Chapter 1

What is a definition of clearance?

The volume of a substance cleared from the blood per unit time

You have been invited to take part in an exercise study measuring the effect of a new sports drink on athletic performance compared with a sports drink already available. Both sports drinks are marketed as increasing aerobic capacity if consumed just before exercise, so that the same exercise causes a smaller increase in heart rate and respiration. After consuming either the new beverage or the control beverage, you will run 20 minutes on a treadmill at a set pace. The study is being performed by a graduate student. You tell the graduate student that the control beverage, a popular drink among the athletes on campus, is readily recognizable, whereas the test beverage is a nasty greenish-brown color. You warn the experimenter that the results might be affected by a _________ effect.

placebo

Used to show the relationship between two variables. A best fit line can be used to indicate a trend in the data

scatter plot

Which type of graph would be the most appropriate to present these data?

scatter plot

You collect data on the effects of exercise on the heart rate of untrained female college students. You select 25 subjects for your data collection. As a first step to obtain a control value, you measure the heart rates of the subjects while they stand on the treadmill. You then ask each of the 25 subjects to start walking on the treadmill at a speed of 2 miles per hour for 3 minutes. The subjects are then instructed to increase the speed on the treadmill in increments of 0.5 MPH. What is the independent variable?

varying walking speeds

Read the following passage and construct a flow chart by matching the following events with their proper sequence. Physical exercise results in skeletal muscle contraction, an active process that requires chemical energy in the form of ATP. Initially, as contractions begin, small amounts of ATP are available within the skeletal muscle fibers; however, because of the limited stores of ATP, contractions may only be sustained for about 15 seconds before the ATP needs to be replenished. Cellular respiration is one mechanism by which muscle fibers produce and replenish their ATP. While cellular respiration increases the availability of ATP, it does so by consuming oxygen and glucose while producing water and carbon dioxide as a waste byproduct. Thus, during exercise, as the metabolic activity of the muscle fibers increase, the concentration of oxygen in the muscle tissue decreases. Other byproducts of metabolic activity (temperature, acidity, and CO2 concentrations) also increase as the muscle fibers continue to contract and consume glucose and oxygen. The increased presence of these metabolic byproducts is detected by specific homeostatic sensors that send out signals to the local vasculature and cause vasodilation, thereby shifting blood flow from less active tissues to the nearby exercising muscles. The greater flow of blood into the exercising muscle resolves the oxygen loss while simultaneously removing the waste and other byproducts of the increased metabolic activity.

- person starts to exercise - skeletal muscle metabolism increases - skeletal muscle oxygen demand increases - oxygen sensors cause local blood vessels to dilate - blood delivery to the skeletal muscle increases is order to provide more oxygen

Independent Variable

- plotted on the horizontal x-axis - the variable manipulated by the experimenter

Dependent Variable

- plotted on the vertical y-axis - the variable measured by the experimenter

Which type of research study recruits and follows healthy subjects for a long period of time to determine the factors that contribute to the development of disease?

A prospective study

Used when the independent variables are distinct entities

Bar Graph

Used when the independent variable on the x-axis is a continuous phenomenon (i.e. time)

Line graph

Which of the following is the best example of a mechanistic understanding of a function?

Skeletal muscle cells contract when myosin heads attach to actin filaments and rotate, producing force

You collect data on the effects of exercise on the heart rate of untrained female college students. You select 25 subjects for your data collection. As a first step to obtain a control value, you measure the heart rates of the subjects while they stand on the treadmill. You then ask each of the 25 subjects to start walking on the treadmill at a speed of 2 miles per hour for 3 minutes. The subjects are then instructed to increase the speed on the treadmill in increments of 0.5 MPH. What is the dependent variable?

heart rate

What is a review article and why might it be beneficial for a novice in a subject matter to read?

it contains a synopsis of recent research on a particular topic; because it gives a general summary of several technical papers, making it easier for a novice to understand

The hormone cortisol is secreted in a circadian rhythm, with the highest levels at breakfast time and lowest around midnight. Which statement is the most likely explanation of this observation?

the homeostatic set point for cortisol varies over a 24-hour cycle

What does it mean if an article has been peer reviewed?

the work has been read by an anonymous panel of scientists qualified to judge the science