Lec 7

Question 1

What does psychosomatic mean?

Answer 1

physical illness with an apparently psychological etiology

Question 2

What is affected when you are stressed?

Answer 2

• -immunity, digestion, and the cardiovascular system

- -When you are stressed, every single cell in your body is affected

Question 3

What is sickness behaviour?

Answer 3

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

Question 4

What might sickness behaviour be good for?

Answer 4

may represent a motivational state responsible for helping individuals cope with infection

Question 5

What is psychoneuroimmunology?

Answer 5

The study of the interaction between the mind, brain, and immune system.

Question 6

What can our psychological state interact with? Why are these interactions important?

Answer 6

• -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.

Question 7

The brain and immune system have a ____________ communication

Answer 7

bidirectional

Question 8

What did psychoneuroimmunology advance?

Answer 8

advanced earlier viewpoints that saw infectious diseases as strictly physical phenomena

Question 9

What is the immune system?

Answer 9

• -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

Question 10

Why is the immune system decentralized?

Answer 10

– decentralized because it is all over the body to attack any bad bacteria/microbes

Question 11

What regulates the immune system?

Answer 11

the HPA axis

Question 12

What acts as factories and repositories for immune cells?

Answer 12

• -spleen
• -lymph nodes
• -thymus
• -bone marrow

Question 13

The immune system relies on ___________________

Answer 13

on chemical communication to organize its functions

Question 14

What are the two basic divisions of the immune system?

Answer 14

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)

Question 15

What are cytokines?

Answer 15

• -Cytokines are like hormones for immune signaling

- -Cytokines are molecules that coordinate the immune response, and tell the body that it is under attack.

Question 16

What is the innate immune system?

Answer 16

• -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

Question 17

How do macrophages identify pathogens?

Answer 17

use TLR’s (toll-like receptors) to identify pathogens

Question 18

What is the adaptive immune system?

Answer 18

• -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

Question 19

What do T-cells do?

Answer 19

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

Question 20

What do B cells do?

Answer 20

• -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.

Question 21

How are cytokines released?

Answer 21

• -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.

Question 22

What do cytokines do?

Answer 22

• -Trigger an inflammatory response (redness, fever, aches, etc.)
• -Attract more innate immune cells.
• -Activate the adaptive immune system.

Question 23

How do cytokines interact with the brain?

Answer 23

• -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

Question 24

Cytokines in the brain are linked to _________ behaviour

Answer 24

sickness; by informing the brain of infection, cytokines allow the animal to make appropriate adjustments to its behavior.

Question 25

What are the three pieces of evidence that cytokines play a role in depression?

Answer 25

- -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

Question 26

How does stress affect/interact with the immune system?

Answer 26

- -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)

Question 27

How does acute stress help the body deal with short term challenges?

Answer 27

- -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.

Question 28

How are diseases affected by stress?

Answer 28

- -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

Question 29

What do we call the placebo effect?

Answer 29

--Treatments with no known physiological mechanism may work simply by reducing stress (we call this the placebo effect

Question 30

How do social factors affect stress?

Answer 30

- -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

Question 31

How can brain disorders be caused by inflammation?

Answer 31

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