Anatomy and Physiology assigned reading notes
Anatomy and Physiology assigned reading notes Biology 220 Human Anatomy and Physiology
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Biology 220 Human Anatomy and Physiology
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Anatomy Lab/lecture Notes Emergent property: an ability/feature that emerges when subparts are combined in a particular way. All of the parts = the sum of the parts. Put all the parts togethergain purpose of the sum of the parts. Anatomy: the study of the structure of the human body and relative relationships among body parts. Physiology: is the study of normal function in the human body. Levels of organization: Organism level: is the highest level of organization and includes the structure and function of all the organ systems in the body. Organ systems level: a collection of organs functions as a unit to carry out a collection of related body activities. Organ level: two or more tissues are arranged into a structure that has a well- defined, three-dimensional shape and a specific body function. Tissue level: collections of cells that are grouped to perform a similar function. Cellular level: organelles, which are composed of molecules, are organized in a unique way to form cells. The cell represents the fundamental unit of life. Chemical level: the chemical bonds between atoms give rise to molecules. Anatomical position: a universally accepted standard position for the body. An individual in the anatomical position stands erect with the head and eyes directed forward. The upper limbs are by the sides, with palms facing forward, and the lower limbs are together with the toes facing forward. Integumentary system: skin, hair, and nails. Provides protection from injury and fluid loss and provides physical defense against infection by microorganisms. Involved in temperature control. Skeletal system: Muscular system: Nervous system: Cardiovascular system: Heart, blood, and blood vessels. Transports oxygen, nutrients, and other substances to the cells, and transports wastes, carbon dioxide, and other substances away from the cells; it can also help stabilize body temperature and pH. Lymphatic system: Lymph, lymph nodes, and lymph vessels. Defends against infection and disease. Transfers lymph between tissues and the blood stream. Digestive system: Mouth, salivary glands, esophagus, stomach, liver, gallbladder, exocrine pancreas, small intestine, and large intestine. Processes foods and absorbs nutrients, minerals, vitamins, and water. Endocrine: Pituitary, pineal, thyroid, parathyroid, endocrine pancreas, adrenals, testes, and ovaries. Provides communication within the body via hormones. Directs long-term change over other organ systems to maintain homeostasis. Medical terminology involves using word roots, prefixes, suffixes, and combining forms to build terms related to the body in health and disease. Most are derived from Greek or Latin. Assigned reading Week 1-2 Week 2: 1-1 through 1-4 (pgs. 2-7), 1-8 (pages 18-22), Chapter 2 2-1 (pgs. 27-31), chapter 3 page 65, chapter 4 4-1, 4-2, 4-4, (Pgs. 114-118), chapter 5 5-1 and 5-5 (pages 151-155, 160-162) Note: notes are taken directly from textbook. Some may be direct quotes, some may be paraphrases, and all credit goes to author of textbook. Section 1-1 through 1-4: Anatomy: study of body structure. the oldest medical science Physiology: study of body function Medical terminology: uses word roots (basic, meaningful parts of a term that cannot be broken down into another term with another definition), prefixes (word elements that are attached to the beginning of words to modify their meaning but cannot stand alone), suffixes (word elements or letters added to the end of a word or word part to form another term.), and combining forms (independent words or word roots that are used in combination with words, prefixes, suffixes, or other combining forms to build a new term) to build terms related to the body in health and disease. Pathology: study of disease Eponyms: commemorative names International anatomical terminology: book that serves as the international standard for anatomical vocabulary Principle of complementarity of structure and function: all specific functions are performed by a specific structures, and the form of a structure relates to its function Gross anatomy: involves examining relatively large structures, can be seen without a microscope 1. Surface anatomy: the study of general form and superficial (toward the body surface) markings 2. Regional anatomy: focuses on the anatomical organization of specific areas of the body, such as the head, neck, or trunk. Many advanced courses in anatomy stress a regional approach, because it emphasizes the spatial relationships among structures already familiar to students 3. Systemic anatomy: the study of the structure of organ systems. 4. Clinical anatomy: includes a number of subspecialties important in clinical practice. Examples include pathological anatomy (anatomical features that change during illness), radiographic anatomy (anatomical structures seen using specialized imaging techniques), and surgical anatomy (anatomical landmarks important in surgery) 5. Developmental anatomy: describes the changes in form that take place between conception and adulthood. The techniques of developmental anatomists are similar to those used in gross anatomy and in microscopic anatomy (discussed next) because developmental anatomy considers anatomical structures over a broad range of sizes from a single cell to an adult human. The most extensive structural changes take place during the first two months of development. Organ systems: groups of organs that function together in a coordinated manner. Microscopic anatomy: study of structures that cannot be seen without a microscope 1. Cytology: the study of the internal structure of individual cells, the simplest units of life. 2. Histology: examination of tissues (groups of specialized cells and cell products that work together to perform specific functions) tissues combine to form organs. Human physiology: the study of the functions, or workings, of the human body. 1. Cell physiology: the study of the functions of cells is the cornerstone of human physiology. Cell physiology looks at events involving the atoms and molecules important to life. It includes both chemical processes within cells and chemical interactions among cells. 2. Organ physiology: is the study of the function of specific organs. 3. Systemic physiology: includes all aspects of the functioning of specific organ systems. Cardiovascular physiology, respiratory physiology, and reproductive physiology are examples 4. Pathological physiology: is the study of the effects of diseases on organ functions or system functions. Modern medicine depends on an understanding of both normal physiology and pathological physiology. Signs: an objective disease indication like a fever Symptoms: a subjective disease indication like tiredness Levels of organization: 1. The chemical level: atoms are the smallest stable units of matter. 2. Cellular level: cells are the smallest living units in the body 3. The tissue level: a tissue is a group of cells working together to perform one or more specific functions. 4. The organ level: organs are made of two or more tissues working together to perform specific functions. 5. The organ system level: a group of organs interacting to perform a particular function forms an organ system. 6. The organism level: an organism is the highest level of organization that we consider Week 3: Chapter 1, Sections 1-5 and 1-6, pages 7-14 Homeostasis: refers to the existence of a stable internal environment. Homeostatic regulation: adjustment of physiological systems to preserve homeostasis in an environment that is often inconsistent, unpredictable, and potentially dangerous. Consists of two general mechanisms: autoregulation and extrinsic regulation 1. Autoregulation: a process that occurs when a cell, a tissue, an organ, or an organ system adjusts in response to some environmental change. For example, when oxygen levels decline in a tissue, the cells release chemicals that widen, or dilate, blood vessels. This dilation increases the rate of blood flow and provides more oxygen to the region 2. Extrinsic regulation: a process that results from the activities of the nervous system or endocrine system. These organ systems detect an environmental change and send an electrical signal (nervous system) or chemical messenger (endocrine system) to control or adjust the activities of another or many other systems simultaneously. For example, when you exercise, your nervous system issues commands that increase your heart rate so that blood will circulate faster. Your nervous system also reduces blood flow to less active organs, such as the digestive tract. The oxygen in circulating blood is then available to the active muscles which need it most. Nervous system is rapid, short-term, and very specific in its response. The endocrine system releases chemical messengers called hormones into the bloodstream. May not be immediately apparent but effects are longer lasting. Blood volume, composition, and the adjustment of organ system function during starvation are dictated by endocrine system A homeostatic regulation mechanism consists of three parts 1. A receptor (a change) 2. A control center: which receives and processes information supplied by the receptor and sends out commands 3. An effector: a cell or organ that responds to the commands of the control center and whose activity either opposes or enhances the stimulus Set point: desired value Section 1-6: negative feedback opposes variations from normal, whereas positive feedback exaggerates them Negative feedback: a way of counteracting a change. (ex. Thermoregulation control of body temperature) hypothalamus When body temperature changes it targets two effectors 1. Muscle tissue lining the walls of blood vessels supplying blood to the skin 2. Sweat glands. The muscle tissue relaxes so the blood vessels dilate, increasing blood flow through vessels near the body surface and the sweat glands speed up their secretion of sweat. The body loses heat to the environment, and the evaporation of sweat speeds the process. Negative feedback is the primary mechanism in homeostatic regulation and provides long term control over the body’s internal conditions and systems. Body temperature can vary due to small fluctuations around the set point or changes in the set point. Positive feedback: an initial stimulus produces a response that exaggerates or enhances the original change in conditions, rather than opposing it. “Continual rise until it is stopped positive feedback loop” A state of equilibrium exists when opposing processes or forces are in balance. Dynamic equilibrium: continual adapting and adjusting to changing condition The roles of organ systems in homeostatic regulation o Body temperature Integumentary system (heat loss) Muscular system (heat production) Cardiovascular system (heat distribution) Nervous system (coordination of blood flow, heat production, and heat loss o Body fluid composition Nutrient concentration Digestive system (nutrient absorption, storage, and release) Cardiovascular system (nutrient distribution) Urinary system (control of nutrient loss in the urine) Skeletal system (mineral storage and release) Oxygen, carbon dioxide levels Respiratory (absorption of oxygen, elimination of carbon dioxide) Cardiovascular system (internal transport of oxygen and carbon dioxide) Levels of toxins and pathogens Lymphatic system (removal, destruction, or inactivation of toxins and pathogens) o Body fluid volume Urinary system (elimination or conservation of water from the blood) Digestive system (absorption of water; loss of water in feces) Integumentary system (loss of water through perspiration) Cardiovascular system and lymphatic system (distribution of water throughout body tissues) o Waste product concentration Urinary system (elimination or conservation of water from the blood) Digestive system (elimination of waste product from the liver in feces) Cardiovascular system (transport of waste products to sites of excretion o Blood pressure Cardiovascular system (pressure generated by the heart moves blood through blood vessels) Nervous system and endocrine system (adjustments in heart rate and blood vessel diameter can raise or lower blood pressure) Section 1-7 Superficial anatomy: involves locating structures on or near the body surface A plane that lies at right angles to the long axis of the body is the transverse (or horizontal) plane. It divides the superior and inferior portions. Frontal or coronal section separates anterior and posterior portions of the body. Coronal usually refers to sections passing through the skull Sagittal plane: plane is oriented parallel to the long axis Section 1-8: Three major regions established by the body wall: thoracic, abdominal, and pelvic regions. Body cavities: closed, fluid-filled, and lined by a thin tissue layer called serous membrane or serosa. o Thoracic (chest) cavity) o Pericardial cavity (heart) o Abdominopelvic (stomach) o Mediastinumsection of tissue between the lungs o Diaphragm (flat muscular sheet) separates the thoracic (chest) cavity from abdominopelvic (stomach) cavity o Viscera: organs that are enclosed in cavities. Section 2-1 Chemistry: the science that deals with the structure of matter (anything that takes up space and has mass Mass: the amount of material in matter Atoms: smallest stable units of matter Subatomic particles compose atoms. (protons, neutrons and electrons) Nucleus: central region of an atom Atomic number: defined by number of protons Electron cloud: the spherical area the electrons travel around the nucleus in. Element: purse substance composed of atoms of only one kind. Isotopes: element whose nuclei contain different numbers of neutrons o Radioisotopes: radioactive isotopes The decay rate of a radioisotope is commonly expressed as its half-life: the time required for half of a given amount of the isotope to decay Mass number: total number of protons and neutrons Mole: specific quantity with a weight in grams equal to that elements weight Valence shell: the outermost energy level forms the surface of the atom Chapter 3 page 65 Cytology: the study of cellular structure and function which is a part of cell biology (which integrates aspects of biology, chemistry, and physics) Sex cells: (also called germ cells or reproductive cells) are either the sperm or egg. Somatic cells: or body cells include all other cells in the human body. Chapter 4 4-1, 4-2, 4-4, (Pgs. 114-118), tissue types: epithelial, connective, muscle, and neural Tissues: collection of specialized cells and cell products that carry out a limited number of functions. Histology: study of tissues Epithelial tissue: covers exposed surfaces, lines internal passageways and chambers, and forms glands. Skin o Functions: provide physical protection, control permeability, provide sensation, and produce specialized secretions (in a glandular epithelium, most or all of the epithelial cells produce secretions. These cells either discharge their secretions onto the surface of the epithelium (to provide physical protection or temperature regulation) or release them into the surrounding interstitial fluid and blood (to act as chemical messengers) o Epithelia: layers of cells that cover internal or external surfaces To maintain integrity of epithelia 1) Intercellular connections: involve extensive areas of opposing plasma membranes or specialized attachment sites. Large areas of opposing plasma membranes are interconnected by transmembrane proteins called cell adhesion molecules (CAMs) which bind to each other and to extracellular materials. For example, CAMs on the basolateral surface of an epithelium help bind the cell to the underlying basement membrane. The membranes of adjacent cells may also be bonded by a thin layer of proteoglycans that contain polysaccharide derivatives known as glycosaminoglycan’s (GAGs) most notably hyaluronic o Cell junctions: specialized areas of the plasma membrane that attach a cell to another cell or to extracellular materials. (three common types) Tight junctions: (also known as occluding junction) the lipid portions of the two plasma membranes are tightly bound together by interlocking membrane proteins. Inferior to the tight junctions, a continuous adhesion belt forms a band that encircles cells and binds them to their neighbors. The bands are attached to the microfilaments of the terminal web, this kind of attachment is so tight that tight junctions largely prevent water and solutes from passing between the cells. Lumen: passageway that enables tight junctions to be permeable Gap junctions: some epithelial functions require rapid intercellular communication. At a gap junction, two cells are held together by two interlocking transmembrane proteins called connexons. Each connexon is composed of six connexon proteins that form a cylinder with a central pore. Two aligned connexons form a narrow passageway that lets small molecules and ions pass from cell to cell. Gap junctions are common among epithelial cells, where the movement of ions helps coordinate functions such as the beating of cilia. Gap junctions are also common in other tissues. For example, gap junctions in cardiac muscle tissue and smooth muscle tissue are essential in coordinating muscle cell contractions. A number of human diseases are caused by mutations in the genes that code for different connexon proteins Desmosomes: “stretchy” and strong epithelial cells Spot desmosomes: small discs connected to intermediate filament. Intermediate filaments stabilize the shape of the cell Hemi desmosomes: look like half a spot desmosomes. Attaches a cell to extracellular filaments in the basement membrane. Helps stabilize the position and anchors it to underlying tissues 2) Attachment to the basement membrane: the deeper portion (dense layer) of the basement membrane is very strong. 3) Epithelial maintenance and repair: continual division of stem cells. Most of these stem cells (germinative cells) are located near the basement membrane o Glands: structures that produce fluid secretions. They are either attached to or derived from epithelia. o Cellularity: epithelia are made almost entirely of cells bound closely together by interconnections known as cell junctions. They may be specialized for the movement of fluids over the epithelial surface (providing protection or lubrication), the movement of fluids through the epithelium to control permeability, or the production of secretions that provide physical protection or act as chemical messengers. Specialized epithelial cells generally possess a strong polarity. o Polarity: an epithelium has an exposed surface, which faces the exterior of the body or an internal space, and a base which is attached to underlying tissues. The term polarity refers to the presence of structural and functional differences between the exposed and attached surfaces. An epithelium consisting of a single layer of cells has an exposed apical surface and an attached basal surface. The two surfaces differ in plasma membrane structure and function. o Attachment: the base of an epithelium is bound to a thin, non-cellular basement membrane (which is also called basal lamina). The basement membrane is a complex structure produced by the basal surface of the epithelium and the underlying connective tissue. o Avascularity: epithelia are avascular which means they lack blood vessels. Epithelial cells get nutrients by diffusion or absorption across either the exposed or the attached epithelial surface o Regeneration: epithelial cells that are damaged or lost at the exposed surface are continuously replaced through stem cell divisions in the epithelium. Regeneration is a characteristic of the other tissues as well, but the rates of cell division and replacement are typically much higher in epithelia than in other tissues. o Ciliated epithelium: a typical ciliated cell contains about 250 cilia that beat in a coordinated manner. The synchronized beating of the cilia moves substances over the epithelial surface. Connective tissue: fills internal spaces, provides structural support for other tissues, transports materials within the body, and stores energy Muscle tissue: specialized for contraction and includes skeletal muscles of the body, the muscle of the heart, and the muscular walls of hollow organs Neural tissue: carries information from one part of the body to another in the form of electrical impulses Section 4-4 126-133 Connective tissue: connects the epithelium to the rest of the body. Other types of connective tissue include bone fat, and blood. They provide structure, store energy, and transport materials throughout the body respectively. Basic components: specialized cells, extracellular protein fibers, and a fluid known as ground substance. Together the extracellular fibers and ground substance make up the matrix which surrounds the cells. Functions: establish a structural framework for the body, transports fluids and dissolved materials, protects delicate organs, supporting, surrounding, and interconnecting other types of tissue, storying energy, especially in the form of triglycerides, defending the body from invading microorganisms. Classification of connective tissues Connective tissue proper: includes those connective tissues with many types of cells and extracellular fibers in a syrupy ground substance. This broad category contains a variety of connective tissues that are grouped into loose connective tissues and dense connective tissues. These groupings are based on the number of cell types present, and on the relative properties and proportions of fibers and ground substance. Both adipose tissue (a loose connective tissue) and tendons (a dense connective tissue) are connective tissue proper but they have very different structural and functional characteristics. 1. Local maintenance, repair and energy storage: fibroblasts, fibrocytes, adipocytes, and mesenchymal cells 2. Cells that defend and repair damaged tissues (are more mobile): macrophages, mast cells, lymphocytes, plasma cells, and microphages. Not permanent residents, migrate and collect at site of injury. Fluid connective tissues: have distinctive populations of cells suspended in a watery matrix that contains dissolved proteins. The only two types are blood and lymph Supporting connective tissues: differ from connective tissue proper in having a less diverse cell population and a matrix containing much more densely packed fibers. Supporting connective tissues are cartilage and bone. The matrix of cartilage is a gel with characteristics that vary with the predominant type of fiber. The matrix of bone is calcified, because it contains mineral deposits (primarily calcium salts) that provide rigidity. Connective tissue proper cell populations: 1. Fibroblasts: are the only cells are ALWAYS present in connective tissue proper. They are also the most abundant, permanent, or fixed, residents of connective tissue proper. Fibroblasts secrete hyaluronic (a polysaccharide derivative) and proteins. (Recall that hyaluronic is one of the ingredients that helps lock epithelial cells together.) In connective tissue proper, extracellular fluid, hyaluronic, and proteins interact to form the proteoglycans that make ground substance viscous. Each fibroblast also secretes protein subunits that assemble to form large extracellular fibers. 2. Fibrocytes: are the second most abundant fixed cell in connective tissue proper. They differentiate from fibroblasts. Fibrocytes are spindle shaped cells that maintain the connective tissue fibers of connective tissue proper 3. Adipocytes: also known as fat cells. Contain a single lipid droplet. Nucleus, organelles, and cytoplasm squeezed to one side. Sectional view of cell resembles class ring. Number of adipocytes vary between connective tissues, regions of body, and individuals 4. Mesenchymal cells: stem cells that are present in many connective tissues. These cells respond to local injury or infection by dividing to produce daughter cells that differentiate into fibroblasts, macrophages, or other connective tissue cells 5. Macrophages: large phagocytic cells scattered throughout the matrix. “Scavengers” engulf damage cells of pathogens that enter the tissue. Not abundant but are important in mobilizing the bodies important in mobilizing the body’s defenses. When stimulated they release chemicals that activate the immune system and attract large numbers of additional system and attract large numbers of additional macrophages and other cells involved in tissue defense. Are either fixed or free (migrates where needed). Fixed macrophages provide frontline defense and free macrophages provide “reinforcements” 6. Mast cells: small and mobile connective tissue cells that are usually near blood vessels. Cytoplasm is filled with granules containing histamine and heparin. Histamine is released after injury or infection and stimulates local inflammation. Basophils blood cells that enter damaged tissues and enhance the inflammation process. Also contain granules of histamine and heparin. Heparin levels in the blood are normal low. It is an anticoagulant that enhances local blood flow during inflammation and reduces the development of blood clots in areas of slow-moving blood. 7. Lymphocytes: migrate throughout the body travelling through connective tissues and other tissues. Their numbers increase markedly wherever tissue damage occurs. Some lymphocytes may develop into plasma cells which produce antibodies- proteins involved in defending the body against disease 8. Microphages: phagocytic blood cells that move through connective tissues in small numbers. Attracted to site of infection or injury by chemicals released by macrophages and mast cells. 9. Melanocytes: synthesize and store melanin which gives tissues dark color. Common in the epithelium. Abundant in connective tissues of the eye and dermis. Differs in body region and individuals. Connective tissue fibers o Collagen fibers: most common. Every collagen fiber consists of fibrous protein subunits wound together like the strands of a rope. Is flexible like a rope but is stronger than steel. Tendons are generally almost entirely made of collagen fibers. Ligaments are similar but they connect one bone to another bone. Both can withstand tremendous forces. Uncontrolled muscle contractions or skeletal movements are more likely to break a bone than to snap a tendon or a ligament. o Reticular fibers: contain same subunits as collagen fibers but are arranged differently. Thinner, branching, interwoven framework that is tough yet flexible. Resist forces from many directions because they form a network rather than share a common alignment. Interwoven network is called a stroma and it stabilizes the relative positions of the functional cells or parenchyma of organs such as liver. Reticular fibers also stabilize the positions of an organs blood vessels, nerves, and other structures, despite changing positions and the pull of gravity. o Elastic fibers: contain elastin. Fibers are branched and wavy. After stretching, they return to their original length. Elastic ligaments, which are dominated by elastic fibers, are rare but have important functions, such as interconnecting vertebrae. Ground substance: fills spaces between cells and surrounds connective tissue fibers. In connective tissue proper, ground substance is clear, colorless, and viscous because of proteoglycans and glycoproteins. So viscous that bacteria have trouble moving through it. Slows the spread of pathogens and makes them easier for phagocytes to catch Embryonic connective tissues o Mesenchyme: embryonic connective tissue. First connective tissue to appear in a developing embryo. Contains star shaped stem cells separated by a matrix with very fine protein filaments. Gives rise to all other connective tissues o Mucous connective tissue is a loose connective tissue found in many parts of the embryo including the umbilical cord. o Adults have neither form of embryonic connective tissue. Most adult connective tissues contain scattered mesenchymal stem cells that can assist in tissue repair after an injury Loose connective tissues: “packing materials” of the body. Fill spaces between organs, cushion and stabilize specialized cells in many organs, and support epithelia. These tissues surround and support blood vessels and nerves, store lipids, and provide a route for diffusion of materials. Loose connective tissues include mucous connective tissue in embryos and areolar tissue, adipose tissue, and reticular tissue in adults o Areolar tissue: found: within and dep to the dermis of skin, covered by the epithelial lining of the digestive, respiratory, and urinary tracts; between muscles, around joints, blood vessels, and nerves. Functions: cushions organs; provides support but permits independent movement; phagocytic cells provide defense against pathogens least specialized connective tissue in adults. May contain all the cells and fibers of any connective tissue proper in a very loosely organized array. Open framework. Viscous grounds substance provides volume and absorbs shocks. Can distort without damage because its fibers are loosely organized. Elastic fibers make it resilient. Returns to original shape after pressure is relieved. Layer separates skin from deeper structures. Provides padding. Elastic properties of this layer allow independent movement. Common injection site for drugs because it has extensive blood supply. Two capillaries deliver oxygen and nutrients and remove carbon dioxide and waste products. Carry wandering cells to and from the tissue. Epithelia commonly cover areolar tissue and fibrocytes maintain the dense layer of the basement membrane that separates the two kinds of tissue. The epithelial cells rely on the oxygen and nutrients that diffuse across the basement membrane from capillaries in the underlying connective tissue. o Adipose tissue: found: deep to the skin especially at sides, buttocks, and breasts, padding around eyes and kidneys. Functions: provides padding and cushions shocks; insulates and stores energy. Adipocytes account for most of the volume of adipose tissue, but only a fraction of the volume of areolar tissue. Provides padding, absorbs shocks, acts as an insulator to slow heat loss through the skin and serves as packing or filler around structures. Common under the skin between the last rib and the hips (flanks), buttocks, and breasts. Fills bony sockets behind the eyes and surrounds the kidneys. Also common beneath the mesothelial lining of the pericardial and peritoneal cavities. Most of adipose tissue in the body is white fat (pale, yellow-white color). In infants and young children, however, the adipose tissue between the shoulder blades, around the neck and possibly elsewhere in the upper body is highly vascularized, and the individual adipocytes contain numerous mitochondria. Together these characteristics give the tissue a deep rich color that give its name of brown fat. When stimulated by the nervous system, lipid breakdown speeds up. Cells to not capture the energy that is release. Surrounding tissues absorb it as heat. Heat warms circulating blood to distribute throughout the body. Infants can double its metabolic heat generation very quickly. It had been thought that very little brown tissue is found in adults but recently it’s indicated its presence in adults, and that its absence may be connected to obesity. Adipocytes are metabolically active. Lipids are constantly broken down and replaced. Adipocytes deflate like collapsing balloons as their lipids are broken down and the fatty acids released to support metabolism. When nutrients are plentiful the lost body wait can be regained. Cells are not killed, merely shrunk. You always have the same amount of adipocytes in your body from birth to death. Liposuction provides a dangerous solution to fat. Other cells turn into fat cells. o Reticular tissue: found: liver, kidney, spleen, lymph nodes, and bone marrow. Functions: provides supporting framework. Spleen and liver contain reticular tissue. Reticular fibers form a complex three- dimensional stroma. The stroma supports the functional cells, or parenchyma, of these organs. Fibrous framework also found in lymph nodes and bone marrow. Fixed macrophages, fibroblasts, and fibrocytes are associated with the reticular fibers but these cells are seldom visible because specialized cells with other functions dominate the organs. Dense connective tissues: fibers contain most of volume, often called collagenous tissues. Collagen fibers are the dominant type of fiber in them. The body has two types of dense connective tissues, dense regular connective tissue found: between skeletal muscles and skeleton (tendons and aponeuroses) between bones or stabilizing positions of internal organs (ligaments): covering skeletal muscles; deep fasciae. Function: provides firm attachment conducts pull of muscles reduces friction between muscles; stabilizes positions of bones. And dense irregular connective tissue. Collagen fibers are parallel to each other, packed tightly and aligned with the forces applied to the tissue. Tendons are cords of dense connective tissue that attach skeletal muscles to bones. Collagen fibers run longitudinally along the tendon and transfer the pull of the contracting muscle to the bone. Ligaments resemble tendons, but connect on bone to another or stabilize positions of internal organs. o An aponeurosis is a tendinous sheet that attaches a broad flat muscle to another muscle or to several bones of the skeleton. Can also stabilize the positions of tendons and ligaments. Associated with large muscles of the skull, lower back, and abdomen, and with the tendons and ligaments of the palms of the hands and soles of the feet. Large numbers of fibroblasts are scattered among the collagen fibers of tendons, ligaments, and aponeuroses Dense IRREGULAR tissues found: capsules of visceral organs; periostea and perichondria; nerve and muscle sheaths; dermis. Functions: provides strength to resist forces from many directions; helps prevent overexpansion of organs such as the urinary bladder. Form an interwoven meshwork with no consistent pattern. Tissues strengthen and support areas subjected to stresses from many directions. Gives skin its strength. Except at joints, forms a sheath around cartilages and the bones. Also forms a thick fibrous layer called the capsule which surrounds internal organs such as the liver, kidneys and spleen and encloses the cavities of joints. Both contain variable amounts of elastic fibers. When elastic fibers outnumber collagen fibers, the tissue has a springing resilient nature that allows it to tolerate cycles of extension and recoil. Abundant elastic fibers are present in the connective tissue that supports transitional epithelia, walls of large blood vessels: as the aorta, and around respiratory passageways. Elastic tissue found between vertebrae of the spinal column, ligaments supporting penis, epithelia, and in blood vessel walls. Functions: stabilizes positions of vertebrae and penis; cushions shocks: permits expansion and contraction of organs. Is a dense regular connective tissue made up mainly of elastic fibers? Elastic ligaments are almost completely dominated by elastic fibers. They help stabilize the positions of the vertebrae of the spinal column Fluid connective tissues: blood and lymph. The fluid matrix that surrounds the cells also includes many types of suspended proteins that do not form insoluble fibers under normal conditions. o Blood: red blood cells (erythrocytes) are responsible for the transport of oxygen and carbon dioxide in the blood. Account for half of the volume of blood and give its color. White blood cells (leukocytes) help defend the body from infection or disease. Monocytes are phagocytes similar to free macrophages in other tissues. Lymphocytes are uncommon in the blood but they are the common cell type in lymph, the second type of fluid connective tissue. Eosinophilic and neutrophils are phagocytes. Basophils promote inflammation much like mast cells in other connective tissues. Watery matrix is called plasma. Plasma contains blood cells and fragments of cells. Known as formed elements. Three types of formed elements: red blood cells, white blood cells, and platelets. Human body contains lots of extracellular fluid. Fluid has three subdivisions plasma, interstitial fluid, and lymph. Plasma is membrane enclosed packets of cytoplasm that functions in blood clotting... these cell fragments are involved in the clotting response that seals leaks in damaged or broken blood vessels. Plasma is confined to the vessels of the cardiovascular system. Contractions of the heart keep it in motion. Arteries carry blood away from the heart and into the tissue of the body. In the tissue, blood pressure forces water and small solutes out of the bloodstream across the walls of capillaries (smallest blood vessels). This process is the origin of the interstitial fluid that bathes the body’s cells. Remaining blood flows from the capillaries into veins that return it to heart o Lymph: forms as interstitial fluid enter lymphatic vessels. As fluid passes along the lymphatic vessels, cells of the immune system monitor its composition and respond to signs of injury or infection. The lymphatic vessels ultimately return the lymph to large veins near the heart. This recirculation of fluid – from the cardiovascular system, through the interstitial fluid to the lymph and then back to the cardiovascular system. This is a continuous process that is essential to homeostasis. It helps eliminate local differences in the levels of nutrients, wastes, or toxins, maintains blood volume and alerts the immune system to infections that may be under way in peripheral tissues Chapter 5 5-1 and 5-5 (pages 151-155, 160-162) 5-1 Skin = integument. Makes up about 16% of body weight in surface. First line of defense Cutaneous membrane: epidermis (protects the dermis, prevents water loss and the entry of pathogens and synthesizes vitamin d3. Sensory receptors detect touch, pressure, pain and temperature), dermis (papillary layer (nourishes and supports epidermis), reticular layer (has sensory receptors that detect touch, pressure, pain, vibration, and temperature. Blood vessels assist in thermoregulation)) Accessory structures: o Hair shaft o Pore of sweat gland duct o Tactile (Meissner’s corpuscle) o Sebaceous gland o Arrestor pili muscle o Sweat gland duct o Hair follicle (protects skull and provides delicate touch sensations on general body surface) o Lamellate corpuscle o Nerve fibers o Sweat gland o Exocrine glands (assist in temperature regulation and waste excretion) o Nails (protect and support tips of fingers and toes) Cutaneous plexus o Artery o Vein Hypodermis: under the dermis, loos connective tissue, known as superficial fascia or subcutaneous layer. Separates integument from deep fascia around other organs such as muscles and bones. Function of integumentary system: physical protections from environmental hazards Storage of lipids Coordination of immune response to pathogens and cancers in skin Sensory information Synthesis of vitamin d3 Excretion Thermoregulation The epidermis is composed of layers with various functions Stratified squamous epithelium. Provides protections and helps keep microorganisms outside the body. Is avascular Rely on diffusion of nutrients and oxygen from capillaries within the dermis. Epidermal cells with the highest metabolic demands are found close to the basement membrane, where the diffusion distance is short. The superficial cells far removed from the source of nutrients are dead. Keratinocytes Body’s most abundant epithelial cells dominate the epidermis. Form several layers (strata) and contain large amounts of the protein keratin. Thin skin covers most of body surface Thick skin is found on the palms of the hands and the soles of the feet. Thick and thin refer to epidermis thickness not skin as a whole Layers in order from the basement membrane toward the free surface: o Stratum Basale Hemi desmosomes attach the cells of this layer to the basement membrane that separates the epidermis from the areolar tissue of the dermis. The stratum Basale and the underlying dermis interlock, increasing the strength of the bond between the epidermis and dermis. f Forms epidermal ridges, which extend into the dermis and are adjacent to dermal projections called dermal papilla (nipple shaped mound) that project into the epidermis. These ridges and papillae are important because the strength of the attachment is proportional to the surface area of the basement membrane. The more numerous and deeper the folds, the larger the surface area becomes. Ridge patterns vary from small conical pegs (thin skin) to the complex’s whorls seen on the thick skin of the palms and soles. Cause friction. Increase grip. Ridges are determined partially by genes and partially by the intrauterine environment. Basal cells or germinative cells dominate the stratum Basale. Basal cells are stem cells that divide to replace the more superficial keratinocytes that are shed at the epithelial surface. Skin surfaces that lack hair also contain specialized epithelial tactile cells known as merkel cells scattered among the cells of the stratum Basale. Each merkel cell together with a sensory nerve terminal is called a tactile disc. Tactile cells are sensitive to touch and when compressed release chemicals that stimulate their associated sensory nerve endings. Brown tones of skin result from the synthesis of pigment by cells called melanocytes. These pigment cells are distributed throughout the stratum Basale, with cell processes extending into more superficial layers Deepest basal layer Attachment to basement membrane Contains basal cells (stem cells) melanocytes and tactile cells (merkel cells) o Stratum spinosum Every time a stem cell divides one of the daughter cells is pushed superficial to the stratum Basale into the stratum spinosum. Consists of 8-10 layers of keratinocytes bound together by desmosomes Cells look like miniature pincushions in standard histological sections. Contains cells that participate in the immune response (dendritic cells) because of their branching projects. Known as Langerhans cells as well They stimulate defense against microorganisms that manage to penetrate the superficial layers of the epidermis and superficial skin cancers. Keratinocytes are bound together by desmosomes o Stratum granulosum Superficial to the stratum spinosam Consists of 3-5 layers of keratinocytes Derived from the stratum spinosum Most have stopped dividing and have stated making large amounts of the proteins keratin and keratohyalin. As fibers accumulate, cells grow thinner and flatter and plasma membranes thicken and become less permeable. Keratohyalin forms dense cytoplasmic granulese that promote dehydration of the cell as well as aggregation and cross linking of the karatin fibers. The nuclei and other organelles then disintegrate and the cells die. Further dehydration creates a tightly interlocked layer of cells that consists of keratin fibers surrounded by keratohyalin. Keratinocytes produce keratohyalin and keratin Keratin fibers develop as cells become thinner and flatter Gradually the plasma membranes thicken, the organelles disintegrate, and cells die o Stratum lucidum Appears as a glassy layer in thick skin only Covers the stratum granulosum Cells are flattened, densely packed, largely without organelles, and filled with keratin o Stratum corneum Multiple layers of flattened, dead, interlocking keratinocytes Water resistant but not waterproof Permits slow water loss by insensible perspiration At exposed surface Contains 15-30 layers of keratinized cells. Keratinization is the formation of protective superficial layers of cells filled with keratin, takes place on all exposed layers of cells except anterior surfaces of the eyes. Dead cells in each layer of the stratum corneum remain tightly interconnected by desmosomes. Connection is so secure that cells are generally shed in large groups or sheets rather than individually. Takes 7-10 days for a cell to move from the stratum Basale to stratum corneum. Dead cells generally remain in exposed stratum corneum for an additional two weeks before shed or washed away. Water resistant, not waterproof Insensible water loss (water loss you are unaware of moisture of skin) Sensible perspiration (sweat glands sweat) 5-5 Dermis o Papillary layer Consists of areolar tissue Contains capillaries, lymphatic vessels, sensory neurons that supply the surface of the skin o Reticular layer Deeper than papillary Consists of interwoven meshwork of dense irregular tissue containing both collagen and elastic fibers. o Accessory structures such as hair follicles and sweat glands are found in dermis. o Inflammation of the skin primarily involving papillary layer dermatitis o Collagen and elastic fibers give the dermis strength and elasticity o Tretinoin (retina-A) can help stretch marks and acne heal by increasing blood flow to the dermis and stimulating dermal repair. o Dermal blood supply come from branches of two networks (plexuses) of arteries in the dermis o Tactile discs are fine touch and pressure receptors o Corpuscles are receptors to deep pressure and vibration
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