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Essentials of Human Anatomy & Physiology Seventh Edition Elaine N. Marieb Chapter 3 Cells and Tissues Slides 3.38 – 3.54 Lecture Slides in PowerPoint by Jerry L. Cook; some slides adapted or added by Kerry C. Roy Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Tissue: The Living Fabric Cells in multicellular organisms (i.e. humans) do not operate independently or in isolation. Instead, cells are highly specialized to perform specific functions. – This cell specialization allows the body to function in very sophisticated ways. Behold, the cell… Body Tissues Tissues--groups of closely associated cells with similar structure and function Four primary tissue types 1. 2. 3. 4. Epithelial—protection Connective—support Nervous tissue—control Muscle—movement Most organs contain several tissue types and the arrangement of tissues determines the structure and function of the organ. Specialized Cells form Tissues 4.26.asf Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings; adapted by K. Roy Slide 3.41 1. Epithelial Tissue (epithelium) Found in different areas 1. Body coverings & linings 2. Glandular tissue Functions 1. 2. 3. 4. Protection Absorption Filtration Secretion Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.42 Areas where epithelium is found … 1. Covering & lining epithelium – Found on free surfaces of body such as outer layer of skin, dipping into and lining the open cavities of the digestive and respiratory systems, lines blood vessels and heart, and covers walls and organs of closed ventral cavity – Nearly all substances received or given off by the body must pass thru the epithelium 2. Glandular epithelium – Fashions (forms) the glands of the body 4 functions of the epithelium 1. protection—skin (protects mechanical/ chemical/ bacterial) 2. Absorption—digestive tract 3. Filtration—kidneys (also do protection and absorption) 4. Secretion—specialty of glands excretion, sensory reception (other functions, but not primary functions) 5 Epithelium Characteristics 1. Cellularity— • Composed almost entirely of cells • Epithelial cells fit closely together to form continuous sheets (in contrast, muscle & connective tissue cells are often widely separated) • Bound together by desmosomes & tight junctions Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings: adapted by K. Roy Slide 3.43 Epithelium Characteristics cont. 2. Polarity— • always has one free (apical) surface – • portion of epithelium exposed to the body exterior or the cavity of an internal organ some exposed surfaces are smooth & slick, others exhibit modifications such as microvilli or cilia – microvilli—fingerlike extensions of the plasma membrane; increase surface area & are common in tissues that absorb & secrete substances (intestine & kidney) – cilia—hairlike projections commonly found in lining of trachea (& other internal tracts); propel substances along the epithelial surface Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings: adapted by K. roy Slide 3.43 Epithelium Characteristics cont. 3. Avascularity (have no blood supply) • well supplied with nerve fibers, but has no blood vessels • all cells receive nutrients (food & O2) by diffusion from underlying connective tissue Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings: adapted by K. roy Slide 3.43 Epithelium Characteristics cont. 4. Basement membrane—membrane that reinforces epithelial tissues, helping it to resist stretching & tearing forces 2 parts: • Basal lamina (epithelial) • Reticular lamina (connective) 5. Regeneration • As long as the cells receive adequate nutrition, they can replace lost cells rapidly by cell division (mitosis) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings: adapted by K. roy Slide 3.43 Classification of Epithelium The types of epithelia are identified by shape of cells arrangement of cells (number of cell layers present) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.44a Classification of Epithelium All epithelial cells are irregularly polyhedral (many-sided) in cross section, but differ in cell height. By height, there are 3 common shapes – Squamous – flattened like fish scales – Cuboidal – cube-shaped (as tall as they are wide), like dice – Columnar – column-like (tall & column shaped) *In each, the shape of the nucleus conforms to that of the cell. Thus, nuclear shape can be very helpful when attempting to distinguish epithelial types Figure 3.16b Slide 3.44b Classification of Epithelium Cell arrangement (# of cell layers) 2 major types of epithelium 1. Simple – one layer; usually very thin, not good at protection; typically found where absorption & filtration occur 2. Stratified – more than one layer stacked on top of the other; more durable; typically found in high abrasion areas where protection is important (skin surface & lining of mouth) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.16a Slide 3.44a Classification of Epithelium 4 major classes of simple epithelial tissue 1. simple squamous 2. simple cuboidal 3. simple columnar (may or may not contain cilia) 4. pseudostratified columnar (may or may not contain cilia) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.44a Classification of Epithelium 4 major classes of stratified epithelial tissue 1. stratified squamous 2. stratified cuboidal 3. stratified columnar 4. transitional epithelium FYI—classification of epithelia by cell type and arrangement reveals nothing about the tissue’s body location Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.44a In your notes… • Make a table that lists the 4 major simple & stratified epithelial tissues. Include columns for description, location, & function. • Use textbook pgs. 79-81 Now, let’s review your table… Simple Epithelium Simple squamous Single layer of flat cells (like floor tiles) Usually forms membranes where filtration or exchange of substances by rapid diffusion occurs Lines body cavities Lines air sacs of lungs and walls of capillaries Forms serous membrane (serosae) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.17a Slide 3.45 Simple Epithelium Simple cuboidal Single layer of cubelike cells Common in glands and their ducts (salivary glands & pancreas) Forms walls of kidney tubules Figure 3.17b Covers the ovaries Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.46 Simple Epithelium Simple columnar Single layer of tall cells Often includes goblet cells, which produce mucous Figure 3.17c Lines digestive tract Forms mucous membranes Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.47 Simple Epithelium Pseudostratified Single layer, but some cells are shorter than others Often looks like a double cell layer Sometimes ciliated, such as in the respiratory tract; mucous traps dust/debris while cilia propels mucous up & away from lungs Figure 3.17d May function in absorption or secretion Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.48 Stratified Epithelium Stratified squamous Most common stratified epithelium Cells at the free edge are flattened (squamous) Basement membrane cells are cuboidal or columnar Figure 3.17e Found as a protective covering where friction is common Locations Skin (outer) Mouth Esophagus Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.49 Stratified Epithelium Stratified cuboidal Two layers of cuboidal cells Stratified columnar Surface cells are columnar, cells underneath vary in size and shape Both: Rare in human body Found mainly in ducts of large glands— function in protection Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.50 Stratified Epithelium Transitional epithelium Highly modified, stratified squamous epithelium Shape of cells depends upon the amount of stretching Lines organs of the urinary system Cells slide past one another & change shape allowing structures to stretch Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.17f Slide 3.51 Epithelial Tissue cont. Epithelial membrane – Continuous multicellular sheet composed of at least 2 primary tissue types: epithelium bound to an underlying layer of connective tissue – 3 common types of epithelial membranes 1. 2. 3. Mucous membranes Cutaneous membrane Serous membrane 3 Epithelial membrane types 1. Mucous membranes (mucosae) – – – – Epithelial membranes that line the body cavities that are open to the exterior (digestive, respiratory, & urogenital tracts) In all cases, they are “wet,” or moist, membranes bathed by secretions Often adapted for absorption and secretion Often made of simple columnar cells 3 Epithelial membrane types 2. Cutaneous membrane – – – Your SKIN An organ made of keratinized stratified squamous epithelium (epidermis) firmly attached to a thick connective tissue layer (dermis) Uniquely different b/c it is exposed to air and is a dry membrane 3 Epithelial membrane types 3. Serous membrane (serosae) – Moist membranes found in closed ventral body cavities Typically made of simple squamous Remember that each serosa consists of parietal and visceral layers Serosae are named according to site & specific organ association – – – • Ex. Pleura—lining of thoracic wall & covering the lungs Pericardium—encloses the heart Peritoneum—abdominopelvic cavity Glandular Epithelium Gland – one or more cells that make & secrete an aqueous (water-based) fluid that typically contains proteins = secretion. Glandular cells obtain needed substances from the blood and use them to make their secretion. Glands are classified as: 1. endocrine 2. exocrine Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.52 Endocrine gland Ductless Produce hormones (regulatory chemicals) Ex. Thyroid, adrenals, pituitary, ovaries, testes Exocrine gland Empty through ducts to the epithelial surface Include sweat and oil glands, salivary glands, liver, pancreas, mammary glands, mucous glands, etc. 2. Connective Tissue (2nd primary tissue type) Connects body parts Found everywhere in the body; but the amount varies greatly Includes the most abundant and widely distributed of the tissue types Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.53 Connective Tissue cont. Major functions are 1. Binding—connective tissue 2. Support—bone & cartilage 3. Protection—bone, cartilage, & fat 4. Insulation—fat 5. Transportation—blood 6. Serve as a water reservoir Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.53 3 Connective Tissue Characteristics 1. Common origin – all connective tissue forms from mesenchyme (embryonic tissue derived from the mesoderm germ layer) 2. Degrees of Vascularity – Variations in blood supply – Most connective tissues are well vascularized (good blood supply), but there are exceptions • Cartilage is avascular (thus heal very slowly when injured) • Tendons & ligaments—poor blood supply 3 Connective Tissue Characteristics 3. Extracellular matrix – What is matrix? • Nonliving substance found outside the cells; typically includes ground substance (fluid to hard) & fibers (collagen, elastic, or reticular) which separates the living cells of tissue – Why is matrix important? • Matrix is what enables connective tissue to bear weight, withstand great tension, & endure abuses such as physical trauma or abrasion 3 Structural Elements of Connective Tissue 3 main components of connective tissue 1. Ground substance matrix 2. Fibers White fibers—collagen Yellow fibers—elastic 3. Cells Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Fine collagen—reticular Slide 3.55 Primary Cell Types of Connective Tissue 1. Connective tissue proper (loose & dense) fibroblast 2. Cartilage chondroblast 3. Bone osteoblast 4. Blood hemocytoblast (always actively mitotic) • Each cell type exists in immature & mature forms – These cells are actively mitotic when immature & less active when mature “—blast” = immature cell “—cyte” = mature cell Connective Tissue cont. Classes of Connective Tissue • All classes consist of living cells surrounded by a matrix • Major differences reflect cell type, fiber type, & # fibers in matrix • Major connective tissue classes (from softest to most rigid) 1. Loose connective 2. Dense connective 3. Cartilage 4. Bone FYI—Blood is also a connective tissue class that will be discussed. 1. Loose Connective Tissue --softer & has more cells, fewer fibers than any other conn. tissue type (except blood) Loose Conn. Tissue Types 1. Areolar—packages organs & surrounds capillaries 2. Adipose—reserve E, insulation, support, & protection 3. Reticular—soft internal skeleton to support other cell types Loose Connective Tissue Types Areolar Most widely distributed in body Soft, pliable tissue “cobwebby” Wraps, cushions & protects organs Functions as universal packing tissue/glue b/c it helps hold internal organs together & in place Figure 3.18e Provides a reservoir of water & salts for surrounding tissues *all body cells obtain their nutrients from & release their wastes into this “tissue fluid” Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.60 Loose Connective Tissue Types Adipose (fat) an areolar tissue in which fat cells predominate Functions Insulates Protects from heat/cold Figure 3.18f Serves as a site of fuel storage (source of E)—ex. hips and breasts serve as fat “depots” Protects some organs individually (surrounds them with fat) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.61 Loose Connective Tissue Types Reticular connective tissue Delicate network of interwoven fibers Forms stroma (supporting framework) of lymphoid organs Lymph nodes Spleen Bone marrow Figure 3.18g Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.62 2. Dense Connective Tissue Slide 3.59 aka dense fibrous tissue Main matrix element is collagen fibers Makes up lower layers of skin (dermis) where it is arranged in sheets Forms strong, ropelike structures such as tendons & ligaments Tendon – attach muscle to bone (BMT) Ligaments – connect bones to bones at joints (more stretchy & contains more elastic fibers than tendons) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.18d Connective Tissue Classes 3. Cartilage • Less hard & more flexible than bone • Found in only a few places in body • Avascular and lacks nerve fibers 3 Varieties of Cartilage 1. Hyaline cartilage Most common/abundant cartilage Forms the supporting structures of larynx (voice box), attaches ribs to sternum (breast bone), covers ends of bones at joints Figure 3.18b Fetal skeleton begins as hyaline cartilage Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.57 3 varieties of cartilage cont. 2. Elastic cartilage Found where structure with elasticity is desired Maintains shape of a structure while allowing great flexibility Example: supports the external ear & found in epiglottis Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.57 3 varieties of cartilage cont. 3. Fibrocartilage Highly compressible forms cushion-like discs between vertebrae & spongy cartilage of knees Figure 3.18c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.58b Connective Tissue Classes— 4. Bone (osseous) Figure 3.18a Used to support & protect the body Exceptional ability to protect & support other body organs Provides cavities for fat storage & synthesis of blood cells Composed of: Bone cells in lacunae (cavities) Hard matrix of calcium salts (bone salts) Large numbers of collagen fibers Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings b/c of these 2, bone matrix is harder & more rigid than cartilage matrix Slide 3.56 Bone cont. Osteoblasts— immature bone cells Osteocytes—mature bone cells; *unlike cartilage, bone is very well supplied by blood vessels Other Connective Tissue Classes 5. Blood (vascular tissue) Most atypical connective tissue Does NOT connect things or give mechanical support Classified as connective tissue b/c it develops from mesenchyme & consists of blood cells surrounded by a nonliving fluid matrix called blood plasma Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.18h Slide 3.63 5. Blood cont. Functions --transport vehicle for materials for CV system, carries nutrients, wastes, respiratory gases, & other substances Magic School Bus Blood Cells & Throat Tissue.asf Figure 3.18h Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.63 3. Nervous Tissue (3rd primary tissue type) Found in brain, spinal cord, & nerves Functions in regulation & control of body functions Neuron—primary cell type All neurons receive & conduct electrochemical impulses from 1 part of body to another Figure 3.20 2 major functional characteristics: 1. Irritability 2. Conductivity Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.68 Nervous Tissue cont. 2 major cell types 1. Neuron • • • Highly specialized nerve cells that generate & conduct nerve impulses Branching cells The presence of cytoplasmic extensions, or processes, allow them to transmit electrical impulses over substantial distances w/n the body 2. Supporting cells • • Nonconducting cells that support, insulate, and protect the delicate neurons. Ex. Myelin sheath 4. Muscle Tissue (4th primary tissue type) Highly cellular, well-vascularized tissues Highly specialized to contract (short) to produce body mvmts Called muscle fibers since cells are elongated to provide a long axis for contraction Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.64 3 Types Muscle Tissue Figure 3.19b 1. Skeletal muscle Packaged by connective tissue sheets into organs called skeletal muscle Form the flesh of the body As they contract , they pull on bones or skin causing body mvmts Can be controlled voluntarily Cells are long, cylindrical, and striated/banded which shows precise alignment of myofilaments (actin & myosin) Cells have many nuclei (multinucleate) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.65 3 Types Muscle Tissue Figure 3.19a 2. Smooth muscle (visceral) No visible striations Involuntary muscle Individual cells are spindle shaped & contain one centrally located nucleus Found in walls of hollow organs (except heart); stomach, bladder, uterus, & blood vessels Functions to squeeze substances thru organs by alternately contracting & relaxing (peristalsis) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.67 3 Types Muscle Tissue 3. Cardiac muscle Found only in the wall of the heart Function is to pump blood (involuntary) thru vessels to all parts of body Cells are striated, like skeletal, but there are structural differences: Figure 3.19c Branching cells that fit together tightly at unique junctions called intercalated disks One nucleus per cell (uninucleate) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.66 Muscle Tissue cont. *b/c skeletal muscle is under our control, it is often called voluntary muscle * Cardiac and smooth are called involuntary muscle Tissue Repair (aka wound healing) Body has many ways to protect itself: 1. Mechanical barriers—skin & mucosae and ciliary action 2. Chemical barriers—strong acid produced by stomach glands 3. Ciliary activity of epithelial cells *when tissue injury does occur, stimulates the body’s inflammatory & immune responses Tissue Repair cont. Inflammatory Response – Generalized (nonspecific) body response that attempts to prevent further injury – Fast acting Tissue Repair cont. Immune Response – Extremely specific response, takes longer to activate – Mounts a vigorous attack against recognized invaders (bacteria, viruses, toxins) What is required for Tissue Repair? • Required that cells divide & crawl (migrate). • This is initiated by growth factors (wound hormones) released by injured cells How does Tissue Repair Occur? 1. regeneration—replacement of destroyed tissue with same kind of tissue 2.fibrosis— repair by dense (fibrous) connective tissue, formation of scar tissue Which will occur? Depends on… 1.Type of injury (severity) 2.Type of tissue damaged 4 Steps to Repair 1. Inflammation 2. Capillaries become very permeable – Allows fluid rich in clotting proteins & other substances to seep into injured area 3. Granulation tissue forms – Delicate pink tissue composed largely of new capillaries that grow into the damaged area from undamaged blood vessels 4. Surface epithelium regenerates Regeneration of Tissues Regeneration varies widely among types of tissues Tissues that regenerate easily (GOOD) Epithelial tissue Fibrous connective tissue and bone Tissues that regenerate poorly (POOR) Skeletal muscle Tissues that are replaced largely with scar tissue (NONE) Cardiac muscle Nervous tissue within the brain and spinal cord Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slide 3.71