Immunity and Lymphatics Flashcards

Flashcards on Immunity and Lymphatics based on lecture notes.

Lymphatic System Function

Picks up extracellular tissue fluid, carries fat from GI tract, carries small proteins lost in capillary filtrate, carries immune cells, helps immune cells mature, cleans extracellular fluid.

Edema and Infection

Consequences of a non-working lymphatic system, leading to conditions like Elephantiasis and festering infections.

Lymphatic System

Vast collection of cells and biochemicals that travel in lymphatic vessels, and the organs and glands that produce them.

Lymph

Fluid flowing in the lymphatic system that stretches lymph vessels, causing them to contract and push the fluid forward.

Lymph Capillaries

Microscopic, closed-ended tubes made up of simple squamous epithelium, extending into interstitial spaces and parallel to blood capillaries.

Lymph Vessel

Similar to cardiovascular venous system but carries different substances and excess fluid from tissues.

Lymph Nodes

Large nodules along lymph vessels that capture (filter) antigens (Ag) and help develop immune cells to maturity.

Lymphatic Trunks

Large collections of lymph vessels named after the areas they drain.

Collecting Ducts

Two main regions (Right Lymphatic Duct and Thoracic Duct) where lymph vessels and trunks collectively drain back into general circulation.

Semilunar Lymphatic Valve

Prevents backup in lymphatic vessels, similar to veins, especially in vessels below the heart.

Right Lymphatic Duct (RLD)

Drains into the right subclavian vein.

Thoracic Duct (TD)

Drains into the left brachiocephalic vein between the left subclavian and left internal jugular veins.

Lymph fluid reabsorption

About 9/10 of all filtration at capillaries are reabsorbed into the venous end of the capillaries. About 1/10 is picked up by lymphatic flow.

Primary Functions of Lymph Nodes

Filter potentially harmful substances from the lymph and monitor body fluids for immune response.

Lymph Node Structure

Contains sinuses with lymphocytes (many B-cells) and macrophages to clear lymph of bacteria, debris, and foreign material.

Hilum

Indented region of lymph nodes where blood vessels and nerves enter, allowing filtration of both blood and lymph.

Palpation of Lymph Nodes

Enlargement and tenderness can indicate active infection; common palpation sites are axillary and cervical nodes.

Cervical Lymph Nodes Location

Lower border of mandible, anterior and posterior auricular (ears), deep cervical (along pathway of major vessels).

Axillary Lymph Nodes Location

Along the armpit; receives drainage from upper limb, part of thorax, and breasts.

Supratrochlear Lymph Nodes Location

Along the medial side of the elbow; may enlarge after cuts and scrapes of hands.

Inguinal Lymph Nodes Location

Receive lymph from genitalia, lower limb, and lower abdominal area.

Thymus Function

Site of T-lymphocyte maturity; located anterior to the aortic arch and just behind the superior portion of the sternum.

Spleen Function

Largest lymphatic organ; filters blood, site of RBC death and cleansing by macrophages and lymphocytes; located in the upper left portion of the abdominal cavity.

Antigens

Anything that is foreign to the body.

Pathogens

Disease-causing invaders, usually coated by antigens.

Infection

The presence and multiplication of pathogens.

Innate Defenses (Innate Immunity)

Includes species resistance, natural barriers (skin, hair, mucous), chemical barriers (acidic stomach, lysosome activity), competition in the colon, inflammation, phagocytic cells, natural killer cells, and fever.

First Line of Defense

Mechanical barriers such as the skin.

Second Line of Defense

All other innate defenses.

Adaptive Response (Third Line of Defense)

More specific defense involving MHC identifiers and specialized immune cells.

Immunity

Specific defense against a specific pathogen or antigens.

Leukocytes

Include neutrophils, lymphocytes, monocytes, eosinophils, and basophils.

Lymphocytes

B-cells and T-cells, crucial for immune response.

T-cells (T-lymphocytes)

Made in red marrow, develops and matures in thymus, make up 70-80% of circulating lymphocytes; activated by antigen presenting cells.

Helper T Cells (CD-4, T4)

Activated by binding to foreign antigen; helps B cells specialize and proliferate to form plasma cells, secreting antibodies.

Cytotoxic T Cells (CD-8, T8)

Activated by helper T cells or APCs; initiate cellular immune response, destroying harmful antigens by secreting perforins.

Cellular Immunity

When a T-cell attacks an antigen directly.

Memory T cells

Provide future immune response by remembering antigens after cytotoxic T cell contact with an antigen presenting cell.

B-cells

Divide when they come in contact with an antigen or a helper T cell, producing plasma cells (antibody/immunoglobulin producing) and memory B cells.

Antibody-mediated immune response

Also known as humoral immune response. Antibodies are soluble, globular proteins.

Antibodies React to Antigens

Directly attack, activate complement system, stimulate local changes such as inflammation.

Antibodies Direct Attack Method

Cause agglutination (clumping) or neutralize antigens by blocking active portions.

IgG

In plasma and tissue fluid; attacks bacteria, viruses, and toxins; can cross the placenta.

IgA

Found in exocrine gland secretions (breast milk, tears, nasal fluid, etc.).

IgM

Produced in plasma in response to contact with certain antigens in food or bacteria; activates the complement system.

IgD

On the surface of most B cells; acts as an antigen receptor and is important in activating B cells.

IgE

Associated with allergic reactions.

Primary Immune Response

First contact with antigens; body defends and memory B-cells and T-cells are formed.

Secondary Immune Response

Same antigen activates dormant memory cells for a quick response.

Naturally Acquired Active Immunity

Have disease and survive after response to live antigens.

Artificially Acquired Active Immunity

Given in vaccines and comes from immune response to dead or attenuated bacteria/viruses.

Artificially Acquired Passive Immunity

Injection of antibodies; lasts a few weeks.

Naturally Acquired Passive Immunity

IgG made in the mother crosses the placenta and helps protect the child for a few months.

Type I Allergy

Immediate response or anaphylactic type; overproduce IgE, activates mast cells and B cells, releases histamines, prostaglandins, and leukotrienes; worst case scenario is anaphylactic shock.

Anaphylactic Shock

Extreme response to an allergen, causing low BP and difficulty breathing.

Type II Hypersensitivity Reaction

Antibody-dependent cytotoxic reactions; example is blood transfusion.

Type III Hypersensitivity Reaction

Body is unable to clear antibody-antigen complexes; example is autoimmunity.

Type IV Allergy

Delayed-reaction allergy; example is dermatitis to skin irritation.

Allergin

Any antigen that triggers an allergic reaction.

Isograft

Tissue from identical twin.

Autograft

Tissue taken from elsewhere in a person’s body.

Allograft

Tissue comes from another person (not a person’s twin).

Xenograft

Comes from different species.

Autoimmunity

Immune system fails to distinguish self from nonself, producing autoantibodies and T cells that attack host's own tissue.