The macula densa cells respond to

A. The kidneys are retroperitoneal: Kidneys lie behind the peritoneum, making them retroperitoneal organs.
B. The ureters connect the kidneys to the urinary bladder: The ureters transport urine from each kidney to the bladder.
C. The urethra of males is longer than the urethra of females: The male urethra is significantly longer, due to its passage through the penis.
D. The kidneys are at equal heights within the pelvic cavity: This is incorrect-the right kidney is lower than the left due to the position of the liver. Also, kidneys are located in the upper abdomen, not the pelvic cavity.
E. The right kidney is located more inferiorly than the left kidney: True-the right kidney lies lower than the left because of the liver's size.

A. The voluntary phase of swallowing takes place within the mouth: The oral phase is under voluntary control and involves tongue movement to push the bolus to the oropharynx.
B. The epiglottis assists in propelling food into the trachea: This is incorrect. The epiglottis prevents food from entering the trachea by covering the glottis during swallowing; it does not propel food.
C. The involuntary portion of swallowing takes place in the pharynx: After the oral phase, swallowing becomes involuntary, involving reflexive contractions of pharyngeal muscles.
D. The mouth, pharynx and esophagus all take part in swallowing: All three structures are involved in the three phases of deglutition: oral, pharyngeal, and esophageal.