Anatomy and Physiology 1 Ch 4-5 PDF

- Tissues Lectures Homeostasis: balance of materials and energy used to keep an individual alive. Maintained through cells. Organs: When two or more tissues combine Tissue: the fabric of the body, tissue is defined as woven The type of tissue will define the functio...

- Tissues Lectures Homeostasis: balance of materials and energy used to keep an individual alive. Maintained through cells. Organs: When two or more tissues combine Tissue: the fabric of the body, tissue is defined as woven The type of tissue will define the function of the tissue There are four primary tissue types: Nervous tissues provide us with control and communication, the muscle tissue provides us with movement, and epithelial tissues = line our body cavitys and organs essentially covering and protecting the body. Connecting tissues = provides support. Histology : the study of the tissues Carmine: A red dye derived from the scaled of crushed up insects used to stain tissue to find different types of cell strcuture Nervous Tissue: Forms central nervous system and nerves for the periphreal nervous system, functions to sense stimuli and send electrical impulses through the body Nuerons: Specialized building blocks of the nervous system, function to generate and conduct the electrochemical nerve impulses (i.e. think, dreaming, eating, etc) Gilal Cells: Provide support, insulatioin, protection and fuses to blood vessels Nervous Tissue Composed of: Cell bod/ (some) : Nueron's life support Nucleus , Mitochondria , DNA Dendrites: Collect signals from other cells and send signals back to the cell body/ (soma) Axon: Carries messages to the other neurons, muscles, and glands. Nervous system: Composed of the brain and spinal cord of the central nervous system, function to regulate and control the body's functions. Periphreal Nervous System: Nerves, function to regulate and control the body's functions Muscle tissues: Contract and move Three types of muscle tissues: Skeletal muscle tissue: long multinculeate parallel cells containing stritations, attaches boen muscle and support body but functions to make the body move. Moves voluntary. Location: Throughout the body Multinucleate: Long, cylindrical cells Striations: Fine black lines running perpendicular to the fibers In short: long straight cells, striationis, multiple nuclei Cardiac muscle tissue: cells divide and converge, one nucleus per cell, striated, with intercalated disks, works involuntarily, functions to propel blood through the circulatory system Location: In the heart. Unlike skeletal muscles their cells are uninucleate meaning there is only one nucleus Intercalated disks: Hold muscle cells together during contraction and contain pores for electicla and chemical signals to pass- through one cell to the next In short: Striated, one nucleus, branching structure Smooth muscle tissue: short tapered cells, but no striations. Moves involuntary. Functions to squeeze substances through a contraction Location: Blood vessels and hollow organs in the digestive and urinary tracts as well as the uterus. The difference from the other two muscle tissues: No striations In short: Uninucleate, packed together, and no striations. Epitheal Tissues: There are two types: Proper also known as Primary Epithelium (covers and lines the outer and inner body) and Glandular Epithelium (forms the glands and secretes hormones and other substances) Epithelial tissues are Avascular meaning not associated with or supplied by blood vessels. Instead they rely on the blood supply to the connective tissues around them for the materials they need. Criter for Classification of Epithelial Cells: Shape of the individual cells and the number of layers that they form in. Three Basic Shapes: Squamous cells: Flatt4ened shape and a flat nucelus, fast absorption and diffusion, making thin membranes. Cuboidal Cells: Sepherical nucleus, cubodial cell shape, absorb nutrients and produce secrets like sweat Columnar cells: Elliptical nucelus, columb shapes cel with hexagonal cross - section, tall, thick and cushion underlying tissus, absorb nutrients and produce secretions. Usually the form (shape and layering) of the epithelial cell is related to its function and purpose Producing Cells takes a lot of time, energy and raw materials. SO in places where we lose a lot of cells (like outer skin or mouth) we have squamous cells becasue they are biologically cheaper. Types of Layering: SImple Epithelium: One layer of cells Stratified: Multiple layers set up on top of each other, like bricks Pseudostratified: Mostly one layer but formed with cells of different shapes and sizes. The cells nuclei can be at a lot of different levels (i.e., they don't lie on the same plane rather they're at different heights). So it seems to be multilayered. Naming of A Epithelial Tissue: First Name: The number of layers Last Name: Shape of its cells. Example: Simple squamous Epithelium All Epithelial cells are POLAR, they have distinct sides The boundaries of many of these cells are 'Selectively Permeable' ( allows for some level of absoprtion, filteration, and excretion of substances). Example: Tissues lining the small intestine allows absorption of the nutrients through diffusion and active transport. This is what makes possible all interaction we have with the world since Epithelial cells line both the inside and outside of the body (U tube). Glandular EPithelium forms two different types of glands: The ENDOCRINE glands (secrete hormones directly into the blood stream or to nearby cells) and EXOCRINE glands (secrete their juices into tubes or ducts that lead to the outside of the body. Connnective Tissues: Function of connective tissue (most abundant tissue in the body) 1. Binding and supporting 2. Insulating 3. Protecting 4. Storing reserve fluid and eneregy 5. Transporting substances within the body 6. Movement Types of Connective Tissues: proper connective Fat- provide insulation and fuel storage cartilage connective Most avuscalr (no blood vessels) Bone connective Blood connective Transportation Characteristics of Connective tissue: They are all developed in the same origin i the Mesenchyme, a loose and fluid embryonic tissue Different degree of vascularity and blood flow All connective tissues are mostly composed of nonliving material - extracellular matrix Extracellular matrix components 1. Ground Substance A watery, rubbery unstructured material that fills in the space between cells and protect cell from their surrounding. Flexible made of starch and protein molecules mixed with water Proteoglycans (protein) from each sprouts lots and lots of long, starchy strands called Glycosminoglygans (GAGS) radiating out from those protein. It clumps together to trap water 2. Fibers Provides suport and structure to the shapeless ground substances Types of fibers: Collagen fiber (protein) Strongest and most abundant type of fiber Elastic fibers Long thin, a branding framework within the matrix made out of protein elastic  Allows to stretch and coil Find in skin, lungs, and vessel wall Reticular fibers Short, finger collagen fibres with glycoproteins Form spong like networks that cradle and support. Immature cells are called blast Means forming Stem cell still dividnig and replicate themselves Function: to secrete the ground substance and fibres that form its unique matrix Types of Immature cells (blast --> cytes) Chondroblasts: the blast cell of cartilage Osteoblast: The blast cells of bone tissue After blast they develop into cytes, but cytes can go back to blast, if they need to repair or generate a new matrix. Types of Connective tissue Proper connective tissue (most diverse) Loose (e.g., skin) a lot of ground substances, fewer fibres, more cells and elastic fibre helps go back into shape, collagen helps anchor (stable) it (won't snap) Areolar ( the most common) Found under epithelial tissue and wrapped around your organs it looks like it has a lot of open space Random arrangement of fibres, a few fibroblast cells This arrangement of open space makes it great at holding the watery, salty ground substance Reticular: Mostly made up of reticular fibres rather than collegen Found in lymph node bone marrow and supports developing blood cells Holds blood in place in many of your organs Adipose: mostly cells Store lipids, insulate the body against heat loss Dense: contains a lot of collagen, great resistance to tension (e.g., tendon, ligament) considered regular Irregular forms thicker fibres arranged irregularly Found in places that exert tension in a lot of direction E.g., dermis under our skin. Elastic: found in the joint made up of elastic fibres E.g., connecting vertebrae, some largest artery wall Provies support and flexibility Cartilage Connective Tissue (White) doesn't have any blood or nerves standsup against both tension and compression pretty well Hyaliine cartilage (the most common type looking glassy and transparent) Provides pliable support E.g., connection between the sternum and ribs Ground substance, sticky starchy proteoglycans, collagen fibres (just a little bit) Elastic: Chondrocytes, elastic fibers Provide strength and stretchability e.g., pulling on ur ear without pulling out Fibro: Chrondrocytes, elastic fiers Consider these the shock absorbers composed of Chondrocyte and thick collagen fibres E.g., makes up the dsic between your vertebrae, knee joint. Bone Connective Tissue (osseous tissue) spongy strong porous internal layer of bone uses porous to make and store bone marrow E.g., flat bones like sternum Compact: external layers of your bones store calcium Blood Connective Tissue (no fibre, but a lot of protein) Plasma Ground substance and protein fibres Erythrocytes (red blood cells) Leukocytes (white blood cells) Platelets NOTE: THIS DIAGRAM IS NOT REALLY APART OF THE LECTURE VIDEOS HOWEVER, THIS IS HELPFUL FOR VISUALIZATION SO.... - 4.1 Tissue and Histology Tissue classification based on structure of cells, composition of noncellular extracellular matrix, and cell function. Tissues are groups of specialized cells and the extracellular substances surrounding them Histology: is the microscopic study of tissue structure. Microscopic examination of tissues can identify abnormalities, including cancer, resulting from changes in a tissue. The Four primary tissue types from whcih all organs of the body are formed: Epithelial tissue - Connective tissue - Muscle tissue - Nervous tissue Biopsy: removal of tissues from a patient surgically or with a needle for diagnostic purposes Autopsy: Examination of organs of a dead body to determine cause of death Ex. some red blood cells have an abnormal shape in people suffering from sickle-cell disease, and red blood cells are smaller than normal in people with iron - deficiency anemia. Textbook Questioins 1. What components make up a tissue? 2. Name the four primary tissue types and the characteristics that are used to classify them. 3. Define Histology. Explain how the histology of tissues taken by biopsy or autopsy is used to diagnose some diseases. - 4.2 Embryonic Tissue Approximately 13 to 14 days after fertilization, the embryonic stem cells that give rise to a new individual form a slightly elongated disk consisting of two layers. 1. Hypoblast (the suffix blast, means bud or germ) 2. Epiblast The cells of the Epiblast migrate between 2 layers to form 3 Embrygonic germ layers. Endoderm: inner layer forms the lining of the digstive tract and derivatives Mesoderm: Middle Layer Forms tissues as such muslce, bone, blood vessels Ectoderm: Outer layer Forms the skin Forms a portion of the ectoderm called neuroectoderm Nueroectoderm: The part of the ecotoderm of an embry giving rise to the brain and spinal cord. The group of cells that breaks away from the Neuroectoderm during development, are caled nueral crest cells. Neural Crest Cells: Gives rise to parts of the periphreal nerves, skin pigment cells, the medulla of the adrenal gland and many tissues of the face. Why is it called germ layers? Embyronig Germ layers: form early in embryonic development and give rise to all tissues of the body. TEXTBOOK QUESTIONS: 4. Name the three Embryonic Germ layers 5. What adult structures are derived from each layer of 6. What is formed from neural crest cells. - 4.3 Epithelial Tissue Characteristics of the Epithelial Tissue: 1. Mostly composed of cells ; very little extracellular matrix between them. 2. Covers body surfaces. Epithelial tissue covers body surfaces and forms glands that are derived developmentally from body surfaces. Body surface: defined as including both inside and outside surface Includes lining of the digestive, respiratory, and urogenital systems Heart and blood vessels Linings of many body cavities 3. Has an exposed surface RECALL: The epithial tissues form coverings and linings --> therefore one surface of their cells is in direct contact with either the outside environment or the contents of our hollow organs. Ex: The skin is in contact with the air inthe atmosphere, and the lining of the stomach is in contact with the food we eat. Free Space: As in the surface that is exposed Epithelial Cells are always oriented in that the free surface points toward the space inside a hollow organ or the exteral environment, even when part of multilayered epithelial tissue. Only the most superficial layer of cells is in contact with the environment. Has Distinct tissue surfaces Free (apical), basal, and laterla surfaces Basement membrane - connects the basal layer to underlying tissue Cells connect to surrounding cells and extracellular mix Avascular materials must move by diffusion from underluing connective tissue High regeneration capacity (undifferentiated cells aka stem cells continuously divide to produce new cells) Basement Membrane 4. Attaches at the basal surface The surface of the cells that is anchored in place is called the BASAL SURFACE The basal surface is held in place by attachment to Noncellular material known as the basement membrane that is somewhat like a mortar for a brick. The Basement Membrane has 2 layers: Basal Lamina subdivisions: Basal Lamina and Reticular Lamina Lamina lucida and Lamina Densa NOTE: The 2 layers are only visible with a light microscope Basement Membrane is composed of specialized extracelular material secreted by the epithelial cells: Collagen Glycoprotiens (laminin and fibronectin) Proteoglycans Supports and guides cell migration during Tissue Repair : porus to allow movement of materials to and from the epithelial cells above. RECALL: Epithelial cells are always oriented such that their basal surface contacts the basement membrane, even as part of a multilayered epithelial tissue. HOWEVER, only the deepest layer of cells is in conact with the basement membrane Between the Epithelial cells is the Lateral Surface, where the epithelial cells are attached to each other. Functions of Epithelial Tissues The major functions of this tissue are: Protecting underlying strcutures think the skin of the body. Acting as a barrier, think of the skin not letting in water and reduces water loss from the body. Permitting the passage of substances: think of how o2 and CO2 are exchanged between the air and blood by diffusion through the epithelium in the lungs Secreting substances: for example the sweat glands are composed of epithelial cells that secrete their products onto the surface or ducts that carry them to other areas of the body. Absorbing Substances; for example the lining of the small intestine TEXTBOOK QUESTIONS 7. List seven characteristics common to most types of epithelial tissue 8. What are the distinct cell surfacs found in epithelial tissue? Describe them 9.List and describe the major functions of epithelial tissue Classification of Eptihelial Tissue The classifications of Epithelial tissues are based on the number of cells layers and the shape of the superficial cells: 1. Simple Epithelium: Consists of 1 layer of cells. Each extends from basement membrane to the free surface 2.Stratified Epithelium: Consists of more than 1 layer of cells, but only the basal layer attaches to the deepest layer to the basement membrane. Shape of cells of the apical layer used to name the tissue 3.Psuedostratified Columnar Epithelium: This type of layer appears to be stratified but it is not. It consists of one layer of one layer of cells, with all the cells attached to the basement membrane. 4.Transitional Epithelium: A special type of stratified epithelium. The cell shape changes from cubodial and columnar to squamouslike when stretched. Classifications based on the cell shape Squamous: Flat, scalelike Cubodial: about equal in height and width Columnar: taller than wide  TEXTBOOK QUESTIONS 10. Describe simple, stratified, and psuedostratified epithelial tissues. Distinguish among squamous, cuboidral, and columnar epithelial cells. 11. How do nonkeratinized stratified squamous epithelium and keratinized stratified squamous epithelium differ? WHere is each type found? 12. Describe the changes in cell shape and number of cell layers in transitional Epithelium as it is stretched. Where is trasitional Epithelium found? 13. List the types of epithelial tissue, giving the structure, functions, and major locations of each. 14. What functions would a single layer of epithelial cells be expected to perform? A stratified layer? 15.. WHy are cuboidal or columnar cells found where secretion or absorption is occuring? Free Surface Modifications RECALL: Free surfaces of Epithelial tissues are not in contact with other cells Smooth: reduces friction The lining of blood vessels is a specialized simple squamous epithelium with a smooth surface called endothelium Folds: In transitional epithelium where an organ must be able to to change shape; urinary bladder. Microvilli: Increase surface area for absorption or secretion Specialized microvili are modified as sensory receptors; stereocilla of the inner era (not cilla). Cilla; move mucus across the surface Cells have structures that hold them to one another or to the basement membrane. Found on lateral and basal surfaces of cells. Functions: 1. Mechanically bind cells together 2. Help form a permeability barrier 3. Provide a mechanism for intercelluar communication Types: Desmosomes and Hemidesmosomes Tight junction Adhesion belt Gap Junction Cell Connections Continued Desmosomes: Disk- shaped regions of cell membrane; often found in areas that are subjected to stress consists of an especially adgesive material between the cells and intermediate protien filaments that extend into cytoplasm of cells Stratified squamous epithelium of the skin. Hemidesmosomes: half of desmosome; attach epithelial cells to basement membrane preventing movement of the tissue. Tight Junction: Hold cells together, form permeability barrier form a barrier to movement of molecules or ions between epithelial cells anchors cells together Adhesion Belts: Found just below the tight junctions. Helps anchor epithelial cells to each other to prevent passage of materials between cells; provides additional strength to the tight junctions. Gap Junctions; Protien channels aid intercellular communication These are small, specialized contact region between cells Allows ions and small molecules to pass through In Epithelium the function is inclear Coordinate function of cardiac and smooth muscle by allowing electrical signals to pass from cell to cell; intercalated disks, found between cardiac muscle cells are composed of gap junctions and desmosomes. May help coordinate movement of cillia in cilliated types of epithelium TEXTBOOK QUESTIONS 16.What is the function of each of the following characteristics of an epithelial free surface is smooth, has cillia, has microvilli, is folded? Give an example if where each surface type is found in the body? 17. Name the possible ways by which epithelial cells are bount to one another and to the basement membrane. 18. What role do desmosomes play in the skin? 19. What is the general function of gap junctions Glands Glands are what's known as specialized secretory rogans of epithelium with supporting network of C.T. Glands are composed of epithelium supported by a network of connective tissue These glands develop from an infolding or an outfolding of epithelium in the embryo. Two types of glands formed by infolding of epithelium: Endocrine: No open contact with exterior; no ducts: have an extensive network of blood vessels; produce hormones Exocrine: Open contact maintained with exterior by way ducts that open onto the free surface of the epithelium. Exocrine glands are classified by strcuture of the duct, structure of the secretory portion, and by the method of secretion Gland Classification by Structure Unicellular Glands: Single cell, For example, goblet cells that secrete mucus. Simple Glands Multicellular glands with a single, nonbranched duct Secretory portion can be tubular or acinar (sac-like) Includes simple tubular, simple branched tubular, simple acinar, and simple branched acinar  QUICK DEFINITIONS FOR THE TERMONOLOGY Duct: Refers to the tube in contact with the epithelial tissue free surface, which transports the secreted material Secretory portion of the gland is found deeper in the epithelium and is composed of the cells responsible for producing secreted material. Compound Glands Multicellular glands with ducts with my branches Secretory portioin may be tubular, acinar, or both Includes compound tubular, compound acinar, and compound tubuloacinar Modes of Exocrine Gland Secretion Merocrine: exocytosis (most common type) Apopcrine: portion of the free suface of the epithelial cell pinches off fragments of gland cells; mammary glands and ceruminous glands. The remainder of the cell is repaired Release of the fatty portion of milk by mammary glands occurs through apocrine secretion, as does secretion of earwax. Holocrine: the release of secretory products through shedding of entire cells; sebaceous glands. TEXTBOOK QUESTIONS 20.Distinguish between exocrine and endocrine glands. How are multicellular exocrine glands calssified on the basis of their duct system? Their secretory portion shape? 21.Give an example of a unicellular exocrine gland. What does it secrete? 22. Describe three ways in which exocrine glands release secretions. Give an example of each method. - 4.4 Connective Tissue Connective tissue differes from the other three tissue types in that it consists of cells seperated from each other by abundant extracellular matrix. Connective tissue is diverse in both structure and function. FUNCTIONS OF THE CONNECTIVE TISSUE: Enclosing organs and seperating other tissues Connective tissue also forms layers that seperate tissue and organs Ex: tendons, and ligaments Support and movement: for example, hones Storage: Adipose tissue stores high - energy molecules, and bones store minerals such as calcium and phosphate Cushioning and Insulating: Adipose / fat tissue cushions and protects the tissue it surrounds and provides an insulating layer beneath the skin Transport: for example, blood transports gases, nutrients, hormones, etc Protecting: Ex) Cell of immune system Cells of Connective Tissue Specialized cells produce the extracellular matrix Name of the cell identifies the cell functions by means of one of the following sufixes Blasts: creates the matrix Cytes: Maintain the matrix Clasts: break the matrix down for remodeling  C.T. cells that form the structural framework of the body include bone cells, cartilage cells, and fibrous tissue cells. Osteoblasts: known as bone forming cells, osteocytes (mature bone cell surrounded by bone matrix) maintain it, and osteoclasts (multinucleated cell that absorbs bone) break it down. Chrondoblasts known as a cartilage producing cells and chondrocytes (mature cartilage cell) maintain it. Fibroblasts known as spindle shaped or stellate cells that form connective tissue and fibrocytes (mature cell of fibrous connective tissue) maintain it. Adipose or fat cells (adipocytes): contains large amounts of lipids. Common in some tissues (dermis of skin); rare in some (cartilage). Mast Cells: Common beneath membranes and along small blood vessels. Important role in inflammation; can release heparin, histamine, and proteolytic enzymes, that are released in response to injury, such as trauma and infection. White blood cells (leukocytes): Continously move from blood vessels into connective tissue Rate of movement increases dramaticaly in response to injury, such as truama or infection Accumulation of Lymphocytes, a type of white blood cell, are common in some connective tissues, such as that beneath the epithelial lining of certain parts of the digestive system. Macrophages: are large, phagocytic cells found in some connective tissues. Derived from monocytes, a type of white blood cell FIxed: stay in position in connective tissue Wandering: move by amoeboid movement through the conective tissue Platelets: fragments of hematopoietic cells containing enzymes and special protiens Functions: Involved in clotting process to reduce bleeding from a wound Undifferentiated mesenchyme (stem cells): a type of adult stem cell and has potential to form multiple cell types such as fibroblasts or smooth muscle cells.  Extracellular Mix COMPOSED OF 3 MAJOR COMPONENETS: Collagen: Appears as ropelike protien of the extracellular matrix Most common protien in the body Accounts for 1/3 of the body protein and 6 percent of total body weight Very strong and flexible, like microscopic ropes, but are not very elastic HOW IS COLLAGEN MADE YOU ASK??? 1. Synthesized with fibroblasts and secreted into extracellular space 2. Collagen dibrils are then joined together in bundles to form collagen fibers NOT ALL COLLAGEN IS THE SAME CHECK IT OUT! Technically speaking there are 20 types of collagen fibers Type 1: is the most abundant in the body. Flexible ropelike stength of type 1 collagen fibers makes them well suited for tendons, ligaments skin and bone. Type 2: Found in cartilage Type 3: Found in reticular fibers.. Reticular: Relating to a fine network of cells or collagen fibers. The fibers are very short, thin fibers that branch to form a network Networks of fibers fill spaces between tissues and organs Composed of type 3 collagen. Not considered as strong as most other collagen fibers because they mainly play a space filling role in the body. Elastic: Consists of the protein Elastin, appears as yellow, elastic, fibrous, mucoprotein that is the major connective tissue protein of elastic structures This protein has the ability to return to its orignal shape after being stretched or compressed, giving tissue an elastic quality.  Fibroblasts secrete elastin polypeptide chains, which are linked together to form a network. The elastin network stretches like a rubber band in response to force and recoils when relaxed Elastic fibers provide the elasticity of skin, lungs,, and arteries. Ground Substance of the Matrix (Most common moelecules) Considered a gel like mixture of nonfibrous molecules There are two major componenets... Hyaluronic: Mucopoly-saccharide made up of alternating B-14 linked residues of hyalobiuronic acid, forming a gelatinous material in the tissue space and acting as a lubricant and shock absorbant generally throughout the body. It gives a very sliper quality to the fluids that contain it Is a good lubricant for joint cavities Presents in large quantities in connective tissue and is the major component of the vitreous humor of the eye Proteoglycans: Protein and long polysaccharides called glycosaminoglycans. Protein part attached to hyaluronic acid. Trap large amounts of water. Adhesive Molecules: hold proteoglycan aggrates together Chondronectin in cartilage Osteonectin in bone Fibronectin in fibrous connective tissue TEXTBOOK QUESTIONS 23.What is the main characteristic that distinguishes connective tissue from other tissues? 24.List the major functions of connective tissue, and give an example of a type of connective tissue that performs each function 25. Explain the differences amongst blast, cyte and clast cells of connective tissue 26. What are the three componenets of the extracellular matrix of the connnective tissue? 27.Contrast the structure and characteristics of collagen fibers, reticular fibers, and elastic fibers. 28. Describe the structure and functions of hyaluronic acid and proteoglycan aggregates. 29.What is the function of adhesive molecules? Give some specific examples. Classification of Connective Tissue Embryonic Connective Tissue: Called mesenchyme: Composed of fibroblasts surrounded by semifluid extracellular matrix containing delicate reticular fibers. It forms in the embryo during the third and fourth weeks of development from meodern and neural crest cells, and all adult connective tissue types develop from it. By 8 weeks of develpment most of the mesenchyme has becoome specialized to form the types of connective tissue seen in adults The major source of remaing embryonic connective tissue in the newborn is the umbillical cord, where it is called mucous connective tissue, or Wharto's jelly. The structure of mucous connective tissue is similar to that of mesenchyme. Mucous tissue helps support the umbilical cord blood vessels between mother and child. After birth, the mucous connective tissue can also be a rich source of stem cells.  Adult Connective Tissue: Consists of three types: Connnective Tissue Proper Loose: fewer fibers, more ground substances; areolar, adipose, reticular Dense: more fibers, less ground substance; dense regular and irregular collagenous, dense regular and irregular elastic Loose connective tissue / Adipose Tissue: Yellow adipose tissue is white at birth but turns yellow with age Brown adipose gets its color from cytochromes and is specialized to generate heat (because oxidative metabolism of lipid molecules in mitochondria) Contains large amounts of lipids Composed of. a large cells and a small amount of extracellular mix Matrix is composed of loosely arranged collagen and reticular fibers with scattered elastic fibers. Brown color results from cytochrome pigments in the tissue's numerous mitochondria and its abundant blood supply.. Supporting Connective Tissue: Cartilage: semisolid matrix; hyaline, fibrocartilage, elastic Bone: solid matrix; spongy compact  Fluid Connective Tissue: Blood Hematopoietic tissue; red and yellow bone marrow Has the special property of predominating in areas of the body with a high cellular content it means a lot of cells in a certain part of the body Reticular cells produce the reticular fibers and remain closely attached to them. The space between the reticular fibers can contain a wide variety of other cells, such as macrophag blod cells, and dendritic cells, which look very much like reticular cells but are cells of the immune system. Dense Connective Tissue: Has a relatively large number of protein fibers, which forms thick bundles and fill nearly all of the extracellular space. Most of the cells of developing dense connective tissue are spindle-shaped fibroblasts. Once fibroblasts become completely surrounded by matrix, they are fibrocytes. Dense connective tissue can be subdivided into two major groups, 1) dense regular 2)Dense Irregular Dense Regular Connective Tissue: Has protein fibers in the extracellular matrix that are oriented predominantly in one direction. Dense Regular Collagenous Connective Tissue: has abdundant collagen fibers, which give this tissue a white appearance. Dense regular collagenous connective tissue forms structure such as tendons, which connects muscle to bones. Most ligaments, which connects bones to bones  Collagen fibers of dense connective tissue resist stretching and give the tissue considerable strength in the direction of the fiber orientation. Tendons and most ligaments consist almost entirely of thick bundles of densely packed, parallel collagen fibers with orientation of the collagen fibers in one directioin, which makes the tendons and ligaments very strong, cablelike structure. General structure of tendons and ligaments are similar, but they differ in the following respects: 1) The collagen fibers of ligaments are often less compact, 2) some fibers of many ligaments are not parallel, and 3) ligaments are usually more flattened than tendons and form sheets or bands of tissues. Dense regular Elastic Connective Tissue: consists of parallel bundles of collagen fibers and abundant elastic fibers. The elastin in elastic ligaments gives them a slightly yellow color. Dense regular elastic connective tissue forms some eleastic ligaments such as those in the vocal folds and the nuchal ligament, which lies along the posterior of the neck, helping hold the head upright. When elastic ligaments are stretched, they tend to shorten to their original length, much as an elastic band does. Dense Irregular Connective Tissue: Contains protein fibers arranged as a meshwork of randomly oriented fibers. Alternatively, the fibers within a given layer of dense irregular connective tissue can be oriented in one direction Whereas the fibers of adjacent layers are oriented at nearly right angles to that layer Dense irregular connective tissue: forms sheet of connective tissue that have strength in many directions but less strength in any single directioin than does regular connective tissue. Dense Irregular Collagenous Connective Tissue: forms most of the dermis, which is the tough, deeper portion of the skin also forms the connective tissue capsules that surroun organs such as the kidney and spleen Dense Irregular Elastic Connective Tissue: is found in the walls of elastic arteries. In addition to collagen fibers, oriented in many directions, the layers of this tissue contain abundant elastic fibers. TEXTBOOK QUESTION 30. List the two types of embryonic tissue. What does mesenchyme give rise to in the adult? What is the purposee of mucous connective tissue? 31. What are the three classifications of adult connective tissue, and what tissue types are included in each? 32. Describe the fiber arrangement in loose (areolar) connective tissue. What are the functions of this tissue type, and where is tissue found in the body? 33. What structural feratures distinguish adipose tissue from other types of connective tissue? What is an adipocyte? 34. Name the two types of adipose tissue, and give the functions of each. Which type is primarily found in infants? 35. What is the function of reticular tissue? Where is it found? 36. Structurally and functionally, what is the difference between dense regular connective tissue? 37. Name the two kinds of dense regular connective tissue, and give an example of each. DO the same for dense irregular connective tissue. Supporting Connective Tissue: Cartilage: Composed of cartilage cells within an extensive and relatively rigid matrix The surface of nearly all cartilage is surrounded by a layer of dense irregular connective tissue called the perichondrium ( it is the double layered connective tissue sheath surrounding cartilage). Once completely surrounded by matrix the cartillage cells are called Chondrocytes ( a mature cartilage cell), and the space in which they are located are called lacunae. The matrix contains protein fibers, ground substance, and fluid. Protein fibers are collagen fibers or a mixture of collagen and elastic fibers. Ground Substance: consists of proteoglycans and hyaluronic acid complexed together trap large amounts of water. Tissue can spring back after being compressed. The collagen fibers give cartilage considerable strength. Next to the bone, cartilage is the firmest structure in the body. Cartilage has no blood vessels or nerves, except those of the perichondrium; it therefore heals very slowly after an injury because the cells and nutrients for tissue repair cannot reach the damaged area easily. There are three types of cartilage: Hyaline Cartilage: Hylaine is gelatinous glossy cartilage tissue consisting of cartilage cells and their matrix; contains collagen, proteoglycans, and water Has large amounts of both collagen fibers and proteoglycans Collagen fibers are evenly dispersed throughout the ground substance, and hyaline cartilage joints has a very smooth surface. Specimens appear to have a glassy, translucent matrix when viewed through a microscope. Found where strong support and flexibility are needed, such as in the rib cage and within the trachea and bronchi.  Also covers the surface of bones that move smoothly against each other in joints. Hyaline cartilage forms most of the skeleton before it is replaced by bone in the embryo, and it is involved in growth Perichondrium: Dense irregular connective tissue that surrounds cartilage. Fibroblasts of perichondrium can differentiate into chrondoblasts. Fibrocartilage: Has more collagen fibers then proteoglycans Compared with hyaline cartilage, fibrocartilage has much thicker bundles of collagen fibers dispersed through its matrix. Fibrocartilage is slightly compressible and very tough Found in areas of the body where a great deal of pressure is applied to joints, such as in the knee, in the jaw, and between the vertebrae. Some joints such as the knee, have both hyaline and fibrocartilage connective tissue. In these joints, pads of fibrocartilage help absorb shocks and prevevent bone to bone abrasion. Fibrocacartilage injuries of the knee joint (meniscus tear) are common sports related injuries. Elastic Cartilage: Has numerous elastic fibers in additon to collagen and proteoglycans dispersed throughout its matrix. It is found in areas that have rigid but elastic properties, such as the external ears. Supporting Connective Tissue: Bone Bone: is a hard connective tissue that consits of living cells and miineralized matrix. Bone matrix has organic and inorganic portions The organic portions consists of protein fibers, primarily collagen, and other organic molecules Hard connective tissue composed of living cells (osteocytes) and mineralized matrix. The mineral, or inorganic portion consists of specialized crystals called hydroxyapatite, which contains calcium and phosphate. The strength and rigidity of the mineralized matrix allows bones to support and protect tissues and organs Osteocytes: or bone cells, are located within holes in the matrix, which are called lacunae and are similar to the lacunae part of cartilage. Two Types of Bones Exist: Spongy bone: has spaces between trabeculae, or plates of bone and therefore resembles a sponge. Compact Bone: is more solid, with almsot no space between many thin layers or lamellae of bone Fluid Connective Tissue: Blood: is unusual among the connective tissues because the matrix between the cells is liquid Most cells of connnective tissue are more or less stationary within a relatively rigid matrix, but blood cells move freely within a fluid matrix. Blood's liquid matrix allows it to flow rapidly through the body, carrying nutrients, oxygen, waste products, and other materials. Matrix of blood is also unusual in that most of it is produced by cells contained in other tissues, rather than by blood cells. Moves through vessels, but both fluid and cells can move in/ out of the vessel. There are three types of cellular structures: (a) red blood cells, (b) white blood cells, and (C) cell fragments called platelets. Fluid Connective Tissue: Hematopoietic Tissue Forms blood cells Found in bone marrow, which is the soft connective tissue in the cavities of the bones. Red Marrow: Soft, puply connective tissue filling the cavities of the bone; consists of reticular fibers and the development stages of blood cells and platelets; gradually replaced by yellow marrow in long bones and the skull. Yellow Marrow: Connective tusse filling the cavities of bones; consists primarily of reticular fibers and fat cells; replace red marrow in long bones and the skull. In simpler terms...  Red Marrow: Hematopoietic tissue surrounded by a framework of reticular fibers produces red and white blood cells Yellow: yellow adipose tissue does not produce blood cells As children grow, yellow marrow replaces much of red marrow. TEXTBOOK QUESTIONS 38. Describe the cells and matrix of cartilage. What are lacunae? What is the perichondrium? Why does cartilage heal slowly? 39. What are three types of cartilage? How do they differ in structure and function? Where would each type be found in the body? 40. Describe the cells and amtrix of bone. Differentiate between spongy and compact bone. 41. What characteristics seperates blood from other connective tissues? What are the three formed elements in blood? 41. Describe the function of hematopoietic tissue. Explain the difference between red marrow and yellow marrow. SUMMARY OF CONNECTIVE TISSUE - 4.5 MUSCLE TISSUE Characteristics: Muscle contractionis accomplished by the interaction of contractile Contracts or shortens with force proteins Moves body and pumps blood Types: Skeletal: Constitutes about 40 percent of a person's body weight. Skeletal musc;e is under voluntary (conscious) control because a person can purposefully cause skeletal muscle contraction to achieve specific body movements. The nervous system can cause skeletal muscles to contract without conscious involvement, as occurs during reflex movements and the maintenance of muscle tone. Skeletal muscle cells are long, cylindrical cells, each containing many nuclei located at the periphery of the cell. Some skeletal muscle cells extend the entire legnth of a muscle. Skeletal muscle cells are striated ( striped; marked by stripes or bands), or banded because of the arrangement of contractile proteins within the cells. Cardiac Muscle: Muscle of the heart; responsible for pumping blood Under involuntary (unconscious) control technically a person can learn to influence their heart rate by using techniques such as meditatioon and biofeedback. Cardiac muscle cells are cylindrical but much shorter than skeletal muscle cells. Cardicac muscles are striated and usuallly have 1 muscle per cell They are often branched and connected to one another by intercalated disks which contain specialized gap unctions and are important in coordinating cardiac muscle cells contractions. Smooth Muscle: Forms the walls of hollow organs (except the heart) Found in the skin and eyes Smooth muscle is responsible for a number of functions, such as moving food through the digestive tract and emptying the urinary bladder Smooth muscle cells are tapered at each end, having a single nucleus, and are not striated. TEXTBOOK QUESTIONS 43. Functionally, what is unique about muscle tissue? 44. Compare the structure of skeletal, cardiac, and smooth muscle cells. 45. Which type of muscle is under voluntary control? 46. Where is each type of muscle tissue found, and what tasks does each perform? - 4.6 Nervous Tissue Nervous Tissue: found in the brain, spinal cord, and nerves and is characterized by the ability to conduct electrical signals called Action Potential. Neurons: (nerve cells) have the ability to produce electrical signals called action Parts: Cell Body: Contains nucleus and is the site of general cell functions Axon: Usually conducts action potential away from the cell body. Axons can be much longer than dendrites, and they have a constant diamter along their entire length. Dendrites: usually recieve action potentials They are much shorter than axons and have multiple branches at their ends. Neurons can be grouped based on their structure: Multipolar Neurons: consisting of a nueron cell body, an axon, and two or more dendrites Bipolar Neurons: consisting of a neuron with two processes, one dendrite, and one axon arising from opposite poles of the cell body. Pseudo-unipolar Neurons: consists of a nerve cell body with a single axon projecting from it. Extends to the periphery and to the central nervous system Gila: are the support cells of the brain, spinal cord, and peripheral nerves. Nourish, protect, and insulate neurons TEXTBOOK QUESTION 47. What is the characteristics function of nervous tissue? 48. Define and list the functions of the cell body, dendrites, and axon of a neuron 49. Differentiate among multipolar, bipolar, and psuedo - unipolar neurons. 50. What are the functions of gila? - 4.7 Tissue Membrane A tissue membrane is a thin sheet of tissue that covers a structure or lines a cavity. Most membrane are formed from a superficial epithelial tissue and the connective tissue on which it rests. Four tissue membrane in the body, one external and three internal. There are.3 major categories of internal tissue membranes Mucous Membranes Line cavities that open to the outside of body Found in digestive, respiratory, excretory, and reproductive passages Composed of Epithelial cells, their basement membrane, and a thick layer of loose connective tissue called the lamina propria (Layer of connective tissue underlying the epithelium of a mucous membrane) SOME Mucous contain a layer of smooth muscle cells Many, but not all, mucous membranes contain goblet cells or multicellular mucous glands that secrete mucus, a viscous protein substance. Functions of the mucous membranes vary, depending on their location, and include protection, absorption, and secretion. Serous Membranes Lines cavities that do not open to the exterior of the body Ex: pericardial, pleural, and peritoneal cavities Consits of three components: A layer of simple squamous epithelium called mesothelium, its basement membrane, and a delicate layer of loose connective tissue. DO not contain glands Secretes a small amount of fluid called serous fluid ---> lubricates the serous membranes making surfaces slippery Protects the internal organs from friction Helps hodl organs in place acts as selectively permeable barriers to prevent large amounts of fluid from accumulating within the serous cavities. Synovial Membranes Line freely movable joints Made up of only connective tissue Consists of modified connective tissue, either intermixed with part of the dense connective tissue of the joint capsule or seperated from the capsule by areolar or adipose tissue. Produce Synovial Fluid, which is rich in hyaluronic acid, making the joint fluid very slippery, thus facilitating smooth movement within the joint. TEXTBOOK QUESTION 51. Compare the mucous, serous, and synovial membranes according to the type of cavities they line and their secretions 52. What are the functions of mucous, serous, and synovial membranes?  4.8 Tissue Damage and Inflammation Body responds to tissue damage or infection with an inflammatory response. Inflammatory Response: Complex sequence of events involving chemicals and immune cells that result in the isolation and destruction of antigens and tissues near the antigens. or in other terms... Inflammatory Response: Is a defense mechanism that mobolizes the body's immune cells to isolate and destroy microorganisms and other injurious agents, and remove foreign materials and damaged cells. Inflammatory response allows tissue repair to occur illustrates the stages of the inflammatory response. Manifestation: Redness, heat, swelling, pain, and disturbed function Chemical Mediators Include histamine, kinins, prostaglandins, leukotrienes. Stimulate pain receptor and increase blood vessel permeability as well movement of WBCs to affected area. Tissue swells, called Edema Stages of the Inflammatory Response TEXTBOOK QUESTIONS 53. What is the function of the inflammatory response? 54. Name the five manifestations of inflammation; explain how each is produced and the benefits of each. - 4.9 Tissue Repair Defined as the substitution of viable cells for dead cells by regneration or replacement. Regeneration: The new cells are the same type as those that were destroyed, and normal function is usually restored. Replacement: New type of tissue develops, which eventually produces a scar and causes the loss of some tissue function Most wounds heal through regeneration and replacement, which process dominates depend on the tissues involved and the nature and extent of the wound. Classification of cells based on ability to regenerate: 1. labile Cells: they continue to divide throughout life. Includes undifferentiated adult stem cells in various organs of the body, such as boen marrow Differentiated labile cells can be found in the skin, mucous membranes, and hematopoietic and lympathic tissue. The ability to engineer and transplant adult stem cells and other reprogrammed labile cells is an emerging therapeutic strategy for a number of diseases. 2. Stable cells: DO not normally divide after growth cases, but they retain the ability to divide and are capable of regeneration in response ot injury 3.Peremanet Cells: Not able to replicate, INSTEAD they are replaced by a different type of cell Permanent cells are postmitotic Limited regenerative ability Some undifferentiated cells of the central nervous system are stem cells that can undergo mitosis and form functional neurons in adults. Nervous, Skeletal, and cardiac muscle Skin Repair Example of tissue repair: 1. Primary Union: edge of wound are close together Wounds fill with blood Clot forms: fibrin threads start to contract; pull edges together Scab Inflammatory response; pus forms as white cells die. Granulation tissue: Replaces, clot, delicate C.T. composed of fibroblasts, collagen fibers, capillaries. Scar. Formed from granulation tissue. Tissue turns from red to white as capillaries are forced out. 2. Secondary Union: Edges of wound are not closed; greater chance of infection Clot may not close gap Inflammatory response greater Wound contraction occurs leading to greater scarring During the first week, the inflammatory response induces vasodilation and takes more blood cells and other substances to the area. Blood vessel permeability increases, resulting in edema. Fibrin and blood cells, move into the wounded tissue because of the increased permeability. Fibrin isolates and walls off microoorganisms and other foreign matter. Phagocytic white cells called neutrophils then move into the tissue to help fight the infection They ingest bacteria and tissue debris to clear the area for repair. Neutrophils killed through this process creates pus. Fibroblasts from surrounding CT migrate into the clot and produce collagen and other extracellular matrix componenets. Capillaries grow from blood vessels at the edge of the wound and revascularize the area, and fibrin in the clost is broken down and removed. 3. By two weeks, the clot has been replaced by granulation tissue that will eventually form a scar at the wound site. Granulation tissue is a delicate, granular appearing connective tissue that consists of fibroblasts, collagen, and capillaries 4.By a month, a large amount of granulation tissue has convered to a scar, which consists of dense irregular collagenous CT. At first, the scar is bright red because numerous blood vessels are present. Later, the scar becomes white as collagen accumulated and the vascular channels are compressed. VISUAL REPRESENTATION OF THE TEXT Repair by secondary union is similar, but with some differences: The clot may not completely close the gap It takes longer for epithelial tissue to regenerate and cover the wound Generally, more inflammation, more risk of infection, and more pus. More granulationt issue forms, and contraction of the fibroblasts leads to wound contracture that results in disfiguring scars. It is advisable to suture a large wound so it can heal by primary union instead of secondary union. Molecular Tissue Profiles of Cancer Tissue The most common types of cancer are from epithelial tissue with its more rapid cell division. Carcinomas: cancer of epithelial tissue; include nearly all lung, breast, colon, prostate, and skin cancers. Adenocarcinomas: derived from glandular epithelium Sacrcomas: relatively rare cancers of mesodermal tissue (connective tissue and muscular) Effects of Aging on Tissues Cells divide more slowly Rate of blood cell synthesis declines in the elderly Injuries don't heal as readily Collagen fibers become mroe irregular in structure, though they may increase in number; tendons and ligaements become les flexible and more fragile. Elastic fibers become less elastic Changes in collagen and elastin result in Arterial walls and elastic ligaments become less elastic Atherosclerosis and reduced blood supply to tissues. Wrinkling of the skin Increased tendency for bones to break TEXTBOOK QUESTIONS 55.Define tissue repair. Differentiate between repair by regeneration and repair by replacement. 56. Compare labile, stable and permanent cells according to their ability to regenerate. Give examples of each type, 57.Describe the process of wound repair. Contrast healing by primary union and healing by secondary healing. Which process is better, and why? 58. What is granulation tissue? How does granulation tissue conribute to scars and wound contracture. The Integumentary system - 5.1 Functions of the Integumentary System Structures that are part of the Integumentary System Skin Hair Nails Glands Functions: Protection: The skin covers the body, protects the body from harfmul Uv Light, forms a barrier against microorganisms and prevents water loss (dehydration) Sensation: sensory receptors for heat, cold, touch, pressure and pain Temperature regulation: through the odulation of blod flow through the skin and the activity of sweat glands ( think exercise) Vitamin D production from a molecule made in the skin when exposed to UV light Excretion of small amounts of waste products through the sweat glands in the skin TEXTBOOK QUESTIONS 1. Provide an example for each function of the integumentary system - 5.2 Skin Epidermis: Superificial layer of stratified squamous epithelial tissue. Protection and reduces water loss ( due to the keratinocytes) seperated from the underlying dermis by a basement membrane Contains no blood vessels Living cells of the epidermis receive nutrients and excrete waste products by the diffuson of substances between the epidermis and the capillaries of the dermis Considered Avascular Composed of epithelial cells arranged into layers or strata Epidermis is stratified, it is not as thick as the dermis Most cells of the epidermis are called keratinocytes because they produce a protein mixture called keratin Keratin makes the cells more durable Other cells of the Epidermis include, melanocytes, Langerhans cells, and Merkel cells. Dermis: Deep layer of connective tissue. Structural strength Subcutaneous tissue: Not part of skin Losose connective tissue that connects skin to underlying structures  Epidermal Cells keratinocytes: most cells, produce keratin for strength Melanocytes: contribute to skin color. Melanin produces by these cells then trasnferred to Keratnocytes. Same number of melanocytes in all people. Langerhands cells: part of the immune system Merkel Cells: specialized epidermal cells associated with the nerve endings responsible for detecting light and sueprficial pressure Keratinization: as cells move outward through the layers they fill with keratin, die, and serve as a layer that resists abreasion and forms permeability layer. The many layers of cells in the epidermis are divided into regions or strata. These range from the deepest to the most superficial. Epidermal Strata Stratum basale (germinativum) Deepest portion of epidermis and single layer of cuboidal or columnar cells At the stratum basale, the epidermis is anchored to the basement membrane by hemidesmosomes desmosomes provide structural strength for the epidermis. High mitotic activity; keratinocyte stem cells undergo mitsosis about every 19 days; one daughter cell remains intact eh statum basale to divide again, while the other daughter cell is pushed to the surface and becomes keratinized. It takes 40 to 56 days to move from the stratum basale to the surface and be sloughed off. Stratum Spinosum Eight to ten layers of many sided cells that flatten as they are pushed upard Contain new desmosomes, lipid-filled lamellar bodies, and additonal keratin fibers As the cells in this statum are pushed to the surface, they flatten; desmosomes beak apart, and new desmosomes form. During prep for microscope observation, the cells usually shrink from one another except where they are attached by demosomes, causing the cells to apear spiny. Stratum Granulosum Two or five layers of flattened, diamond shaped cells. Contains protein granules of Keratohyalin that accumulate in the cytoplasm lamellar bodies move to the plasma membrane and release their lipid contents into the extracellular space Inside the Keratinocyte, a protein envelope forms beneath the plasma membrane. the most superifical layers of the stratum granulosum, the nucleus and other organelles degenerate, and the keratinocyte dies. Unlike the other organelles and the nucleus, the kerarin fibers and keratohyalin grannules within the cytoplasm do not degenerate. Stratum lucidum Located above the stratum granuslosum Thin, clear zone of several dead layers of keratinocytes with indistinct boundaries Found only in palms and soles Keratin fibers are present, but the keratohyalin, which was evident as granules in the stratum granulosum, has dispered around the keratin fibers and the cells appear somewhat transparent. Present in only a few areas (this will be clearer in the next section) Stratum Corneum The last and most superficial stratum of the epidermis Composed of 25 or more layers of dead, overlapping squamous cells joined by desmosomes. Eventually desosomes break aprt and the cells are shed from the surface of the skin. Fun fact! Excessive shedding causes dandruff. Unlike dandruff, skin cells are less noticeable and continue to shed from other areas as clothes rub against the body or as the skin is washed.  composed of dead keratinocytes with a hard protein envelope, filled with protein keratin known as cornified cells. Keratin is a mixture of keratin fibers and keratohylin. Evenlope and keratin are responsible for the structural strength For skin you'll find soft keratin Nails and external parts of the hair contains hard keratin Lipids are released from lamellar bodies surrounding the skin cells. The lipids are responsible for many of the skin's permeability charatcteristics. Here's a visual depiction of the layers from above! Thick and Thin Skin Skin is classified as thick or thin based on the structure of the epidermis The variation in the structure of skin is relative to degree of exposure or friction, such as the palms of the hands, the soles of the feet, and the fingertips. Thick Skin: ( designation refers only to the epidermis) Has all 5 epitheloal strate Found in area subject to pressure or friction Ex) palms of the hands, the soles of the feet, and the fingertips Fingerprints and footprints. Papille of underlying dermis in parallel rows. found in the areas subject to pressure and friction Thin Skin Composed of 4 strata (no statum lucidum) Coverrs the rest of the body is more flexible than thick skin Hair grows only here Callus: Increase in number of layers in stratum corneum. from being subject to friction or pressure. when this occurs over a bony prominence, a corn forms which is a cone-shaped structure. The base of the cone is at the surface, but the apex extends deep into the epidermis, and the presure on the corn may be quite painful. calluses and corn can develop in both thin and thick skin. The entire skin, including both epidermis and the dermis, varies in thickness from.5 mm in the eyelids to 5.0 mm on the back and shoulders. "thin" and "thick" should only be used to refer to the epidermis not the total skin thickness. Skin Color Determines by 3 factors: pigements in the skin, blood circulating through the skin, thickness of stratum corneum. Pigments Melanin: primarily responsible fo reye color, hair and skin color. provides protection against UV light. Large amounts of melanin are found in certain regions such as the freckles, moles, and the nipplesm and the areolae of the breasts, the axillae, and the genitalia. Lips, palms of the hands, and soles of the feet, contain less melanin. Colored brown to black, may be yellowish or reddish. Melanocytes: produce melanin Irregularly shaped cells with many long process that extend between the Keratinocytes of the strtuym basale and the stratum spinosum ; deposit melansomes Albinism occurs with a single genetic mutation, the person has a defeciency or absence of pigment; production determined by genetics, hormoens, exposure to light. ( for those who can at least produce some) Typically albinism is a recessive gene trait. Carotene: Yellow pigment from vegetables; accumulates in stratum corneum, in adipose cells of dermis, and in subcutaneous tissue Humans normally ingest and use carotene as a source of vitamin A Lipid soluble when large amounts are conscumed the excess acumulates in the stratum corneum and in the adipocytes of the dermis/ subcutaneous tissue, causing the skiin to develop a yellowish tint. The yellowish tint slowly disappears once carotene intake is reduced. Melanin Transfer to Keratinocytes 1. Melanocytes produce and package melanin into vesicles called melanosomes. 2. These melanosomes moved into cell processes of the melanocytes 3. Keratinocytes phagocytize the top of the melanocyte cell processes, thereby acquiring melanosomes Melanin production involves the enzymatic modification of the amino acid tyrosine to an intermediate. This can be modified in diferent ways producing pigments that can be brown, black, yellow and red. types of melanin produced is based on genetic factors The degree to which melanin is produced is influenced by exposure to light and hormones The number of Melanocytes in the skin is relatively the same for all humans regardless of race. Racial variations in skin color are determined by several major factors: types of melanin produces amount of melanin produced size of melanosomes (melanin filled visciles in cells) Number of melanosomes Distribution of melanosomes Certain hormones, such as estrogen and MSH, can increase melanin production during pregnancy. Blood circulating through the skin imparts reddish hue and increases during blushing, anger, inflammation. Cyanosis: blue color caused by decrease in blood oxygen content the skin can appear paler  Erythema: red color caused by increased blood flow An inflammatory response stimulated by infection, sunburn, allergic reactins, insect bites, or other causes. Exposure to cold and blushing, flushing when angry or hot can also produce this. Thickness of stratum corneum impacts color Thicker areas can be yellowish Pigements and other substances in the dermis or subcutaneous tissue may impart a blush color to the skin; the depper, the bluer. Skin Cancer The most common type of cancer Most skin cancer results from damage from UV radiation that damages the DNA in epidermal cells. 1. UV raidatioin damages the genes (DNA) in epidermal cells, producing mutations 2. If a mutation is not repaired, the mutation is passed to one of the two daughter cells when a cell divides by mitosis. 3. if the mutation affect genees that regulate the cell cycle.. uncontrolled cell division and skin cancer can result The amount of melanin affects the likelihood of developing skin cancer; fair skinned people are at a greater risk than dark-skinned people. Long term exposure or intense exposure to UV radiation can also increase the risk. Individuals older than 50, who have engaged in repeated recreational or occupational exposure to the sun, or who have experienced sunburn are at an increased risk. Develops on the parts of the body that are frequently exposed to sunlight: face, neck, ears, and dorsum of the forearm and hand. Three Major Types: Basal cell carcinoma Squamous cell carcinoma Melanoma Types of Skin Cancer Basal cell carcinoma Most common Affects cells in the stratum basale Varied appearance - Open sores that bleed - Ooze - crust for several weeks - Others are reddish patches; shiny, pearly, or translucent bumps; or scarlike areas of shiny, taut skin. Removal or destruction of the tumor cures most cases. Squamous cell carcinoma Affects Cells of stratum spinosum Second most common type of skin cancer. Varied appearence; may bleed Can appear as a wartlike growth a persistent, scaly red patch; an open sore; or an elevated growth with a central depression. These lesions may bleed. Removal or destruction of the tumor cures most cases Melanoma Least common Most deadly type Accounts for 77 percent of the skin cancer deaths in the United States Arise from melanocytes, most melanomas are black or brown. Ocasionally a melanoma stops producing melanin and appears skin- colored, pink, red, or purple 40 percent of melanomas develop in pre- existing moles treatment of melanomas when they are confineed to the epidermis is almost always successful. If a melonoma invades the dermis and metastasizes (spreads) to other parts of the body, it is difficult to treat and can be deadly. ABCDE Rule for Signs Of Melanoma A - asymmetry B - border irregularity C - diameter greater than 6mm E - evolving or changing TEXTBOOK QUESTIONS 2. From deepest to most superficial name and describe the five strata of the epidermis. In which stratum are new cells formed by mitosis? WHich strata have live cells, and which strata have dead cells? 3. Describe the structural features resulting from keratinozation that make the epidermis structurally strong and resistant to water loss. 4. Compare the structure and location of thick and thin skin. Is hair inthick or thin skin? 5. WHich cells of the epidermis produce melanin? What happens to the melanin once it is produced? 6. How do genetic factors, exposure to sunlight, and hormones determine the amount of melanin in the skin? 7. How do carotene, blood flow, blood O2 content, and collagen affect skin color? Dermis Considered a connective tisue Gives structural strength. C.T. with many fibers ( collagen, elastic, and reticular), fibroblasts, macrophages, and adipocytes. Contain nerves, blood vessels, hair follicles, smooth muscles, glands, and lympathic vessels. Sensory function: pain, itchy, tickle, temperature, touch, pressure, two- point discrimination. Recall: Connective tissue consists of cells distributed widely in an extensive extracellular matrix, which includes protein fibers. Collagen is the main type of protein fiber of the extracellular matrix, but elastic and reticuar fibers are also present. Nerve endings are varied in structure and function they include: 1. free nerve endings for pain: itch, tickle, and tempature sensations 2. Hair follicle receptors for ligh totuch 3. Pacinian corpuscles for deep pressure 4. Meisnner corpsucles for detecting stimulataneous stimulation at two points on the skin 5. Ruffni end organs for sensing continous touch or pressure Two Layer of dermis, varies in thickness Papillary: Superficial. Areolar with lots of elastic fibers The naming of the layer derives its name from projections called dermal papillae which extends towards the epidermis Loose connective tissue with thin fibers that are somewhat loosely arranged also contains blood vessels that supply the overlying epidermis with O2 and nutrients, remove waste products, and aid in regulating body temperature.  The dermal papillae under the thick siin of the palms of the hands and soles of the feet lie in parallel, curving ridges. These ridges then form the overlying epidermis into patterns called friction edges! Impression leeft on surfaces by these friction edges form fingerprints and footprints Friction ridges improve the grip of the hands and feet Everyone has unique friction ridge patters, even identical twins Reticular: Composed of dense irregular connective tissue, is the main layer of the dermis Continous with the subcutaneous tissue and forms a mat of irregularly arranged fibers these fibers are resistant to stretching in many direction Elastic and collagen fibers are oriented more in some directions than in other and produce cleavage lines, or tensions lines, in the skin It is important for health professioanls to understand clevage line directions because an incesion made parallel to the clevage lines is less likely to gap than an incision made across them. The development of infections and the formation of scar tissue are reduced in wounds where the edges are closer together. if the skin is overstretched, the dermis may rupture and leave lines that are visible through the epidermis. These lines of scar tissue are known as stretch marks, can develop in the skin of individuals who have experienced rapid growth. For ex) pregnant women get scars on their breasts and abdomen because they increase in size due to hormonal changes and yk carrying a baby. TEXTBOOK QUESTION 8. Name and compare the two layers of the dermis. Which layer is responsible for most of the structural strength of the skin? 9. What are formed byu the dermal papillae in thick skin? What roles do they have? 10. What are clevage lines, and how are they related to the healing of a cut? - 5.3 Subcutaneous Tissue The subcataneous tissue attaches the skin to underlying bone and muscle and supplies the skin with blood vessels and nerves. Formed with loose connective tissue with collagen and elastic fibers Main types of cell within the subcutaneous tissue: fibrolasts, adipocytes, macrophages. The subcutaneous tissue, which is not part of the skin, it is sometimes called the hypodermis Approximately half the body's store lipids are in subcutaneous tissue, where they function in insulation and padding and as a source of energy. can be used to estimate total body fat by pinching the skin at selected locations and measuring the thickness of the skin fold and underlying subcutaneous tissue. The thicker the fold, the greater amount of total body fat. The amount of adipose tissue varies with age, sex and diet. Infants have a chubby appearance because they have proportionately more adipose tissue than adults. Females have proportionately more adipose tissue than males, especially in thighs, buttocks, and breasts. This accounts for the difference in body shape between the sexes; it is also responsible for some of the differences in body shape between individuals of the same sex  Injections Three types of Injections: Intradermal: goes into the dermis; the skin must be taut; needle inserted at a shallow angle into the skin Subcutaneous: extends into the subcutaneous layer; the skin is pinched; short needle Intramuscular: reaches a muslce deep to the subcutaneous tissue; long needle at a 90 degree angle. Intramuscular injections are used for injecting most vaccines and certain anitbiotics TEXTBOOK QUESTION 11. Name the type of tissue forming the subcutaneous tissue layer. 12. How is the subcutaneous tissue related to the skin? 13. List the functions of the adipose tissue within the subcutaneous tissue - 5.4 Acessory Skin Structures The skin includes several types of structures that are embedded in or otherwise associated with the epidermis and dermis and are therefore reffered to as accessory structures. The accessory skin structures include the hair, glands, and nails. Hair Found everywhere on human body except palms, soles, lips, nipples, parts of external genitalia, and histal segments of fingers and toes. Hair strucure and coloration changes as a person ages. Lanugo: delicate, unpigmented hair of the fetus Terminal Hair: long, course pigmented hair of the scalp, eyelids, eyebrows, and with puberty, axilla, pubic and face. Vellus Hair: fine, short hair on the rest of the body Hair Structure Shaft protrudes above skin surface Root comprised of columns of dead, keratinized epithelial cells arranged in cocentric layers;located below the surface;base of root is the hair bulb Has 3 concentric layers Medulla: central axis Cortex: forms bulk of hair Cuticle: forms hair surface  The medulla has two or three layers of soft keratin Cortex has hard keratin Cuticle contains. asingle layer of cells also containing hard keratin. The edges of the cuticle cells overlap like shingles on a roof. Hair bulb expanded base of root Internal Matrix is a source of hair Dermis projects into bulb as hair papilla, serves as blood supply Hair Follicle Dermal Root Sheath: part of the dermis that surrounds the epithelial root sheath. Epithelial root sheath is divided into external and internal parts Internal parts contain stratum basale that may remain after injury and suply a source of new epidermis When hairs are pulled out, internal part comes out and is visible as white bulb. If the epidermis and the superficial part of the dermis are damabged, then the keratinocyte stem cells located in the stratum basale of the undamged part of hair follicle can be a source of new epithelium. Inside the hair bulb is a mass of undifferentiated epithelial cells called the matrix Matrix produces: hair Internal epithelial root sheath Dermis of the skin projects into the hair bulb as hair papilla. Within the hair papilla there are blood vessels that provide nourishment to the cells of the matrix Hair Growth Growth and resting stages are cylic Growth stage: cells are added at the base of the hair root and the hair elongates Resting Stage: follows after the growth stage follicle shortens holds hair in place Rest, then hair falls out follicle New hair begins. The amount of time spent in each stage depends on the type or location of the hair. Regular hair loss emans the hair is being replaced Permanent hair loss: pattern baldness most common cause Alopecia areta is spot baldness most likely due to an autoimmune response Hair Color and Muscles caused by varying amonts and types of melanin. Melanin can be black- brown and red. Color is controlled by several genes. Muscle Arrector Pili: Type of smooth muscle Extends from the dermal root sheath of the follicle to the papillary layer of the dermis Muslce contracion causes hair to "stand on end" Skin pushed up by movement of hair follicle to produce "goose bumps" TEXTBOOK QUESTIONS 14. When and where are lanugo, vellis, and terminal hairs found in the skin? 15. What are the regions of a hair? What type of cells make up most of a hair? 16. Describe the thre layers of a hair seen in cross section 17. Describe the parts of a hair folllicle. How is the epithelial root sheath important in skin repair? 18. In what part of a hair does growth take place? 19. What determines the different shades of hair color? 20. Explain the location and action of arrector pili muscles. Accessory Skin Structures: Glands Sebaceous Glands Holocrine (death of secretory cells). Located in the dermis Composed of simple or compound alveolar glands that produce sebum, an oily white substance rich in lipids. Most sebaceous glands release their secretions into the upper part of the hair follicles through a duct The secretion of sebum onto the hair and surrounding skin prevents drying and protects against some bacteria A few subaceous glands located in the lipds, eyelids (meibomian glands), and the genitalia are not associated with hairs but open directly onto the skin surface. Sweat (Sudoriferous) Glands Two types traditionally called apocrine and merocrine, but apocrine may secrete in a merocrine or holocrine fashion Eccrine (merocrine) glands. Most common; numerous in palms and soles Simple coiled tubular glands Open directly onto the surface of skin. Have own pores. Has two parts: the deep, coiled portion mostly located in the dermis The duct, which pases to the skin surface Coiled part od the gland produces an isotonic fluid that is mostly water but also contains some salts (mainly sodium choride) and small amounts of ammonia, urea, uric acid, and lactic acid. As the fluid moves through the duct, sodium chloride moves through active transport from the duct back into the body therbey conserving salts. The result here is hyposmotic fluid known as sweat containing mostly water and some wastes. Interestingly enough the sweat you produce from either evaporates and cools the body. Eccrine sweat glands are NOT found on the margins of the lipds, the labia minora, and the tips of the penis and the clitoris Apopcrine Glands Simple coiled tubular, usually open into hair folicles superifcial to opening of sebaceous gland. Apopcrine glands are found in the axillae and genitallia ( scrotum and labia majora) and around the anus. These glands do not help with regulatin gthe body's temperature Active during pubery as a result of the sex hormones  Secretions contain organic substances that are essentiallu odorless when first released but are quickly metabolized by bacteria to cause what is commonly known as body odor. Physiologists have suggested that the activity of apocrine sweat glands may signal maturity. Other Glands Ceruminous Glands: modified eccrine sweat glands in the external auditory canal (external auditory canal) Earwax (cerumen) composed of a combination of sebum and secretion from ceruminous Function: In combination with hairs, prevent dirt and insects from entry. Mammary Glands: modified apocrine sweat glands that produce milk; found in the breasts. Acessory Skin Structures: Nails Structure: thin plate of layers of dead stratum corneum cells with hard keratin. Nail Body: stratum corneium visible portion Eponychium or cuticle is corneum superficial to nail body,, hyponchium is corneum beneath the free edge Matrix and the Nail bed: cells that give rise to the nail Nail root: covered by skin; extends from nail matrix Cuticle: Stratum corneum of the nail folds and growns onto the nail body Beneath the free edge of the nail there is the Hypony, a thickened region of the stratum cornieum. The nail matrix and bed are composed of epithelial tissue with a stratum basale that gives rise to the cells that form the nail. Growth continously unlike hair Fingernails grow.5 to 1.2mm/day; faster than the toenails Lunula: small part of nail matrix seen through the nail body as whitish, crescent shapeed area at the base of the nail. TEXTBOOK QUESTIONS 21. What do sebaceous glands secrete? What is the functin of the secretion? 22. WHich glands of the skin are responsible for cooling the body? Where are they located? Which glands are involved with producing body odor? Where are they located? 23. Name the parts of a nail. Which part producs most of the nail? What is the lunula? 24. What makes a nail hard? DO nails have growth stages? - 5.5 Physiology Of The Integumentary System Protection: Against Abrasion, slighing off of bacteria as desquamation occurs The dermis and the epidermis play roles in this line of defense Dermis, particularly the irregular dense connective tissue of the reticular layer, provides structural strength, preventing the tearing of the skin Stratified Epithelium specifically protects against abrasion Outer cells of the stratum corneum slough off, they are replaced by cells from the stratum basale. Skin prevents microorganisms and other foreign substances from entering the body Secretions from the skin glands produce an environment unsuitable for some microorganisms Skin also contains components of the immune system that act against microorganisms. Melanin absorbs the ultraviolet light and protects underluing structures from its effects. Hair on the head acts as an insulator and protects from UV light and abrasion. Eyebrows keeps sweat out of the eyes, the eyelashes protect eyes from foreign objects, and hair in the nose and ears prevent dust and other materials from entering. Auxillary and pubic hair protect against abrasion. Nails protect the ends of the fingers and toes from damage and can be used in defense Intact skin plays an importnat role in reducing ater loss because its lipids act as a barrier to the diffusion of water. Note: The skin acts as a barrier, it is interesting to note that some lipid-soluble substances readily pass through the epidermis. Lipid solube medications can be administered by applying them to the skin, after which the medication slowly diffuses through the skin into the blood. Physiology of the Integumentary System Sensation: Pressure, temperature, pain, heat, cold, touch, movement of hairs ( the hair fllicles are typically responsible for sensation) Sensory receptors surrounding the base of hair follicles can detect hair movment Temperature Regulation: sweating and radiation Sweat causes evaporative cooling Arterioles in dermis change diameter as temperature changes. More or less blood flows through the dermis. Vitamin D Production Begins in skin: aids in Ca2+ absorption Vitamin D (calcitriol): hormone Stimulates uptake of Ca2+ and PO 2- 4 from intestines Promotes Ca2+ and PO2- 4 release from bones. Reduces Ca2+ loss from kidneys. Increases blood Ca2+ levels. 7-dehydrocholesterol converts to cholecalciferol when exposed to UV radiation. Cholecalciferol released to blood and modified in the liver and kidneys to form calcitriol (active vitamin D). People in cold climates and those who cover the body can be deficient, but calcitriol can be absorbed through intestinal wall. Sources: dairy, liver, egg yolks, supplements. 36 1. Vitamin D syntheisis involves a precusor molecule, 7 dehydrocholesterol, which is stored in the skin. When exposed to UV light, the precursor molecule is converted into cholecalciferol, which is released into the blood. 2.Cholecalciferol is transported first to the liver where it is modifiied. The modified cholecalciferol re-enters the blood and is transported to the kidneys. 3. At the kidneys, the substance is again modified to form active vitamin D3, also called calcitriol. Calcitriol stimulates the uptake of calcium and phosphate at the small intestine. Excretion: Removal of waste products from the body Includes: water, salt, also contains a small amount of waste products including urea, uric acid, and ammonia The loss amount of sweat lost is insignificant in comparison to the kidneys.. becuase the urinary system does excrete most of the body's waste products. TEXTBOOK QUESTIONS 25. In what ways dos the skin provide protection? 26. What kinds of sensory receptors are in the skin, and why are they important? 27. How does the skin help regulate body temperature? 28. Name the locations where cholecalciferol is produced and then modified into active vitamin D (calcitriol). What are the functions of active Vitamin D (calcitriol)? 29. What substances are excreted in sweat? Is the skin an important site of excretion? - 5.6 Burns Burns are an injury to tissue caused by cold, friction, chemicals, electricity, or radiation. Burns are classified according to the extent of surface area involved and depth of the burn. Partial - Thickness First degree burns: involve only the epidermis and may result in redness, pain and slight edema (swelling) Second - degree: damage the epidermis and the dermis. Minimal damage causes redness, pain, edema, and blisters Full Thickkness also known as Third - Degree Burns The epidermis and dermis are completely destroyed and tissue just below the skin may be involved. Often surrounded by first and second degree burns The area surrounding the third degree burn is painful the actual burn should be painless because the sensory receptors have been destroyed. Fourth Degree Burns: extremely severe burns that affect tissues deeper than the subcutaneous tissue, often damaging the tendons, fascia, musle, and bone. Because of the severity of tissue damage, fourth degree burns often require amputation or removal of damaged tissue. Skin Grafts: Split skin Artifical Skin Cadavers or pigs Effects of Aging on the Integumentary System Skin more easily damaged because epidermis thins and amount of collagen decreases. Skin infections more likely. Wrinkling occurs due to decrease in elastic fibers. Skin becomes drier. Decrease in blood supply causes poor ability to regulate body temperature. Functioning melanocytes generally decrease; age spots are areas of increased melanin production. Sunlight ages skin more rapidly.