Nutrition And The Immune System Flashcards
What are the external defences to microbes?
Physical barriers eg. Dead skin, cilia, mucosal epithelial
Secretions - epithelial, tears, saliva.
Microbial competition prevents pathogens colonising
Define immune system.
Collection of cells/molecules that protect us from infectious agents and provide surveillance system to monitor integrity of host tissues
What happens when immunodeficiency occurs?
System fails, overreacts to foreign substances, causing tissue damage = immunopathology
What is the innate immune system?
First line of defence. Physical barriers, cellular components, humoral response.
What is the process of the innate immune system?
Cells damaged by pathogens so capillaries constrict.
Histamine released so capillaries dilate and more perm.
Basophils and platelets
Increase neutrophils to kill pathogens.
Macrophages phagocytose dead cells.
What is the adaptive immune system?
Second line of defence. Depends if immune cells can differentiate between self and non self cells.
What is the process of the adaptive immune system?
Antibodies produced when foreign matter identified.
Detect antigens and produce antibodies.
Becomes aggressive to preserve pathogen levels.
What are the primary tissues of immunity?
Bone marrow - all WBS, B cells mature, stem cells.
Thymus - lymphocytes found in outer cortex of lobes. T cells mature.
What are the secondary tissues of immunity?
Lymph nodes - drain tissues, trap microbes arriving in afferent lymph, leave in efferent.
Spleen - immune response against blood borne antigens, removes platelets + RBC
What cells come from stem cells?
Erythrocytes
Platelets
Leukocytes - basophils, eosinophils, neutrophils, monocytes, lymphocytes.
What are examples of innate immunity cells?
Phagocytes
Natural killer cells - protect against tumours
Mast cells
Basophils
Dendritic cells - interact with T + B cells
Define complement.
Important molecules in the innate immune system, group of normally inactive serum proteins. Activated by proteolysis.
What is the process of complement pathway cascade?
- invitation of pathway - C1 binds to Ab-Ag complex. Activates complement and acts as esterase so C3 convertase is formed
- hydrolyses many C3 into 2 fragments - C3a and C3b
- enzyme from making C3b splits C5 into C5a and C5b
- C5b imp for forming MAC
Why are T cells important?
Develop in bone marrow and mature in thymus. Responsible for cell mediated immunity with T cells, macrophages, cytokines.
Regulates B cell response.
How is the immune system regulated in the innate and adaptive pathways?
Innate - phagocytes and NK cells recognise self cells
Adaptive - immune response driven by antigens, T cells, antibodies produced.
Describe antibodies.
Glycoprotein from active B cells that circulates in plasma. Renders foreign bodies more susceptible to damage.
Eg. Immunoglobulins
What are B cells?
Mature in bone marrow and found in blood. Reside in tissues. Part of adaptive response.
What are 5 antibody functions?
- Neutralisation of toxins
- Activation of complement
- Opsoninisation
- Initiation of inflammation
- Some immune control
What is the relationship between the immune system and nutrition?
Health maintenance and disease treatment. Associated with chronic diseases, CVD, T2D, cancer, obesity.
How do saturated FA impact the immune system?
Increase inflammation, alter lipids of immune cell membranes. Designed to sense bacteria. Misguided signalling leads to gut inflammation/dysfunction
How do free sugars and fibre affect immune function?
Free sugars increase inflammation, fibre reduces it.
