Nursing Elites

1. Which of the following structures prevents food from entering the windpipe?

• A. Pharynx
• B. Esophagus
• C. Larynx
• D. Epiglottis

Correct answer: D

Rationale: The epiglottis is the structure that prevents food from entering the windpipe by covering the trachea during swallowing. When food is swallowed, the epiglottis folds over the opening of the trachea to ensure that food goes down the esophagus and not into the airway. The pharynx is a shared pathway for both food and air, leading to the esophagus and larynx respectively. The esophagus is the muscular tube that carries food from the throat to the stomach. The larynx is responsible for producing sound and protecting the airway during swallowing, but the epiglottis is specifically designed to prevent food from entering the windpipe.

2. Where is fat primarily digested, and where is protein primarily digested?

• A. Mouth; stomach
• B. Stomach; small intestine
• C. Small intestine; small intestine
• D. Small intestine; stomach

Correct answer: B

Rationale: The correct answer is B. Fats are primarily digested in the small intestine, where bile from the liver emulsifies fats for enzymatic digestion. The small intestine is where most of the absorption of nutrients occurs. Proteins, on the other hand, are mainly digested in the stomach by the enzyme pepsin under acidic conditions. The stomach's acidic environment helps denature proteins, making them more accessible to pepsin for digestion. Choices A, C, and D are incorrect because they do not accurately reflect the primary sites of fat and protein digestion in the human digestive system.

3. Which type of capillary is the most permeable?

• A. Continuous capillaries
• B. Sinusoidal capillaries
• C. Fenestrated capillaries
• D. Vascular capillaries

Correct answer: B

Rationale: Sinusoidal capillaries are indeed the most permeable type. They are characterized by large gaps between endothelial cells, allowing for the passage of large molecules and cells. These capillaries are commonly found in organs like the liver, bone marrow, and spleen where high permeability is required for specialized functions such as filtration and exchange of substances. Continuous capillaries have tight junctions and are the least permeable, found in muscles, lungs, and the central nervous system where strict control over permeability is needed. Fenestrated capillaries, on the other hand, have small pores or fenestrations and are intermediate in permeability, found in organs like the kidneys, endocrine glands, and intestines where selective permeability is necessary. Vascular capillaries is not a specific type of capillary and is not a valid choice.

4. What is the term for a genetic disorder caused by a mutation on the X chromosome?

• A. Autosomal dominant disorder
• B. Autosomal recessive disorder
• C. Sex-linked recessive disorder
• D. Sex-linked dominant disorder

Correct answer: C

Rationale: A genetic disorder caused by a mutation on the X chromosome is termed a sex-linked recessive disorder (Option C). This type of disorder is more commonly seen in males due to their single X chromosome, making them more vulnerable to X-linked mutations. Females have two X chromosomes, providing a protective effect against X-linked disorders.\n- Autosomal dominant disorders (Option A) result from a mutation in one copy of a gene on non-sex chromosomes (autosomes) and are not specifically related to the X chromosome.\n- Autosomal recessive disorders (Option B) occur due to mutations in both copies of a gene on autosomes, not on the X chromosome.\n- Sex-linked dominant disorders (Option D) are rare and lead to more severe symptoms in males as they only require one copy of the mutated gene on the X chromosome to express the disorder. However, this is not the term for a genetic disorder caused by an X chromosome mutation.

5. Which statement about white blood cells is true?

• A. B cells are responsible for antibody production.
• B. White blood cells are produced in the bone marrow before entering the bloodstream.
• C. Platelets, a specialized class of blood cells, function to clot blood and stop bleeding.
• D. The majority of white blood cells are active throughout life, providing immunity across all age groups.

Correct answer: A

Rationale: The correct answer is A: B cells, a type of white blood cell, are responsible for producing antibodies in response to pathogens. Antibodies play a crucial role in identifying and neutralizing foreign substances like bacteria and viruses in the body, aiding in the immune response and protecting against infections. This function is essential for maintaining a healthy immune system. White blood cells, including B cells, are produced in the bone marrow before entering the bloodstream. Platelets, not white blood cells, are a specialized class of blood cells that function to clot blood and stop bleeding. While white blood cells provide immunity, not all of them are active throughout life as some have specific lifespans and functions.

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