Lymphatic System and Immunity

Question 1

definition of lymphatic system

Answer 1

organs, cells, and vessels associated with immunity

Question 2

definition of immunity

Answer 2

resistance against antigen infection

Question 3

definition of antigen

Answer 3

any foreign substance in the body

Question 4

definition of antibody

Answer 4

molecule that destroys antigens

Question 5

3 major lymphoid organs

Answer 5

1. lymph nodes
2. spleen
3. thymus

Question 6

lymphatic circulation

Answer 6

• fluid from blood leaks out of vascular capillaries into interstitial space
• then the fluid enters into lymphatic capillaries and becomes lymph

Question 7

lymph is delivered by…

Answer 7

lymphatic vessels thru a series of lymph nodes in the body

Question 8

afferent vessels

Answer 8

delivers lymph from peripheral tissues to the lymph node

Question 9

efferent vessels

Answer 9

deliver lymph from the lymph node to another node or to the blood circulation

Question 10

most of the lymph from the body drains into…

Answer 10

the thoracic duct (the largest lymph vessel) which returns the lymph to the venous system

Question 11

lymph nodes:

great filters of lymph

Answer 11

• composed of outer cortex and inner medulla

- both contain lymph nodes and sinuses

Question 12

lymph nodes (structure and function)

Answer 12

• transient structures
• spheres of densely packed lymphocytes (B and T cells)
• lymph slowly passes thru nodules
• 1% of antigens (specific) activates lymphocytes and initiates specific defense (immune response)

Question 13

sinuses (structure and function)

Answer 13

• lymph-filled spaces that contain macrophages
• lymph quickly passes thru sinuses
• 99% of antigens (nonspecific) are destroyed by macrophages thru nonspecific defense

Question 14

functions of spleen:

great filter of blood

Answer 14

1. initiates the immune response in response to antigens in the blood
2. destroys antigens in blood and abnormal RBCs
3. stores iron recycled from RBC breakdown

Question 15

histology of spleen

Answer 15

• composed of red pulp
  
  • contains RBCs and macrophages
  • site of phagocytosis by macrophages
• amongst red pulp is white pulp (aka lymph nodules)
  
  • contains B and T cells
  • site of immune response by B and T cells

Question 16

thymus

Answer 16

• contains outer cortex and inner medulla
• atrophies after puberty
• not involved in the immune response!
• site of T lymphocyte maturation

Question 17

maturation of T lymphocytes

Answer 17

• immature T cells enter cortex of thymus
• most die, the rest migrate thru medulla
• leave thymus via blood vessels
• travel to lymph nodes and spleen

Question 18

major cell components of lymphatic system

Answer 18

1. mast cells
2. macrophages
3. lymphocytes (B and T cells)

Question 19

innate cell components of immune system

Answer 19

1. mast cells
2. macrophages
3. WBCs

• provides initial inflammatory response
• attack any pathogen
• nonspecific defense

Question 20

mast cells in immune system

Answer 20

• “water brigade”

- release histamine to flush away large antigens

Question 21

macrophages of immune system

Answer 21

• “foot soldiers”

- roam the body looking for antigens, then surround them and eat them

Question 22

WBCs of immune system

Answer 22

• neutrophils, eosinophils, and basophils
• dendritic cells: antigen-presenting cells
• natural killer cells: destroy body’s infected cells

Question 23

adaptive cell components of immune system

Answer 23

1. B lymphocytes
2. T lymphocytes

• provide delayed response
• attack a particular pathogen
• specific defense

Question 24

B cells

Answer 24

• produce and mature in bone marrow

- responsible for antibody mediated immunity

Question 25

types of B cells

Answer 25

1. some mature into plasma cells which produce antibodies to destroy the antigen before it reaches the bloodstream 2. some leave the lymph node to travel to other lymph nodes 3. some become memory cells

Question 26

memory: | primary and secondary immune response

Answer 26

- 1st exposure to an antigen - can take 2 week to develop - antigens activate B cells and become memory cells - next exposure to same antigen - occurs faster and lasts longer - memory cells already primed and their plasma cells secrete antibodies

Question 27

T cells

Answer 27

- mature in the thymus - primarily responsible for cell-mediated immunity - directly attack foreign cells or organs

Question 28

4 characteristics of immune response

Answer 28

1. specificity: respond to specific antigen 2. versatility: ready confront foreign antigens 3. memory: active group responds immediately, memory group remembers antigens for next exposure 4. tolerance: immune system doesn't respond to all antigens