Rivka is an active 21-year-old who decided to take a day off from her university classes. The weather was hot and the sun bright, so she decided to go down to the beach. When she arrived, she found a few people playing beach volleyball, and they asked if she wanted to join in. She put down her school bag and began to play. The others were well prepared for their day out and stopped throughout the game to have their power drinks and soda pop. Several hours after they began to play, however, Rivka was not feeling so good. She stopped sweating and was feeling dizzy. One player noted she had not taken a washroom break at all during the day. They found a shaded area for her, and one of the players shared his power drink with her. Rivka was thirstier than she realized and quickly finished the drink.
- In pronounced dehydration, hypotension can occur. How would this affect the glomerular filtration rate of the kidney? What actions by the juxtaglomerular apparatus would occur to restore GFR?
- What is the effect aldosterone has on the distal convoluted tubule? Why would the actions of aldosterone be useful to Rivka in her situation?
- What does a specific gravity test measure? If someone tested the specific gravity of Rivka’s urine, what might it indicate?
Case Study 3
Disorders of Fluid and Electrolyte Balance
Amanda is an 18-year-old with anorexia nervosa. She was recently admitted to an eating disorders clinic with a BMI of 13.9, and although she was a voluntary patient, she was reluctant about the treatment. She was convinced she was overweight because her clothes felt tight on her. She complained that even her hands and feet “were fat.” One of her nurses explained that a protein in her blood was low. The nurse further explained that, as difficult as it may be to believe, eating a normal healthy diet would make the “fat hands and feet” go away.
- What protein do you suspect the nurse was referring to? How would a deficiency in this protein contribute to edema?
- What is the difference between the physiology of pitting and nonpitting edema?
- Because of her weakened condition, Amanda was moved around the ward in a wheelchair when she was not on bed rest. How does this affect her edematous tissues?
Case Study 4
Disorders of Acid–Base Balance
Shauna is a healthy, fit 28-year-old who decided to go on a 2-week tour of Mexico for young singles. One hot afternoon in a small market community, she grabbed some fruit juice from a street vendor. Several hours later, she developed abdominal cramping and diarrhea. The diarrhea became so severe that she missed 3 days of the tour and stayed in her hotel room. By the end of her illness, she felt weak and tired. Her head ached, but the mild fever had disappeared, and she was able to join her new friends for the rest of the tour.
- What is the acid–base imbalance Shauna might have experienced and its etiology?
- What are the functions and importance of the bicarbonate buffer system in the body?