Sickness Behaviours Flashcards
vaccines
- Inactive virus (due to heat, chemicals, radiation) - can’t replicate
- Live attenuated vaccine: unable to activate, attenuated through passage into foreign host
herd immunity
indirect protection from an infectious disease; occurs when a large percentage of the population is immune to infection (ie. Through flu shots)
primary line of defense
barriers that keep foreign material out (ex. Skin, saliva, mucus & cilia, stomach acid); innate immunity
secondary life of defense
mechanisms targeting foreign material that enters the body – in the bloodstream (ex. White blood cells, cytokines); innate & adaptive immunity
cytokines
hormones of immune system
immune system
composed of organs and tissues, including primary lymphatic organs and secondary lymphatic organs
primary lymphatic organs
- where lymphocytes are formed and mature
- Bone marrow
- Thymus
secondary lymphatic organs
- series of filters that sample and monitor the contents of the extracellular fluids (lymph, tissue fluid, blood)
- Lymph nodes
- Spleen
- Tonsils
- Mucosa associated lymphoid tissue (MALT)
functions of immune system
- Protection from pathogens
- Critical role in brain development (cytokines are critical mediator of functions related to brain maturation)
- Impacts behaviour
link between immune system and social behaviour (mice study)
- normal mice and mice lacking functional immune system given social preference task (novel objects vs. novel mouse)
- Normal immune system: mice prefer other mouse
- Lack of immune system: no preference
- Repopulated immune system: now prefer other mice
- cytokine IFN-Gamma required for normal social behaviour
cytokine IFN-Gamma
- required for normal social behaviour in mice
- inhibits neurons in the prefrontal cortex – required for normal social behaviour
- Without IFN-gamma, the PFC is overactive and the mouse is asocial
Why does immune system impact social behaviour?
- evolved alongside it (with social behaviour/close contact, disease spreads quickly)
- rhesus monkey study showed that monkeys housed in social isolation had higher cytokine levels -> correlation with depressive symptoms
Major histocompatibility complex (MHC)
- surface proteins expressed on cells – tells your immune system which cells are “on your team” vs. “intruders” that need to be attacked
- Wide variation within population
- Co-dominantly expressed: express both maternal and paternal copies
- Ex. If you receive an organ transplant, your body would mount an immune response and reject it unless it was from an MHC match
- during cell turnover, microbes break down MHC fragments, resulting in odor -> this odor results in attraction to potential mates (we can sense of similar someone is to us genetically based on odor)
immune system and mate selection experiment
- 90 married couples; 152 randomly-generated control “couples”
- Married couples had more MHC dissimilarities than the control couples
- MHC protein playing role in mate selection
- MHC dissimilarities: implies genetic differences; decreased risk or disorders
- Evolutionary strategy for avoiding incest
sickness behaviour
- an adaptive response to illness, often precipitated by infection
- as a result, energy is shifted to wound healing
