The Immune System

Question 1

What does the lymphatic system consist of

Answer 1

Lymphatic tissue
Bone marrow
Lymph
Lymphatic vessels

Question 2

What does the lymphatic system do?

Answer 2

Protects us against disease

Lymphoid cells respond to
- environmental pathogens
Toxins
Abnorma body cells such as cancers

To produce, maintain and distribute lymphocytes

Return of fluid and solutes from peripheral tissue to blood

Distribute hormones, nutrients and waft produces from tissue of origin to circulation

Question 3

What are the pathogens that can cause disease

Answer 3

Viruses

Bacteria

Fungi

Parasites

Question 4

Explain the 4 parts of the lymphatic system

Answer 4

Lymph - similar to plasma without plasma proteins

Lymphatic vessels - carry lymph from peripheral tissues to venous system

Lymphoid tissues e.g lymph nodes and lymphoid organs e.g thymus, spleen, bone marrow

Lymphoid cells (lymphocytes, phagocytes)

Question 5

Where is thymus

Answer 5

Behind spleen

Question 6

Where are lymphocytes produces

Answer 6

Lymphoid tissues
Lymphoid organs
Red bone marrow

Question 7

What do lymphocytes do

Answer 7

Detective problems
Travel to site of injury or infection

Question 8

Explain lymphatic vessels and capillaries

Answer 8

Vessels begin as capillaries which are closed at one end

L capillaries located between cells of many tissues

Merge to form vessels which have thin walls and many vessels

Question 9

What are the differences between lymphatic vessels and blood capillaries

Answer 9

Start as blind pockets rather than tubes

Have large diameters

Thinner walls

Flat or irregular in section

Question 10

What stops backflow of lymphatic fluids

Answer 10

Valves in lymphatic vessels

Question 11

Explain lymph trunks and ducts

Answer 11

From the lymphatic vessels, lymph passes through lymph nodes and then into lymph duct

Trunks: lumbar, intestinal, bronchomefiastinal, subclavian and jugular trunks

Lymph trunks then merge to form thoratic duct or right lymphatic duct

Question 12

What does the right lymphatic duct do

Answer 12

Clear from upper right quadrant

Question 13

What are the kinds of circulating lymphocytes

Answer 13

T cells: thymus dependent

B cells: bone marrow derived

NK cells: natural killer cells, bone marrow derived

Question 14

What can red bone marrow cells become?

Answer 14

Lymphoid stem cells

Then either:

Natural killer or b cells

Migrate to thymus then T cells

Question 15

Okay are the primary lymphatic organs

Answer 15

Where they become immunocompitant

Red bone marrow
Thymus

Question 16

Okay are the primary lymphatic organs

Answer 16

Where they become immunocompitant

Red bone marrow
Thymus

Question 17

What are the secondary lymphatic organs

Answer 17

Lymph nodes
Spleen
Lymphoid nodules

Question 18

Explain the structure of a lymph node

Answer 18

Afferent vessels - coming in

Efferent vessels- leaving (fluid)

Germinal centre - where b cells mature and produce antibodies

Question 19

What is the difference between lymph organs and lymphoid nodules

Answer 19

Lymph organs (lymph nodes, thymus, spleen) are separated from surrounding tissue by fibrous capsule

Nodule = bundle of tissue without fibrous capsule
E.g tonsils, appendix, digestive system

Question 20

Explain the flow of lymph

Answer 20

Interstitial fluid
L capillaries
L vessels
L trunks
L ducts
Subclavian veins

Question 21

Explain how fluid flows through lymph node sinuses

Answer 21

Subcapsular space
Outer cortex
Deep cortex
Core
Hilium and efferent lymphatics

Question 22

What does the lymph node do

Answer 22

Filter lymph before returns to venous circulation

Removes debris, pathogens, antigens

Question 23

Where are the lymph nodes (glands

Answer 23

Groin and base of neck

Question 24

What is lymphadenopathy

Answer 24

Chronic enlargement of nodes

Infection/endocrine disorder/ cancer

Question 25

What is innate vs specific immunity

Answer 25

Innate - non specific Adaptive- specific

Question 26

What is non specific immunity

Answer 26

Block any potential pathogens Present from birth No memory

Question 27

What is specific immunity

Answer 27

Identify and attack and develop immunity to specific antigen Acquired response to antigen

Question 28

What are the 7 categories aif non specific defence

Answer 28

Physical barriers Phagocytic cells Immunological surveillance (no cells) Interferons (antiviral) Complement system Inflammation Fever

Question 29

What are the physical barriers

Answer 29

Tears Skin - Anatomic barrier, sweat and sebum Anti microbial secretions e.g lactic and ffas Low ph Urine Acidic Stomach acid Enzymes Respiratory Mucosa Ciliated epithelium Antibodies Phagocytes

Question 30

Explain phagocytosis and antigen presentation

Answer 30

Engulphs pathogen Lysozyme breaks it up Antigen binds Antigen then binds to cell membrane

Question 31

What are the classes of phagocytes

Answer 31

Phagocytic cells: remove debris and pathogens Macrophages - Neutrophils and eosinophils Leave bloodstream Enter peripheral tissue to fight infection Macrophages Distributed throughout body Make up monocyte macrophage system Fixed or free

Question 32

Explain activated macrophages

Answer 32

Engulf and destroy pathogen with lysosomal enzymes Bind to pathogen so other cells can destroy it Destroy by releasing toxic chemicals to interstitial fluid

Question 33

Explain immunological surveillance by nk cells

Answer 33

1. Recognition and adhesion 2. Realignment of Golgi apparatus 3. Secrete perforin 4, lysis of abnormal cell

Question 34

Explain anti viral interferons

Answer 34

Interferons = proteins released by lymphocyte and macrophage Alpha stim nk Beta slow inflammation Gamma stim macrophage

Question 35

Explain the complement system

Answer 35

Enhances ability of phagocytes ans antibodies to clear pathogen

Question 36

What are the effects of complement activation

Answer 36

1. Attract phagocytes 2. Enhance them 3. Stim inflammation 4. Destroy target cell membrane

Question 37

Explain inflammation and tissue repair

Answer 37

More blood flow Mast cells release histamine Phagocytes move to site Neutophils move to cite Clot Activate fibrinogen

Question 38

Explain fever

Answer 38

Increase body temp due to release of pyrogens Mobilises defences Accelerated repair Inhibits pathogens

Question 39

What are the two main divisions of specific immunity

Answer 39

1. Cell mediated immunity T cells T cells only recognise fragments of antigenic proteins that are processes and presented in a certain way 2. Humoral or antibody mediated immunity (B cells) B cells can recognise and bind to antigens in lymph, interstitial fluid or blood plasma

Question 40

What are MHC proteins

Answer 40

Class one On all nucleated cells Two Antigen presenting cells Lymphocytes

Question 41

How does the specific immune system recognise foreign antigens

Answer 41

Free living - exogenous Inside host cells - endogenous White blood cells differentiate self antigens - expressed on cell surface Non self antigens - presented on cell surface

Question 42

Explain cell mediated immunity

Answer 42

Mediated by T cells 3 main types of T cells 1. Cytotoxic - cell mediated immunity, destroy virally infected cells 2. Helper T cells - stimulate function of T and b cells 3. Suppressor T cells - inhibits T and B

Question 43

Explain humoral immunity

Answer 43

Mediated by B cells Attack antigens by producing specific antibodies

Question 44

Explain humoral immunity

Answer 44

Mediated by B cells Attack antigens by producing specific antibodies

Question 45

What are the 5 types of antibodies

Answer 45

IgG- (80% of all antibodies, placental transfer) IgA- glandular secretions e.g mucus, saliva, breast milk IgM- igD IgE

Question 46

Explain allergies

Answer 46

Hypersensitivity IgE

Question 47

Explain autoimmune disorder

Answer 47

Immune system fails to display self tolerance and attacks own tissue

Question 48

Explain diseases of the immune system

Answer 48

SCID HIV