endocrine secrete directly into body fluids or blood ductless o Exocrine Secrete their products onto body surfaces skin or into body cavities I Examples include mucous sweat oil and salivary glands I The only important unicellular gland is the goblet cell I Multicellular exocrine glands are composed of a duct and secretory unit I Classified by arrangement of cells simple compound tubular alveolar I Also classified by secretion method I Merocrinewatery I apocrine thicker I holocrine whole cell EpithelialMembranes Cutaneous skin Mucous open Serous closed CONNECTIVE TISSUES Found throughout the body most abundant and widely distributed in primary ssues O Connective tissue proper O Cartilage 0 Bone 0 Blood Functions of 0 Binding and support 0 Protection 0 Insulation 0 Transportation Connective tissues have 0 Mesenchyme as their common tissue of origin 0 Varying degrees of vascularity o Nonliving extracellular matrix consisting of ground substance and fibers Extracellular Matrix and Cells 0 Ground substance fills the space between cells Interstitial fluid I Adhesion proteins fibronectin and laminin I Functions as a molecular sieve through which nutrients diffuse between blood capillaries and cells 0 Fibers I Collagen fibers tough and resistant to stretching I allow some flexibility in tissue I bone cartilage tendons and ligaments I Elastic fibers provide strength and stretching capacity I skin blood vessels and lungs I Reticular fibers composed of collagen and gycoprotein I support in walls of blood vessels in spleen in lymph nodes I supporting network around fat cells nerve fibers muscle fibers 0 Cells I Fibroblasts connective tissue proper I Chondroblasts cartilage I Osteoblasts bone I Hematopoietic stem cells blood I White blood cells plasma cells macrophages and mast cells Classified by extracellularmatrix 0 Loose connective Proper I Mesenchyme embryonic connective tissue I Gellike ground substance with fibers and starshaped mesenchymal cells I Gives rise to all other connective tissues I Areolar I Gellike matrix with all three connective tissue fibers I Fibroblasts macrophages mast cells and some white blood cells I Wraps and cushions organs I Widely distributed throughout the body I Adipose I Reserves food stores insulates against heat loss and supports and protects I Found under skin around kidneys within abdomen and in breasts I Local fat deposits serve nutrient needs of highly active organs I Reticular I Loose ground substance with reticular fibers I Reticular cells lie in a fiber network I Forms a soft internal skeleton or stroma that supports other cell types I Found in lymph nodes bone marrow and the spleen Dense connective proper more fibers less cells and fluid I Dense regular connective I Mainly parallel collagen fibers with a few elastic fibers little fluid I Major cell type is fibroblasts I Attaches muscles to bone or to other muscles and bone to bone I Found in tendons ligaments and aponeuroses I Dense irregular connective I lrregularly arranged collagen fibers with some elastic fibers little fluid I Major cell type is fibroblasts I Withstands tension in many directions providing structural strength I Found in the dermis submucosa of digestive tract and fibrous organ capsules I Elastic connective I abundant in elastic fibers I some collagenous fibers fibroblasts I walls of large arteries airways heart Cartilage solid but flexible gel like matrix I Cells are called chondrocytes I No blood vessels or nerves I Classified by fiber type I Hyaline cartilage I Amorphous firm matrix with imperceptible network of collagen fibers I Chondrocytes lie in lacunae I Supports reinforces cushions and resists compression I Forms the costa cartilage I Found in embryonic skeleton the end of long bones nose trachea and larynx I Fibrocartilage I Matrix similar to hyaline cartilage but less firm with thick collagen fibers I Provides tensile strength and absorbs compression shock I Found in intervertebral discs the pubic symphysis and in discs of the knee joint I Elastic cartilage I Similar to hyaline cartilage but with more elastic fibers I Maintains shape and structure while allowing flexibility I Supports external ear pinna and the epiglottis Bone Calcium matrix I Hard calcified matrix with collagen fibers found in bone I Osteocytes are found in lacunae and are well vascularized I Supports protects and provides levers for muscular action I Stores calcium minerals and fat I Marrow inside bones is the site of hematopoiesis 0 Blood Fluid matrix plasma I Red and white cells in a fluid matrix plasma I Contained within blood vessels I Functions in the transport of respiratory gases nutrients and wastes 0 Summary of Matching Function to Connective Tissue MUSCULAR TISSUE Skeletal 0 Long cylindrical multinucleate cells with obvious striations o Initiates and controls voluntary movement 0 Found in skeletal muscles that attach to bones or skin Cardiac o Branching striated uninucleate cells interlocking at intercalated discs 0 Propels blood into the circulation 0 Found in the walls of the heart Smooth 0 Sheets of spindleshaped cells with central nuclei that have no striations o Propels substances along internal passageways ie peristalsis 0 Found in the walls of hollow organs NERVOUS TISSUE Branched neurons with long cellular processes and support cells Transmits electrical signals from sensory receptors to effectors Found in the brain spinal cord and peripheral nerves Tissue Trauma and Repair Causes inflammation characterized by 0 Dilation of blood vessels 0 Increase in vessel permeability o Redness heat swelling and pain Organization and restored blood supply 0 The blood clot is replaced with granulation tissue Regeneration and fibrosis 0 Surface epithelium regenerates and the scab detaches Fibrous tissue matures and begins to resemble the adjacent tissue Results in a fully regenerated epithelium with underlying scar tissue Developmental Aspects Primary germ layers ectoderm mesoderm and endoderm 0 Three layers of cells formed early in embryonic development 0 Specialize to form the four primary tissues Nerve tissue arises from ectoderm Muscle connective tissue endothelium and mesothelium arise from mesoderm Most mucosae arise from endoderm Epithelial tissues arise from all three germ layers
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