LYMPHATIC IMMUNE SYSTEM

Chapter 14

Introduction Includes:

Network of vessels that transports fluids Similar to cardiovascular Organs, etc:

Lymph nodes/vessels/fluid, capillaries, veins/arteries, thymus, spleen, bone marrow

Functions: Drain interstitial fluid back to the circulatory

system Dietary lipid absorption/transport Initiate & regulate immune responses

Flow of Lymph Lymphatic capillaries →

Lymphatic vessels → Lymphatic Trunks → Collecting Ducts → Veins

The lymph will also pass through lymph nodes found along vessels

Lymphatic Capillaries

Closed-ended tubes

Form network with blood capillaries

Thin-walled Fluid inside is

called lymph

Lymphatic Vessels and Trunks

Lymphatic vessels Structure is very similar to veins

Lymphatic Trunks Larger vessels than lymphatic vessels;

drain into collecting ducts

Collecting Ducts Two Main Ducts

1) Thoracic Duct- collects lymph drained from the lower limbs, abdomen, left upper limb, and left side of the thorax, head, and neck

2) Right Lymphatic Duct- collects lymph drained from right upper limb and right side of the thorax, neck, and head

Tissue Fluid Interstitial fluid surrounding capillaries Constant movement in and out of

capillaries Generally same composition as plasma

(except doesn’t contain plasma proteins) Some excess fluid stays in tissue and is

not recollected by capillaries

Formation of Lymph Volume pressure of interstitial fluid

causes some of the fluid to enter lymphatic capillaries

Lymph will return to the bloodstream but will be filtered along the way Removing: Wastes, pathogens, carbon

dioxide

Movement of Lymph

Controlled by: Skeletal muscle

movement Pressure

changes (due to breathing)

Valves keep the movement going in one direction

Lymph Node Function

Filter foreign particles from blood before returning the lymph to the blood stream

Immune surveillance

Lymph Nodes (outside structure)

Usually small and bean shaped Afferent lymphatic vessels:

Carry lymph into lymph node Come in at various points along convex surface

Efferent Lymphatic vessels: Carry lymph out of lymph node Come out at hilum (area on the concave side)

Blood vessels and nerves enter at hilum

Lymph Node (Inside structure)

Connective tissue encloses lymph node and creates sub-compartments inside

Compartments are lymph nodules Lymph sinus: space inside the nodule Sinuses are filled with lymphocytes and

macrophages

Movie

Thymus Bilobed structure

found in the chest region

Largest during childhood

Creates T-cells Also an endocrine

gland Releases thymosins

(make T-cells mature after leaving the thymus)

Spleen “blood reservoir”

Largest lymphatic organ

Found near stomach Similar structure to

lymph nodes Sinuses contain blood

instead of lymph White pulp

High in lymphocytes Red pulp

High in red blood cells, lymphocytes, and macrophages

Filters Blood

Immunity Protection against pathogens Pathogens include:

Viruses Bacteria Fungi Protozoans

Types of Immunity Innate vs Adaptive Natural vs Artificial Active vs Passive

Innate Defenses Species specific First line of

defense: Skin and mucous

layers Second line of

defense: Chemical barriers

Tears, gastric juices, and sweat

Interferons Fever Inflammation Phagocytosis

Adaptive Immunity Third line of defense Lymphocytes are responsible

Lymphocytes: WBCs specific for adaptive immunity

Types of lymphocytes: B and T cells Responds to specific antigen on the

invading pathogen

Cell Differentiation

Origin of Lymphocytes

Undifferentiated lymphocytes made by fetal bone marrow

T cells Lymphocytes travel to thymus

and become T cells T cells either circulate in blood or

are found in lymph system B cells

Made in marrow B cells either circulate in blood or

found in the lymph system

Differences in response

1) Cellular Immune response Attack up close Performed by T cells soldiers, destroying the invaders that the intelligence

system has identified (hand to hand combat) Signal other cells if needed for additional help

2) Humoral immune response Attack from afar (produce antibodies) Can’t destroy without T cells help Performed by B cells body's military intelligence system, seeking out their

targets and sending defenses to lock onto them

Helper T cells Antigen-presenting cells processes and

displays antigen of pathogen Displayed antigen must be matched with

a circulating helper T cells antibody receptor

Helper T cell is activated

Cytotoxic T cells

Known as Tc

Function: Attack cells

infected virus or cancerous cells

Release destructive enzymes into pathogen

Must be activated by a matching antigen

B cells Sequence of events:

1. B cell must match with an antigen2. Activated Helper T cell secrete cytokines3. Cytokines make B cell proliferate to form

plasma cells and memory cells4. Plasma cell secrete antibodies

Antibodies Globular proteins; all immunoglobulins

Contain heavy and light protein chains Contain variable region (area that is specific to

antigen – foreign body- attachment)

Antibody TypesType Found Function/s

IgG Plasma and tissue fluid (passed down to fetus)

Activates complement system, effective against bacteria, viruses and toxins

IgA Breast milk (passed down to infant), tears, nasal fluid, gastric juice, intestinal juice, bile, urine

Control homeostasis

IgM Plasma (in response to food or bacteria)

Activates complement system

IgD Surface of B cells (esp. infants)

Activate B cells

IgE Exocrine secretions (with IgA)

Allergic reactions/response

Antibody Function Two types: 1) Attack directly

Allows antibody to more easily phagocytize cells, eliminate them

Types of Direct Attack:1. Agglutinate (Clump pathogens together)2. Precipitate (Make pathogen insoluble)3. Neutralize (Cover or destroy toxic part of

antigen)

Antibody Function 2) Complement

Bind antigens Starts a series of rxns that activate the

complements circulating in the plasma Complement Function:

Opsonization- coating antigen-antibody complex Chemotaxis- bringing macrophages to the area Lysis- rupturing membranes Agglutination Neutralization

“And the Band Played On” reaction

Get out a piece of paper: Did you know about the AIDS struggles

illustrated in the movie BEFORE watching it?

Did you find yourself angry at anytime during movie? When?

Did you find yourself sympathetic at anytime? When?

Did you find yourself sad? When? Overall view of movie…

Memory Cells

Memory Cells Memory T and B cells

Circulate after primary immune response Body will be able to respond quickly

during secondary immune response

Natural vs. Artificial Acquired Immunity

Natural: Through exposure to pathogen Resistance is the result of primary immune

response Artificial:

Through vaccine injection Vaccine: bacteria or virus that has been

killed or weakened Contains antigens that stimulate primary

immune response Don’t produce severe symptoms of disease Ex: Measles, mumps, flu, rubella

Active vs. Passive Acquired Immunity

Naturally Acquired Active: Occurs during pregnancy Certain antibodies (IgG) pass from maternal

blood to fetal blood Fetus acquires limited immunity against

pathogens Artificially Acquired Passive:

Through injection of antiserum (ready-made antibodies)

Obtain from globulin proteins from people who have already developed immunity against a certain disease

Allergic Reactions Immune response to everyday, non-

harmful antigens (allergens) Types: Delayed and Immediate Delayed-reaction allergy:

Exposure to allergen on skin Collects T cells and macrophages in the

area Causes dermatitis

Allergic Reactions Immediate-reaction allergy:

Occurs within minutes First exposure- B cells become sensitized;

IgE is attached to basophils and mast cells Subsequent exposures- mast cells and

basophils secrete several substances including histamine

These substances produce the reactions seen in allergy reactions

Transplantation Transplant tissue or organ

Ex: Organ – liver, kidney, heart; Tissue – skin, bone

New transplant tissue/organ has its own antigens Recognized as foreign Starts immune response (which can often

reject the new transplant tissue/organ) Tissue matching helps minimize reaction Immunosuppressive drugs

Suppress immune reaction, avoid rejection (usually)

Autoimmunity Cytotoxic T cells cannot correctly identify

self cells and attacks self cells Why?

Pathogen borrows self antigens during attack

Pathogen antigen is very similar to a self antigen

Disorder Description Symptoms

Lupus Occurs in 1 out of 2,000 Americans

profound fatigue, rashes, and joint pains, severe cases: immune system attacks organs (kidney, brain, lung)

Crohn’s result from intestinal inflammation

diarrhea, nausea, vomiting, abdominal cramps, and pain that difficult to control

Psoriasiscommon , affects more than 2% of Americans, often runs in families

skin or body covered with buildup of red scales, skin rash

Diabetes (Type 1)

destruction of the insulin-producing cells of the pancreas

See chapter 11

Rheumatoid arthritis

immune system targets the lining (synovium) that covers various joints

pain, swelling, and stiffness of the joints

Multiple Sclerosis

immune system targets nerve tissues of the CNS

possible blindness, paralysis, and premature death

Grave’s disease

immune system destruction or stimulation of thyroid tissue

fatigue, nervousness, cold or heat intolerance, weakness, changes in hair texture/amount, and weight gain/loss

Lymphatic System/ Water Cycle