Question

(a) Convert normal blood pressure readings of 120 over 80 mm Hg to newtons per meter squared using the relationship for pressure due to the weight of a fluid (P=hrhog) rather than a conversion factor.

(b) Discuss why blood pressures for an infant could be smaller than those for an adult. Specifically, consider the smaller height to which blood must be pumped.

A. (a) 1,184 Pa, (b) Lower heart rate in infants
B. (a) 2,368 Pa, (b) Higher resistance in infants' arteries
C. (a) 1,184 Pa, (b) Smaller height requires less pressure
D. (a) 2,368 Pa, (b) Greater flexibility of infant blood vessels

Answer 1

(a) To convert blood pressure readings from mmHg to N/m², use the equation P = hρg with known values. (b) Infants have smaller blood pressures due to their shorter height, requiring less pressure to pump blood.

Step-by-step explanation:

(a) To convert blood pressure readings from millimeters of mercury (mmHg) to newtons per meter squared (N/m²) using the relationship P = hρg, where P is the pressure, h is the height of the fluid column, ρ is the density of the fluid, and g is the acceleration due to gravity, we need to know the density of blood. Let's assume the density of blood is approximately the same as the density of water (ρ = 1000 kg/m³) and the acceleration due to gravity is approximately 9.8 m/s². We can convert the height in millimeters of mercury to meters to get:

P = (120 mmHg + 80 mmHg) × (1.0 mmHg / 133 Pa) × (1.33 × 10³ kg/m³) × (9.8 m/s²) = 2,368 Pa

(b) Blood pressure in infants could be smaller than in adults because infants are generally shorter and blood doesn't need to be pumped as high. The height of the fluid column (h) in the pressure equation is smaller, resulting in a smaller pressure reading.