Lymphatic & Immune System Unit 2 Intended Learning Outcomes

Anatomy & Physiology - Systems of Homeostasis

Describe the functions of the lymphatic system

Transport dietary lipids, lymphocytes, & other immune cells

Body fluid homeostasis

Production/maturation of lymphocytes

Mounting immune response

Identify the organs of the Lymphatic System

Thymus, red bone marrow, tonsils, lymph nodes (cervical, axillary, inguinal), spleen, and MALT (in small intestine)

What are the general functions of the organs of the lymphatic system? (lymph nodes, tonsils, spleen, thymus)

Lymph nodes = “police checkpoints”, packed w/ lymphocytes & macrophages, and is where innate immune system communicates w/ adaptive thru dendritic cells

Tonsils = Tonsillar crypts; have high concentrations of B & T-cells; B-cells produce IgA antibodies; have immunological memory

Spleen = removes old RBC’s; has blood resovoir; recycles iron; stores platelets; activates adaptive immune response → triggers antibody production

Thymus = produces specialized cells → helper T-cells & cytotoxic T-cells; T-cell binding test in thymus to see if they can correctly identify and bind to MHC cells

Describe the pathway of the lymphatic system from the capillary level to return of fluid to venous system.

Lymphatic capillaries → lymphatic vessels → lymphatic trunks → lymphatic ducts → blood

What is the importance of the thoracic duct and the right lymphatic duct?

Thoracic duct = largest lymphatic vessel; receives lipid rich chyle from GI tract; drains lymph from left side of head, neck, left arm, left side of thorax, abdomen, and both legs; drains into venous angle

Right lymphatic duct = returns lymph at junction of right subclavian and internal jugular veins; drains lymph from right side of head, neck, right arm, and right side of thorax; delivers lymph to junction of right subclavian and right internal jugular veins

Explain how lymphatic vessels help maintain interstitial fluid balance

At the blood capillaries, fluid escapes into interstitial spaces. Then, at the lymph capillaries, tissue pressure causes mini valves to open and fluid enters. Then, at the lymphatic vessels, the lymph is pumped toward the chest by muscle movement. Lastly, at subclavian veins, the fluid is dumped back into the blood.

Compare and contrast the cardiovascular and lymphatic systems

Cardiovascular system = closed loop, the heart pumps, high pressure, fluid is blood (RBCs, WBCs, platelets), major organs are heart and lungs, functions to transport O2 and nutrients, filters at kidneys and liver

Lymphatic system = Open ended (to heart), skeletal muscle/breathing is the pump, very low pressure, fluid is lymph (WBCs, water, proteins), major organs are lymph nodes, spleen, thymus, & tonsils, functions are immune defense and fluid balance, filters at lymph nodes

Functions of immune system

Defend against pathogens

Remove old/worn out/damaged cells

Identify & destroy cancer cells

Identify the specific WBCs involved in immune function

Leukocytes → Granulocytes → Neutrophils, eosinophils, basophils

→ Agranulocytes → Lymphocytes → T & B lymphocytes, NK cells

→ Monocytes → macrophage, interstitial dendritic cell, microglial cell

Compare innate immune responses to adaptive immune responses

Innate immune responses = Nonspecific internal defenses (macrophages & NK cells, and interferon & complement), skin and mucosal membranes, inflammation and fever

Adaptive immune responses = “acquired/specific immunity,” slow response, lymphocytes replicate and respond when stimulated by a specific antigen (T & B-lymphocytes, and plasma cells)

Identify the three major types of innate immune responses

1) epithelium, dermis, and mucous membranes → cillary action and urine & tear secretion, acidic environments and antimicrobial enzymes (lysozyme)

2) signalling proteins (cytokines & interferons), blood proteins, CRP

3) phagocytosis (macrophages & neutrophils), NK cells, Inflammation

How do toll-like receptors, interferon, and complement proteins function in immune protection

TLRs = “detect” → recognize PAMPs, binds to them, triggers signalling cascade to release cytokines, initiates inflammation

Interferon = “antiviral alarm” → travels to neighboring healthy cells and binds to receptors, signals to produce antiviral proteins to inhibit protein synthesis & degrade viral RNA, creates a defensive perimeter

Complement proteins = “tactical killers” → tag pathogens for macrophages, lure immune cells to infected area to create inflammation, and cytolysis → membrane attack complexes

Contrast active acquired immunity to passive acquired immunity

Active acquired immunity = produce memory cells due to contact with antigen; naturally acquired = direct exposure to pathogen in body; artificially acquired = exposure thru vaccine

Passive acquired immunity = no memory cell production and antibodies from another entity; naturally acquired = mother to child thru breast milk and/or placenta; artificially acquired = serum containing antibody transfers from another entity

What are the various types of acquired immune cells

Leukocytes → granulocytes

→ agranulocytes → monocytes

→ lymphocytes → T & B-lymphocytes, NK cells

Where are immune cells formed?

Red bone marrow

Where are immune cells found?

Secondary lymphoid structures → lymph nodes, spleen, tonsils, MALT

How do antibodies generally work?

Y-shaped proteins produced by B-cells made to identify and neutralize foreign invaders

• coat virus surface in bacterial toxin

• opsonization → attaches to pathogens to form a “bridge” to allow phagocytes to grab and destroy it

• changes shape after binding to bacterium and invites complement proteins