Chapter 6 - Immune System and Inflammation & Sleep and Circadian Rhythm

What are the two types of immunity? Briefly explain each.

Innate = born with, first line of defense against infection, rapid, and non-specific

Adaptive = 2 types: cell-mediated immunity & humoral (anti-body mediated immunity), 

The innate immune system includes…

• Anatomic barriers (ex. skin)

• Physiologic barriers (ex. stomach acid)

• Phagocytic cells that engulf and destroy organisms 

• Inflammation 

• Natural killer cells

• Interferons 

• Complement

• Fever

Innate immunity - inflammation

Produces antibacterial activity & stimulates phagocytosis 

Innate immunity - natural killer cells

Cytotoxic action against cancer cells and virus-infected cells 

Innate immunity - Interferons

Antiviral proteins that stimulate uninfected cells to resist viral infection & increase natural killer cell activity

Innate immunity - complement 

Plasma proteins that kill foreign cells, increase inflammatory response, and attract phagocytes to the area

Innate immunity - fever

Multiple effects including:

• Slows the growth rate of some pathogens 

• Increase phagocytosis

• Accelerates tissue repair

• Very few fevers can cause adverse effects 

Give a detailed explanation of the adaptive immune system

• Aka acquired/specific immunity

• Responds to antigens or specific pathogens 

• Slower than innate immunity 

• Involves the development of immunologic memory so the body responds faster to future exposures to the same antigen (immunologic memory is crucial to the success of a vaccine)

What is an antigen?

A molecule or substance that is foreign to the body that provokes an immune response

What is cell-mediated immunity?

Primarily involves T lymphocytes (T cells). They are derived from bone marrow and undergo further development in the thymus

What are the types of T cells for cell-mediated immunity?

• Cytotoxic T cells

• Helper T cells

• Long-lived memory T cells

Cytotoxic T cells

Aka Tc or CD8 cells. Destroy infected host cells, abnormal cells such as cancer cells, and transplanted organs and tissues

Helper T cells

Aka CD4 cells. Increase antibody production by plasma cells, stimulate cytotoxic T cells and natural killer cells, also increase phagocytosis

Long-lived memory T cells

Produced after initial antigen exposure, mobilize fast if future exposure to same antigen

What is humoral (antibody-mediated) immunity?

When B lymphocytes (B cells) encounter a pathogen, they recognize parts of the antigens on the surface as being foreign (non-self). B lymphocyte binds to antigen, which triggers the cell to divide and develop into plasma cells and long-lived memory B cells

Plasma cells

Make antibodies that are specific for the antigen that initiated their production. Can make up to 2,000 antibody molecules per second

Long-lived memory B cells

Produce a faster, stronger response to future exposures to same antigen

What are antibodies?

Aka immunoglobulins. Proteins secreted into plasma to help eliminate foreign organisms

What are the functions of antibodies?

• Neutralize bacterial toxins

• Neutralize viruses before they infect cells

• Attach to bacteria promoting phagocytosis

• Activate components involved in inflammatory response 

What is active immunity?

After exposure to a foreign organism, immune cells produce antibodies and memory cells. 

• Can be acquired due to infection with organism 

• Can be acquired due to vaccination 

• Memory cells are formed = long-term protection

What is passive immunity?

Involves the transfer of pre-formed antibodies to an individual. No memory cells are formed = short term protection until antibodies are consumed

Ex. transfer of maternal antibodies to fetus in utero

What is tolerance?

Immune system’s appropriate non-response to “self”. Basically the body is appropriately tolerating self

What is autoimmunity?

When tolerance fails and the body develops antibodies to own tissues or self antigens. No known cause and no prevention methods available but early diagnosis and treatment may prevent serious complications.

Sjögren’s syndrome

Type of autoimmune disease. Affects 4 million in the US, 90% women. Symptoms include dry eyes & mouth, problems w kidney, GI, blood vessels, lungs, liver, pancreas, and CNS

What is inflammation?

Body’s response to injury, infection, and certain environmental exposures. Part of innate immunity, nonspecific, rapid early response, and increased blood flow

What are the purposes of inflammatory response?

• Neutralize or destroy foreign particles in body

• Limit damage to tissues

• Prevent spread to infection or damage to other tissues 

What are the symptoms of acute inflammation?

Warmth, redness, throbbing pain, localized swelling, and short-term

What are the symptoms of chronic inflammation?

Often visible, can last for years, and associated with increase risk of chronic disease 

What to know for acute vs. chronic inflammation

Duration: Acute is short while chronic is persistent & non-resolving

Outcomes: Acute is healing and chronic is collateral damage 

What is intestinal dysbiosis?

Agitation in the composition of the gut microbiome relative to the composition of the gut microbiome in healthy individuals 

What is the circadian rhythm?

Biological clocks, governed primarily by light/dark, cyclical 

What is the overall master clock?

The suprachiasmatic nucleus (SCN) which is located in the brain and synchronizes the circadian rhythm in organs and tissues. It receives direct input from the eyes and controls the body’s production of melatonin (hormone that makes you drowsy before sleep)

What can disrupt the circadian rhythm? And how can irregular circadian rhythm affect health?

Jet lag, shift work, light from devices at night. Irregular circadian rhythms are associated with certain chronic health conditions (obesity, diabetes, depression)

Insufficient sleep is associated with…

• Increased risk of obesity

• Decrease in leptin, a hormone that helps you feel full

• Increase in ghrelin, a hormone that stimulates appetite 

• Depression & anxiety

• In people with high blood pressure - elevated blood pressure the day after not getting enough sleep

• Altered processing of glucose = chronic lack of sleep is associated with increased risk of Type 2 diabetes 

What is sleep hygiene?

• Going to bed at the same time every day

• Avoid caffeine and nicotine 4-6 hours before bed

• Create a routine

• Don’t look at bright screens for 2-3 hours before sleep

What are the effects of light color on sleep?

• Blue wavelengths during days: boost mood, attention, reaction time

• Blue wavelengths at night: powerful suppressor of melatonin

• Led light output includes blue light

• Red light: weakest suppressor of melatonin (best for night lights)

• Exposure to bright light during day boosts alertness, mood, and helps with sleep at night

What is insomnia and chronic insomnia?

Insomnia = trouble going to sleep, staying asleep or getting good quality of sleep

Chronic insomnia = trouble sleeping for at least 3 nights per week for more than 3 months