Lec 7 Flashcards
What does psychosomatic mean?
physical illness with an apparently psychological etiology
What is affected when you are stressed?
- -immunity, digestion, and the cardiovascular system
- -When you are stressed, every single cell in your body is affected
What is sickness behaviour?
The behavioral and cognitive changes that accompany physical illness
- -Ignore food and beverages.
- -Lose interest in social interaction.
- -Have excess or fragmented sleep.
- -Feel depressed and irritable.
- -Have impaired attention and memory
What might sickness behaviour be good for?
may represent a motivational state responsible for helping individuals cope with infection
What is psychoneuroimmunology?
The study of the interaction between the mind, brain, and immune system.
What can our psychological state interact with? Why are these interactions important?
- -can interact with the immune system and the immune system can interact with the brain
- -These interactions are important for everything from the common cold to cancer.
The brain and immune system have a ____________ communication
bidirectional
What did psychoneuroimmunology advance?
advanced earlier viewpoints that saw infectious diseases as strictly physical phenomena
What is the immune system?
- -responsible for protecting your body from microbial overgrowth.
- -monitors the internal environment for signs of invasion by bacteria or viruses, as well as evidence of tissue damage
- -is extremely powerful, and is highly regulated in order to maintain optimal levels of function
Why is the immune system decentralized?
– decentralized because it is all over the body to attack any bad bacteria/microbes
What regulates the immune system?
the HPA axis
What acts as factories and repositories for immune cells?
- -spleen
- -lymph nodes
- -thymus
- -bone marrow
The immune system relies on ___________________
on chemical communication to organize its functions
What are the two basic divisions of the immune system?
Innate immune system: coded by DNA (fight off diseases that affected your ancestors)
Adaptive immune system: as you encounter viruses or bacteria, you develop immunity to them (develop antibodies to them)
–Cell-mediated immunity (T cells)
–Antibody-mediated immunity (B cells)
Your innate immune system is activated and it may or may not manage it. If it can’t manage it, then it activates the two branches of the adaptive immune system (T cells B cells)
What are cytokines?
- -Cytokines are like hormones for immune signaling
- -Cytokines are molecules that coordinate the immune response, and tell the body that it is under attack.
What is the innate immune system?
- -used for “general purpose” immunity, and is sensitive to molecules that are universally present on bacteria.
- -macrophages have receptors on their membranes that bind to pathogens and trigger phagocytosis
- -When activated, cells of the innate immune system (such as macrophages) release cytokines into circulation
How do macrophages identify pathogens?
use TLR’s (toll-like receptors) to identify pathogens
What is the adaptive immune system?
- -is activated by cytokines, and involves two systems of leukocytes (white blood cells)
- ->cell mediated immunity (T-cells) developed in thymus
- ->antibody mediated immunity (B-cells) developed in bone marrow
What do T-cells do?
T cells are activated by cytokine signals and interaction with macrophages. Once activated, T cells proliferate and develop into a form that attacks body cells that have been infected
What do B cells do?
- -Develop antibodies which bind to antigens on pathogens to kill or deactivate them. When you have the antibody it recognizes the antigen of that infector and kills it off. Unless you have the antibody, you won’t be able to fight it off necessarily.
- -B cells that produce antibodies are also called plasma cells
- -Memory B cells survive in the body for ages
- -B-cells involved in fighting viruses.
How are cytokines released?
- -After ingesting pathogens, macrophages release cytokines such as interleukin-1 (IL-1)
- -IL-1 stimulates T helper cells (lymphocytes) to release IL-2.
- -IL-2 induces the proliferation and development of antibody producing B cells (plasma cells) and cytotoxic T cells.
What do cytokines do?
- -Trigger an inflammatory response (redness, fever, aches, etc.)
- -Attract more innate immune cells.
- -Activate the adaptive immune system.
How do cytokines interact with the brain?
- -Cytokines are like ‘sickness hormones’, so it makes sense that they can communicate with the brain
- -Cytokines like IL-1 signal sickness to the brain through a variety of mechanisms
- —>The vagus nerve connecting the brain to the abdominal organs
- —>Receptors on blood vessels in the brain detect circulating IL-1 or pathogens and stimulate cytokine production in the brain
- —>Circulating IL-1 can be actively transported into the brain
Cytokines in the brain are linked to _________ behaviour
sickness; by informing the brain of infection, cytokines allow the animal to make appropriate adjustments to its behavior.
What are the three pieces of evidence that cytokines play a role in depression?
- -Giving people cytokine treatment can produce depressive symptoms
- —>Ex. AIDS and cancer patients treated with cytokines often develop depression & suicidality
- Depression is more common among people suffering from inflammatory diseases.
- —> Ex. Cardiovascular disease, type 2 diabetes, rheumatoid arthritis
- -Anti-depressant treatment improves certain components of sickness behavior in mice.
- —>Ex. Sick mice injected with LPS (which promotes inflammation all throughout the mice) show reduced preference for sugar water and social exploration, but these symptoms are improved by anti-depressants
How does stress affect/interact with the immune system?
- -the HPA axis can affect the immune system.
- —>You can think of HPA axis hormones as a negative feedback signal for the immune system.
- —>Cortisol is anti-inflammatory (remember, the immune system increases inflammation via cytokines)
- -Problems arise when the HPA axis is over- or under-activated.
- —>Chronic stress can lead to disease (suppresses immunity)
- —>On the other hand, having a weak HPA axis can lead to the immune system getting out of control (exacerbate inflammatory and autoimmune diseases)
How does acute stress help the body deal with short term challenges?
- -For a short-term challenge, the body can save a lot of energy by shutting down the immune system. This energy can be used to cope with enemy attacks, survive starvation, etc.
- -Leukocytes move from the spleen and blood to the skin, lymph nodes, and other ‘battle stations’ (This may be in order to prepare the animal for physical damage – a wound for example)
- -These rapid effects appear to be mediated by the SAM axis, as treatment with epinephrine and norepinephrine can mimic the immune-enhancing effect of acute mild stress.
How are diseases affected by stress?
- -The frequency and duration of genital herpes flare-ups can be reduced by stress control procedures such as relaxation
- -There is no evidence that stressful life experiences cause cancer, however there is a fair bit of evidence that stress increases the rate of cancer progression and mortality
What do we call the placebo effect?
–Treatments with no known physiological mechanism may work simply by reducing stress (we call this the placebo effect
How do social factors affect stress?
- -Chronic social stress increases susceptibility to the common cold.
- —>Social stress is one of the most potent stressors known
- -On the other hand, having more and better friends seems to reduce the odds of getting sick
- -Positive social support seems to support the immune system. This may explain the success of “holistic” medical treatments that incorporate social support
How can brain disorders be caused by inflammation?
PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections)
—->Obsessive-compulsive disorder (OCD), tic disorder, or both suddenly appear following a streptococcal (strep) infection
Anti-NMDA receptor encephalitis is a disease occurring when antibodies produced by the body’s own immune system attack NMDA receptors in the brain
