Immunology: Exam #1

pathogens

we would not need an immune system if we did not have…?

things that are foreign to the body; can come in a variety of different forms.

provide the general definition of pathogens.

infectious diseases

what do pathogens cause?

live on or in the host

where do pathogens live?

gain nutrients from the host

how do pathogens live?

ectoparasites and endoparasites

what are the two types of pathogens?

ectoparasites

these pathogens attach themselves to the OUTSIDE of the host.

with the aid of specialized mouthparts, they penetrate the skin and feed on their host’s blood. the parasites must have efficient structures for ‘hanging on’ because the host is usually quite mobile.

how do ectoparasites feed? what are their structures like?

• bed bugs

• louse

• mites

• ticks

• fleas

what are examples of ectoparasites?

endoparasites

these pathogens live INSIDE of the host.

they inhabit the human gut, blood vessels, blood cells, muscles, liver, and lungs.

how do endoparasites gain nutrients from their host?

their lifecycles are usually very complex and have adapted highly specialized features in order to live on the inside.

describe the lifecycles of endoparasites.

endoparasites

considering ectoparasites and endoparasites, which are our biggest concern?

• bacteria

• viruses

• roundworm

• tapeworm

• flukes

• protozoa

list the examples of endoparasites.

RECOGNITION and RESPONSE of foreign cells and tissues.

what are considered the two general functions of the immune system?

there are physical, chemical, and cellular defenses that prevent pathogens from entering the body. if they do enter, then our immune system can prevent them from spreading throughout the body.

why don’t pathogens harm us?

the recognition and rejection of foreign cells and tissues.

what is the immune system involved in?

• respiratory tract (i.e. mucus)

• digestive tract (i.e. stomach acidity)

• eyes (i.e. lysozyme)

• skin (i.e. anatomic barrier; sweat, sebum)

• genitourinary tract (i.e. washing by urine)

there are various areas of our body that give us protection against pathogens. what are some?

grew from observations that recovered individuals were protected from re-infection of infectious diseases.

explain how immunology grew from its foundations.

exempt

the word, immunology, is from Latin ‘immunis’ which means…?

written that only those surviving a plague could nurse infected (resist infection).

what occurred within 430 BC regarding breakthroughs with immunology?

first attempts to induce immunity by variolation.

• oozing dried from smallpox pustules.

• inhaled or inserted into small cuts.

what occurred within the 1400s regarding breakthroughs with immunology?

Jenner’s first vaccinate; such an observation within the 1400s was further refined in the late 1700s after observation that milkmaids with cowpox (non-lethal, mild condition) were immune to smallpox.

• people inoculated with oozes from cowpox pustules

• first tested on an 8-year-old boy

  • inoculated with cowpox

  • intentionally infected with smallpox, boy was immune to the disease.

what occurred within the late 1700s regarding breakthroughs with immunology?

in China, 100 years before Edward Jenner, healthy persons took pills made from fleas of cows to prevent smallpox.

what was the first recorded example of an oral vaccination?

It is the first line of defense, always 'on', with a rapid, immediate response. It acts the same way for all pathogens.

What is innate (nonspecific) immunity?

Rapid response, no memory, non-specific, includes barriers and immune cells like macrophages and neutrophils.

What are the key features of innate immunity?

Skin, mucous membranes, and cilia.

Name three physical barriers in innate immunity.

Lysozyme (in tears/saliva), stomach acid, and antimicrobial peptides.

What are some chemical barriers in innate immunity?

A specific immune response that develops over time and creates memory for faster future responses.

What is adaptive (active) immunity?

Humoral immunity (B cells and antibodies) and cell-mediated immunity (T cells).

What are the two major types of adaptive immunity?

B lymphocytes (B cells) and T lymphocytes (T cells).

Which cells are essential to adaptive immunity?

Antibodies that bind to specific antigens.

What do B cells produce?

Activate B cells, cytotoxic T cells, and macrophages; coordinate the immune response.

What do helper T cells (CD4+) do?

Innate immunity

What is another name for nonspecific immunity?

Specific (adaptive) immunity.

What type of immunity are antibodies part of?

It means the immune system attacks all pathogens the same way, without targeting specific ones.

What does "nonspecific" mean in terms of immunity?

Innate immunity.

Which type of immunity is present at birth?

It targets particular antigens with tailored responses (e.g., antibodies made for specific viruses or bacteria).

What does "specific" mean in adaptive immunity?

Nonspecific/innate immunity.

What is the first line of defense in the immune system?

Immediately—it's always "on."

How quickly does the innate immune system respond after exposure?

No—it is not targeted; it responds the same way to all pathogens.

Is innate immunity specific to certain pathogens?

It reacts the same way to mild and deadly pathogens—no distinction.

How does innate immunity handle different levels of pathogen danger?

Antibodies.

What is an example of adaptive (specific) immunity?

It targets specific pathogens and remembers them for future responses.

What does adaptive immunity do that innate immunity doesn't?

It doesn’t require activation by a specific pathogen—it’s ready to act at all times.

Why is the innate immune system described as "always on"?

Innate—it's immediate. Adaptive takes time to develop.

Which system is faster: innate or adaptive?

Adaptive (specific) immunity.

Which immune system creates memory cells for future protection?

“The always-on, nonspecific first response that reacts the same to any pathogen—fast but not targeted."

In one sentence, how would your professor likely define innate immunity?

1. Anatomical/Physical

2. Physiological

3. Phagocytic

4. Inflammatory

What are the 4 general types of innate immunity (defensive barriers)?

The skin—specifically, the epidermis and dermis.

What is the primary anatomical barrier of the body?

Multiple layers of tightly packed, dead, keratinized cells form a waterproof barrier that resists penetration.

How does the epidermis protect against pathogens?

Oil glands produce sebum (with lactic and fatty acids) that maintains acidic pH (~3–5), which inhibits microbial growth. Sweat also contributes to acidity.

What role does the dermis play in immunity?

They line the respiratory, gastrointestinal, and urogenital tracts; produce mucus, saliva, tears to wash away pathogens, and use cilia to mechanically sweep debris.

How do mucous membranes protect the body?

They out-compete pathogens for space and nutrients, helping prevent colonization.

What role does normal flora (microbiota) play in innate immunity?

• Body temperature

• pH (e.g., gastric acid, skin acidity)

• Soluble factors (e.g., lysozyme, cytokines, complement)

What are examples of physiological barriers in innate immunity?

An antibacterial enzyme in saliva, mucus, and tears that breaks down bacterial cell walls.

What does lysozyme do?

Signaling proteins made by immune cells that affect the behavior of other cells. Example: Interferons—produced by virus-infected cells to warn nearby cells and trigger an antiviral state.

What are cytokines and what do they do?

A group of serum proteins that:

• Tag pathogens with molecular flags

• Damage pathogen membranes

• Enhance immune cell recruitment

What is the function of the complement system?

The engulfment of particles by immune cells like macrophages or neutrophils.

What is phagocytosis?

It extends pseudopodia, surrounds the pathogen, and internalizes it into a phagosome for destruction.

How does a cell phagocytose a pathogen?

Infected or injured cells release chemical alarms.

What triggers the inflammatory response?

• Redness (rubor) – from vasodilation

• Heat (calor) – from increased blood flow

• Swelling (tumor) – from plasma entering tissues

• Pain (dolor) – from pressure on nerve endings

What are the 4 signs of inflammation?

To contain infection, recruit immune cells, and begin healing.

What is the overall goal of the inflammatory response?

The movement of immune cells from the blood into tissues by crossing blood vessel walls.

What is diapedesis?

During an immune response, especially when cells are needed at the site of infection or inflammation.

When does diapedesis occur?

Often yes, but persistent infections require adaptive (specific) immunity.

Is innate immunity always sufficient?

It is made and refined during infection—not present at full strength from the start.

When is adaptive immunity developed?

Targeted—it responds to specific pathogens or antigens.

Is adaptive immunity broad or targeted?

A molecule, macromolecule, particle, or cell that:

• Has a recognizable structure

• Is seen as non-self by the adaptive immune system

What does the term “antigen” (Ag) mean?

It must be foreign and contain a structure recognized by adaptive immune cells.

What qualifies something as an antigen?

Yes, but concurrent infections may complicate or slow the adaptive response, as each pathogen requires a specific response.

Can the immune system handle multiple infections at once?

It keeps most people healthy by stopping many infections before they cause harm.

What does innate immunity usually accomplish?

The adaptive immune system is activated to eliminate the remaining infection.

What happens if an infection survives the innate response?

It slows the infection, buying time for adaptive immunity to develop a targeted response.

What role does innate immunity play before adaptive kicks in?

The adaptive response to one infection does not affect a second infection unless they share antigens. Each response is pathogen-specific.

What happens during a concurrent infection?

A non-self molecule recognized by the adaptive immune system as foreign and potentially harmful.

What is an antigen?

A protein made by lymphocytes in response to an antigen. It can:

• Be secreted = antibody (Ab)

• Be B-cell-bound = immunoglobulin (Ig)

What is an antibody (immunoglobulin)?

It recognizes and binds to specific structures on antigens to help eliminate pathogens.

What is the function of an antibody?

1. Specificity – targets specific antigens

2. Diversity – recognizes billions of different molecules

3. Memory – faster, stronger response on re-exposure

4. Self/Non-self recognition – avoids attacking the body’s own cells

What are the four major characteristics of adaptive immunity?

No, they are interactive and mutually supportive systems.

Do innate and adaptive immunity work independently?

• Phagocytes from the innate response activate adaptive immunity

• Soluble factors (like antibodies or cytokines) from adaptive responses enhance phagocytosis

How do innate and adaptive immunity help each other?

To differentiate into other cell types and self-renew to maintain their population.

What is the main function of stem cells in general?

It refers to cells that can become more than one cell type.

What does pluripotent mean?

It refers to cells that can only become one specific cell type.

What does unipotent mean?

It becomes a progenitor cell.

What happens when a stem cell commits to a specific lineage?

No, progenitor cells cannot self-renew.

Can progenitor cells self-renew?

The bone marrow.

Where are all circulating blood cells derived from?

A common precursor in the bone marrow for all blood cells.

What is a Hematopoietic Stem Cell (HSC)?

Pluripotent.

Are HSCs pluripotent or unipotent?

The process of forming red and white blood cells from pluripotent HSCs.

What is hematopoiesis?

They develop into stem cells with more limited developmental potential and commit to a lineage.

What happens to HSCs as they mature?

Expression of lineage-determining genes, lineage-specific genes, and proper timing and order of gene expression.

What is required for stem cell differentiation?

White blood cells.

What are leukocytes?

They migrate to develop further and perform immune functions.

What do leukocytes do after maturation?

Lymphocytes, granulocytes, and phagocytes.

What are the main types of leukocytes?

20–50%

What percentage of the body's WBCs are lymphocytes?

99%

What percentage of cells in lymph are lymphocytes?

Lymphocytes of the adaptive immune system

What immune cells exhibit diversity, specificity, memory, and self/nonself recognition?

They play accessory (supporting) roles.

What roles do granulocytes and phagocytes play in adaptive immunity?