Histology (Tissues) PDF

Chapter 4. Histology (tissues) Nervous tissue Two types of cells: a. Neurons b. Neuroglial cells Skeletal Muscle Muscle tissue Cardiac Muscle Smooth Muscle...

Chapter 4. Histology (tissues) Nervous tissue Two types of cells: a. Neurons b. Neuroglial cells Skeletal Muscle Muscle tissue Cardiac Muscle Smooth Muscle Squamous Cuboidal Columnar 1 layer Simple squamous E. Simple cuboidal E. Simple columnar E. = simple Epithelial tissue Multilayers Stratified squamous Stratified cuboidal Stratified columnar E. = stratified E. E. Keratinized Str. Transitional E. Pseudo-Stratified Squamous E. columnar E. Non-keratinized-Str. Squamous E. Connective tissue Fluid Connective Tissue Supporting Connective Tissue Connective Tissue Proper Blood Cartilage Bone Loose CT Dense CT - Red blood cell 1. Hyaline cartilage 1. Areolar CT 1. Dense Regular CT - White blood cell 2. Fibro-cartilage 2. Adipose CT? 2. Dense Irregular CT - Platelet 3. Elastic cartilage 3. Reticular CT? 3. Elastic CT 1. Nervous Tissue Nervous Tissue Structure Neuroglial cells Contains neurons, which have a cell body, dendrites, and an axon that extend from the cell body; also contains glial cells, which lack the Axon processes seen in neurons Function Cell body Neurons receive, process, and transmit nerve of neuron (soma) impulses, whereas glial cells help protect, nourish, and support neurons Location Brain, spinal cord, and nerves Nucleus Dendrites Contains two types of cells: Neurons: Nerve cells that are capable of initiating and conducting electrical activity throughout the body Neuroglial cells (glial cells): Cells that support and protect neurons 2. Muscle Tissue SKELETAL MUSCLE TISSUE Structure Long, cylindrical fibers (cells) arranged parallel and Skeletal unbranched; fibers are multinucleated with visible muscle fibers striations; fiber is under voluntary control Function Endomysium Primarily responsible for moving skeleton and for thermoregulation (increases body temperature when Multiple muscles contract) nuclei Location Attaches to bones or sometimes to skin; forms external Striations urethral and anal sphincters CARDIAC MUSCLE TISSUE Striations Structure Medium-sized, typically branching cells; contain Heart one or two centrally located nuclei with visible striations; Cardiac intercalated discs between cells; under involuntary control muscle cells Intercalated Function discs Pumps blood through heart and blood vessels Endomysium Location Heart wall (myocardium) Nuclei SMOOTH MUSCLE TISSUE Structure Cells are short and fusiform in shape; contain one centrally located nucleus; cells do not have visible striations; under involuntary control Function Moves and propels materials through internal organs; Smooth controls the size of the lumen Stomach muscle cells Location Walls of hollow internal organs, such as intestines, Nuclei stomach, airways, urinary bladder, uterus, and blood vessels; iris of the eye 3. Epithelial Tissue 4. Connective Tissue (CT) Lines and covers body surfaces, Fills & connects among body tissues cavities and organs. Most glands Among the cells, the space is filled are derived from epithelial tissue. with extracellular matrix. Only cells, no extracellular matrix  3. Epithelial tissue Epithelium Lining or covering surfaces, cavities, organs Functions: Basement membrane Physical protection, Selective permeability, Secretion Connective tissue Characteristics cellularity polarity (apical surface = open space) avascularity innervation high regeneration capacity attachment: basement membrane Cell Connections (a) Tight junctions help to make the spaces between cells Junctional “locking” impermeable. proteins Tight junction (b) Desmosomes Integral increase the resistance “linker” Desmosome proteins of the tissue to mechanical stress. Intermediate Gap junction filaments (c) Protein channels Gap junctions allow small substances to move from one cell to another.  How to name the epithelial tissues 1. Number of the cell layers - one layer (simple) - multi-layers (stratified) 2. Shape of the cells - Flat (squamous) - Cubic or round (cuboidal) - Long (columnar) squamous cuboidal columnar Simple squamous E. Simple cuboidal E. Simple columnar E. 1 layer air sac in lung, kidney tubule (may contain goblet cell, = Simple lining of heart, gland duct cilia, microvilli etc.) blood vessels Intestines, ureter, urethra Stratified squamous E. Stratified cuboidal E. Stratified columnar E. Multilayers Mouth cavity, Secretory portion of ducts Urethra = Stratified inner surface of lip, vagina etc. Keratinized stratified *Transitional E. Pseudo-stratified Modified squamous E. Inner surface of the columnar E. epithelial Skin, outer surface of lip bladder (distinguished by Lining of the respiratory tissues cells with 2 nuclei) track: nostrils to the lungs Simple Epithelial tissues SIMPLE SQUAMOUS EPITHELIAL TISSUE Structure Single layer of thin, flat cells resembling irregular floor tiles; the single nucleus of each cell bulges at its center. Simple Function squamous Thinnest possible barrier to allow for rapid diffusion and epithelium filtration; secretion in serous membranes. Single layer of flat cells Basement Location membrane Air sacs in lungs (alveoli); lining of lumen of blood vessels Underlying and lymph vessels (endothelium); serous membranes of body connective cavities (mesothelium). tissue SIMPLE CUBOIDAL EPITHELIAL TISSUE Structure Single layer of cells about as tall as they are wide; spherical and centrally located nucleus. Simple cuboidal Function epithelium Absorption and secretion; forms secretory tissue of most glands and small ducts. Basement membrane Single layer of Surrounding Location cube-shaped cells connective Kidney tubules, thyroid gland follicles; surface of ovary; tissue secretory regions and ducts of most glands. SIMPLE COLUMNAR EPITHELIAL TISSUE Structure Single layer of cells taller than they are wide; oval-shaped nucleus oriented lengthwise in basal region of cell; apical regions of cell may have microvilli; may contain goblet cells Simple that secrete mucin. columnar epithelium Function Absorption and secretion; secretion of mucin. Basement membrane Location Single layer of tall rectangular Inner lining of most of digestive tract (stomach, small intestine, Underlying cells connective and large intestine). Stratified Epithelial tissues (NON-KERATINIZED) STRATIFIED SQUAMOUS EPITHELIUM KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM Structure Structure Multiple cell layers; basal cells are cuboidal or polyhedral, Multiple cell layers; basal cells are cuboidal or whereas apical cells are squamous; cells lack keratin; polyhedral, whereas apical cells are squamous; apical superficial cells are alive and kept moist cells are dead and filled with the protein keratin Function Function Protection of underlying tissue from abrasion Protection of underlying tissue from abrasion Location Location Lining of oral cavity, part of pharynx, part of larynx, Epidermis of skin esophagus, lining of vagina, and anus STRATIFIED CUBOIDAL EPITHELIUM Stratified Structure cuboidal Two or more layers of cells; cells at the apical surface are about as tall epithelium as they are wide Basement membrane Function Protection and secretion Sweat gland Location Ducts of most exocrine glands and ovarian follicles (CILIATED) PSEUDOSTRATIFIED COLUMNAR EPITHELIUM Structure Cilia Mucus of Looks like multiple layers of cells with varying heights; all cells connect to goblet cell the basement membrane, but not all cells reach the apical surface; has goblet cells and cilia Pseudo- stratified Function epithelium Protection; secretion of mucin and movement of mucus along apical surface of epithelium by cilia Single layer of Location cells that appears to Basement be stratified Lining of the larger airways of respiratory tract, including nasal cavity, membrane pharynx, parts of larynx, trachea, and bronchi STRATIFIED COLUMNAR EPITHELIUM Stratified Structure columnar Rare in the human body; Few layers of cells that are columnar in apical layers epithelium and cuboidal in basal layers, lacks goblet cells and cilia Function Protection Basement membrane Location Salivary gland ducts Rare—lining of part of the male urethra and epididymis TRANSITIONAL EPITHELIUM Structure Epithelial appearance varies, depending upon whether tissue is relaxed or distended; cells at the apical surface; some cells are binucleated Transitional epithelium Function Accommodates urine volume changes in the urinary bladder & ureters Location Urinary Basement Lining of urinary bladder, ureters, and part of urethra bladder membrane Glands Individual cells (goblet cells) or multicellular organs Perform a secretory function: mucin, hormones, enzymes & waste products Glands fall into two categories: Exocrine glands possess ducts and secretory portion (acini) Endocrine glands do not possess ducts and secrete directly into the interstitial fluid or the bloodstream (the Endocrine System in A&P II) (a) Components used to classify multicellular exocrine glands Ductal epithelial cells Simple (not branched) Compound (branched) Secretory cell cluster shapes: Secretory epithelial cells Tubular Acinar Tubuloacinar (b) Examples of multicellular exocrine glands Simple tubular Simple acinar Compound acinar Compound tubuloacinar 4. Connective tissue (CT) Most diverse, abundant, widely distributed, and structurally varied. Arises from mesoderm in embryo. Stem cell (mesenchyme: mesenchymal cell), also found in the mucus of the umbilical cord. Among the cells, the space is filled with extracellular matrix (vs. Epithelial tissues with no extracellular matrix ). Extracellular matrix = protein fibers + ground substance etc. - Protein fibers: Elastic fibers, collagen, reticular fibers. - Ground substance: A mixture of proteins and carbohydrates with variable amounts of salts and water. Functions of Connective Tissue - Physical protection - Support and structural framework - Binding of structures - Storage - Transport - Immune protection  Classification of the Connective Tissues Mesenchymal cells (mother of connective tissue) Fluid Connective Tissue Supporting Connective Tissue Connective Tissue Proper Blood Cartilage Bone Loose CT Dense CT 1. Red blood cell 1. Hyaline cartilage 1. Areolar CT 1. Dense Regular CT 2. White blood cell 2. Fibro-cartilage 2. Adipose CT? 2. Dense Irregular CT 3. Platelet 3. Elastic cartilage 3. Reticular CT? 3. Elastic CT Cartilage cells are called chondrocytes and bone cells are called osteocytes: they occupy small spaces called lacuna(e). 1. Loose CT: serves as the body’s Contains erythrocytes, packing material, found in spaces around organs (filling). leukocytes, & platelets. Plasma contains soluble 2. Dense CT: strong with protein fibers (mostly collagen) packed tightly proteins. together (connecting). Fluid Connective Tissue (blood) Fluid connective tissue refers to the blood Composed of the following components: – Plasma: A watery ground substance containing protein fibers – Erythrocytes: Red blood cells – Leukocytes: White blood cells – Platelets: Fragments of blood cells involved in blood clotting Structure Blood cells and a fluid matrix. Erythrocytes (red blood cells) Function Transports O2, CO2, hormones, nutrients, Leukocytes waste products, and other substances; Blood (white blood vessel cells) protects the body from infections and is involved in temperature regulation. Platelets Location Blood Plasma Within the blood vessels; white blood cells frequently leave the blood vessels and enter the interstitial spaces. Supporting Connective Tissue: Cartilages HYALINE Structure CARTILAGE Glassy-appearing matrix; irregularly arranged chondrocytes in lacunae. Chondrocytes in lacunae Function Provides support; forms most of fetal skeleton. Trachea Location Tip of nose; trachea; most of larynx, costal ECM cartilage; both the epiphyseal (growth) plates and articular ends of long bones; most of fetal skeleton. Intervertebral discs Structure Readily visible, numerous, parallel collagen fibers Chondrocytes with limited ground substance; large chondrocytes in lacunae in lacunae. Function Collagen Resists compression; acts as shock absorber in bundles some joints. Location FIBRO- Intervertebral discs; pubic symphysis; menisci of CARTILAGE knee joints. Structure Abundant elastic fibers that form weblike mesh; closely packed chondrocytes in lacunae. Chondrocytes in lacunae Function Elastic fibers Maintains shape while permitting extensive flexibility. Location ELASTIC External ear; epiglottis of larynx. CARTILAGE  Supporting Connective Tissue: Bone Cells are called osteocytes. Extracellular matrix is a mixture of collagen (protein fibers) and calcium salts. This mixture provides flexibility from the organic components and compressional strength from the inorganic components. Structure Calcified extracellular matrix containing osteocytes trapped in lacunae; compact bone organized in osteons (concentric lamellae arranged around a central canal); spongy bone is a meshwork that has a different organization from compact bone; well Vascularized. Function Provides levers for body movement, supports soft structures, protects organs, stores calcium and phosphorus; spongy bone contains hemopoietic tissue and is the site for hemopoiesis. Location Bones of the body. Osteoclast Osteoblast Osteocytes in lacunae Bone ECM Calcified ECM Bone tissue prepared so that the calcified Bone tissue with all three cell types extracellular matrix (ECM) is visible Connective Tissue Proper: Loose Connective Tissues AREOLAR CONNECTIVE TISSUE Superficial layer Structure of dermis Abundant, viscous ground substance; few Fibroblasts collagen and elastic fibers; scattered fibroblasts; many blood vessels. Ground substance Function Protects tissues and organs; binds skin and some epithelia Elastic fibers to deeper tissue. Collagen Location fibers Papillary layer of the dermis; subcutaneous layer; surrounds organs, nerve cells, some muscle cells, and blood vessels. ADIPOSE (CONNECTIVE) TISSUE Structure Adipose tissue Nuclei Closely packed adipocytes; nucleus pushed to edge of cell by large fat droplet; contains many blood vessels. Adipocytes with lipid inclusions Function Stores energy; insulates, cushions, and protects. Location Subcutaneous layer (hypodermis); surrounds and covers some organs. Skin Collagen fibers RETICULAR CONNECTIVE TISSUE Structure Reticular Viscous ground substance; meshwork of reticular fibers, fibers leukocytes, and some fibroblasts. Function Leukocytes (white blood Provides stroma (supportive framework) to cells) lymphatic organs. Location Spleen, lymph nodes, and red bone marrow. Lymph node  Connective Tissue Proper: Dense Connective Tissues DENSE IRREGULAR CONNECTIVE TISSUE Deepest layer Structure of the dermis Irregular Collagen fibers randomly arranged and clumped together; collagen fibroblasts in spaces among fibers; extensive blood supply. bundles Function Withstands stresses applied in all directions; durable. Ground substance Location Reticular layer of dermis; periosteum covering Fibroblasts bone; perichondrium covering cartilage, epineurium covering nerves, epimysium covering skeletal muscle. DENSE REGULAR CONNECTIVE TISSUE Tendons Structure Parallel Densely packed, parallel arrays of collagen fibers; collagen fibroblasts squeezed between layers of fibers; scarce bundles ground substance; limited blood supply. Fibroblasts Function Attaches bone to bone (most ligaments) as well as muscle to bone (tendon); resists stress applied in one direction. Ground substance Location Tendons (attach muscle to bone); ligaments (typically attach bone to bone. ELASTIC CONNECTIVE TISSUE Structure Parallel Predominantly composed of elastic fibers; fibroblasts occupy Aorta elastic some spaces between fibers. fibers Function Ground Allows for stretching and recoil. substance Location Walls of elastic arteries (such as the aorta), trachea, vocal cords. Heart