Lymphatic & Immune System: Medical Terminology

Medical Terminology in the Lymphatic and Immune System

• Auto- : Indicates self or own.
• -gen : Signifies something that produces or generates.
• Humor- : Relates to bodily fluids or humors.
• Immun- : Pertains to immunity or protection.
• Inflamm- : Denotes inflammation.
• Nod- : Refers to a node or swelling.
• Patho- : Indicates disease or pathology.

Introduction to the Lymphatic and Immune System

• Human bodies host 10 times as many bacterial cells as human cells, some of which are beneficial while others could cause disease.
• The immune system is not an organ system but a cell population distributed throughout the body.
• It defends against agents of disease and is concentrated in the lymphatic system.
• The lymphatic system has organs and vein-like vessels that recover fluid, inspect it for disease agents, activate immune responses, and returns fluid to the bloodstream.

The Lymphatic System's Fluid Recovery

• Fluid continually filters from blood capillaries into tissue spaces.
• Blood capillaries reabsorb 85% of the filtered fluid.
• The lymphatic system collects 15% (2-4 L/day) of water and about half of the plasma proteins, then returns them to the blood.

The Lymphatic System's Immunity and Lipid Absorption

• Excess filtered fluid gathers foreign cells & chemicals from the tissues.
• This fluid passes through lymph nodes where immune cells defend against foreign matter.
• A protective immune response is activated.
• Lacteals within the small intestine absorb dietary lipids not absorbed by blood capillaries.

Red Bone Marrow's Role in Immunity

• Red bone marrow participates in hemopoiesis (blood formation) and immunity.
• It features soft, loosely organized with many blood vessels.
• It is separated from osseous tissue by the endosteum of the bone.
• As blood cells mature, they enter the sinus through reticular and endothelial cells, flowing into the bloodstream.

Thymus Gland Overview

• The thymus is part of the endocrine, lymphatic, and immune systems.
• It houses developing lymphocytes and releases hormones that regulate their activity.
• A bi-lobed organ sits in the superior mediastinum between the sternum and aortic arch.
• There is degeneration (involution) as people age.

Thymus Histology

• A fibrous capsule sends trabeculae (septa) into the gland, dividing it into several lobes.
• Lobes consists of a cortex and medulla densely packed with T lymphocytes.
• Reticular epithelial cells isolate the cortex from the medulla by the blood-thymus barrier.
• These cells produces signaling molecules like thymosin, thymopoietin, thymulin, interleukins, and interferon.

Lymph Nodes and Related Conditions

• Lymphadenitis : Denotes a painful and swollen node in response to a foreign antigen.
• Lymphadenopathy : Describes the collective group of all lymph node diseases.

Lymph Nodes & Metastatic Cancer

• Metastasis: Cancer cells separate from an initial tumor, travel to distant sites, and form secondary tumors.
• Metastasizing cells easily enter lymphatic vessels.
• They tend to settle in the initial lymph node encountered.
• These cells multiply and eventually destroy the node, causing it to become swollen, firm, and usually painless.
• Cancer tends to spread to the next node downstream in the vessels.
• Treatment for breast cancer involves lumpectomy/mastectomy, with removal of axillary nodes nearby.

Tonsils and Their Function

• Tonsils: Patches of lymphatic tissue found at the entrance to the pharynx.
• They prevent pathogens from ingested or inhaled from entering the body.
• Covered with epithelium, containing tonsillar crypts, which are deep pits lined with lymphatic nodules.
• Tonsillitis indicates inflammation of the tonsils, which may lead to a tonsillectomy.

Spleen Composition

• Spleen : The body's largest lymphatic organ
• Parenchyma has two types of tissue: red and white pulp.
• Red pulp consists of sinuses filled with erythrocytes (red blood cells).
• White pulp is lymphocytes and macrophages around small branches of the splenic artery.

Spleen Functions

• The spleen functions by allowing healthy red blood cells (RBCs) to freely enter and exit.
• It serves as the "erythrocyte graveyard" for old, fragile RBCs.
• In fetuses and very anemic adults, it produces blood cells.
• White pulp monitors blood for foreign antigens, deploying monocytes as necessary.
• The spleen stabilizes blood volume via the lymphatic system transport of plasma.
• If trauma or infection damages the spleen, a splenectomy is required, which can make a person at high risk of infections and premature death in the future.

Nonspecific Resistance: Defenses Against Pathogens

• Pathogens : Agents capable of causing disease, including viruses, bacteria, and fungi.
• First line of defense: skin and mucous membranes.
• Second line of defense: nonspecific mechanisms such as leukocytes, macrophages, antimicrobial proteins, natural killer cells, inflammation, and fever.
• Third line of defense: the immune system, which defeats pathogens and remembers them for future encounters.

Nonspecific vs Specific Defenses

• Nonspecific defenses protect against a broad range of pathogens.
• They lack the ability to remember pathogens.
• The three types are protective proteins, cells, and processes.
• Specific/adaptive immunity requires the body to develop distinct immunity to each pathogen.
• The body adapts and responds more effectively upon subsequent exposures.

Antimicrobial Proteins

• Antimicrobial proteins inhibit microbial reproduction.
• Offer temporary, nonspecific resistance to bacteria and viruses.
• Interferons are one family of these proteins.
• Another family of antimicrobial proteins are called the Complement System.

Interferons

• Interferons : Secreted by cells infected by viruses.
• These interferons do not benefit the cells that secrete them.
• They alert neighboring and protect them from infection.
• These bind to surface receptors on neighboring cells.
• These activate second-messenger systems within.

Functions Continued: Interferons

• The alerted cell creates proteins that prevent infection.
• Viral genes are broken down and replication is prevented.
• Natural killer (NK) cells and macrophages are activated.
• These destroy the cells from liberating newly copied viruses.
• Activated NK cells neutralize malignant cells.

Complement System

• The complement system involves 30+ globular proteins.
• These proteins are a potent aid to both nonspecific resistance and adaptive immunity.
• Primarily synthesized by the liver.
• Proteins circulate in an inactive form within the blood.
• It activates when a pathogen is present.

Action and Activation of the Complement System

• Activated complement is responsible for four pathogen elimination methods: inflammation, immune clearance, phagocytosis, and cytolysis.
• Complement activation occurs via three routes: classical, alternative, and lectin pathways.

Classical Pathway of the Complement System

• Depends on an antibody molecule, making it part of adaptive immunity.
• Antibody attaches to the antigen on the surface of the pathogenic organism, creating the antigen-antibody (Ag-Ab) complex.
• The antibody is altered, uncovering a pair of complement-binding sites.
• Attachment of the first complement (C1) prompts a reaction cascade referred to as complement fixation.
• A sequence of complement proteins then attach to the antibody.

Complement System: Alternative and Lectin Pathways

• Alternative pathway : Is nonspecific and does not require an antibody.
• C3 breaks down into C3a and C3b in the blood.
• C3b directly binds to bacteria, viruses, human tumor cells, and yeasts, starting a cascade reaction with an autocatalytic effect with more C3 formed.
• Lectin pathway : Lectins, plasma proteins, bind to carbohydrates.
• They bind to certain sugars on a external microbial cell.
• The pathway triggers another cascade which leads to C3 production.

Mechanisms of Action of Complement Proteins - Inflammation and Immune Clearance

• The C3a stimulates the mast cells and basophils that secrete histamine and other inflammatory compounds.
• The C3a activates and attracts macrophages & neutrophils.
• It speeds the destruction of pathogens involved in the inflammation.
• Immune clearance : C3b binds with antigen-antibody (Ag-Ab) complexes to RBCs.
• RBCs then move through liver and spleen.
• Macrophages in these organs strip off and destroy the complexes(Ag-Ab), leaving RBCs unharmed.
• This is the primary way of clearing foreign antigens flowing in the bloodstream.

Complement System: Phagocytosis and Cytolysis

• Phagocytosis is an action of complement proteins.
• Neutrophils & macrophages are unable to phagocytize "naked" pathogens such as viruses, bacteria and other pathogens.
• C3b serves aids them via opsonization.
• They coat microbial cells and act as binding sites for phagocyte attachment, which makes the cell more appealing.
• Cytolysis: C3b splits complement C5 into C5a & C5b.
• C5b will bind to the enemy cell.
• It then attracts more components-membrane attack complex forms.
• This complex forms a hole in the cell.
• Electrolytes begin to rapidly leak then, cell ruptures.

Fever and Its Effects

• Fever: elevated abnormal body temperature.
• It is also known as pyrexia/febrile.
• Is the result of drug reactions, trauma, tumors and infections.
• Fever is an adaptive defense, benefits outweigh harm assuming it remains in moderation.
• Promotes activity of interferon.
• Elevates the metabolism, and accelerates repair of tissue.
• Prevents reproduction of bacteria and viruses.

Treatment and Causes of Fever

• Antipyretics : Medications which reduce fever.
• Aspirin & ibuprofen prevent synthesis of prostaglandin E2.
• Fever often triggered by exogenous agents that produce fever called pyrogens.
• Glycolipids found on viral/bacterial surfaces.
• Endogenous pyrogens include polypeptides that are released from macrophages/neutrophils.
• They raise the hypothalamic set point for the body.
• Neurons secrete prostaglandin E, which will raise this set point as well.
• Stages are onset, stadium, and then defervescence.

Reye Syndrome

• Reye syndrome : severe disorder in children under 15 after viral infections such as the flu or chickenpox.
• Swelling of neurons.
• Fatty infiltration of viscera, especially in the liver.
• Pressure resulting from the swelling in the brain.
• Symptoms : disorientation, coma, nausea, vomiting, and possible seizures.
• 30% of die, survivors often deal with mental retardation.
• Can be stimulated by use of aspirin.
• Do not administer aspirin to children if they have flu-like symptoms or chickenpox.

Hallmarks of Inflammation

• Inflammation defines local defensive reaction to tissue injury/trauma/infection.
• Its major goals are: to limit pathogen spread/destroy them, remove debris, and initiate repair of tissues.
• The four major signs: Pain, heat, swelling, redness.

Details of Inflammation

• Suffix -itis means the organs are inflamed; arthritis/dermatitis/pancreatitis.
• Cytokines consist of small proteins which control immunity.
• Cytokines secreted via leukocytes.
• Cytokines change physiology in a receiving cell.
• Cytokines impact neighboring (paracrine) or the same cell (autocrine).
• The group includes tumor necrosis interferon, cytokines, and chemotactic agents.

Adaptive Immunity

• The immune system : large distribution of cells that recognize threats, acting to neutralize them.
• Immunity differs in two fundamental ways: memory and specificity.
• Memory: Re-exposure causes a fast response/no illness.
• Specificity occurs when the immunity targets a specific pathogen.

Forms of Immunity: Cellular and Humoral

• The two kinds of immunity are either humoral or it is cellular.
• In cellular (cell-mediated) it attacks foreign cells directly or cells are diseased.
• It rids the body of pathogens/kills the cells and this will affect accessibility.
• In humoral (antibody mediated) it uses no direct interaction with foreign cells, instead the antibodies "flag" the foreign material.
• This material is dissolved in all bodily fluids.
• This will only protect against infections made by microorganisms.

Active Immunity

• Natural active immunity : The body produces its own cells in response to contact with foreign invaders.
• Artificial active immunity : The body develops its own defense against disease from vaccinations.
• Consists of pathogens that are dead/weakened.
• Booster shots : designed to maintain a high level protection by stimulating immune memory.

Passive Immunity

• Natural: protection due to other person antibodies.
• The fetus acquires antibodies from its mother with milk.
• Artificial: protection due to another injection from another animal/person.
• Treating rabies snakebites with tetanus

Stages of Immunity

• The three stages of both humoral and cellular are (3 Rs) : Recognize, React, Remember

Cellular Immunity: T Lymphocytes in Action

• Cellular immunity is a type of defense that occurs when T cells recognize and attack cells.
• This occurs because immune cells remember the antigens, which then prevents the disease.
• There are 4 classes of T-cells: cytotoxic, helper, regulatory, and memory.

Humoral Immunity

• Unlike cellular immunity, this defense is more indirect.
• B lymphocytes create antibodies to tag the antigen, leading to their destruction by another means.
• Works in a three stage process of recognition, attack and memory.

Humoral Immune Response Steps

• Antigen recognition: B cells bind antigens via complementary receptors.
• Antigen then internalizes and shows processed epitope.
• T cell then binds to the B cell and secretes interleukin.
• Interleukin then stimulates B cell clone selection.
• Some cells in this clone become memory B cells.
• Plasma cells synthesize & secrete the antibody.

Hypersensitivity in Immune Response

• Hypersensitivity : Refers to excessive response by body to antigen.
• These are generally tolerated by people.
• Subtypes include :
  • Alloimmunity - reaction to transplant tissue of another person
  • Autoimmunity - Reaction between the one's tissues
  • Allergies : reactions between environmental tissues like venom, mold, pollen etc.

Anaphylaxis & Anaphylactic Shock

• Anaphylaxis : Type one reaction which triggers the most severe response of any type of similar reaction.
• It is immediate to severe.
• Some effects can be offset via use of an antihistamine.
• Anaphylactic Shock : occurs when a allergen spreads wide into the blood and certain foods are digested from allergic person.
• Symptoms : short breath from airway restriction or drops/shock in circulation.
• Antihistamines do not provide relief for this situation.
• Therapies : Epinephrine, fluid therapies, and respiratory support.

Asthma Hypersensitivity

• Asthma : very common illness found in young children
• Almost all cases are from allergy (extrinsic) stimulation with allergens in the air.
• Respiratory distress occurs due to many different items in the body which include:
  • Respiratory crisis resulting from inhaled allergens
  • Secretion of plasma cells stimulate I g E
  • Mast cells start to produce chemicals and it will trigger airway inflammation.
• Certain cases result from infections, emotions and other conditions.
• Similar reaction to allergic effects.

Asthma Effects and Treatments

• Effects of Asthma lead to bronchospasms in as little as minutes after exposure.
• Severe coughing and deadly suffocations are possible side effects from the condition.
• Airways become inflamed by the presence of interleukins, leading to damage.
• Other components which are released paralyze cilia/plug alveoli.
• Therapies include - epinephrine, bronchodilators, other treatments and steroids.

Autoimmune Disease

• Autoimmune conditions occur because of the body's failure to recognize self.
• Happens when body creates defense (autoantibodies) that react to specific antigens.
• Failure to recognition happens because of some reasons:
  • Cross reactivity- similar to foreign antigens.
  • Abnormal exposure results in self exposure and antigen exposure.
  • Self and foreign antigens have similar changes/features

Tolerance Failure and Self-Reactive T Cells

• Native antigens can also result in a failure of self-tolerance. Blood and testes act as a filter and will cause tolerance failures.
• Disease or environmental exposure also will will lead to a failure of self-tolerance.
• Thymus cells and helper T cells that aren't deleted are placed in order.

Immunodeficiency Diseases

• Immune system fails to react vigorously enough.
• SCID Disease is a type which causes immunodeficiency
• This happens because there is hereditary like of T and B cells
• High vulnerability to infection is common, protective measures must be enforced in daily life.

Acquired Immunodeficiency Syndrome (AIDS)

• Non hereditary diseases contracted after birth cause it.
• HIV causes severe depression.
• Tries to attack and destroy macrophages and dendritic cells and receptors can uptake infections easily after exposure

Details of Acquired Immunodeficiency Syndrome (AIDS)

• DNA will dormant itself and copy the immune system.
• Activation induces a copy and is transported via plasma membrane
• Attaches to the cell and repeats.

Signs and Symptoms of Acquired Immunodeficiency Syndrome (AIDS)

• Early infections start from flu like symptoms and sweat with fatigue/ headaches occur.
• This will reduce blood cell and normal function
• Vulnerability increases as immunity weakens.
• Thrush and Kaposi can start to appear as different effects from the exposure.
• Kaposi is the cancer that appears as damaged tissue.

Transmission of HIV

• Semen, vaginal fluid, Blood , placenta, and through breastfeeding transmits the infection
• Sexual contact, products with infected blood, or in needles transmit
• Casual contact isn't high risk
• Condoms are very effective and safe.

How to Combat AIDS?

• Prevent CD4 connection
• Disrupt the assembly by inhibiting the virus assembly, or release from host cells.
• Many medications and drugs:
  • Reverse transcriptase inhibitors(AZT)
  • Protease inihibitors

Explore the medical terminology of the lymphatic and immune systems, including prefixes and suffixes like 'auto-', '-gen', and 'immun-'. Understand the basics of the immune system, its distribution throughout the body, and its role in defending against disease. Learn how the lymphatic system recovers fluid and activates immune responses.