The mountain wind rattled the window of the small cabin as Drewsifted through the papers covering the kitchen table, looking forhis physiology notes. Instead of his blue notebook, a pink sheet ofpaper from Mountain View Labs caught his eye. A closer look showedit to be his 73-year-old grandmother’s lab report from some recentblood tests. Mimi had protested all the way to the appointment andall the way home, but Drew had insisted that if he came home forTanksgiving break, then she was going for the check-up that she hadput of for far too long. Mimi had chronic kidney disease, and thedoctors wanted her to start dialysis more than a year ago. Notsurprisingly, his stubborn Kentucky-born-and-raised grandmother hadrefused. She was not a good candidate for home dialysis and thenearest dialysis clinic was an hour away. She didn’t drive muchbecause of cataracts, and there was no one else to take her. Drewhad immediately ofered to delay his junior year at the Universityof Kentucky to stay home and care for her. Mimi was adamantlyopposed. “You will stay in school, Andrew Paul Killian! Te best wayout of these mountains is college, and you’re not dropping outbecause of me.” Even after Drew discovered the county ofered seniorcitizens free transportation to medical appointments, she shook herhead. “God the Almighty will take me home when He’s ready, dialysisor not.” Mimi had raised Drew since the age of three, and he knewwhen she made up her mind, no one on Earth could change it. Drewglanced at Mimi as she watched TV. He knew her kidney disease wasadvancing. He had noticed over the summer that she tired easily andher feet and ankles were badly swollen. She had always loved todebate politics with anyone who dared, but now she had troublekeeping track of conversation. Last week she only picked at herturkey and cranberry sauce, saying that she was too nauseated toeat much. She blamed it on the doctor scaring her about her highblood pressure at the appointment the day before, but Drew saw howbaggy her clothes were and knew she hadn’t been eating much forquite some time. Drew started to scan the lab report, thinking hisphysiology class might help him understand the results. He had justenough time to note that Mimi’s blood urea nitrogen (BUN) was 208mg/dL and creatinine was 15 mg/dL before she interrupted him.“Drew, there’s a Star Wars marathon starting!” She patted the sofabeside her. “Bring the rest of the snickerdoodle cookies and watchwith me.” Drew found it hard to resist Star Wars or Mimi, so helaid the test results aside and spent the rest of the eveningcheering for Luke and the Jedi. Te next morning Drew packed his carfor the drive back to Lexington. He found his physiology notes, butMimi had squirreled away the lab results. When he asked, Mimifapped her hands at him. “Pffft, stop worrying! You just keepcalling every morning to check on me like you have been. And Jimmylives right over the hill. I’ll call him if I need anything.” Drewshook his head. Jimmy Seavers was at least a decade older than Mimiand relied on two canes to walk. He didn’t know how much help Jimmywould be, but Mimi was shooing him into the car to avoid anyfurther protest. He hugged her long and hard, and reluctantlyheaded down the mountain road.

1. Describe the compensation provided by Mimi’s respiratorysystem. What effect will this have on her P_CO2?