Ch. 3 Cells: The Living Units

Marieb - Human Anatomy & Physiology 7th Edition

Marieb, Hoehn7th EditionHuman Anatomy & PhysiologyISBN: 9780805359091Not the one you use?Change textbook

Marieb, Hoehn 7th Edition

Ch. 3 Cells: The Living Units

Problem 11

Chapter 3, Problem 11

Cells lining the trachea have whiplike motile extensions on their free surfaces. What are these extensions, what is their source, and what is their function?

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Identify the extensions described as 'whiplike motile extensions' on the free surface of tracheal cells. These are known as cilia.

Understand the source of these cilia: they are formed from the cell's cytoskeleton, specifically from microtubules arranged in a 9+2 pattern within the cell's plasma membrane.

Recognize that these cilia arise from basal bodies located just beneath the cell surface, which anchor and organize the microtubules.

Explain the function of the cilia: they beat rhythmically to move mucus and trapped particles upward toward the pharynx, helping to clear debris and pathogens from the respiratory tract.

Summarize that this ciliary action is a key component of the mucociliary escalator, an important defense mechanism in the respiratory system.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Cilia

Cilia are microscopic, hair-like structures that extend from the surface of certain cells, such as those lining the trachea. They are motile, meaning they can move rhythmically to perform specific functions, primarily involved in moving substances across the cell surface.

Origin of Cilia - Basal Bodies

Cilia arise from basal bodies, which are specialized organelles located just beneath the cell membrane. Basal bodies serve as the organizing centers for the microtubules that form the cilia’s internal structure, anchoring and initiating their growth.

Function of Tracheal Cilia

The primary function of cilia in the trachea is to move mucus and trapped particles upward toward the throat, helping to clear debris and pathogens from the respiratory tract. This action is essential for protecting the lungs and maintaining clear airways.

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Textbook Question

The phase of mitosis during which centrioles reach the poles and chromosomes attach to the spindle is

a. Anaphase

b. Metaphase

c. Prophase

d. Telophase

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Textbook Question

A physiologist observes that the concentration of sodium inside a cell is decidedly lower than that outside the cell. She also observes that there is a small leakage of sodium into the cell. What cellular process prevents the sodium concentration gradient from disappearing?

a. Osmosis

b. Diffusion

c. Primary active transport

d. Secondary active transport

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Textbook Question

A nerve cell and a lymphocyte are presumed to differ in their:

a. Specialized structure

b. Suppressed genes and embryonic history

c. Genetic information

d. a and b, e. a and c

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Textbook Question

The RNA species that travels from the nucleus to the cytoplasm carrying the coded message specifying the sequence of amino acids in the protein to be made is

a. mRNA

b. tRNA

c. rRNA

d. all of these

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Textbook Question

The RNA synthesized on one of the DNA strands is:

a. mRNA

b. tRNA

c. rRNA

d. all of these.