Background:
To maintain a stable internal environment, known as homeostasis, cells must exchange nutrients and wastes with the external environment. In single celled organisms like bacteria, nutrients and wastes are transported into and out of the cell directly across the cell membrane. However, the cells of complex, multicellular organisms are isolated from the external environment, and normal cell homeostasis must be maintained by coordinated function of specialized organ systems. In mammals, the cardiovascular system functions to allow exchange between cells and the external environment by transporting blood throughout the different tissues of the body. For example, blood is delivered to the lungs where oxygen is provided from the external environment so it can be delivered to the body’s cells. Conversely, carbon dioxide (CO2) is a cellular waste product that is released into the blood and transported to the lungs for elimination into the external environment. The respiratory system is closely tied with the cardiovascular system since the lungs are the site of gas exchange with the environment. A healthy and efficient cardiovascular system will more easily maintain homeostasis, and measures such as respiratory rate, heart rate, and blood pressure are common clinical measures of cardiovascular health.
Blood pressure is a measure of the amount of force exerted on the walls of your arteries during the cardiac cycle (one heartbeat). It is measured in millimeters of mercury (mmHg) and is expressed as systolic pressure over diastolic pressure. Systolic pressure refers to the pressure on the arterial walls during ventricular systole, the phase of the cardiac cycle during which the ventricles are contracting and pushing blood out. Diastolic pressure refers to the pressure on the arterial walls during ventricular diastole, the phase of the cycle during which the ventricles are relaxed. The average blood pressure in healthy individuals at rest is 120/80 mmHg.
Your heart rate, also referred to as your pulse, is the number of times your heart beats in one minute. At rest, the average heart beats 70-75 times per minute.
Your respiratory rate is the number of breaths you take in a minute.
Blood pressure, heart rate, and respiratory rate are collectively referred to as your vital signs. In this lab, you will measure these vital signs and investigate the effects of exercise on an individual’s cardiovascular and respiratory physiology.
Lab Activity:
Blood Pressure: Place the blood pressure cuff over the upper arm where the hoses are
pointing down through the bend of the elbow. Make sure the valve is closed and pump
the cuff up to the 200 mm of Hg mark on the gauge. The diaphragm of the stethoscope
should be placed in the bend of the elbow and over the brachial artery. Open the valve so
the air is moving out slowly. The needle on the gauge will begin to bounce and you
should hear the blood moving through the artery. The first time you hear the
sound is the systolic pressure (remember the number the needle was on when you heard
this). The number should be recorded in the data table under systolic pressure. The last
time you hear the sound is the diastolic pressure (remember the number the needle was
on when you heard this). The number should be recorded in the data table under diastolic
pressure.
Pulse: Find the carotid (neck) or radial (wrist) pulse and count the number of beats in one
minute. Alternately, you can count your pulse for 15 seconds, then multiply that number by 4.
Respiratory Rate: Count the number of times that the chest rises and falls in one minute. Each rise and fall counts as one breath.
You will collect vital signs for one group member at rest, after one minutes of moderate exercise, and again after 2 additional minutes (for a total of 3 minutes) of moderate exercise. Resting vital signs are collected after the group member has been in a seated position for at least two minutes. Your instructor will provide you with directions on what type of exercise you will do.
Heart Rate (bpm) |
Respiratory Rate (breaths per min) |
Blood Pressure Systolic/Diastolic (mmHg) |
|
|---|---|---|---|
Resting (sitting still for 2 minutes) |
|||
Post-exercise (1 minute) |
|||
Post-exercise (3 minutes) |
1. What changes do you observe in heart rate and respiratory rate? Propose an explanation for the observed changes.
2. Create a line graph of blood pressure data below. On your graph, plot both the systolic and diastolic blood pressures of your group member at each time interval. Use two different colors to trace your systolic line and your diastolic line. Be sure to label the x-axis, the y-axis, and the intervals.
