1. Lymphatic System

2. Functions Put excess fluid in tissue spaces back into the blood stream
Immunity

3. Flow of Lymph
Lymphatic capillaries → Lymphatic vessels → Lymphatic Trunks → Collecting Ducts → Veins
The lymph will also pass through lymph nodes found along these vessels

4. Lymphatic Capillaries
Closed-ended tubes
Form network with blood capillaries
Thin-walled
Fluid inside is called lymph

5. Lymphatic Vessels and Trunks
Structure is very similar to veins
Lymphatic Trunks
Larger vessels than lymphatic vessels; drain into collecting ducts

6. Collecting Ducts Two Main Ducts
Thoracic Duct- collects lymph drained from the lower limbs, the abdomen, the left upper limb, and the left side of the thorax, head, and neck
Right Lymphatic Duct- collects lymph drained from the right upper limb and the right side of the thorax, neck, and head

7. Tissue Fluid Interstitial fluid surrounding capillaries
Constant movement in and out of capillaries
Generally same composition as plasma except plasma proteins
Some excess fluid stays and is not recollected by capillaries

8. 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

9. Movement of Lymph Controlled by
Skeletal muscle movement
Pressure changes due to breathing
Valves keep the movement going in one direction

11. Lymph Nodes (outside) 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

12. Lymph Node (Inside)
Connective tissue encloses lymph node and creates sub-compartments inside
Compartments are lymph nodules
Space inside the nodule is called a lymph sinus
Sinuses are filled with lymphocytes and macrophages

13. Lymph Node Function
Filter foreign particles from blood before returning the lymph to the blood stream
Immune surveillance

14. Thymus Bilobed structure found in the mediastenum
Largest during childhood
Creates T-cells
Also endocrine gland- releases thymosins to make T-cells mature after leaving the thymus

15. Spleen Largest lymphatic organ
Found in upper left quadrant near stomach
Similar structure to lymph nodes except sinuses contain blood instead of lymph
White pulp- high in lymphocytes
Red pulp- high in red blood cells, lymphocytes, and macrophages
Filters Blood

16. Immunity Protection against pathogens Pathogens include Viruses
Bacteria
Fungi
Protozoans

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

18. Innate Defenses Species resistance
First line of defense- skin and mucous layers
Second line of defense
Chemical barriers
Tears, gastric juices, and sweat
interferons
Fever
Inflammation
Phagocytosis

19. Adaptive Immunity Third line of defense Lymphocytes are responsible
Responds to specific antigen on the invading pathogen

20. 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

21. Differences in response
Cellular Immune response
Attack up close
Performed by T cells
Humoral immune response
Attack from afar
Performed by B cells

22. 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

23. Cytotoxic T cells
Cytotoxic T cells- attack cells infected virus or cancerous cells
must be activated by a matching antigen

24. B cells B cell must match with an antigen
Activated Helper T cell secrete cytokines
Cytokines make B cell proliferate to form plasma cells and memory cells
Plasma cell secrete antibodies

25. Antibodies Globular proteins Five Types
Immunoglobulin G (IgG)- in plasma and tissue fluids; activates complement system
IgA- in exocrine gland secretions
IgM- in plasma; activates complement system
IgD- found on surfaces of B cells; activates B cells
IgE- in exocrine gland secretions; associated with allergic reaction

26. Antibody Function Attack Directly
Agglutinate- clump pathogens together
Precipitate- make pathogen insoluble
Neutralize- cover or destroy toxic part of antigen

27. Antibody Function Activate compliment Compliment Function
Done by shape change of IgG and IgM
Starts a series of rxns that activate the compliments circulating in the plasma
Compliment Function
Opsonization- coating antigen-antibody complex
Chemotaxis- bringing macrophages to the area
Lysis- rupturing membranes
Agglutination
Neutralization

28. Memory Cells
Memory T and B cells- circulate after primary immune response
Body will be able to respond quickly during secondary immune response

29. Allergic Reactions
Immune response to everyday, non-harmful antigens (allergens)
Delayed-reaction allergy
Exposure to allergen on skin
Collects T cells and macrophages in the area
Causes dermatitis

30. 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

32. Transplantation Transplant tissue or organ
Antigen is recognized as foreign and starts immune response
Tissue matching helps minimize reaction
Immunosuppressive drugs- suppress immune reaction

33. Autoimmunity
Cytotoxic T cells cannot correctly identify self cells and attacks self cells
Why?
“catalogue” is incomplete
Pathogen borrows self antigens during attack
Pathogen antigen is very similar to a self antigen