The nursing instructor is leading a discussion with a group of nursing students who are analyzing the preterm infant's physiologic immaturity and the associated difficulties the newborn and family must deal with. The instructor determines the session is successful when the students correctly choose which body system that presents with the most critical concerns related to this immaturity

Asoccer mom is driving her 75 year old grandmother and her 9 year old daughter home after the game. the grandmother and daughter were both in the back seat and both were wearing their seat belts. a car ran a red light in front of them, causing them to t-bone that car on the passenger side. fortunately there were no serious injuries, but the grandmother did sustain several rib fractures. the mother, daughter and driver of the at-fault car were shaken up but unhurt. what are some possible reasons that the grandmother sustained rib fractures while the other victims did not?