Histology Notes PDF

SEM of adipocytes & protein fibers Histology – study of normal structures of tissues Tissue: a. Discrete population of cells related in structure & function b. Have surrounding material: extracellular matrix (ECM) © 2016 Pearson Educati...

SEM of adipocytes & protein fibers Histology – study of normal structures of tissues Tissue: a. Discrete population of cells related in structure & function b. Have surrounding material: extracellular matrix (ECM) © 2016 Pearson Education, Inc.  Types of Tissues Four primary tissue types a. Epithelial tissues (epithelia) – tightly packed sheets of cells with no visible ECM - cover and line all body surfaces and cavities - glands that manufacture secretions (sweat, saliva) or chemical messengers (hormones) b. Connective tissues (CT) - connect tissues to one another; - ECM is a prominent feature for most CT with cells scattered throughout - bind, support, protect, and transportation of substances © 2016 Pearson Education, Inc.  Types of Tissues c. Muscle tissues - contraction d. Nervous tissues consist of cells: - neurons capable of generating, sending, receiving messages - neuroglia that support this © 2016 Pearson activity Education, Inc.  The Extracellular Matrix Extracellular matrix a. Composed of substances in a liquid, gel, or solid that surround cells b. Functions: – Provides tissue with strength to resist tensile (stretching) and compressive forces – Directs cells to proper positions within tissue and holds those cells in place – Regulates development, mitotic activity, and survival of cells© 2016 Pearson Education, Inc.  The Extracellular Matrix c. 2 main components [ground substance & protein fibers] 1) Ground substance - makes up most of ECM extracellular fluid (ECF or interstitial fluid) - components: water, nutrients, ions, and macromolecules © 2016 Pearson Education, Inc.  The Extracellular Matrix Macromolecules: a. Glycosaminoglycans (GAGs) – ex. chondroitin sulfate (cartilage) and hyaluronic acid b. Proteoglycans - GAGs bound to a protein core (bottle brush) c. Cell-adhesion molecules (CAMs) – made up of different types of glycoproteins - bind surface proteins © 2016 Pearson Education, Inc.  The Extracellular Matrix Figure 4.1 Extracellular matrix. © 2016 Pearson Education, Inc.  The Extracellular Matrix 2. Protein fibers a. Collagen fibers (white, fibrous) - 20–25% of all proteins in body - resistant to tension b. Elastic fibers (yellow) – protein elastin surrounded by glycoproteins - exhibit elasticity c. Reticular fibers (weblike) – meshwork or scaffold that supports cells and ground substance of many tissues © 2016 Pearson Education, Inc.  The Extracellular Matrix Figure 4.1 Extracellular matrix. © 2016 Pearson Education, Inc.  Diseases of Collagen and Elastic Fibers (p.126) Protein fibers vital to structural integrity of many tissues and organs Ehlers-Danlos syndrome – abnormal collagen fibers; - recurrent joint dislocations, hyperextensibility of skin, fragility of blood vessels, bruising, plus various effects in intestines, heart, and lungs Marfan syndrome – abnormal elastic fibers; - tall stature with long limbs and fingers; skeletal abnormalities, joint dislocations, heart valve and lens (eye) problems; aortic anuerysm (rupture)  Epithelial Tissues Epithelial tissues – found on every internal and external body surface Functions: 1. Protection – shield underlying tissues from mechanical and thermal injury 2. Immune defenses – form physical barriers; contain cells of immune system © 2016 Pearson Education, Inc.  Epithelial Tissues 3. Secretion – hormones and oils 4. Transport into other tissues – form selectively permeable membranes 5. Sensation – detects changes in internal and external environments (ex. taste buds = specialized sensory epithelial cells) © 2016 Pearson Education, Inc.  Concept Boost: But It All Looks Pink! Key to identifying tissues is look at simplest components: cells and extracellular regions Shown here is a section of esophagus Each structure that contains a dark purple nucleus is a cell © 2016 Pearson Education, Inc.  Concept Boost: But It All Looks Pink! Shown here is a section of esophagus : Ground substance generally looks clear or has just a slight tinge of color Protein fibers generally look like wavy or straight lines Collagen fibers form bundles that might resemble certain cell types; if bundles lack nuclei, then they are likely to be collagen fibers © 2016 Pearson Education, Inc.  Concept Boost: But It All Looks Pink! Next section is sublingual gland (salivary gland that produces saliva) Contains clusters of small, light red, round discs that lack nuclei These are red blood cells (RBCs) or erythrocytes © 2016 Pearson Education, Inc.  Components and Classification of Epithelia Consist of tightly packed cells that form continuous sheets Fairly impermeable and resistant to physical stresses and mechanical injury Avascular BM (basement membrane) Figure 4.3 Structure of epithelial ©tissue. 2016 Pearson Education, Inc.  Components and Classification of Epithelia Classified based on: Number of cell layers - Simple epithelia consist of a single cell layer - Stratified epithelia consist of 2 or more layers - Pseudostratified looks layered but is not Pseudostratified Figure 4.4a Classification of epithelial cells.  Components and Classification of Epithelia Shape of cell – Squamous cells are flattened – Cuboidal cells are short – Columnar cells are tall and elongated Figure 4.4b Classification of epithelial cells. © 2016 Pearson Education, Inc.  Covering and Lining Epithelia Four types of simple epithelia: 1. Simple squamous epithelium – very thin single layer of cells with a “fried egg” appearance; - adapted for rapid diffusion of substances - found in air sacs of lung, parts of kidney, and lining blood vessel walls (endothelium) Figure 4.5a Structure of simple epithelia.  Covering and Lining Epithelia 2. Simple cuboidal epithelium – single layer of cube-shaped cells - found in renal tubules, respiratory passages, ducts of glands, and thyroid gland Figure 4.5b Structure of simple epithelia. © 2016 Pearson Education, Inc.  Covering and Lining Epithelia 3. Simple columnar epithelium – single layer of rectangular-shaped cells - often has microvilli (increases surface area for absorption of substances) or cilia (propel substances through hollow organs) Figure 4.5c Structure of simple epithelia. © 2016 Pearson Education, Inc.  Covering and Lining Epithelia 4. Pseudostratified ciliated columnar epithelium (PSCCE) - appears to be layered because nuclei are found at various heights, but only one cell-layer thick - found in segments of respiratory tract and nasal cavity; ciliated Figure 4.5d Structure of simple epithelia.  Covering and Lining Epithelia Stratified epithelium – more than one layer of cells; - protective barriers due to wear and tear 1. Stratified squamous epithelium a. Keratinized stratified squamous epithelium outercellular layers are dead lack nuclei filled with protein keratin outer layers of skin (epidermis) Figure 5.3 Structure of the epidermis.  Covering and Lining Epithelia b. Nonkeratinized stratified squamous epithelium  apical cellular layers retain nuclei; still alive  wet mucous membranes (ex. mouth, throat, esophagus, anus, and vagina) Figure 4.7a Structure of stratified epithelia.  Covering and Lining Epithelia 2. Stratified cuboidal epithelium  rare in humans  lines ducts of sweat glands Figure 4.7b Structure of stratified epithelia.  Covering and Lining Epithelia 3. Stratified columnar epithelium  relatively rare in humans  found in male urethra, cornea of eye, ducts of salivary glands Figure 4.7c Structure of stratified epithelia.  Covering and Lining Epithelia 4. Transitional epithelium  only found in urinary system (ureters, urinary bladder, urethra)  basal cell layers are cuboidal while apical cell layers are dome- shaped when tissue is relaxed  ability of apical cells to flatten contributes to ability of urinary tissues to stretch Figure 4.7d Structure of stratified©epithelia. 2016 Pearson Education, Inc.  Covering and Lining Epithelia Name that Epithelial tissue: Figure 4.8 Summary of epithelial tissues.  Glandular Epithelia Gland – specialized cells that produce secretions Products are released by two mechanisms: Endocrine Exocrine © 2016 Pearson Education, Inc.  Glandular Epithelia Endocrine glands secrete hormones, directly into bloodstream (no ducts) ductless Allows products to have widespread systemic effects on distant cells in different areas of body Glands vary in complexity from single cells to large multicellular glands with branching Ex. thyroid, pituitary, ovary © 2016 Pearson Education, Inc.  Glandular Epithelia Exocrine glands Have ducts Secretions have only local effects on cells in general vicinity Unicellular (goblet cells  mucus) - digestive & respiratory tracts - protects underlying epithelia Multicellular (sweat glands, salivary glands) © 2016 Pearson Education, Inc.  Glandular Epithelia Figure 4.10 Multicellular exocrine glands.  Glandular Epithelia Types of Exocrine glands secretions: Merocrine secretion - fluid product in vesicles - salivary and sweat glands Holocrine secretion – entire cells released - sebaceous gland Figure 4.11a,b Modes of secretion in exocrine glands.  Carcinogens and Epithelial Tissues (p. 130) Epithelia cover all body surfaces; therefore more subject to injury than most other tissues Carcinogens – agents that induce DNA changes (injury); can lead to cancer Carcinoma – term for epithelial cancer – Lung Adenocarcinoma – Ductal and Papillary Carcinoma – cancer of breast Basal Cell Carcinoma – - Cancer of skin  B.M. provides barrier to prevent/slow spread of carcinomas  Connective Tissue Connective tissues Connective tissue proper – Loose Widely distributed – Dense (regular & irregular) Connects tissues & organs Internal structure of some organs – Reticular – Adipose Specialized connective tissue – Cartilage – Bone – Blood © 2016 Pearson Education, Inc.  Connective Tissue Connective tissue functions: Connect and bind – anchor tissue layers in organs and link organs together Support – bone and cartilage support weight of the body Protection – bone tissue protects certain internal organs - cartilage and fat provide shock absorption - components of immune system found throughout CT Transport – blood main transport medium in body © 2016 Pearson Education, Inc.  Connective Tissue Characteristics of CT: – Cells are surrounded by protein fibers and embedded in ground substance – ECM plays an extensive role in the function of CT – Usually vascular © 2016 Pearson Education, Inc.  Connective Tissue Cells Fibroblasts – produce fibers Mast cells – produce histamine that causes inflammation Phagocytes -includes macrophages Adipocytes – fat cells that ingest foreign invaders Figure 4.12a Cells of connective tissue proper.  Connective Tissue Proper Four basic types of connective tissue proper: – Loose connective tissue – Dense connective tissue – Reticular tissue – Adipose tissue © 2016 Pearson Education, Inc.  Connective Tissue Proper 1. Loose connective tissue (areolar tissue) – mostly ground substance, also fibers, fibroblasts, and occasionally adipocytes - located beneath epithelium of skin, in membranes lining body cavities, and within walls of hollow organs © 2016 Pearson Education, Inc.  Connective Tissue Proper 2. Dense connective tissue (fibrous connective tissue) a. Dense irregular connective tissue – mostly disorganized collagen bundles - located in dermis, surround organs and joints © 2016 Pearson Education, Inc.  Connective Tissue Proper b. Dense regular connective tissue (Figure 4.14b) – Organized into parallel collagen bundles – Located in tendons and ligaments © 2016 Pearson Education, Inc.  Connective Tissue Proper c. Dense regular elastic CT(elastic tissue) (Figure 4.14c) – Mostly parallel-oriented elastic fibers with some collagen fibers – Found in walls of organs that need to stretch (large blood vessels and some ligaments) © 2016 Pearson Education, Inc.  Connective Tissue Proper Note: arrangement of fibers in dense regular and irregular connective tissues is another example of the Structure-Function Core Principle Figure 4.14 Structure of dense connective tissue. © 2016 Pearson Education, Inc.  Connective Tissue Proper 3. Reticular tissue – composed mostly of reticular fibers produced by fibroblasts (reticular cells); - form fine networks that support vessels (Figure 4.15) Also found in lymph nodes and spleen Forms part of B.M. that supports epithelia, internal structure of liver and bone marrow Figure 4.15 Structure of reticular tissue.  Connective Tissue Proper 4. Adipose tissue (fat tissue) – consists of fat-storing adipocytes (& surrounding fibroblasts and ECM) Fat storage (major energy reserve) Insulation (warmth) Shock absorption and protection © 2016 Pearson Education, Inc.  Adipose Tissue and Obesity (p. 142) Obesity – condition of having excess adipose tissue in proportion to lean body mass: – Hypertrophic – lipid inclusions accumulate excess fatty acids and increase in size; number of adipocytes remains unchanged – Hypercellular – number of adipocytes increases; correlates with development of obesity in infancy or early childhood and not adulthood; adult adipocytes lack ability to divide to form new cells Both types increase risk for certain health problems; depends on distribution of adipose tissue and genetic factors  Specialized Connective Tissues Specialized connective tissues Cartilage – found in joints, in ear, nose, and parts of respiratory tract Bone tissue (osseous tissue) – supports & protects; muscle attachments; stores calcium, and bone marrow (produces blood cells and stores fat) Blood –liquid ECM called plasma; consists of mostly water, dissolved solutes, and proteins © 2016 Pearson Education, Inc.  Specialized Connective Tissues Cartilage – Rigid matrix – Chondroblasts – immature cells that divide by mitosis ECM – Chondrocytes in lacunae – Mostly avascular (blood supply limited to outer sheath - perichondrium) © 2016 Pearson Education, Inc.  Specialized Connective Tissues 3 types of cartilage: Hyaline cartilage – most abundant - ends of long bone, trachea, nose, most of fetal skeleton Fibrocartilage - great tensile strength - intervertebral discs, menisci of knee, symphysis pubis Elastic - flexible - external ear, auditory tube, epiglottis  Specialized Connective Tissues Bone – Hard matrix – Supports and protects – Hemopoiesis (blood cell formation) – Skeleton – Osteoblasts, osteocytes in lacunae, osteoclasts © 2016 Pearson Education, Inc.  Specialized Connective Tissues Blood – ECM is fluid = plasma – Plasma proteins – not like fibers in other CT; smaller and involved in transport & blood clotting – Erythrocytes (red blood cells) transport oxygen – Leukocytes (white blood cells) function in immunity – Thrombocytes (platelets) – cell fragments; major role I in blood clotting © 2016 Pearson Education, Inc.  Osteoarthritis and Glucosamine Supplements (p. 144) Osteoarthritis – caused by age, joint trauma, genetic disorders, and infection – Degeneration of hyaline cartilage lining joints – Leads to destruction of proteoglycan and collagen fibers;  bone on bone Chondroblasts use glucosamine in synthesis of proteoglycans; further studies needed to determine if glucosamine supplementation will slow osteoarthritic degeneration of joints © 2016 Pearson Education, Inc.  Connective Tissues © 2016 Pearson Education, Inc. Figure 4.20 Summary of connective tissues.  Connective Tissues © 2016 Figure 4.20 Summary of connective Pearson Education, Inc. tissues.  Muscle Tissues Muscle tissues are specialized for contraction (use ATP as energy source) Movement of skeleton, heart beating, and propulsion of substances through hollow Muscle cell or myocyte; excitable (ability to respond to electrical or chemical stimulation) 3 types of muscle tissue: - Skeletal muscle - Cardiac muscle - Smooth muscle © 2016 Pearson Education, Inc.  Types of Muscle Tissue Skeletal muscle – Attached to bone – Striated – Voluntary Cardiac - Heart - Striated - Involuntary - Intercalated discs Smooth - Walls of hollow organs, blood vessels - Non-striated - Involuntary  Nervous Tissues Nervous tissue - brain, spinal cord, nerves - two main cell types: Neurons – capable of sending and receiving messages Neuroglial cells – provide support; do not conduct nerve impulses © 2016 Pearson Education, Inc. Concept Boost: But It All Looks Pink! Part 2 In Examples A, B, and C: 1. Identify the cells, protein fibers, and ground substance (review basics from Concept Boost Part 1 as needed) 2. Notice how the cells are shaped and arranged: – Are the cells packed tightly together, or are they widely spaced? – Do they form a continuous sheet, as in epithelial tissue—or do they seem to be surrounded by ECM, as in connective tissue? – Are the cells all identical, or are there clearly different types? – Do the cells have “arms” extending from a central body? © 2016 Pearson Education, Inc. Concept Boost: But It All Looks Pink! Part 2 3. Notice how the ECM is arranged: – Is the ECM confined to one specific part of the tissue, or is it spaced evenly between the cells? – Does ground substance predominate, or are protein fibers the main elements? – What types of protein fibers can you see? 4. Determine the class of tissue. Using your analysis in the preceding steps, now you are ready to identify the class of tissue (answers are in text) © 2016 Pearson Education, Inc. Concept Boost: But It All Looks Pink! Part 2 © 2016 Pearson Education, Inc.  Module 4.6 Putting It All Together: The Big Picture of Tissues in Organs © 2016 Pearson Education, Inc.  The Big Picture of Tissues in Organs Two or more tissues that combine structurally and functionally form an organ: Simple organ example – skeletal muscle: – Composed of two main tissues—skeletal muscle and dense irregular collagenous connective – Each has distinct functional role; skeletal muscle tissue allows it to contract; surrounding connective tissue binds muscle cells together and supports them so that their activity produces a contraction of whole organ © 2016 Pearson Education, Inc.  The Big Picture of Tissues in Organs More complex organ; consists of many different tissue types – trachea – Hollow organ; provides passageway through which air passes on its way into/out of lungs – Figure 4.23 (next slide) – illustration of tissues of trachea from superficial to deep with list of their main functions – Each tissue layer serves an important role in overall function of trachea: conducting air © 2016 Pearson Education, Inc.  The Big Picture of Tissues in Organs Figure 4.23 The Big Picture of Tissues in Organs. © 2016 Pearson Education, Inc.  Membranes Membranes – thin sheets of tissues that line a body surface or cavity: Serous membranes – line pericardial, peritoneal, and pleural cavities (mesothelium) Synovial membranes - composed of CT - line joints © 2016 Pearson Education, Inc.  Membranes Mucous – line tubes/organs that connect to outside of body – nasal and oral cavities – secrete mucus Cutaneous - skin  Concept Check 1. Why do the pharynx, esophagus, anus, and vagina have the same organization of epithelium? These areas are subject to wear & tear. 2. The secretory cells of sebaceous glands fill with secretions and then rupture to release their contents. What is this type Holocrine of secretion? 3. A gland has no ducts to carry its secretion so it is released directly into the ECF. What type of gland is this? Endocrine 68 4. An epithelial surface has many microvilli. What is the function of this epithelium? Increase surface area for absorption.  Skin- review questions 9. The elderly cannot tolerate heat as well as they did when they were younger and they are prone to heat-related illnesses. What changes took place to explain this? 71  10. Dandruff is excessive shedding of keratinized cells from the outer layer of the skin? Name that specific layer! 11. Which body cavities are lined with serous membranes? 12. Which type of membrane lines the nasal cavity? 72