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2 pages/≈550 words
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APA
Subject:
Biological & Biomedical Sciences
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Coursework
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English (U.S.)
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Homework. Respiratory Questions. Biological & Biomedical

Coursework Instructions:

Respiratory Questions


1)     Identify two anatomical features shared by gills, lungs, and trachioles. Then, identify one feature that is unique to each.


 


 


 


2)     Examine the hemoglobin binding curve in Figure 42.31b. Estimate how much more O2 is unloaded from hemoglobin at pH 7.2 than at pH 7.4, when the tissue has a PO2 of 20 mm Hg.


 


3)     Explain what determines whether O2 diffuses into tissue capillaries.


 


 


4)     Draw a picture predicting how the oxygen-hemoglobin curves measured in Tibetan peoples, whose ancestors have lived at high elevations for thousands of years, should compare to curves from people whose ancestors have lived at sea level for thousands of years.


 


 


 


5)     Explain why ventilation in birds is considered much more efficient than the respiratory system of humans and other mammals.


 


 


 


 


6)     Toadfish are fishes that live in stagnant-water habitats with low PO2. Compared with the hemoglobin of many other fish species, toadfish hemoglobin has an extremely high affinity for O2. Is this trait adaptive? Explain your answer.

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Below are graphs of membrane potential (and action potentials) over time from two types of cardiomyocytes: contractile cells and autorhythmic (pacemaker) cells. Note that the x-axes measure time, but are not quite on the same scale. Which one trace shows the potential changes occurring in pacemaker cells? Explain your choice.
Answer: Pacemaker cells (also known as autorhythmic cells) are able to generate action potentials spontaneously (meaning without any input from the nervous system). They can generate an action potential as their resting membrane potential is unstable. On the other hand, contractile cells are tightly linked to each other through intercalated disks that ensure that force is being transmitted from myocardial cells to adjacent cells. Thus, the second graph or trace shows potential changes that take place in pacemaker cells.
Some snake venoms (produced by cobras and their relatives) block the low voltage-gated, T-type Ca2+ channels on pacemaker cells. On the appropriate axis above, draw a new trace of membrane potential over time, showing how this venom will change membrane potential and action potential frequency. Explain the channel mechanics that underlie your answer.
Answer:
An action potential starts right after the depolarization of the plasma membrane at the axon hillock. It can induce the opening of different voltage-gated ion channels. This graph shows different ...
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