Immunity: History, Innate Defense, and Ion Transport Mechanisms

Question-and-answer flashcards reviewing major points about immunity history, innate defenses, and ion transport mechanisms in mucus production.

What does the Latin term “immunis” translate to, and what concept does it underpin?

“Immunis” means “exempt,” underpinning the idea that immunity exempts the body from disease caused by pathogens.

What is a pathogen?

Anything that enters the body and causes disease or pathology, commonly microorganisms such as bacteria, archaea, parasites, protozoa, or viruses.

During the Peloponnesian War, what observation suggested that recovered plague victims had immunity?

Only individuals who had contracted and survived the plague could safely care for the sick soldiers, indicating they had developed immunity.

Which occupational group provided the clue that exposure to cowpox confers protection against smallpox?

Milkmaids who worked closely with cows.

Who used cowpox to create the first smallpox vaccine, and in what century?

Dr. Edward Jenner in the 18th century (late 1700s).

In Louis Pasteur’s chicken experiments, what happened when attenuated fowl cholera was injected into chickens?

The chickens survived and became immune to virulent cholera.

What does the term “attenuated” mean in the context of vaccines?

Weakened; the pathogen is alive but reduced in virulence.

Why did Pasteur coin the term “vaccine,” and what does “vacca” mean?

He named it in honor of Jenner’s cowpox work; “vacca” is Latin for cow.

How did Pasteur demonstrate immunity to anthrax in sheep in 1881?

He vaccinated sheep with heat-attenuated anthrax bacilli, then exposed them to virulent anthrax; the vaccinated sheep did not die.

Why was Pasteur’s 1885 rabies treatment for a bitten boy remarkable?

The attenuated rabies vaccine worked post-exposure during the virus’s incubation period, preventing disease.

What is the primary difference between innate (non-specific) and acquired (specific) immunity?

Innate immunity provides broad, immediate defense against any pathogen, whereas acquired immunity targets specific pathogens and develops after exposure.

List at least three physical or chemical barriers that are part of innate immunity.

Examples include dead skin cells, acidic pH, sneezing, tearing, coughing, or certain white blood cells.

What defensive role does mucus play in the respiratory tract?

It traps inhaled pathogens, dust, and debris so they can be moved out of the airway.

Which epithelial cells secrete respiratory mucus?

Goblet cells.

How do cilia contribute to clearing mucus from the airway?

They beat upward (superiorly), propelling mucus toward the oral cavity for removal.

In anatomy, what is meant by the term “lumen”?

The hollow interior space of a tubular structure such as the trachea or intestine.

Which ions are co-transported into tracheal epithelial cells by the NKCC cotransporter?

Sodium (Na⁺), Potassium (K⁺), and Chloride (Cl⁻).

What does CFTR stand for, and what is its function in airway epithelium?

Cystic Fibrosis Transmembrane Conductance Regulator; it is a chloride channel that moves Cl⁻ from the cell into the tracheal lumen.

Why does sodium move paracellularly into the tracheal lumen after chloride secretion?

Positive Na⁺ ions follow the negative Cl⁻ ions to maintain electrical neutrality.

What causes water to enter the tracheal lumen and keep mucus fluid?

Osmosis—water follows the accumulated NaCl (solute) into the lumen.

How does the absence of functional CFTR channels in cystic fibrosis affect respiratory mucus?

Chloride and sodium are not secreted, so water does not follow; mucus becomes thick, stagnant, and prone to infection.

How does cholera toxin in the intestines lead to severe diarrhea?

It up-regulates CFTR activity, causing massive Cl⁻ and Na⁺ secretion into the intestinal lumen; water follows osmotically, producing profuse watery diarrhea (dysentery).