A normal PR interval measures 0.12-0.20 seconds which is 3 to 5 small boxes on the EKG strip. When you measure a PR interval, you start measuring at the BEGINNING of the p-wave until the BEGINNING of the QRS complex. Here are some simple steps on how to measure the PR interval: Find the P-wave on the EKG strip. Determine where the PR interval is, and to do this you start measuring at the beginning of the p-wave until the beginning of the QRS complex. Count the SMALL boxes between there measurements. Remember each box represents 0.04 seconds.
The role of the excretory system is to rid the body of toxic waste products. Which of these body systems also plays a direct role in removing waste products from the body? A) endocrine B) nervous C) respiratory D) skeletal.
Rating Newest Oldest. Best Answer: In a closed system where exposure to toxic substances is controlled, your body does indeed deal with most toxins very effectively (mostly processed in liver and excreted via kidney.) HOWEVER... the amount of toxic exposure we're experiencing is unprecidented.