Tissues Chapter 5 PDF

Chapter 5 Tissue Organization  Tissue Organization Cells organized into more complex units termed tissues – Groups of similar cells and extracellular material – Perform a common function – E.g., providing protection – The study of tissues termed histology...

Chapter 5 Tissue Organization  Tissue Organization Cells organized into more complex units termed tissues – Groups of similar cells and extracellular material – Perform a common function – E.g., providing protection – The study of tissues termed histology Four types of tissues – Epithelial, connective, muscle, nervous – Have varied structure and function  Today’s Objectives Compare & contrast epithelial cells Compare different gland structures and functions Compare and contrast different types of connective tissues 3  Characteristics Epithelial tissue – Covers body surfaces – Lines body cavities – Forms majority of glands Epithelium – Composed of one or more layers of closely packed cells – Contains little or no extracellular matrix – Contains no blood vessels  Characteristics Cellularity – Composed almost entirely of tightly packed cells Polarity – Has apical surface exposed to external environment or internal body space may have microvilli or cilia – Lateral surface with intercellular junctions – Has basal surface epithelium attached to connective tissue  Characteristics Attachment to basement membrane – Complex structure produced by epithelium and connective tissue – Consists of three layers: lamina lucida, lamina densa, reticular lamina – Contains collagen fibers and specific proteins and carbohydrates – Forms a selective barrier between epithelium and connective tissue Avascularity – Nutrients obtained across apical surface or from basal surface  Characteristics Extensive innervation – Detects changes in the environment in that region High regeneration capacity – Apical surface exposed to environment – Cells frequently damaged or lost – Frequent mitosis of deepest epithelial cells stem cells, adjacent to basement membrane – Continual replacement of lost cells  Apical surface Epithelium Lateral surface Basement membrane Basal surface Connective tissue Figure 5.1  Functions Physical protection – Protects external and internal surfaces – Protects from dehydration, abrasion, destruction Selective permeability – Relatively impermeable to some substances – Promoting passage of other molecules  Functions Secretions – Some specialized to secrete – May be scattered among other cell types – May form exocrine or endocrine glands Sensations – Contain nerve endings – Supply information to nervous system info on touch, pressure, temperature, pain – Specialized epithelium, termed neuroepithelium houses cells responsible for sight, taste, smell, hearing, equilibrium  Classification Epithelia classification indicated by two-part name – First part, number of epithelial cell layers – Second part, shape of cells at apical surface  Classification by Number of Cell Layers Simple epithelium – One cell layer thick – All cells in direct contact with basement membrane – Found in areas where stress is minimal – Found where filtration, absorption, or secretion primary function – E.g., lining of air sacs of lungs, intestines, blood vessels  Classification by Number of Cell Layers Stratified epithelium – Two or more layers of epithelial cells – Only basal layer in contact with basement membrane – Found in areas subjected to mechanical stress better able to resist wear and tear e.g., skin, lining of the pharynx, esophagus – Cells in basal layer continuously regenerate as apical layer cells lost  ALE Think, Pair, Share Compare and contrast the differences between simple and stratified, and what is the benefit/function of these differences? 14  Classification by Number of Cell Layers Pseudostratified epithelium – Type of simple epithelium – All cells attached to basement membrane – Appear layered due to cell’s nuclei distribution at different levels – Some cells not reaching apical surface  Classification by Cell Shape Squamous cells – Flat, wide, irregular in shape – Arranged like flattened floor tiles – Nucleus flattened Cuboidal cells – Approximately as tall as they are wide – Nucleus spherical and in center of cell  Classification by Cell Shape Columnar cells – Slender and taller than they are wide – Nucleus oval Transitional cells – Change shape, depending on stretch of epithelium – Occur where epithelium stretches and relaxes e.g., lining of the bladder – Polyhedral in shape when epithelium relaxed – More flattened when epithelium stretched  Basement Nucleus membrane Apical surface Squamous cell Basal surface Basement membrane Simple epithellum Nucleus Basement membrane Apical surface Cuboidal cell Nucleus Basement membrane Basal surface Basement membrane Stratified epithellum Columnar cell (a) Layer classifications (b) Shape classifications  ALE Let your inner artist out! Select a card – any card – one from each stack Using the combination of the 2 cards, use your group to help you draw that tissue Can you find an example of where this tissue is? 19  Classification Simple Squamous Epithelium – Thinnest possible barrier – Consists of single layer of flattened cells – Spherical to oval nucleus – Allows rapid movement of molecules across surface – Forms lining of air sacs of lung – Found lining blood and lymph vessel walls termed endothelium – Portion that forms serous membrane of cavities termed mesothelium  Simple Squamous Epithelium Simple Squamo squamous us cell epithelium Loose Nucleus connectiv of e tissue squamo us cell  Classification Simple Cuboidal Epithelium – Contains uniformed shaped cells – Ideal for small ducts and glands – Single layer of cells, cuboidal shaped – Absorbs fluids across apical surface – Secretes specific molecules – Forms walls of kidney tubules – Forms secretory regions of most glands – Forms smaller ducts of exocrine glands – Covers surface of ovary – Lines thyroid gland  Simple Cuboidal Epithelium Simple cuboidal Cuboidal cell epithelium Lumen of Nucleus of cuboidal tubule cell  Classification Simple Columnar Epithelium – Single layer of columnar cells – Ideal for secretory and absorptive function Nonciliated – Often contains microvilli collectively appear as fuzzy structure, brush border – Often contains unicellular glands, termed goblet cells secrete glycoprotein, mucin forms mucus when mixed with water – Lines most of digestive tract from stomach to anal canal Simple Columnar Epithelium (nonciliated) Simple columnar Goblet cell epithelium Simple columnar Lumen of jejenum Microvilli (brush Lamina propria  Classification Simple Columnar Epithelium Ciliated – Has cilia projecting from apical surface move mucus along – Goblet cells interspersed – Present in the bronchioles – Lines uterine tubes helps move oocyte from ovary to uterus Simple Columnar Epithelium (Ciliated) Simple columnar Basement epithelium membrane (ciliated) Simple columnar Lamina propria cell (ciliated) Lumen of uterine Cilia  Classification Pseudostratifed Columnar Epithelium – Appears to consist of multiple cell layers – Not really stratified nuclei scattered at different distances not all cells reaching apical membrane Ciliated – Houses goblet cells – Mucus moved by beaten cilia – Found in large passageways of the respiratory system Nonciliated – Lacks goblet cells and cilia – Occurs mainly in male urethra and epididymis  Pseudostratified Columnar Epithelium Lumen of trachea Pseudostratified Nucleus of basal cell columnar epithelium Cilia Columnar epithelial cell (ciliated) Lamina propria  Classification Stratified Squamous Epithelium – Protects against abrasion and friction – Has multiple cell layers only deepest in direct contact with basement membrane – Apical cells with squamous shape – Basal layers with cuboidal shape – Stem cells in basal layer that continuously divide replace lost cells – Exists in nonkeratinized and keratinized forms  Classification Stratified Squamous Epithelium Nonkeratinized – Alive all the way to tissue’s apical surface – Have microscopically visible cell nuclei – Kept moist with secretions (e.g., saliva, mucus) – Lack keratin, protective protein – Lining found in: oral cavity, part of pharynx, esophagus vagina, anus  Stratified Squamous Epithelium (Nonkeratinized) Stratified squamous epithelium (nonkeratinized) Lamina propria Squamous cell  Classification Stratified Squamous Epithelium Keratinized – Superficial layers of dead cells – Cells lacking nuclei, filled with keratin – Cells in basal region migrating toward apical surface – Fill with keratin, and die – Found in epidermis  Stratified Squamous Epithelium (Keratinized) Epidermi Dermi s s (Stratified squamous epithelium) Stratum Stratum Stratum Stratum spinosum granulosum corneum basale  Classification Stratified Cuboidal Epithelium – Contains two or more layers of cells – Superficial cells cuboidal in shape – Mainly protective function – Forms walls of ducts of most exocrine glands e.g., ducts of sweat glands strengthens walls of gland ducts strengthens some sections of male urethra  Stratified Cuboidal Epithelium Stratified cuboidal Cuboidal cell Lumen of parotid Venule duct  Classification Stratified Columnar Epithelium – Two or more layers of cells – Cells at apical surface columnar in shape – Protects and secretes – Found in large ducts of salivary glands – Found in membranous segment of male urethra – Relatively rare  Stratified Columnar Epithelium Stratified columnar Lamina epithelium propria Lumen of spongy urethra Columnar cell  Classification Transitional Epithelium – Limited to the urinary tract – In relaxed state: apical cells are large and rounded – In stretched state: apical cells are flattened – Contains binucleated cells (two nuclei) – Allows for stretching as bladder fills Transitional Epithelium Lumen of bladder Transitional epithelium Lamina propria Luminal cells Blood capillary  Classification Simple epithelia – Better designed for diffusion, absorption, and secretion functions thinner than stratified epithelium Stratified epithelia – Better suited for protective functions  Glands Glands – Individual cells or multicellular organs – Composed predominantly of epithelial tissue – Secrete substances for use elsewhere or for elimination – May secrete: mucin electrolytes hormones enzymes urea (nitrogenous waste)  Endocrine and Exocrine Glands Endocrine glands (Endocrine System) – Lack ducts – Secrete hormone products into interstitial fluid and blood act as chemical messengers influence cell activity elsewhere  Endocrine and Exocrine Glands Exocrine glands – Formed from invaginated epithelium in connective tissue – Connected with epithelial surface by duct epithelium-lined tube for gland secretion – Includes sweat glands, mammary glands, salivary glands  Endocrine and Exocrine Glands Unicellular exocrine glands – Typically do not contain a duct – Located close to epithelium surface – Most common type the goblet cell  Endocrine and Exocrine Glands Multicellular exocrine glands – Contain numerous cells – Contain acini, cells clusters producing secretions – Contain ducts transporting secretions to epithelial surface – Surrounded by fibrous capsule – Partitioned into lobes via extensions of the capsule  Exocrine gland Duct Lobe Acinus Duct (secretory portion) (conducting portion)  ALE Think, Pair, Share How does a duct benefit a gland? 51  Simple glands Unbranched duct Secretory portion Simple tubular Simple branched tubular Simple coiled tubular Simple acinar Simple branched acinar (a) Compound glands Branched duct Secretory portion Compound tubular Compound acinar Compound tubuloacinar (b)  Classification of Exocrine Glands Method of secretion – Merocrine glands package secretions into vesicles release secretions by exocytosis include: – lacrimal (tear) glands – salivary glands – some sweat glands – exocrine glands of the pancreas – gastric glands of the stomach  Classification of Exocrine Glands Classification by method of secretion – Apocrine glands pinching off of apical membrane around portion of cytoplasm contains secretory product damage repaired by glandular cells release secretions by exocytosis include: – mammary glands – some sweat glands in axillary and pubic regions  Classification of Exocrine Glands Classification by method of secretion – Holocrine glands accumulation of a product in a cell followed by cell disintegration viscous mixture of cell fragments and cell product ruptured cells replaced include: – oil producing glands in the skin (sebaceous glands)  Disintegrating Secretions cells becoming Secretory contents the secretion Pinching off of apical portion of Secretory secretory cell vesicle Nucleus Cells Nucleus of dividing Secretory vesicles secretory cell releasing their contents via exocytosis (a) Merocrine gland (b) Apocrine gland (c) Holocrine gland Connective Tissue: Cells in a Support Matrix Connective tissue – Most diverse, abundant, widely distributed tissue – Designed to support, protect, and bind organs – All with cells, protein fibers, and ground substance – Examples include: tendons and ligaments body fat cartilage and bone blood  Support Matrix: Characteristics Cells – Each class of connective tissue with specific types e.g., adipose connective tissue with adipocytes e.g., cartilage with chondrocytes – Most cells not in direct contact with each other – Resident cells stationary cells permanently housed within connective tissue  Support Matrix: Characteristics Cells Examples of resident cells – Fibroblasts most abundant resident cells in connective tissue proper produce fibers and ground substance of extracellular matrix flat cells with tapered ends – Adipocytes also called fat cells appear in small clusters with some types of connective tissue proper if dominate an area, tissue termed adipose connective tissue  Support Matrix: Characteristics Cells Examples of resident cells – Mesenchymal cells type of embryonic stem cell divide to replace damaged cells divided cell becomes committed connective tissue cell – Fixed macrophages relatively large, irregular shaped cells derived from monocytes, type of white blood cell dispersed throughout the matrix phagocytize (engulf) damaged cells or pathogens  Support Matrix: Characteristics Cells Wandering cells – Continuously move through connective tissue – Components of immune system – May help repair damaged extracellular matrix – Are primarily types of leukocytes, white blood cells  Support Matrix: Characteristics Cells Types of wandering cells – Mast cells small, mobile cells close to blood vessels secrete heparin to inhibit blood clotting secrete histamine to dilate blood vessels – Plasma cells formed when B-lymphocytes activated by foreign material produce antibodies, proteins that immobilize foreign material  Support Matrix: Characteristics Cells Types of wandering cells – Free macrophages mobile phagocytic cells function like fixed macrophages – Other leukocytes include neutrophils – phagocytize bacteria include lymphocytes – attacks and kills foreign materials  Support Matrix Protein Fibers – Strengthen and support tissue – Collagen fibers strong, flexible, and resistant to stretching numerous in tendons and ligaments – Reticular fibers thinner than collagen fibers, tough but flexible abundant in stroma (connective tissue framework) of: – lymph nodes, spleen and liver – Elastic fibers branching wavy fibers that stretch and recoil easily found in skin, lungs, and arteries  Support Matrix Ground Substance – Nonliving material produced by connective tissue cells – Contains different large molecules and water – May be viscous (e.g., blood) – May be semisolid (e.g., cartilage) – May be solid (e.g., bone) – Ground substance + protein fibers = extracellular matrix  Blood vessel Ground substance Extracellular matrix Protein fibers Elastic fiber Collagen fiber Reticular fiber Resident cells Mesenchymal cell Macrophage Adipocyte Fibroblast  ALE Think, Pair, Share What are the three basic components of connective tissue? 67  Connective Tissue—Cells in a Supportive Matrix: Characteristics Clinical View: Scurvy – Collagen is an important protein – Strengthens and supports almost all body tissues – Vitamin C needed for healthy collagen fibers – Scurvy caused by vitamin C deficiency – Symptoms of weakness, gum ulceration, hemorrhages, abnormal bone growth – Treated by consuming foods high in vitamin C or supplements  Functions Functions of connective tissue – Physical protection bones of skull and thoracic cage protecting delicate organs adipose tissue protecting kidneys and posterior eyes – Support and structural framework bones as framework for the body cartilage keeping trachea and bronchi open supportive tissues around kidney and spleen – Binding of structures ligands binding bone to bone tendons binding muscle to bone dense irregular tissue anchoring skin to muscle and bone  Functions Functions of connective tissue – Storage adipose tissue the major energy reserve bone primary reserve for calcium and phosphorus – Transport blood carrying nutrients, gases, wastes – Immune protection leukocytes protecting body against disease extracellular matrix restricting movement of infectious organisms Clinical View: Marfan Syndrome – Genetic disease of connective tissue – Causes skeletal, cardiovascular, and visual abnormalities – Patients may have: abnormally long limbs, fingers, toes malformation of the thoracic cage, vertebral column easily dislocated joints, resulting from weak ligaments, tendons, and joint capsules weakness in the aorta and abnormal heart valves slipped lens of the eye – Often death before age 50 due to cardiovascular problems Chapter 5 Histology continues!  Connective Tissue Summary: Loose, Dense, & Supporting Connective Tissue Proper: Loose Connective Tissue (Table 5.6) Connective Tissue Proper: Dense Connective Tissue (Table 5.7) Supporting Connective Tissue: Cartilage (Table 5.8)  Classification of Connective Tissue Connective Tissue Proper Areolar connective tissue – Loose organization of collagen and elastic fibers – Abundant distribution of blood vessels – Contains all fixed and wandering cells of connective tissue proper – Found in the papillary layer of the dermis – Major component of subcutaneous layer – Surrounds organs, nerve and muscle cells, and blood vessels  Areolar Connective Collagen fibers Tissue Ground substance Elastic fibers Capillary Endothelial cell of capillary Mast cell with Nucleus of granules fibroblasts  Classification of Connective Tissue Connective Tissue Proper Adipose connective tissue – Commonly known as fat – Composed primarily of adipocytes filled with lipid droplets weight gain or loss due to enlarging or shrinking adipocytes – Stores energy – Acts as an insulator – Serves as packing and cushion around structures – Located in subcutaneous layer – Surrounds various organs  Adipose Connective Tissue Adipocytes Lipid inclusions of adipocytes Nuclei of adipocytes Capillaries  Classification of Connective Tissue Connective Tissue Proper Reticular connective tissue – Contains meshwork of reticular fibers, fibroblasts, leukocytes – Forms the structural framework of many lymphatic organs e.g., spleen, thymus, lymph nodes, bone marrow Reticular Connective Tissue Reticular Ground fibers substance Leukocytes Macrophages  Classification of Connective Tissue Connective Tissue Proper Dense connective tissue – Composed primarily of protein fibers – Has proportionately less ground substance than loose connective tissue – Collagen fibers usually the dominant fiber type – Three categories: dense regular connective tissue dense irregular connective tissue elastic connective tissue  Classification of Connective Tissue Connective Tissue Proper Dense regular connective tissue – Contains tightly packed parallel collagen fibers – Resemble stacked lasagna noodles – Found in tendons and ligaments stress typically applied in a single direction – Has few blood vessels – Takes a long time to heal Dense Regular Connective Tissue Collagen fibers Ground substance Nuclei of fibroblasts  Classification of Connective Tissue Connective Tissue Proper Dense irregular connective tissue – Contains clumps of collagen fibers in all directions – Provides support and resistance to stress in multiple directions – Has extensive blood supply – Found in: most of the skin dermis periosteum of bone perichondrium of cartilage capsules around some internal organs (e.g., liver) Dense Irregular Connective Tissue Collagen fibers Ground substance Nuclei of fibroblasts  Classification of Connective Tissue Connective Tissue Proper Elastic connective tissue – Branching, densely packed elastic fibers – Has more fibroblasts than loose connective tissue – Able to stretch and recoil – Found in: walls of large arteries trachea vocal cords suspensory ligament of the penis  Elastic Connective Tissue Lumen of Elastic elastic artery lamellae Nuclei of Endothelium fibroblasts of elastic artery Nuclei of Tunica intima Tunica media Internal elastic smooth of elastic of elastic lamella muscle cells artery artery Connective Tissue Classification  Figure 4.16 Types of Cartilage Cartilage is a connective tissue consisting of collagenous fibers embedded in a firm matrix of chondroitin sulfates. (a)Hyaline cartilage provides support with some flexibility. The example is from dog tissue. (b)Fibrocartilage provides some compressibility and can absorb pressure. (c)Elastic cartilage provides firm but elastic support. From top, LM × 300, LM × 1200, LM × 1016. (Micrographs provided by the Regents of University of Michigan Medical School © 2012) Chondrocytes Lacuna perichondrium  Connective Tissue: Supporting Connective Tissue Bone and Cartilage Bone – More solid than cartilage Contains organic components (collagen and glycoproteins) Contains inorganic components (calcium salts) – Bone cells called osteocytes – Covered by a dense irregular connective tissue, periosteum Bone functions – Provides levers for movements – Supports tissues and protect vital organs – Stores minerals, e.g., calcium and phosphorus – Houses hemopoietic cells  Fluid Connective Tissue Blood – Delivers nutrients and oxygen, hormones and removes waste – Temperature and pH regulation – Plasma and Formed Elements Lymph – Derived from blood plasma – Function in immunity – Ultimately returned to bloodstream Figure 4.18 Muscle Tissue (a)Skeletal muscle cells have prominent striation and nuclei on their periphery. (b)Smooth muscle cells have a single nucleus and no visible striations. (c)Cardiac muscle cells appear striated and have a single nucleus. From top, LM × 1600, LM × 1600, LM × 1600. (Micrographs provided by the Regents of University of Michigan Medical School © 2012)  Figure 4.19 The Neuron The cell body of a neuron, also called the soma, contains the nucleus and mitochondria. The dendrites transfer the nerve impulse to the soma. The axon carries the action potential away to another excitable cell. LM × 1600. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)  Figure 4.20 Nervous Tissue Nervous tissue is made up of neurons and neuroglia. The cells of nervous tissue are specialized to transmit and receive impulses. LM × 872. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)  ALE Think, Pair, Share Contrast loose connective tissue & dense connective tissue. 97  Integration of Tissues in Organs and Body Membranes Organs – Structures composed of two or more tissue types – Work together to perform specific complex functions – E.g., the stomach, contains all four tissue types  Organs The stomach – Lined by epithelium secretes substances for chemical digestion of nutrients – Areolar and dense connective tissue in walls houses blood vessels and nerves and provides shape and support – Three layers of smooth muscle in walls contract and relax to mix materials – Abundant nervous tissue responsible for regulating muscle contraction and gland secretion  Tissue types Epithelial tissue Connective tissue Muscular tissue Nervous tissue Stomach (organ) Mucosa Simple columnar epithelium Areolar connective tissue Dense irregular connective tissue Nerve plexus Gastric glands Oblique layer (formed from epithelium) Smooth muscle (3 layers) Nerve plexus between muscle layers Circular layer Areolar Serous connective tissue Longitudinal layer membrane Mesothelium, (simple squamous Nerve ending epithelium)  Integration of Tissues in Organs and Body Membranes Body membranes – Formed from epithelial tissue bound to underlying connective tissue – Line body cavities – Cover viscera – Cover body’s external surface – Four types: mucous, serous, cutaneous, synovial  Body Membranes Mucous membrane – Also called a mucosa – Lines compartments that open to the external environment – Include digestive, respiratory, urinary, and reproductive tracts – Perform absorptive, protective, and secretory functions – Formed from epithelium and underlying connective tissue connective tissue component termed lamina propria often covered with a layer of mucus  Body Membranes Serous membrane – Lines body cavities that do not open to external environment – Membrane composed of a simple squamous epithelium termed mesothelium – Produce thin, watery serous fluid derived from blood plasma reduces friction between opposing surfaces  Body Membranes Cutaneous membrane – Also known as skin – Covers the external surface of the body – Composed of: keratinized stratified squamous epithelium underlying connective tissue – Protects internal organs and prevents water loss  Body Membranes Synovial membrane – Lines some joints in the body – Composed of: areolar connective tissue covered by squamous epithelial cells lacking basement membrane – Synovial fluid secreted by epithelial cells reduces friction among moving bone parts distributes nutrients to cartilage  Tissue Development and Aging: Tissue Modification Metaplasia – Change of mature epithelium to a different form – May occur as epithelium adapts to environment – E.g., smokers experience metaplastic changes in trachea epithelium normal pseudostratified ciliated columnar epithelium changed becomes nonkeratinized stratified squamous epithelium – E.g., chronic acid reflux nonkeratinized stratified squamous epithelium in esophagus changed becomes simple columnar epithelium now similar to cells seen in stomach  Tissue Development and Aging: Tissue Modification Hypertrophy – Increase in size of existing cells of a tissue Hyperplasia – Increase in number of cells of a tissue Neoplasia – Tissue growth proceeding out of control – Development of tumor of abnormal tissue  Tissue Development and Aging: Tissue Modification Atrophy – Shrinkage of tissue by decrease in cell number or size – May result from normal aging – May result from failure to use organ or tissue – Bedridden individual affected muscles with disuse atrophy skeletal muscle fibers becoming smaller can usually be reversed by physical therapy  Tissue Development and Aging: Tissue Modification Necrosis – Term for tissue death – Due to irreversible tissue damage – Inflammatory response in tissue in response to the damage – E.g., gangrene  Tissue Development and Aging: Aging of Tissues Changes to aging tissue – Support, maintenance, replacement of cells and extracellular matrix less efficient after middle age – Structure and chemical composition of many tissues altered e.g., epithelial becoming thinner e.g., connective tissues losing pliability and resiliency – Declining amount of collagen – Delayed tissue repair – Bones increasingly brittle – Muscle and nervous tissues beginning to atrophy – Accelerated declines with poor diet and circulation problems