Tissues, Glands, and Membranes PDF

TISSUES GLANDS AND MEMBRANES Histology – is the study of tissue structure. Knowledge of tissue structure and function is important in understanding how individual cells are organized to form tissues and how tissues are organized to form organs, organ systems, and the complete organism. Changes in...

TISSUES GLANDS AND MEMBRANES Histology – is the study of tissue structure. Knowledge of tissue structure and function is important in understanding how individual cells are organized to form tissues and how tissues are organized to form organs, organ systems, and the complete organism. Changes in tissues can result in development, growth, aging, trauma, or disease. For example, skeletal muscles enlarge because skeletal muscle cells increase in size in response to exercise. Reduced elasticity of the blood vessel walls in aging people results from gradual changes in the connective tissues. Many tissue abnormalities, including cancer, result from changes in tissues that can be identified by microscopic examination. Cells are arranged in tissues that provide specific functions for the body. Therefore, a tissue is a group of specialized cells and the extracellular substances surrounding them. The cells of a particular tissue share a common structure and function. Cells of different tissues are structured differently, which leads to their differences in function. The tissues of the human body include four major types. These four tissue types have a wide range of functions, as shown in the following table.  Epithelial Tissues: A. General Characteristics 1. Epithelial tissue is widespread throughout the body, covers organs, and lines body surfaces like the skin 2. Epithelial tissues are anchored to a basement membrane, are made up of tightly packed cells containing little intercellular material, generally lack blood vessels, and are replaced frequently. 5- 6 Types of Epithelial Cells 5- 18 20 A. Simple Squamous Epithelium 1. Simple squamous epithelium is made up of a single layer of thin, flattened cells (squashed). 2. Because it is suited for diffusion, it functions in the exchange of gases in the lungs and lines blood and lymph vessels as well as body cavities. 5 - 23 B. Simple Cuboidal Epithelium 1. Simple cuboidal epithelium consists of a single layer of cube-shaped cells with centrally located nuclei. 2. It functions in secretion and absorption in the kidneys, and in secretion in glands. 5 - 27  C.Simple Columnar Epithelium 1. Simple columnar epithelium is made up of a row of elongated cells whose nuclei are all located near the basement membrane. It may be ciliated. 2. It lines the uterus, stomach, and intestines where it protects underlying tissues, secretes digestive fluids, and absorbs nutrients. 3. In the intestine, these cells possess microvilli that increase the surface area available for absorption. 4. Mucus-secreting goblet cells can be found among columnar cells. D. Pseudostratified Columnar Epithelium 1. These cells appear layered due to the varying positions of their nuclei within the row of cells, but are not truly layered. 2. Cilia may be present, along with mucus-secreting globlet cells, that line and sweep debris from respiratory tubes. 5 - 35  E. Stratified Squamous Epithelium 1. This type of tissue is made up of layers of flattened cells that are designed to protect underlying layers. 2. It makes up the outer layer of skin, and lines the mouth, throat, vagina, and anal canal. 3. In the skin, outer layers of cells undergo keratinization; however, this process does not occur where tissues remain moist in the throat, vagina, or anal canal. F. Stratified Cuboidal Epithelium 1. This tissue consists of two to three layers of cuboidal cells lining a lumen of the mammary glands, sweat glands, salivary glands, and pancreas. 2. Several layers of cells provide greater protection than one single layer. 5 - 41 G. Stratified Columnar Epithelium 1. This tissue consists of several layers of cells and is found in the vas deferens, part of the male urethra, and parts of the pharynx. H. Transitional Epithelium 1. Transitional epithelium is designed to distend and return to its normal size, as it does in the lining of the urinary bladder. 2. This design provides distensibility and keeps urine from diffusing back into the internal cavity. 5 - 46 I. Glandular Epithelium 1. This tissue is made up of cells designed to produce and secrete substances into ducts or into body fluids. 2. Glands that secrete products into ducts are exocrine; those that secrete into body fluids and blood are called endocrine. In naming epithelial cells A. Simple Squamous Epithelium B. Simple Cuboidal Epithelium C. Simple Columnar Epithelium D. Pseudostratified Columnar Epithelium E. Stratified Squamous Epithelium F. Stratified Cuboidal Epithelium G. Stratified Columnar Epithelium H. Transitional Epithelium I. Glandular Epithelium A. Simple Squamous Suited for diffusion B. Simple Cuboidal -secretion and absorption in the kidneys -secretion in glands C. Simple Columnar It lines the uterus, stomach, and intestines D. Pseudostratified Columnar Respiratory tract E. Stratified Squamous -outer layer of skin -lines the mouth, throat, vagina, and anal canal. F. Stratified Cuboidal lining a lumen of the mammary glands, sweat glands, salivary glands, and pancreas. G. Stratified Columnar vas deferens, part of the male urethra, and parts of the pharynx. H. Transitional lining of the urinary bladder I. Glandular Endocrine and Exocrine Gland CONNECTIVE TISSUE Connective Tissues: A. General Characteristics 1. Connective tissues bind (ex ligament and tendons), support, protect, serve as frameworks, fill spaces, store fat (bones store calcium and phosporous), produce blood cells (transportation), protect against infection, and repair tissue damage. 2. Unlike epithelial tissues, connective tissues have abundant matrix, or intercellular material, throughout, and have good blood supplies (except cartilage). The connective tissues include several types of fibrous tissue that vary only in their density and cellularity, as well as the more specialized and recognizable variants— bone, ligaments, tendons, cartilage, and adipose (fat) tissue. Components of connective tissue All forms of connective tissue are composed of (1) extracellular fibres (protein fibers), (2) an amorphous matrix called ground substance (non cellular material) , and (3) stationary and migrating cells. (living cells) The proportions of these components vary from one part of the body to another depending on the local structural requirements. In some areas, the connective tissue is loosely organized and highly cellular; in others, its fibrous components predominate; and in still others, the ground substance may be its most conspicuous feature. The anatomical classification of the various types of connective tissue is based largely upon the relative abundance and arrangement of these components. Ground Substance + Fibers + Cells Major Cell Types 1. The fibroblast is the most common cell type, and is a fixed, star-shaped cell that secretes fibers and is large in size. 2. Wandering macrophages function as scavenger cells and defend against infection. Connective Tissue Fibers 1. Strong collagenous fibers (white fibers), made of the protein collagen, add strength for holding body parts together. 2. Elastic fibers (yellow fibers), made of the protein elastin, are stretchy and add flexibility to certain types of connective tissues. 3. Reticular fibers are thin collagenous fibers that form supportive networks in a variety of tissues. Connective Tissues can be: Loose Connective (areolar) Tissue 1.This type of tissue forms delicate, thin membranes throughout the body that bind body parts together such as skin and underlying organs. 2.The majority of the cells are fibroblasts that are separated by a gel-like ground substance that contains collagenous and elastic fibers. 5 - 68 Adipose Tissue 1. Adipose tissue is loose connective tissue designed to store fat. 2. It is found beneath the skin, around joints, padding the kidneys and other internal organs, and in certain abdominal membranes. Copyright©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5 - 71 Dense Connective Tissue 1. This tissue consists of densely packed collagenous fibers and is very strong but lacks a good blood supply. 2. It is found as part of tendons and ligaments. Cartilage 1. Cartilage is a rigid connective tissue that provides a supportive framework for various structures. It lacks a vascular system and so heals slowly. 2. Cartilage cells (chondrocytes) lie within lacunae in the gel-like fluid matrix. 3. Cartilaginous structures are enclosed within a connective tissue perichondrium. 4. The most common, hyaline cartilage, is white with abundant fine collagen fibers, is found at the ends of bones, and supports respiratory passages. 5. Elastic cartilage, with elastic fibers, provides a framework for the external ears and parts of the larynx. 6. Fibrocartilage, with many collagenous fibers, is a tough tissue that provides a shock-absorbing function in intervertebral disks and in the knees and pelvic girdle. Bone 1. Bone is the most rigid connective tissue, with deposits of mineral salts and collagen within the matrix. 2. Bone internally supports the body, protects, forms muscle attachments, and is the site for blood cell formation. 3. Bone cells, called osteocytes, lie within lacunae and are arranged in concentric circles (osteons) around osteonic canals interconnected by canaliculi. 4. Bone has a good blood supply, enabling rapid recovery after an injury. 5 - 83 Blood 1. Blood is composed of cells (red and white) suspended in a liquid matrix called plasma. 2. It functions to transport substances throughout the body.  5- 85 MUSCLE TISSUE Muscle Tissues: General Characteristics 1. Muscle cells, or fibers, can contract and consist of three major types.  A. Skeletal Muscle Tissue 1. Skeletal muscle is attached to bone and can be controlled by conscious effort (voluntary). 2. The cells (muscle fibers) are long and cylindrical, striated, have many nuclei, and contract from nervous impulse. SKELETAL MUSCLE ▪ about 40% of a person’s body weight. ▪ attaches to the skeleton and enables the body to move. ▪ described as voluntary (under conscious control) ▪ nervous system can cause skeletal muscles to contract without conscious involvement, as occurs during reflex movements nd the maintenance of muscle tone. SKELETAL MUSCLE ▪ tend to be long and cylindrical, with several nuclei per cell. ▪ extend the length of an entire muscle. ▪ cells are striated, or banded, because of the arrangement of contractile proteins within the cell B. Smooth Muscle Tissue 1. Smooth muscle tissue lacks striations, is uni-nucleate, and consists of spindle-shaped cells. 2. This involuntary muscle is found in the walls of internal organs, and in the digestive tract, blood vessels, and urinary bladder. 5 - 94 SMOOTH MUSCLE ▪ forms the walls of hollow organs (except the heart) ▪ is controlled involuntarily. ▪ are tapered at each end, have a single nucleus, and are not striated. SMOOTH MUSCLE ▪ it is also found in the skin and the eyes ▪ is responsible for a number of functions, such as moving food through the digestive tract and emptying the urinary bladder. C. Cardiac Muscle Tissue 1. Cardiac muscle tissue is found only in the heart and consists of branching fibers that are connected to each other with intercalated disks. 2. This involuntary muscle has a single nucleus in each cell but appears striated.  ▪ is the muscle of the CARDIAC MUSCLE heart; it is responsible for pumping blood ▪ is under involuntary (unconscious) control, although a person can learn to influence the heart rate by using techniques such as meditation and biofeedback ▪ cylindrical but much shorter than skeletal muscle cells.  CARDIAC MUSCLE ▪ striated and usually have one nucleus per cell. ▪ often branched and connected to one another by intercalated disks. ▪ intercalated disks, which contain specialized gap junctions, are important in coordinating the contractions of the cardiac muscle cells Copyright©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5- 101  5- 10 2 Nervous Tissues Nervous Tissues: A. Nervous tissues are found in the brain, spinal cord, and nerves. B. Cell types: Neurons, or nerve cells, conduct nervous impulses while helper cells, or neuroglia or glia, support and nourish the neurons. NERVOUS ▪ Nervous tissue forms the brain, TISSUE spinal cord, and nerves. ▪It is responsible for coordinating and controlling many body activities. ▪Action potentials – ability of nervous tissue cells to communicate with one another by means of electric signals  NERVOUS TISSUE ▪ Neurons – responsible for conducting action potentials ▪ Cell Body – contains the nucleus; site of general cell functions ▪ Dendrites – receive electric impulses ▪ Axon – conduct electric impulses Copyright©The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5- 107  Astrocytes are a subtype of glial cells that make up the majority of cells in the human central nervous system (CNS).  They perform metabolic, structural, homeostatic, and neuroprotective tasks such as clearing excess neurotransmitters, stabilizing and regulating the blood-brain barrier, and promoting synapse formation  Schwann cells (SCs) are a type of glial cell that surrounds neurons, keeping them alive and sometimes covering them with a myelin sheath, and are the major glial cell type in the peripheral nervous system. They play essential roles in the development, maintenance, function, and regeneration of peripheral nerves Membranes  TISSUE MEMBRANES BODY MEMBRANES - cover surfaces, line body cavities, and form protective (and often lubricating) sheets around organs. TWO MAJOR GROUPS: 1.EPITHELIAL MEMBRANES, which include the cutaneous, mucous, and serous membranes 2.CONNECTIVE TISSUE MEMBRANES, represented by synovial membranes.  EPITHELIAL MEMBRANES: Cutaneous Membrane ▪ cutaneous membrane - is composed of two layers, the superficial epidermis and the underlying dermis. ▪ epidermis is composed of stratified squamous epithelium, whereas the dermis is mostly dense (fibrous) connective tissue. ▪ Unlike other epithelial membranes, the cutaneous membrane is exposed to air and is a dry membrane EPITHELIAL MEMBRANES: Mucous Membranes ▪ consist of various kinds of epitheium resting on a thick layer of loose connective tissue. ▪ line cavities that open to the outside of the body, such as the digestive, respiratory, and reproductive tracts ▪ have mucous glands, which secrete mucus. EPITHELIAL MEMBRANES: Mucous Membranes ▪ FUNCTION: protection, absorption, and secretion. ▪ stratified squamous epithelium of the oral cavity (mouth) ▪ Simple columnar epithelium of the intestine ▪ mucous membranes also line the nasal passages  ▪ consist of simple EPITHELIAL MEMBRANES: squamous epithelium resting on a delicate layer Serous Membranes of loose connective tissue ▪ line the trunk cavities and cover the organs within these cavities ▪ secrete serous fluid, which covers the surface of the membranes a. Pleural – lungs b. Pericardial – heart c. Peritoneal – abdominopelvic cavity : Serous Membranes ▪ When the suffix - itis is added to the name of a structure, it means that the structure is inflamed ▪ PERICARDITIS - inflammation of the pericardial membranes ▪ PERITONITIS – inflammation of the peritoneal membranes ▪ PLEURISY - inflammation of the pleural membranes.  ▪ are made up of only Synovial MEMBRANES connective tissue. ▪ line the inside of joint cavities (the space where bones come together within a movable joint) ▪ produce synovial fluid, which makes the joint very slippery ▪ Synovial fluid - reducing friction and allowing smooth movement within the joint  5- 12 6 GLANDS  GLANDS An organ that makes one or more substances, such as hormones, digestive juices, sweat, tears, saliva, or milk. Your glands play a role in almost every bodily function. Endocrine glands secrete hormones to your bloodstream. Exocrine glands secrete other substances to your body’s exterior. What glands do Glands are important organs located throughout the body. They produce and release substances that perform certain functions. Though you have many glands throughout your body, they fall into two types: endocrine and exocrine. Types of glands Endocrine and exocrine glands serve very different purposes in the body. The key difference between the two types is that, whereas exocrine glands secrete substances into a ductal system to an epithelial surface, endocrine glands secrete products directly into the bloodstream Exocrine glands Your exocrine glands produce other substances — not hormones — that are released through ducts to the exterior of your body, such as sweat, saliva, and tears. The substances released by your exocrine glands play important roles in your body. They do things like help regulate your body temperature, protect your skin and eyes, and even help mothers feed babies by producing breast milk. Your exocrine glands include: salivary sweat mammary sebaceous lacrimal Lymph nodes are often referred to as glands, but they’re not true glands. They’re part of your immune system and help your body fight infection. Endocrine glands Endocrine glands are part of your endocrine system. They make hormones and release them into your bloodstream. These hormones control a number of important functions in your body, such as: your growth and development metabolism mood reproduction Your endocrine glands include: adrenal glands pituitary gland hypothalamus thyroid pineal gland There are also organs that contain endocrine tissue and act as glands. These include the: pancreas kidneys ovaries testes What Are Glands in the Body? Glands to know You have glands throughout your body, all varying in size and function. Here are a few examples of these glands and what they do. Thyroid gland Your thyroid gland is located in the front of your neck, just below your larynx. It measures approximately two inches and has a shape similar to a butterfly. It secretes hormones that affect virtually every tissue in your body. Thyroid hormones regulate your metabolism, heart, and digestive function. They also play a role in your brain and nerve development, muscle control, and mood. Your thyroid function is controlled by your pituitary, which is a small gland at the base of your brain. Pituitary gland The pituitary gland is a pea-sized gland at the base of your brain, just behind the bridge of your nose. It’s controlled by the hypothalamus, which sits just above it. The pituitary gland is often called the master gland because it controls a number of other hormone glands, including the: thyroid adrenal gland testes ovaries Hypothalamus The hypothalamus functions as a communication center for your pituitary gland, sending signals and messages to the pituitary to produce and release hormones that trigger the production and release of other hormones. Your hypothalamus influences a number of your body’s functions, including: temperature regulation food intake sleep and wakefulness thirst memory emotional behavior Pineal gland Your pineal gland is located deep in the center of your brain. Its function is not completely understood, but we do know that it secretes and regulates certain hormones, including melatonin. Melatonin helps regulate your sleep patterns, which are also known as circadian rhythms. The pineal gland also plays a role in the regulation of female hormones, which affect the menstrual cycle and fertility. Adrenal glands Your adrenal glands are located at the top of each kidney. They produce various hormones, some of which include: cortisol aldosterone adrenaline a small amount of sex hormones called androgens The hormones produced by your adrenal glands have several important functions. They help your body: control blood sugar burn fat and protein regulate blood pressure react to stressors Pancreas The pancreas — a long, flat organ located in your abdomen — is made up of two types of glands: exocrine and endocrine. The pancreas is surrounded by the small intestine, stomach, liver, gallbladder, and spleen. The pancreas plays an important role in converting the food you eat into fuel for your body’s cells. It does this by producing digestive enzymes that are released into your small bowel to break down and digest food. It also makes hormones that control your blood glucose levels. Pancreatitis is inflammation of the pancreas. Pancreatitis occurs when digestive enzymes become activated while still in the pancreas, irritating the cells of your pancreas and causing inflammation. Sweat glands Your skin is covered in sweat glands of which there are two types: eccrine and apocrine. Your eccrine glands open directly onto your skin and regulate your body temperature by releasing water to the surface of your skin when your body temperature rises. Apocrine glands open into the hair follicle and are found in hair- bearing areas, such as the skin, armpits, and groin. These glands secrete a milky fluid, usually as a response to stress. Your body also contains modified apocrine glands: on the eyelids on the areola and nipples in the nose in the ears Sebaceous glands Sebaceous glands are located throughout your skin, though there are few on your hands and feet and none on your palms and soles. They secrete an oily substance called sebum that lubricates your skin. Most of these glands release onto a hair follicle, though a few open directly onto the skin’s surface, such as Meibomian glands on the eyelids, Fordyce spots on the genitals an upper lip, and Tyson glands on the foreskin. These glands perform a few functions in your body, such as:  regulating your body temperature by working with your sweat glands  helping your skin retain moisture  helping fight infection caused by bacteria and fungi Salivary glands Your salivary glands are located in your mouth. You have hundreds of small glands located throughout your: tongue palate lips cheeks You have three pairs of major salivary glands, including the: parotid glands, located in front of and just below your ears sublingual glands, located just under your tongue submandibular glands, located below your jaw Salivary glands produce saliva and empty into your mouth through ducts. Saliva serves a few important purposes, including moistening your food to help you chew, swallow, and digest it. Saliva also contains antibodies that kill germs to keep your mouth healthy. Mammary glands Mammary glands, which are a type of sweat gland, are responsible for the production of breastmilk. Males also have glandular tissue in the breasts, but estrogen produced during puberty triggers the growth of this tissue in females. Hormonal changes during pregnancy signal the ducts to produce milk in preparation for the baby. INFLAMMATION  INFLAMMATION ▪ INFLAMMATION - occurs when tissues are damaged ▪ For example, when bacteria/viruses infect epithelial cells of the upper respiratory tract, inflammation and the symptoms of the common cold are produced. ▪ Inflammation can also result from the immediate and painful events that follow trauma, such as closing your finger in a car door or cutting yourself with a knife.  INFLAMMATORY INFLAMMATORY RESPONSE - is a defense mechanism RESPONSE that mobilizes the body’s immune cells to isolate and destroy microorganisms and other injurious agents, and remove foreign materials and damaged cells allows tissue repair to occur.  STAGES OF THE INFLAMMATORY RESPONSE 1.Chemical mediators released: ▪ A splinter in the skin causes damage and introduces bacteria. ▪ Chemical mediators of inflammation are released or activated in injured tissues and adjacent blood vessels. ▪ Some blood vessels rupture, causing bleeding. CHEMICAL MEDIATORS IN INFLAMMATORY RESPONSE CHEMICAL MAJOR ACTION Histamine Immediate vasodilation and increased capillary permeability Chemotactic factors Attract neutrophils to site Platelet activating factor (PAF) Activate neutrophils and plt. aggregation Prostagladin Vasodilation, inc. permeability Pain, fever, potentiate histamine effect  STAGES OF THE INFLAMMATORY RESPONSE 2. TISSUE SWELLING: ▪ Chemical mediators cause capillaries to dilate and the skin to become red. ▪ Chemical mediators also increase capillary permeability, and fluid leaves the capillaries, producing swelling STAGES OF THE INFLAMMATORY RESPONSE 3. RECRUITMENT OF IMMUNE CELLS: White blood cells (e.g., neutrophils) leave the dilated blood vessels and move to the site of bacterial infection, where they begin to phagocytize bacteria and other debris. Inflammation has five major manifestations: (1) redness, (2) heat, (3) swelling, (4) pain, and (5) disturbed function. CARDINAL SIGNS OF INFLAMMATION ▪ Healing is a quality of living tissue ▪ regeneration (renewal) of tissues. WOUND ▪ Types of Wound Healing HEALING 1. Primary intention healing: occurs where the tissue surfaces have been approximated (closed) and there is minimal or no tissue loss ▪ It is also called primary union or first intention healing. ▪ An example: closed surgical incision.  WOUND HEALING 2. Secondary intention healing: wound that is extensive and involves considerable tissue loss, and in which the edges cannot or should not be approximated. Example: pressure ulcer. ❖Secondary intention healing differs from primary intention healing in three ways: ▪ repair time is longer, scarring is greater, susceptibility to infection is greater Phases of Wound Healing 1. INFLAMMATORY PHASE: begins immediately after injury and lasts 3 to 6 days. Two major processes occur during this phase: Hemostasis: (the cessation of bleeding) results from vasoconstriction of the larger blood vessels in the affected area Phagocytosis: cell migration, leukocytes (specifically, neutrophils) move into the interstitial space macrophages engulf microorganisms and cellular debris; secrete an angiogenesis factor  PHASES OF WOUND HEALING 2. PROLIFERATIVE PHASE: second phase in healing, extends from day 3 or 4 to about day 21 post-injury. ▪ Fibroblasts (connective tissue cells), which migrate into the wound starting about 24 hours after injury, begin to synthesize collagen. ▪ Collagen is a whitish protein substance that adds tensile strength to the wound. ▪ Capillaries grow across the wound, increasing the blood supply.  Phases of Wound Healing 3. MATURATION/REMODELING PHASE: begins on about day 21 and can extend 1 or 2 years after the injury. ▪ Fibroblasts continue to synthesize collagen. ▪ wound is remodeled and contracted. ▪ scar becomes stronger but the repaired area is never as strong as the original tissue. ▪ abnormal amount of collagen, can result in a hypertrophic scar, or keloid. What is the difference between acute inflammation and chronic inflammation? There are two types of inflammation: Acute inflammation: The response to sudden body damage, such as cutting your finger. To heal the cut, your body sends inflammatory cells to the injury. These cells start the healing process. Chronic inflammation: Your body continues sending inflammatory cells even when there is no outside danger. For example, in rheumatoid arthritis inflammatory cells and substances attack joint tissues leading to an inflammation that comes and goes and can cause severe damage to joints with pain and deformities. What are the symptoms of acute and chronic inflammation? Acute inflammation may cause: Flushed skin at the site of the injury. Pain or tenderness. Swelling. Heat. Chronic inflammation symptoms may be harder to spot than acute inflammation symptoms. Signs of chronic inflammation can include: Abdominal pain. Chest pain. Fatigue. (example: systemic lupus) Fever. (example: tuberculosis) Joint pain or stiffness. (example: rheumatoid arthritis) Mouth sores. (example: HIV infection) Skin rash. (example: psoriasis) What conditions are associated with chronic inflammation? Chronic inflammation is involved in the disease process of many conditions, including: Alzheimer’s disease. Asthma. Cancer. Heart disease. Rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Type 2 diabetes. What are the most common causes of inflammation? The most common reasons for chronic inflammation include: Autoimmune disorders, such as lupus, where your body attacks healthy tissue. Exposure to toxins, like pollution or industrial chemicals. Untreated acute inflammation, such as from an infection or injury. Some lifestyle factors also contribute to inflammation in the body. You may be more likely to develop chronic inflammation if you: Drink alcohol in excess. Have a high body mass index (BMI) that falls within the ranges for obesity, unless that is a result of being very muscular. Exercise at your maximum intensity too frequently, or you don’t exercise enough. Experience chronic stress. Smoke. How is inflammation treated? Inflammation does not always require treatment. For acute inflammation, rest, ice and good wound care often relieve the discomfort in a few days. If you have chronic inflammation, your healthcare provider may recommend: Supplements: Certain vitamins (vitamin A, vitamin C, vitamin D) and supplements (zinc) may reduce inflammation and enhance repair. For example, your healthcare provider may prescribe a fish oil supplement or vitamin(s). Or you may use spices with anti- inflammatory properties, such as turmeric, ginger or garlic. Nonsteroidal anti-inflammatory drugs (NSAIDs): These over-the- counter medicines lower inflammation. Your healthcare provider may recommend ibuprofen (Advil®), aspirin (Bayer®) or naproxen (Aleve®). Steroid injections: Corticosteroid shots decrease inflammation at a specific joint or muscle. For example, if you have rheumatoid arthritis that affects your back, your healthcare provider may give a steroid shot in your spine. You should not have more than three to four steroid injections in the same body part per year. What is a fever? A fever is a higher-than-normal body temperature. It’s a sign of your body's natural fight against infection. For adults, a fever is when your temperature is higher than 100.4°F. For kids, a fever is when their temperature is higher than 100.4°F (measured rectally); 99.5°F (measured orally); or 99°F (measured under the arm). The average normal body temperature is 98.6° Fahrenheit (or 37° Celsius). When you or your child’s temperature rises a few degrees above normal, it’s a sign that the body is healthy and fighting infection. In most cases, that’s a good thing. But when a fever rises above 102°F it should be treated at home and, if necessary, by your healthcare provider if the fever doesn’t go down after a few days. What causes a fever? A fever has many causes and can be a symptom of almost any illness. Among the most common are: Colds or flu. Earaches. Bronchitis. Strep throat. Urinary tract infections. Mononucleosis. However, if a child is experiencing a higher-than-normal body temperature and no other symptoms of illness, don’t assume something is wrong. A person's body temperature changes throughout the day and varies with many normal activities and emotions. For example, stress, excitement, heavy clothing, food, certain medications, a menstrual cycle and exercise can all raise body temperature. Also, children tend to have a slightly higher body temperature than adults. Infections cause most fevers. You get a fever because your body is trying to kill the virus or bacteria that caused the infection. Most of those bacteria and viruses do well when your body is at your normal temperature. But if you have a fever, it is harder for them to survive. The presence of a fever is usually related to stimulation/activitation of the body's immune response. Fever can support the immune system's attempt to gain advantage over infectious agents, such as viruses and bacteria, and it makes the body less favorable as a host for replicating viruses and bacteria, which are temperature sensitive. Cellular Level: Senior researchers Profs. David Rand and Mike White led teams of mathematicians and biologists to understand what happens at cellular level when fever takes hold. Their findings reveal that higher body temperatures drive the activity of certain proteins that, in turn, switch genes responsible for the body’s immune response on and off, as required. Nuclear Factor kappa B (NF-κB) Nervous System: The hypothalamus, which sits at the base of the brain, acts as the body's thermostat. It is triggered by floating biochemical substances called pyrogens, which flow from sites where the immune system has identified potential trouble to the hypothalamus via the bloodstream. Some pyrogens are produced by body tissue; many pathogens also produce pyrogens. When the hypothalamus detects them, it tells the body to generate and retain more heat, thus producing a fever. Children typically get higher and quicker fevers, reflecting the effects of the pyrogens upon an inexperienced immune system. Should one eat little or nothing while feverish? Yes. The reasons for this are threefold. First, during fever, all the body's functions are occurring amidst increased physiologic stress. Provoking digestion during physiologic stress over stimulates the parasympathetic nervous system when the sympathetic nervous system is already active. Second, it is possible that the body could misinterpret some substances absorbed from the gut as allergens during a fever. Finally, excessive fever can, on rare occasions, cause seizures, collapse and delirium--all of which may be further complicated by recent eating.