Lecture 4: Innate immunity and Adaptive immunity Flashcards
Why do we need the immune system and the nervous system
To stay alive by; conserving autopoiesis (self generation), having coherent internal relations and conserving adaption (relations to nonself and the environment)
What is the purpose of the immune system
To distinguish self from non-self by responding to molecular shapes (antigens) for the purpose of
- Protect against infection
- Recovery from infection and tissue damage and
- Maintaining an adequate relationship with the organisms environment
What is the immune system made up of
The immune system is made of constantly changing collection of organs, vessels, cells and molecules.
What are the types of antigens/ molecular shapes that the immune system responds to
- Unusual shapes
- Familiar shapes in unusual contexts
Compare the point in time of activation, the antigen specificity and affect of repeated exposure on the innate and adaptive immunity
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
How does the innate and adaptive immunity relate to each other timewise in an immune response
Innate defences are part of early exposure to infection and help to invoke the adaptive response which occurs later
What are the 2 defences that make up the external surface protection from the innate immune system
- 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
What are the 4 main sites of infection via epithelial surfaces
Nasopharanyx, gut, lungs or genitourinary tract
What are the internal defences from the innate immune system
Phagocytosis and the Complement system (enzymatic cascade in the blood)
What types of cells do phagocytosis and what are the general 5 steps of the process
Neutrophils (short lived) and Monocytes (long lived) migrate from blood to tissues to phagocytose.
- Adherence,
- Membrane activation,
- phagosome formation,
- fusion and digestion
- release of degraded products
How does complement work (amplification)
- The first complement components recognise common cell wall components of bacteria and form an enzyme complex on its surface
- This activates other complement components by cleaving them.
- These components:
- increase vascular permeability -> oedema
- Chemotaxis (C3a) attracting neutrophils
- Opsonisation (C3b) which attach increasing affinty of neutrophils to bacteria for enhanced phagocytosis
What do neutrophils recognise
Common bacterial cell wall components,
C3b complement component (for opsonisation) and Fc region of antibodies (opsonisation by adaptive)
What does the lymphatic system do
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
Describe the structure of a lymphatic vessel and the direction of fluid flow. What helps it flow
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
Describe the larger structure of the lymphatic system comparing afferent and efferent vessels
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
What are the primary lymphoid organs and why are they called primary
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
What are secondary lymphoid organs
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.
What are the secondary lymphoid organs that receive antigens from the digestive, lymphatic and blood systems, all connected by blood
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
What causes lymph nodes to become enlarged from normal size of broad bean to bigger
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.
Shingles- varicella zoster what is it?
Varicella zoster, it resolves but some of the viral DNA hides in the nerves without producing virus particles. Reactivates later to cause infection.
How do you tell the physical difference between basophils, eosinophils, lymphocytes, neutrophils and monocytes
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
What are the main functions of neutrophil
Phagocytosis and anti bacteria
Compare appearance and function of erythrocytes vs platelets
RBCS are pale pink biconcave discs for gas transport whereas Platelets are much smaller fragments of cytoplasm of megakaryocytes which act as clotting factors
What are two WBCs that work together to help adaptive immunity
Monocytes through antigen presentation work with lymphocytes who do adaptive immunity responses. Monocytes also phagocytose
Compare the functions of eosinophil and basophil
basophil: mucosal surface protection
eosinophil: anti parasite immunity
What is the precursor to all blood cells and what influences its differentiation into specific lineages
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
Under what lineage is the phagocytic cells made and what cells do these include
Myeloid lineage: Basophil, eosinophil, neutrophil + monocyte (->differentiate into macrophages in tissues)
What cells are in the lymphoid lineage and what differentiates them
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.
Describe the location and function of the spleen
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.
Where are Peyers patches
Islands of lymphoid tissue along the surface of the intestinal wall
