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Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) LEVEL 3 DIPLOMA IN AROMATHERAPY MODULE 16 KNOWLEDGE OF ANATOMY, PHYSIOLOGY & PATHOLOGY FOR COMPLEMENTARY THERAPIES THE LYMPHATIC & IMMUNE SYSTEM MODULE 9 COURSE MANUAL CHRISTINA LYNE [email protected] 1 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) THE LYMPHATIC SYSTEM The lymphatic system is a network of lymph vessels, nodes and ducts that stretches throughout the entire body. Lymph flows through this system. The main function of the lymphatic system is to drain fluid from the spaces between cells in order to filter out waste and toxins, destroy foreign particles and prevent infection. The lymphatic system is made up of the following: Lymph Lymphatic capillaries Lymphatic vessels Lymph nodes Lymphatic ducts Areas of lymph tissue - thymus gland, spleen, tonsils and adenoids Areas of specialist lymph tissue - lacteals and Peyer’s patches Our body actually has two circulatory systems. While they work individually to perform their main functions, they also work together to some degree. One of these, the Cardiovascular System, provides our body tissues with the needed oxygen, nutrients, and hormone-rich blood required for everyday functions. The other, the Lymphatic System, rids our body of the waste products (including old red blood cells) produced during daily internal functions, thus protecting us from the harmful effects we would experience otherwise. In addition, the spleen (part of the Lymphatic System) also serves as a blood reservoir for the Cardiovascular System until the blood is needed. The Cardiovascular System is related to the Lymphatic System. In the Cardiovascular System, blood is the vehicle used to deliver oxygen, nutrients and hormones to the various muscle and organ tissues within the body. Arteries deliver this loaded blood into the various body parts, using capillaries for some of the delivery. Then, the veins return the depleted blood back to the heart for oxygenation again. While the kidneys serve as the main blood cleaning station in the body, removing waste and fluid excess from it, the Lymphatic System also plays a role in the purifying of the blood. It removes the old red blood cells and any wayward blood that may have seeped into muscle tissues accidentally during transit through the body. 2 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) WHAT IS LYMPH? - Lymph is the fluid that flows through the lymphatic system. Lymph is a pale milky-coloured fluid. Its composition is very similar to that of blood plasma, but it contains less protein than plasma. Lymph has no red blood cells, but does contain white blood cells called lymphocytes. As it flows around the body, lymph picks up bacteria and cell debris from damaged tissues, which are then filtered out and destroyed as they pass through the lymph nodes. Lymph contains many dissolved substances and the remains of micro-organisms that invade the body. It will also contain protein molecules that are too large to pass through blood capillary walls, and fat molecules that have been absorbed through lacteals that line the small intestine walls. HOW IS LYMPH FORMED? It is formed by plasma (the liquid part of blood) seeping out of the capillaries. This tissue fluid or interstitial fluid bathes all the tissue cells. As it does this, it acts as a medium of exchange i.e. it transfers food, oxygen and water (nutritive materials) and receives urea and carbon dioxide (waste products) in return. It creates the environment that cells need to survive. Each day about 20 litres of fluid filter from blood into tissue spaces. About 85% of this fluid is returned to the blood system. The remaining 15% enters the lymphatic vessels and becomes lymph. LYMPH CAPILLARIES - these are located throughout the body Lymphatic capillaries are slightly larger than blood capillaries and have a unique structure that permits interstitial fluid to flow into them but not out. They are closedended vessels and their walls are made up of endothelial cells enabling them to soak up proteins and cell debris. Lymphatic capillaries unite to form larger and larger lymph vessels. LYMPH VESSELS - tubes that carry lymph Lymph vessels often lie close to arteries and veins. These thin-walled collapsible tubes are structurally similar to veins - they are made up of the same layers of tissue: a fibrous covering, a middle layer of smooth muscle and elastic tissue and an inner lining of endothelium. The function of these vessels is to transport lymph from the capillaries to lymph nodes. 3 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) HOW LYMPH MOVES THROUGH THE LYMPHATIC VESSELS The lymphatic system, unlike the circulatory system, has no pump. Like veins, lymph vessels have numerous cup-shaped valves that ensure that the lymph flows in one direction and that the backward flow is avoided. The larger lymph vessels have a smooth muscle layer in the walls, which contract rhythmically (the lymphatic pump) and this is how lymph is pushed towards the heart. Additionally, lymph moves through the vessels with the help of a: skeletal muscle pump - when the muscles contract they compress the lymphatic vessels and force the lymph towards the subclavian veins. The valves ensure the lymph flows in one direction only. respiratory pump - pressure changes occur during inhalation. Lymph flows from the abdominal region, where the pressure is higher, toward the thoracic region, where the pressure is lower. When the pressures reverse during exhalation, the valves prevent the backflow of lymph. LYMPH NODES or GLANDS Lymph nodes are often referred to as lymph glands, even though they are non-secretory. They vary considerably in size: some as small as a pin head and the largest are about the size of an almond. Lymph nodes are composed of reticular and lymphatic tissue. They are enclosed in a tough fibrous capsule made of dense connective tissue and are usually found embedded in fat. Each node has an outer cortex and inner medulla containing numerous lymphocytes and macrophages which help to carry out the cleaning-up process. As many as five or six afferent vessels will bring lymph to a node while only one or two efferent lymph nodes carry lymph out of the node. An artery enters and a vein leaves the node. 4 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) Lymph is filtered very slowly, allowing foreign substances to become trapped by reticular fibres within the lymphatic sinuses or trabeculae. Macrophages, antibodies and lymphocytes within the node then destroy the foreign substances. Lymph passes through several lymph nodes (usually about 8 – 10 times) where it is filtered before being returned to the venous bloodstream. Approximately 2 - 4 litres of lymph are filtered back into the venous bloodstream every day. Swollen lymph nodes commonly indicate disease. During an infection, they may swell, become inflamed and tender. This swelling may be noticeable even before the infection itself is apparent. E.g. swelling of the glands in the side of the neck during a throat infection is a common experience - a condition called ‘swollen glands‘. The function of lymph nodes is to filter lymph and remove / destroy harmful substances before it is returned to the bloodstream. LOCATION OF MAJOR LYMPH NODES IN THE BODY There are numerous lymph nodes situated along the length of lymph vessels, and are arranged in deep and superficial groups. The main areas are in the neck, armpit, breast, abdomen, groin and behind the knee. They are: Submandibular – these are situated just under the jaw and filter lymph from the head and neck areas. Deep / superficial cervical - these are situated in the neck and filter lymph from the head, tongue and mouth. Axillary - these are situated under the arms and filter lymph from the upper limbs and breast areas. Iliac - these are situated mainly in association with the blood vessels supplying the abdominal organs. Supratrochlear - these are situated in the elbow joint and filter lymph from the upper limbs. Inguinal - these are situated in the groin and filter lymph from the lower limbs. Popliteal - these are situated in the knee joint and filter lymph from the lower legs. 5 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) THE LYMPHATIC DUCTS The lymph vessels get larger as they join together, until finally the fluid is carried to the two largest vessels called lymph ducts: the thoracic duct and the right lymphatic duct. After being filtered thoroughly by the nodes, lymph is emptied into these ducts and is then returned to the bloodstream via the subclavian veins. This is how lymph drains back into blood. THE THORACIC DUCT This is the largest lymph vessel in the body through which most of the lymph flows. It commences at the cisterna chyli, which is a lymph vessel situated in front of the first two lumbar vertebrae. The duct is approx. 40 cm long and opens into the left 6 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) subclavian vein situated at the base of the neck. It drains lymph from both legs, the pelvic and abdominal cavities, the left half of the head, neck, chest and left arm. THE RIGHT LYMPHATIC DUCT This is the smaller of the 2 ducts, measuring approx. 1 cm long. It is also situated at the base of the neck and opens into the right subclavian vein. It drains lymph from the right half of the head, neck, right arm and chest. FUNCTIONS OF THE LYMPHATIC SYSTEM It transfers nutritive materials to the cells i.e. food, oxygen and water, allowing the body to grow and work with other body systems to function efficiently. It removes waste products from the cells i.e. urea and carbon dioxide. It filters lymph to remove and purify it from unwanted matter. It produces anti-bodies, thus helping to fight infection. It assists in the maintenance of bone and muscle repair after injury. It produces lymphocytes to help protect the body from foreign cells, microbes and cancer cells. It drains interstitial fluid from the tissues (this helps with the prevention of oedema). Lacteals absorb dietary lipids (triglycerides & cholesterol) and fat-soluble vitamins (A, D, E, and K) from the villi in the gastrointestinal tract to the blood. 7 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) AREAS CONTAINING LYMPHATIC TISSUE Lymphatic tissue contains many types of cells, the principal one being the lymphocyte. This white blood cell is made in the bone marrow. Once released into the bloodstream from the bone marrow, lymphocytes are further processed to make two functionally distinct types: the T-lymphocyte and the B-lymphocyte. T-lymphocytes: These are processed in the thymus gland. The hormone thymosin is responsible for the development of lymphocytes into fully specialised, mature, functional Tlymphocytes. A mature T-lymphocyte will recognise only one type of antigen and will not recognise or attack any other, no matter how dangerous it might be. B-lymphocytes: These are produced and processed in bone marrow. They produce antibodies (immunoglobulins) which are proteins designed to bind to and destroy an antigen. They function in the same way as T-lymphocytes in that they will only recognise and react with one type of antigen and no other. Lymphatic tissue is the main tissue in lymph nodes and lymphatic nodules and is found in the tonsils and adenoids, thymus, spleen, digestive, respiratory, urinary and reproductive tracts. THE THYMUS GLAND The thymus is situated behind the sternum, or breastbone, in the upper part of the chest. It lies very close to the heart in the thoracic cavity. It consists of two lobes joined by areolar tissue. A layer of connective tissue covers each lobe. The lobes are enclosed by a fibrous capsule which is further divided into lobules that are made up of an irregular branching framework of epithelial cells. Each lobule has a dense concentration of immature T- lymphocytes. FUNCTIONS OF THE THYMUS GLAND Before birth, small, medium and large lymphocytes migrate to the thymus. They develop into T-cells and will attack foreign cells. From there they go to the lymph nodes where they are stored or released when required to provide immunity. The epithelial cells secrete the hormone thymosin, which stimulates general growth and is involved in processing and stimulating lymphocytes to reproduce in lymphoid tissue. T-cells include: Helper cells - they help B-cells and feeding cells Killer cells - they kill the body's own cells that have been invaded by antigens and also kill tumour cells in the body Suppressor cells - they suppress over-aggressive lymphocytes. 8 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) THE SPLEEN The spleen is the largest lymph organ in the body. It is a dark, purplish oval organ that lies behind the stomach and beneath the diaphragm. It is composed of reticular fibres and fibroblasts through which trabeculae extend. The bulk (pulp) of the organ is composed of two types: white pulp and red pulp. The white pulp is composed of lymphatic nodules and the red pulp consists of blood sinuses lined with epithelial cells. The red pulp is the portion of the spleen which functions to filter the blood and remove worn-out erythrocytes with the help of macrophages before it is delivered to the liver. It is covered by a capsule of dense connective tissue. The spleen is not exposed to infections carried or spread by lymph, because it does not filter lymph. Structures entering and leaving the spleen are: Splenic artery Splenic vein - a branch of the portal vein Lymph vessels (efferent only) Nerves FUNCTIONS OF THE SPLEEN The spleen controls the quality and quantity of blood in circulation. Worn-out erythrocytes are destroyed in the spleen and the breakdown products - bilirubin and iron - are passed to the liver via the splenic vein. Leukocytes, platelets and microbes are engulfed by phagocytes present in the spleen. Acts as a reservoir for all types of blood cells. Can contain up to 350mls of blood. Contains T and B lymphocytes, which are activated in the presence of antigens e.g. in infection. Lymphocyte proliferation during serious infection can cause enlargement of the spleen (splenomegaly) Platelets live between 8 - 11 days in the spleen and promote blood clotting. Those not used are destroyed by spleen cells. Produces foetal blood cells. LYMPHATIC NODULES The tonsils and adenoids are made of oval-shaped concentrations of lymphatic tissue that are strategically positioned to protect against ingested or inhaled organisms which attempt to enter the digestive and respiratory tracts. They are found in the connective tissue of mucous membranes lining the respiratory and digestive tracts. They are not surrounded by a capsule. 9 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) THE TONSILS The tonsils are two almond-shaped glands consisting of a mass of lymphatic tissue covered by a mucous membrane. Running through the mucosa of each tonsil are pits, called crypts. There are two tonsils (palatine tonsils) at the back of the roof of the mouth, and a smaller pair (lingual tonsils) at the base of the tongue. They help to protect the throat and airways from infection. THE ADENOIDS This is a mass of lymphatic tissue at the rear of the nasal cavity. The surfaces are composed of ciliated epithelium and are covered by a thin film of mucus. The two adenoids protect the upper part of the respiratory tract. When they become swollen, the connection between the nose and throat narrows and it is this that affects the voice, giving a nasal or "adenoidal" sound. SPECIALIST LYMPH TISSUE LACTEALS The lacteals are a network of lymph and blood capillaries that lie inside projections called villi on the wall of the small intestine. Each villi is covered by a layer of epithelial cells. These cells also have projections called microvilli and together the villi and microvilli increase the surface area of the small intestine for maximum and efficient absorption of nutrients. Lacteals collect microscopic globules of fat from the small intestine. The fat then travels through the lymphatic system and is slowly emptied into the bloodstream. This process gives the lymph a milky appearance. Lymph entering the thoracic duct from the small intestine is called chyle. PEYER’S PATCHES There are numerous, smaller lymph nodes found in the mucous membrane at irregular intervals throughout the length of the small intestine. The larger nodes called Peyer’s patches are found in the lower part of the small intestine (ileum). These clusters of protective lymphatic tissue are packed with defensive cells, and are strategically placed to intercept ingested antigens. APPENDIX This is found at the end of the small intestine (at the end of the caecum). Its function is unknown. BODY FLUIDS An important aspect of homeostasis is maintaining the volume and composition of body fluids, which are dilute, watery solutions found inside cells as well as surrounding them. 10 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) About two thirds of body fluid is intracellular fluid and this is found inside cells. The other third, called extracellular fluid, is found outside body cells and includes all other body fluids. About 80% of extracellular fluid is interstitial fluid - this is the fluid that occupies the microscopic spaces between tissue cells. 20% of extracellular fluid is plasma. Extracellular fluid: within blood vessels is called plasma within the lymphatic vessels is called lymph within joints is called synovial fluid in and around the brain and spinal cord is called cerebrospinal fluid Both interstitial and intracellular fluid are made up of oxygen, nutrients, waste and other particles dissolved in water. 11 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) THE IMMUNE SYSTEM The immune system is a collection of special cells that help the body to resist infection and to defend itself against particular invading antigens. Antigens are molecules (usually proteins) on the surface of cells, viruses, fungi or bacteria. Non living substances such as toxins, chemicals, drugs and foreign particles (such as a splinter) can be antigens. The immune system recognises and destroys substances that contain these antigens. Definition of Immune response: The immune response is how the body recognises and defends itself against bacteria, viruses and substances that appear foreign and harmful to the body. Primary immune response When the immune system meets an antigen for the first time, antibodies are produced. This can sometimes take a few days to trigger and the disease may already have developed. Secondary immune response. Should the same antigens invade again however, the body then produces the antibodies very quickly, and in much larger amounts. Because the response is more immediate the second time around, the body rarely suffers the same disease again. INNATE IMMUNITY Innate immunity is a defensive system that we are born with. It protects us against all antigens. Innate immunity involves barriers that keep harmful materials from entering the body. These barriers form the first line of defense in the immune response. The following are examples of innate immunity: Cilia in the nose prevent entry of dust and micro-organisms. Sneezing helps to expel foreign material from the respiratory tract. Breast feeding transfers antibodies from mother to newborn baby. Tears contain a bacterial-killing enzymes called lysozyme. Saliva in the mouth washes away food debris to discourage bacterial growth. It also contains the enzyme lysozyme which attacks bacteria. Hydrochloric acid found in gastric juice is strongly acidic and kills the majority of ingested microbes. 12 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) Sebum is an oily substance secreted by sebaceous glands in the skin. The unsaturated fatty acids in sebum inhibit the growth of certain bacteria and fungi. Beneficial (good) bacteria in the intestines control harmful organisms. Mucus helps to trap many microbes and foreign substances. Vaginal and penile secretions are slightly acidic, which discourages bacterial growth. Perspiration contains the antibacterial fluid lysozyme which helps to wash away microbes found on the skin’s surface. ACQUIRED IMMUNITY This is immunity that develops with exposure to various antigens. Immunity may be acquired naturally or artificially and both forms may be active or passive. It is not innate and is obtained over a lifetime. NATURALLY ACQUIRED PASSIVE IMMUNITY - this is the transference of antibodies obtained from the mother through the placenta to the foetus or to the infant through colostrum and breast milk. NATURALLY ACQUIRED ACTIVE IMMUNITY - if foreign substances (antigens) come into contact with the skin or the lining of the nose, mouth, eyes or gastrointestinal tract, the immune system will respond by producing its own antibodies. ARTIFICIALLY ACQUIRED PASSIVE IMMUNITY - the body is given (injected with) antibodies which induces an active immune response but does not make the person ill. A new-born has passive immunity to several diseases such as measles, mumps and rubella, transferred through the placenta from the mother. These antibodies disappear between 6 to 12 months, which is why MMR is given just after a child's first birthday. ARTIFICIALLY ACQUIRED ACTIVE IMMUNITY - when a vaccine triggers the immune system to produce antibodies against a disease as though the body had been infected with it. This also teaches the body’s immune system how to produce appropriate antibodies quickly. If the immunised person then comes into contact with the disease itself, their immune system will recognise it and immediately produce the antibodies needed to fight it. BLOOD COMPONENTS & THE ALLERGIC RESPONSE An antigen is any substance that the body regards as foreign. Once the body decides it is an antigen, the immune system will mount a response. The immune system contains certain types of white blood cells. There are two types of 13 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) lymphocytes (white blood cells) and these are responsible for responding to antigens: B cells are formed in red bone marrow. These attach to a specific antigen and this helps to destroy it more easily. They secrete antibodies. T cells are formed in red bone marrow, and then move to the thymus gland to mature. Here they develop antigen receptors enabling them to recognise specific antigens. There are two types of T cells: CD4+ cells and CD8+ cells. Both B cells and T cells respond differently to pathogens. B cells secrete antibodies and T cells develop antigen receptors. There are two types of immune responses, both triggered by antigens: Antibody-mediated immune response (cells attack cells) B-cells change into plasma cells, which synthesise and secrete proteins called antibodies. These antibodies are released into the lymph and blood systems and bind to and inactivate the antigen. The antigen is then destroyed. This type of immunity works mainly against antigens present in body fluids and extracellular pathogens that multiply in body fluids but rarely enter body cells (primarily bacteria). Cell-mediated immune response (antibodies attack cells) Certain T cells proliferate into cytotoxic T cells, which directly attack the invading antigen. CD8+ T cells become ‘ killer cells ‘ and will specifically target intracellular pathogens i.e. ones that reside in host cells - primarily viruses, parasites and fungi, some cancer cells and sometimes foreign tissue or organ transplants. Mixed – Antibody-mediated and cell-mediated immune response A given pathogen can provoke both types of immune responses. CD4+ T cells become ‘helper’ cells that come to the aid of both the above-mentioned responses. Antigens An antigen causes the body to produce specific antibodies and / or specific T cells that react with it. Antigens will stimulate the formation of specific antibodies and will react specifically with the produced antibodies. An entire microbe, such as a bacterium or virus may act as an antigen. Toxins secreted by bacteria are also highly antigenic. Non microbial examples of antigens include foods, pollen, drugs, cancer cells and serum from insects and humans. The plasma membrane surface of most body cells contain what are called ‘selfantigens’. Their function is to help T cells recognise that an antigen is foreign and not a ‘self’. This recognition is the first important stage in any immune response. The body’s own molecules, recognised as ‘self’ do not normally act as antigens. 14 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) Sometimes, however, the distinction between self and nonself antigens breaks down, leading to an auto immune disease where the immune system attacks and starts to destroy its own body tissues. Antibodies An antibody is a protein produced by plasma cells. These proteins have special receptors which allow them to bind to foreign substances known as antigens. The portion of the antibody that identifies and neutralises the antigen so that it cannot affect the host organism is called an antigen-binding site. Antibodies belong to a group of plasma proteins called globulins – this is why they are also known as immunoglobulins or Igs. Immunoglobulins are grouped in five different classes: The five types of antibodies are: Type of Antibody Function IgA This is found in breast milk and saliva, and prevents antigens crossing epithelial membranes and invading deeper tissues. IgD This is made by B-cells and displayed on their surfaces. Antigens bind here to activate B-cells. IgE These are found on cell membranes of basophils and mast cells. If it binds its antigen, this activates the inflammatory response. It is often found in abundance in allergy. IgG This is the largest and most common antibody. It attacks many different pathogens and crosses the placenta to protect the foetus. IgM This is produced in great quantities in the primary response. 15 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) ALLERGY TRIGGERS and the BODY’S RESPONSE The immune system works to protect us from many micro-organisms, some of which cause infectious diseases. An allergy is an overaggressive response by the body’s immune system to a substance that, for many people, is usually harmless. While food remains the most common cause, there are many other substances, known as allergens, that can cause a reaction - for example: plants animal fur feathers chemicals - paint plasters medicines - penicillin bee & wasp stings Allergens may be inhaled or swallowed, or they may come into direct contact with the eyes or skin. The antibodies that are produced to attack the allergen also lead to a release of various substances including histamine. Histamine is responsible for causing most of the allergy symptoms. So, it is not the allergens that cause allergy symptoms but the way in which the body’s immune system reacts to them. Most people do not produce an excessive reaction when exposed to dust or pollen, but some people’s bodies overreact by producing lots of histamine and other substances that create the common allergy symptoms such as; hayfever, rhinitis (running nose), coeliac disease, asthma, eczema, sneezing, migraine, urticaria (itching) and watery eyes. It is likely that around 15% of the population is allergic to some fluids - shellfish is one of the commonest and most dramatic, with rashes, asthmatic attacks, swollen lips and eyes, stomach cramps, vomiting and constriction of the throat occurring in seconds. This type of reaction is called anaphylactic shock and is caused by a breakdown of the body’s immune defence mechanisms, which protect against invading organisms. Sometimes the antibodies produced by the immune system react violently to certain foods causing ‘ classic ‘ allergy reactions. These foods can be easily identified and avoided. Some individuals are affected by ‘masked’ allergies i.e. they do not produce symptoms which are typically linked to allergies, such as spots or rashes, but they nevertheless undermine health in a more subtle way. The substances which cause these masked allergies are usually ones that we come into contact with on a daily basis. Once the substance is removed, tremendous improvements in health and well-being are noticed. 16 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) STAGES OF INFECTION Infection occurs when germs enter into the tissues, survive, grow and multiply. ENTRY OF GERMS - Pathogens are organisms that can invade the body and cause disease. They attack the body’s cells, or release powerful poisons called toxins. Nearly all pathogens are microscopic living things, called micro-organisms. The most important pathogens are bacteria and viruses. INFECTION - If a micro-organism breaks through the body’s defences, it may grow and reproduce very quickly inside the body. The result is infection. Unless the infection is rapidly dealt with, it will cause an infectious disease. INCUBATION PERIOD - After a pathogen successfully invades the body, some time passes before a disease develops. This interval is known as the incubation period. Some pathogens have an incubation period of a few hours or days, other are between one and a number of years. The pathogen may be passed on to other people during this time. INFECTIOUS STAGE - This is the time during which the germs of the infectious disease can spread. The person can be infectious during the incubation period, during the illness itself, and sometimes after it (as a carrier). CONVALESCENCE - The symptoms disappear and the patient regains strength. SYMPTOMS & SIGNS OF INFECTIOUS DISEASE Fever / chills Dark,yellow urine Hot, dry skin Dehydration / Thirst Sweating Headache Furred tongue ORGANISMS THAT CAUSE INFECTION Understanding infection vs. disease There is a distinct difference between infection and disease. Infection, often the first step, occurs when bacteria, viruses or other microbes enter the body and begin to multiply. Disease occurs when the cells in the body are damaged — as a result of the infection — and signs and symptoms of an illness appear. In response to infection, the immune system springs into action. An army of white blood cells, antibodies and other mechanisms goes to work to rid the body of whatever is causing the infection. For instance, in fighting off the common cold, the body might react with fever, coughing and sneezing. 17 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) Infectious agents come in a variety of shapes and sizes. Categories include: Bacteria Viruses Fungi Parasites - (protozoa and helminths) BACTERIA Bacteria are one-celled micro-organisms. They are very small. They are shaped like short rods, spheres or spirals. Not all bacteria are harmful. In fact, less than 1% cause disease, and some bacteria that live in the body are actually beneficial. For instance, Lactobacillus acidophilus — a harmless bacterium that resides in the intestines — helps to digest food, destroys some disease-causing organisms and provides nutrients to the body. Harmful bacteria will gain access to host tissue and will multiply. They do this by penetrating the skin, mucous membranes or intestinal epithelium or surfaces that normally act as a microbial barrier. Entry is also gained through open wounds. Bacteria cling to specific cells on the mucous membranes of the respiratory, digestive or genitourinary tracts allowing the bacteria to invade and multiply. The organisms often remain localised producing a small infection e.g. a boil, carbuncle or pimple. Or they may gain access to distant sites and this can happen via the lymphatic system where the bacteria is deposited in the lymph nodes. Or if it enters the blood stream it can end up in the liver or spleen. The spread of bacteria throughout the body via blood or lymph can result in systemic infection of the body. Many disease-causing bacteria produce toxins — powerful chemicals that damage cells and cause illness. Bacteria cause diseases such as: Strep throat is a bacterial throat infection that can make the throat feel sore and scratchy. Most sore throats are caused by viruses and usually go away on their own. Only a small portion of sore throats are the result of strep throat. It's important to identify strep throat for a number of reasons. If untreated, strep throat can sometimes cause complications such as kidney inflammation and rheumatic fever. Rheumatic fever can lead to painful and inflamed joints, a rash and even damage to heart valves. Tuberculosis (TB) is a potentially serious infectious disease that primarily affects the lungs. Tuberculosis is spread from person to person through tiny droplets released into the air. Most people who become infected with the bacteria that cause tuberculosis don't develop symptoms of the disease. Cellulitis is a common, potentially serious bacterial skin infection. Cellulitis appears as a swollen, red area of skin that feels hot and tender, and it may spread rapidly. Cellulitis may affect only the skin's surface — or, cellulitis may also affect 18 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) tissues underlying the skin and can spread to the lymph nodes and bloodstream. Left untreated, the spreading infection may rapidly turn life-threatening. VIRUSES Viruses are much smaller than cells. Viruses are capsules that contain genetic material. They may be shaped like rods, spheres or tiny tadpoles. Viruses replicate by invading and infecting the cells of living hosts. The newly made viruses then leave the host cell, sometimes killing it in the process, and then seek out other cells within the host to infect. A virus is not a cell and it doesn’t have any cellular parts. Because viruses invade cells, no drugs have been found yet, that can kill viruses. The only defence against a viral disease at the moment is the human immune system. Viruses are responsible for causing a wide range of diseases, including: AIDS is a chronic, life-threatening condition caused by the human immunodeficiency virus (HIV). By damaging the immune system, HIV interferes with the body's ability to fight off viruses, bacteria and fungi that cause disease. HIV makes people more susceptible to certain types of cancers and to infections the body would normally resist, such as pneumonia and meningitis. The virus and the infection itself are known as HIV. "Acquired immunodeficiency syndrome (AIDS)" is the name given to the later stages of an HIV infection. Common cold is a viral infection that causes inflammation of the mucous membranes lining the nose and throat, resulting in a stuffy, runny nose and sometimes also a sore throat, headache and other discomfort. Most colds are contracted by breathing in virus-containing droplets that have either been sneezed or coughed into the atmosphere. Genital herpes is a common sexually transmitted disease that affects both men and women. Features of genital herpes include pain, itching and sores in your genital area. The cause of genital herpes is a type of herpes simplex virus (HSV), which enters the body through small breaks in the skin or mucous membranes. Sexual contact is the primary way that the virus spreads. Influenza is a viral infection that attacks the respiratory system, including the nose, throat, bronchial tubes and lungs. People who are generally healthy and who catch influenza — commonly called the flu — are likely to feel rotten for a few days, but probably won't develop complications or need hospital care. If they have a weakened immune system or chronic illness, though, influenza can be fatal. Measles is a potentailly dangerous viral illness that causes a characteristic rash and a fever. It is highly infective and is spread primarily by airborne droplets of nasal secretions. Measles mainly affects children but can occur at any age. 19 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) Yellow Fever Yellow fever is a haemorrhagic fever caused by a virus spread by a particular species of mosquito. It's most common in areas of Africa and South America, affecting travellers to and residents of those areas. In mild cases, yellow fever causes fever, headache, nausea and vomiting. But yellow fever can become more serious, causing bleeding (haemorrhaging), heart, liver and kidney problems. Up to 50 percent of people with the more severe form of yellow fever die of the disease. Plantar warts are non cancerous skin growths found on the soles of the feet, caused by the human papillomavirus (HPV), which enters the body through tiny cuts and breaks in the skin. This virus causes a rapid growth of cells on the outer layer of the skin. Plantar warts often develop beneath pressure points in the feet, such as the heels or balls of the feet. Common warts usually grow on the hands or fingers. They are as above treatment helps to prevent them from spreading to other parts of the body or to other people. Antibiotics have no effect on viruses. FUNGI There are many different varieties of fungi, and we eat quite a few of them. Mushrooms are fungi, as is the mould that forms the blue or green veins in some types of cheese. And yeast, another type of fungi, is a necessary ingredient to make most types of bread Other fungi can cause illness. One example is candida — a yeast that can cause infection. Candida can cause thrush — an infection of the mouth and throat — in infants and in people taking antibiotics or who have an impaired immune system. Fungal diseases are called mycoses and those affecting humans can be divided into four groups based on the level of penetration into the body tissues: 1. Superficial mycoses are caused by fungi that grow only on the surface of the skin or hair. This type of fungus lives off keratin which is found in abundance on skin, hair and nails. 2. Cutaneous mycoses or dermatomycoses include such infections as athlete's foot and ringworm. This type of fungus combines with bacteria to cause soggy and itching skin between the toes. 3. Subcutaneous mycoses penetrate below the subcutaneous, connective, and bone tissue. skin to involve the 4. Systemic or deep mycoses are able to infect internal organs and become widely disseminated throughout the body. This type is often fatal. Oral thrush is a condition in which the fungus Candida albicans accumulates on the lining of the mouth. Oral thrush causes creamy white lesions, usually on the tongue or inner cheeks. The lesions can be painful and may bleed slightly when scraped. 20 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) Sometimes oral thrush may spread to the roof of the mouth, gums, tonsils or the back of the throat. Fungi are also responsible for such skin problems as athlete's foot and ringworm. Athlete's foot is a fungal infection that develops in the moist areas between the toes and sometimes on other parts of the foot. Athlete's foot usually causes itching, stinging and burning. Also called tinea pedis, athlete's foot is closely related to other fungal infections with similar names, which include: Ringworm of the body (tinea corporis). This form causes a red, scaly ring or circle of rash on the top layer of your skin. Jock itch (tinea cruris). This form affects your genitals, inner upper thighs and buttocks. Ringworm of the scalp (tinea capitis). This form is most common in children and involves red, itchy patches on the scalp, leaving bald patches. PARASITES Parasites may be protozoa or multi-cellular organisms that behave like tiny animals — hunting and gathering other microbes for food. Many protozoa reside in the intestinal tract and are harmless. Protozoa often spend part of their life cycle outside of humans or other hosts, living in food, soil, water or insects. Some protozoa invade the body through the food we eat or the water we drink. Others, such as malaria, are transmitted by mosquitoes. Others cause disease, such as: Giardia infection is an intestinal infection marked by abdominal cramps, bloating, nausea and watery diarrhoea. Giardia infection is caused by a parasite that is found worldwide, especially in areas with poor sanitation and unsafe water. Giardia infection (giardiasis) is one of the most common waterborne diseases in the United States. The parasites are found in backcountry streams and lakes, but also in municipal water supplies, swimming pools and spas. Giardia infection can also be transmitted through food and person-to-person contact. Malaria is an infectious disease caused by a parasite that's transmitted by mosquitoes. The illness results in recurrent attacks of chills and fever, and it can be deadly. Toxoplasmosis is a parasitic infection that may cause flu-like symptoms. The organism that causes toxoplasmosis — Toxoplasma gondii — is one of the world's most common parasites. Most people affected never develop signs and symptoms. But for infants born to infected mothers and for people with 21 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) compromised immune systems, toxoplasmosis can cause extremely serious complications. HELMINTHS Helminths are among the larger parasites. The word "helminth" comes from the Greek for "worm." If this parasite — or its eggs — enters the body, it takes up residence in the intestinal tract, lungs, liver, skin or brain, where it lives off the nutrients in the body. They cannot produce food or energy for themselves. They are harmful to humans because the consume needed food, eat away body tissue and cells, eliminating toxic waste, which makes people sick. The most common helminths are tapeworms and roundworms. Tapeworm infection is caused by ingesting food or water contaminated with tapeworm eggs or larvae. If certain tapeworm eggs are ingested, they can migrate outside the intestines and form cysts in body tissues and organs (invasive tapeworm infection). If tapeworm larvae are ingested, however, they develop into adult tapeworms in the intestines (intestinal tapeworm infection). An adult tapeworm consists of a head, neck and chain of segments called proglottids. If an intestinal tapeworm infection is present, the tapeworm head adheres to the intestine wall, and the proglottids grow and produce eggs. Adult tapeworms can live for up to 20 years in a host. Intestinal tapeworm infections are usually mild, but invasive tapeworm infections can cause serious complications. Trichinosis sometimes called trichinellosis, is a type of roundworm infection. Roundworms are parasites that use a host body to stay alive and reproduce. Trichinosis occurs primarily among meat-eating animals (carnivores), especially bears, foxes and walruses. Trichinosis infection is acquired by eating larvae in meat. When humans eat undercooked meat containing trichinella larvae, the larvae mature into adult worms in the intestine over several weeks. The adults then produce larvae that migrate through various tissues, including muscle. Ascariasis is a type of roundworm infection. Roundworms are parasites that use the body as a host to stay alive and reproduce, maturing from eggs to adult worms inside your body. Eggs of the ascaris roundworm are microscopic, but adult worms are the largest of the intestinal roundworms, reaching lengths up to 16 inches (41 centimeters). 22 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) THE INFLAMMATORY PROCESS Inflammation is the body’s response to tissue damage. It represents a protective response designed to rid the body of the initial cause of tissue damage and the consequences of that injury. Tissue damage may occur due to: trauma, physical and chemical agents, foreign bodies, immune reactions and infections. Inflammation occurs locally and can be: Acute - rapid onset and of short duration Chronic - prolonged duration and results in tissue necrosis The purpose of the inflammatory process within the body is to isolate, then inactivate, then remove the cause of the damaged tissue and the damaged tissue itself. What happens to protect the integrity of the body when the tissue is damaged? 1. Tissue is made up of millions of cells (cells make tissue, tissue make organs, organs makes systems). Cells, when they are damaged release histamine and serotonin from their cell walls. This sets off a chain reaction, firstly causing dilation of tiny capillaries because histamine stimulates the dilation of blood capillary walls. More blood flows to the site of the damage and this causes warmth in the area and reddening. 2. Because the capillary walls have dilated, tissue fluid within the cell is stimulated to increase in volume. But the cell walls are broken at the site of the tissue damage, so tissue fluid normally held within the cell structure oozes out of the damaged cell through its leaky walls into the spaces between the cells (interstitial spaces). This is called oedema. This is also how the site of the tissue damage becomes isolated, because the area swells due to the amount of tissue fluid leaking into the interstitial spaces. 3. Because histamine is present in the blood, and antigens are circulating in the blood due to damage in the tissues, leucocytes migrate to the damaged area to mop up the antigens (phagocytosis) and render them inactive. 4. Macrophages then are stimulated to the area because of the changes in blood constituents (histamine, leucocyte proliferation) and mop up dead tissue that has been left over. This provides the removal part of the chain of events. 23 Christina Lyne Ltd©2014 Aromalyne Training Level 3 Diploma in Aromatherapy (ABC) Signs to look for when the inflammatory process is happening in the body: redness, heat, pain, swelling, and occasionally, loss of function. CELLS INVOLVED IN THE INFLAMMATORY PROCESS NERVE CELLS These are elongated cells that transmit information rapidly between different parts of the body. MAST CELLS These are part of a group of cells called leucocytes. Leucocytes are white blood cells and are found in blood plasma. They are found in most tissues characteristically surrounding blood vessels and nerves. They play a key, protective role in the inflammatory process. They are rich in histamine and heparin. Heparin - prevents blood from clotting to allow blood to flow to the area of infection or injury. Histamine - dilates the blood capillary walls, causing tissue fluid to ooze from damaged cell walls - swelling (oedema). It also initiates nerve endings (leading to itching and pain). Think of the bump and redness and itching after a mosquito bite. MONOCYTES These are a type of leucocyte (or white blood cell). Low monocyte count is a good sign, high count indicates that a problem is present. MACROPHAGES These are a type of white blood cell that eats foreign material / debris, bacteria, viruses in the body. They are part of the innate immune response and also make up an important part of the body’s acquired immune system. NEUTROPHILS These are the most common type of white blood cell, comprising about 50 - 70% of all white blood cells. They are phagocytic (can ingest other cells) and are the first immune cells to arrive at a site of infection. 24 Christina Lyne Ltd©2014