Bio 2601: Gas Exchange Lecture 6

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Questions and Answers

According to the provided information, what is the primary challenge faced by air-breathers regarding CO2 excretion?

The limited surface area available for gas exchange in the respiratory system, affecting CO2 removal.
The rapid conversion of CO2 to carbonic acid in the lungs, hindering direct excretion.
The high concentration of CO2 in the air, creating a diffusion gradient that is unfavorable for excretion.
The low concentration of CO2 in the air necessitates a high partial pressure of CO2 for diffusion to occur. (correct)

In mammals, which of the following chemoreceptors plays the most significant role in regulating breathing, as indicated by the content?

Central chemoreceptors in the medulla. (correct)
Peripheral chemoreceptors in the carotid bodies.
Peripheral chemoreceptors in the aortic bodies.
Both peripheral and central chemoreceptors play equal roles in regulating overall breathing.

Considering the information provided, what is the main advantage water-breathers have over air-breathers in regard to CO2 excretion?

Water-breathers usually have low CO2 concentrations in water, which allows for easier diffusion out of their body. (correct)
Water-breathers have high concentrations of CO2 in their respiratory medium, causing a higher expulsion gradient.
The higher solubility of CO2 in water facilitates better excretion of the gas for water-breathers.
Water-breathers have a more developed respiratory system, allowing for efficient transfer.

For bimodal breathers, how is blood typically re-routed to manage oxygen and carbon dioxide exchange effectively?

Blood is re-routed such that oxygen is taken up mainly by the lungs from air while carbon dioxide is released mostly through the gills into the water. (A) Signup and view all the answers

Based on the provided content, what strategy do some air-breathing animals use when in water?

They absorb oxygen through the lungs in air and release carbon dioxide through their permeable skin in water. (C) Signup and view all the answers

In the context of oxygen transport, what is the role of respiratory pigments, and what unique adaptation is observed in the Antarctic icefish?

Respiratory pigments facilitate oxygen binding and transport; icefish lack them, utilizing increased blood volume to ensure sufficient oxygen supply. (B) Signup and view all the answers

According to the content, what is the primary mechanism by which most carbon dioxide is transported in the blood, and what role does carbonic anhydrase (CA) play in this process?

Most CO2 is transported as bicarbonate; CA facilitates its conversion to carbonic acid, in red blood cells from where it dissociates into bicarbonate and hydrogen ions (A) Signup and view all the answers

Based on the content, in what direction will the reaction $HbH + O_2 \rightleftharpoons HbO_2 + H^+$ in the tissues and the lungs?

The reaction favors $HbO_2$ formation in the lungs and $HbH$ formation in tissues due to the changes in partial pressure of oxygen. (A) Signup and view all the answers

During CO2 excretion at working tissues, how is the charge balance maintained when bicarbonate ($HCO_3^−$) is transported from red blood cells to the plasma, and what specific protein is responsible for this process?

Chloride ions ($Cl^−$) are transported into the RBCs through band 3 protein. (B) Signup and view all the answers

Following the description of $CO_2$ excretion, what happens to the majority of $HCO_3^−$ when it reaches the gas exchange surface (lungs/gills)?

It is converted back to $CO_2$ which then diffuses out into the lung/gill. (D) Signup and view all the answers

Flashcards

CO2 Excretion

The process of removing carbon dioxide (CO2) from the body.

CO2 Excretion in Air Breathers

The partial pressure of CO2 (pCO2) in the air is relatively low. This makes diffusion of CO2 from the body to the air challenging for air-breathing animals.

Fick's Law of Diffusion

The rate of diffusion is directly proportional to the surface area and the difference in partial pressure (P1 - P2) between the two compartments, and inversely proportional to the distance (X).

Peripheral Chemoreceptors

Chemoreceptors in the carotid and aortic bodies detect changes in blood oxygen, carbon dioxide, and pH levels. These signals are sent to the medulla oblongata, the brain's respiratory center.