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Diet and the immune system - Coggle Diagram
Diet and the immune system
What is the immune system
Four functions
Creating a barrier to prevent pathogens entering the body
Identifying pathogens if they breech the barrier
Eliminating pathogens
Generating immunological memory
Vital once an individual is exposed to an infectious agent e.g. bacteria, virus, fungi, parasites
Different infectious agents illicit different responses due to their attack
bacteria mostly remain extracellular so remain accessible to the host immune system
Viruses invade host cells so these are eliminated
2 forms of response; innate and acquired
Infection vs. inflammation
Infection = invasion and amplification of pathogen in the body
Inflammation = biological response to harmful stimuli
from pathogens, damaged cells, irritants
Aimed at protecting the body
involves a complex response of different cell types and mediators
Acute or chronic
Innate response (non specific defence
)
Bloodbourne
Phagocytes
Neutrophils
Macrophages
Death of dangerous organisms
Basophils
Eosinophils
Natural killer cells
Complement cascade (alternative pathway)
Direct killing of bacteria
Physical barriers
Skin
Stops infection before it enters the body
Mucous membranes
Saliva
Flushing action of tears and urine
Stomach acid
No memory of previous encounters
Rapid
Non-specific
Acquired Response (specific response)
T-Cell immunity (cell mediated immunity)
Whole T-cells released into:
Suppressor T-cells
Helper T-cells
Death of the body's cells which are infected or damaged
Cytotoxic T-cells
B-Cell immunity (humoral immunity)
Antigen exposure
Lymphoblasts
Clonal B- Cells
Memory B-Cells
Plasma cells
Antibodies
Complement cascade (classical pathway)
Remembers previous infections
Characterised by specificity, diversity, memory and self regulation
Cytokines
Messenger molecules
Polypeptides mainly produced in lymphocytes, monocytes and macrophages
Function in blood cell production (hematopoiesis), inflammation and tumour suppression
Pro-inflammatory cytokines
Induce and maintain inflammation
Direct symptoms
Fever
Loss of apetite
Weight loss
Negative nitrogen and mineral balance
Indirect symptoms
Increased secretion of catabolic hormones
e.g. Interleukin 1 & 6 (IL-1,-6) and tumour necrosis factor alpha (TNF-a)
Effects of PICs
Increased temp = hostile environment for pathogens
Catabolism of proteins and fat to amino and fatty acids = nutrients to support immune system
enhance defence system through acute protein changes and change in micronutrient metabolism
Acute phase proteins
Type of PIC
Plasma concentrations increase 25% during inflammation, trauma or disease
e.g. C-reactive protein (CRP), serum amyloid A, Fibrinogen, Haptoglobin
Sources of variation in immune function
Diet
Gut flora
Obesity
associated with loss of immunocompetence
Impaired activity of
T-helper lymphocytes
cytotoxic t-lymphocytes
b-lymphocytes
Natural killer cells
reduced antibody and IFN-g production
Increased susceptibility to bacterial, fungal and viral infection
Poorer response to vaccination
Alcohol consumption
Smoking
Exercise
Acute
Chronic
Stress
Environmental
Physiological
Psychological
Vaccination history
Exposure to pathogens
Present
Historic
Hormonal status
Age
Immunosenescence
Loss of immunocompetence
decreased output of immune cells from bone marrow
involution of thymus leading to decreased output of naive t-lymphocytes
Older people show increased susceptibility to infections and poorer response to vaccinations
Linked to inflammaging
An increase in circulatory inflammatory markers
Increased risk of chronic disease e.g. CVD, metabolic diseases, neurodegeneration and some forms of cancer
Gender
Genetics
Early life events
Nutrition status
Inadequate nutrient supply results in
inadequate nutrition status
impaired immune function
impaired pathogen defence
more severe infections, illnesses and death