Lecture 4: Innate immunity and Adaptive immunity

Question 1

Why do we need the immune system and the nervous system

Answer 1

To stay alive by; 
conserving autopoiesis (self generation), having coherent internal relations and conserving adaption (relations to nonself and the environment)

Question 2

What is the purpose of the immune system

Answer 2

To distinguish self from non-self by responding to molecular shapes (antigens) for the purpose of

1. Protect against infection
2. Recovery from infection and tissue damage and
3. Maintaining an adequate relationship with the organisms environment

Question 3

What is the immune system made up of

Answer 3

The immune system is made of constantly changing collection of organs, vessels, cells and molecules.

Question 4

What are the types of antigens/ molecular shapes that the immune system responds to

Answer 4

• Unusual shapes

- Familiar shapes in unusual contexts

Question 5

Compare the point in time of activation, the antigen specificity and affect of repeated exposure on the innate and adaptive immunity

Answer 5

Innate is not antigen specific like the adaptive and it doesn’t change with repeated exposure unlike adaptive where resistance is improved by repeated infection due to immunological memory

Question 6

How does the innate and adaptive immunity relate to each other timewise in an immune response

Answer 6

Innate defences are part of early exposure to infection and help to invoke the adaptive response which occurs later

Question 7

What are the 2 defences that make up the external surface protection from the innate immune system

Answer 7

• Biophysical defence: mucus, respiratory tract cillia, stomach acid and skin
• Biochemical defence making it difficult for bacteria to colonise : lysozyme in most secretions, sebaceous gland secretions, comensal organisms in gut+vagina and spermine

Question 8

What are the 4 main sites of infection via epithelial surfaces

Answer 8

Nasopharanyx, gut, lungs or genitourinary tract

Question 9

What are the internal defences from the innate immune system

Answer 9

Phagocytosis and the Complement system (enzymatic cascade in the blood)

Question 10

What types of cells do phagocytosis and what are the general 5 steps of the process

Answer 10

Neutrophils (short lived) and Monocytes (long lived) migrate from blood to tissues to phagocytose.

1. Adherence,
2. Membrane activation,
3. phagosome formation,
4. fusion and digestion
5. release of degraded products

Question 11

How does complement work (amplification)

Answer 11

1. The first complement components recognise common cell wall components of bacteria and form an enzyme complex on its surface
2. This activates other complement components by cleaving them.
3. These components:
   - increase vascular permeability -> oedema

• Chemotaxis (C3a) attracting neutrophils
• Opsonisation (C3b) which attach increasing affinty of neutrophils to bacteria for enhanced phagocytosis

Question 12

What do neutrophils recognise

Answer 12

Common bacterial cell wall components,

C3b complement component (for opsonisation) and Fc region of antibodies (opsonisation by adaptive)

Question 13

What does the lymphatic system do

Answer 13

It helps to drain away the fluid that leaks out of capillaries into the extracellular tissue spaces and filters this before returning it back to the blood stream to stop swelling

Question 14

Describe the structure of a lymphatic vessel and the direction of fluid flow. What helps it flow

Answer 14

They are fine vessels in the periphery anchored into the tissues with anchoring filament and lined with endothelium. Fluid flows in one direction (from interstitial fluid between endothelium) due to one way leaf valves. The fluid is pumped as a by product by normal muscle activity so its slow

Question 15

Describe the larger structure of the lymphatic system comparing afferent and efferent vessels

Answer 15

smaller Afferent lymphatic vessels in the periphery drain interstitial fluid from tissues into the lymph nodes where lymph is exposed to the immune system. After that Efferent lymph vessels drain out of the lymph nodes and connect up with other lymphatic vessels until eventually going to the thoracic duct which empties into the bloodstream through subclavian veins

Question 16

What are the primary lymphoid organs and why are they called primary

Answer 16

Primary lymphoid organs are where the lymphocytes are made not where they’re doing work.
This is Bone marrow -b lymphocytes, Thymus -t lymphocytes and the fetal liver - stem cells and b lymphocytes

Question 17

What are secondary lymphoid organs

Answer 17

These are the organs where mature lymphocytes migrate to as they are needed for Adaptive immune responses where foreign matter is filtered out of the lymph.

Question 18

What are the secondary lymphoid organs that receive antigens from the digestive, lymphatic and blood systems, all connected by blood

Answer 18

Adenoids, Tonsils, Peyer’s patches (in intestines) and Appendix : antigens from digestive system

Lymph nodes : antigens from the lymphatic system (tissues)

Spleen: antigens from the blood system

Question 19

What causes lymph nodes to become enlarged from normal size of broad bean to bigger

Answer 19

In the lymph node immune effectors start proliferating to show that its responding to an infection. Can also be haematological malignancy - blood cell cancer, where they can grow unchecked.

Question 20

Shingles- varicella zoster what is it?

Answer 20

Varicella zoster, it resolves but some of the viral DNA hides in the nerves without producing virus particles. Reactivates later to cause infection.

Question 21

How do you tell the physical difference between basophils, eosinophils, lymphocytes, neutrophils and monocytes

Answer 21

Basophils have basic staining cytoplasmic granules
Eosinophils orange staining granules
Lymphocytes are smaller but have relatively large dark staining nucleus
Neutrophils have strange polymorphic nucleus(s)
Monocytes: have a lighter lavender cytoplasm and one elongated nucleus

Question 22

What are the main functions of neutrophil

Answer 22

Phagocytosis and anti bacteria

Question 23

Compare appearance and function of erythrocytes vs platelets

Answer 23

RBCS are pale pink biconcave discs for gas transport whereas Platelets are much smaller fragments of cytoplasm of megakaryocytes which act as clotting factors

Question 24

What are two WBCs that work together to help adaptive immunity

Answer 24

Monocytes through antigen presentation work with lymphocytes who do adaptive immunity responses. Monocytes also phagocytose

Question 25

Compare the functions of eosinophil and basophil

Answer 25

basophil: mucosal surface protection
eosinophil: anti parasite immunity

Question 26

What is the precursor to all blood cells and what influences its differentiation into specific lineages

Answer 26

Haemopoietic stem cells in the bone marrow generate all blood cells

Signals trigger preferential differentiation when more of a specific blood cell is needed.
These signals are cell surface molecules, cytokines and hormones

Question 27

Under what lineage is the phagocytic cells made and what cells do these include

Answer 27

Myeloid lineage: Basophil, eosinophil, neutrophil + monocyte (->differentiate into macrophages in tissues)

Question 28

What cells are in the lymphoid lineage and what differentiates them

Answer 28

Lymphocytes that fully matures in the bone marrow are b lymphocytes and stem cell progeny that migrate to thymus to differentiate and mature are t lymphocytes.

Question 29

Describe the location and function of the spleen

Answer 29

On the side of the stomach, the size of a fist with a lot of blood flow through it.
Acts as a reservoir for RBCS to be pumped out if we need and a place for the iron in RBCs to be recycled when they go there to die.

Question 30

Where are Peyers patches

Answer 30

Islands of lymphoid tissue along the surface of the intestinal wall