Lab Instructions_ Physiology Act II Mission Memo

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Arizona State University *

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Biology

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Oct 30, 2023

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Lab Instructions: Physiology Act II Mission Memo Greetings Fellow Explorer: Thanks to your efforts, we were able to rule out two of the possible causes of Xor’s symptoms. Xor’s blood oxygen concentration and blood glucose concentrations are within the typical ranges. It seemed that Xor’s blood pressure was too high - so I decided to administer Xor a drug that would dilate her blood vessels. Unfortunately, I only made matters worse. On top of that - the gravity in the megaraffe enclosure seems to be too high. I’m really in a bind now and I need your help yet again. The fate of Xor and the megaraffe population rests in your hands. Xor’s symptoms, her response to the vasodilators, and the seemingly elevated gravity in the megaraffe enclosure must be connected. We must determine if an increase in the gravity was the cause of Xor’s symptoms and, if so, by how much I need to correct the gravity before it's too late. If the gravity needs to be reset, we’ll need to make sure we have the proper treatments on hand to keep Xor stabilized while I reset the gravity in the enclosure. Use the following questions to guide your work. ● Why did Xor collapse after we administered a drug to dilate her blood vessels? (Appendix 1) ● How much should we reduce the gravitational force in Xor's environment? (Appendix 2) ● How should we treat Xor to stabilize her cranial blood pressure? (Appendix 3) The appendices to this mission memo will guide you in answering these questions. Once you have completed your analyses, report your conclusions via Canvas before

returning to the Sanctuary. Do not underestimate the urgency of your work. Universally in your debt, The AI

Appendix 1 Why did Xor collapse after we administered a drug to dilate her blood vessels? Thanks to GUS, we might have discovered the cause of Xor’s illness—an increase in the gravitational force of her environment. In other words, the current gravitational force exceeds the set point of the Sanctuary's gravitational control system, a homeostatic system designed to regulate gravity. If GUS is correct, the problem likely resulted from damage to the system, caused when the Sanctuary collided with space debris. Still, we must be sure that all of our observations support GUS's hypothesis. We already administered an incorrect treatment, making Xor's condition worse. We don't want to administer another incorrect treatment! Complete the following steps to determine whether an increase in gravitational force can explain why Xor fainted after we dilated her blood vessels. Step 1: Model the effect of gravity on the distribution of blood. Construct a model illustrating how a change in gravitational force would affect the distribution of blood in a megaraffe. This step will enable us to construct an argument in Step 3. Step 2: Model how a change in the distribution of blood would affect the cranial blood pressure. Using the model constructed in Step 1, explain how the blood pressure in each part of the circulatory system would change as the gravitational force increased. This step will enable us to construct an argument in Step 3. Step 3: Determine why Xor fainted after we dilated her blood vessels. Construct an argument to answer the question “Could an increase in gravitational force explain why Xor fainted after we dilated her blood vessels?” Your argument should draw on your answers in Steps 1 and 2.

Step 1: Model the effect of gravity on the distribution of blood The challenge here is that because the gravitational fields in the Sanctuary were pre- programmed by my creators, I don’t have any data that would explain how a change in gravitational force would impact blood pressure or the distribution of blood in megaraffes, let alone other species. However, humans have been a spacefaring species for more than 60 years and, based on your archives, it appears that the effects of microgravity have been well documented in humans. Perhaps this could lend some insight as to what was happening to Xor? Let’s work together to find out. Effects of microgravity on blood distribution in humans Organisms on Earth, like in the megaraffe enclosure, are subjected to a constant force of gravity. On Earth, the gravitational force equals 9.8 N kg -1 . How does Earth’s gravity affect the distribution of blood in your body? A typical adult human has about 5 liters of blood. But how is that blood distributed throughout the body? Is it evenly distributed, or does one part of the body have more blood than other parts? 1. The answer choices below show three distributions of blood in the body of an adult human. This person is standing but not performing any other physical activity. The darker the shading of an area, the greater the amount of blood in that area. Select the figure that best represents the distribution of blood in the body of a human on Earth.

a. Answer choice 1 b. Answer choice 2 c. Answer choice 3 Through careful research, scientists on Earth discovered that more blood lies in the lower half of the body when a person stands (Figure 1). At first, this might seem counterintuitive. Important organs, such as the brain, reside in the upper half of the body. So why would more blood occur in the lower half? The answer is gravity. Figure 1. Diagram illustrating how blood is distributed in a typical adult human who is standing, not performing any physical activity, and experiencing Earth’s gravity. The double-sided vertical arrow to the right of the body indicates the distribution of blood in the body. The darker the shading of an area as indicated by the double-sided vertical arrow, the greater the amount of blood in that area. The shading of the double-sided arrow has a gradient where shading is darkest in the feet and lightest in the head of the human. As blood flows through arteries, delivering oxygen and vital nutrients to cells, it

eventually must travel back to the heart through veins (Figure 7, Mission Memo 1, Appendix 1, Step 1 of the Physiology module). Traveling back to the heart is a straightforward task for blood returning from the head, because gravity pulls it downward. However, blood returning from the legs must move against the force of gravity. As a consequence, more blood remains in the lower half of the body than in the upper half. In space, one lies so far from Earth that the force of gravity drops to a very small value, which we call microgravity. The lack of gravity in space is why the Sanctuary has mechanical systems to create artificial gravity. Life on Earth has evolved under the same gravitational conditions for several billions years. Thus, when human astronauts leave Earth and transition to microgravity, they experience a novel condition. How does this sudden decrease in gravitational force affect the distribution of blood in the body? 2. The answer choices below show three possible distributions of blood in the body of a typical adult human in space, where the gravitational force is effectively zero. This person is standing but not performing any other physical activity. The darker the shading of an area, the greater the amount of blood that occurs in that area. Select the figure that best represents the distribution of blood in the body of a human in space. a. Answer choice 1

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