Lab 10 Physiology of the Circulatory System
The human circulatory system is a collection of structures thorough which
oxygen and nutrient rich blood flows to all tissues of the body for metabolism and
growth, and to remove metabolic wastes. The blood is pumped to these tissues by the
heart through a circuit composed of arteries, arterioles, capillaries, venules, and veins.
Oxygenated blood is pumped to the tissues from the left side of the heart, whereas
deoxygenated blood is pumped to the lungs from the right side of the heart. This circuit
where gas exchange takes place within the alveoli of the lung is very important and is
known as the pulmonary circuit. When the body is exercised changes can take place in
the circulatory system that allow more blood to pass to actively respiring muscle cells and
less to nonmuscular tissue. Increased heart rate, arterial pressure, body temperature, and
breathing rate also occur during exercise.
Arterial blood pressure is directly dependant on the amount of blood pumped by the heart
per minute and the resistance to blood flow through the arterioles. This is an important
measurable aspect of the circulatory system and it is measured using a
sphygmomanometer. This device has an inflatable cuff that connects to a hand pump and
a pressure gauge, graduated in millimeters of mercury, by rubber tubing. The cuff is
wrapped around the upper arm and inflated, the person taking the pressure then listens for
two sounds and observes the gauge to determine what the blood pressure is. The systolic
number is determined by the first noise heard as the cuff is deflated, and the diastolic
number is determined by the last distinct noise heard.
From this experiment it is expected that a subject’s heart rate and blood
pressure will change during rest and exercise based on how physically fit they are. If the
subject is in good shape the heart rate will not increase significantly and the blood
pressure will increase. The opposite is true of someone in poor shape.
The materials used in this experiment include a blood pressure kit, alcohol
swabs, a stopwatch, two depression slides, a cotton ball, four rubber bands, a pipet, a
petri dish, a
culture, a stereomicroscope, and some ice.
A. Measuring Blood Pressure:
To measure blood pressure, one member of the lab
group sat down in a chair, rolled up his sleeve, and then the sphygmomanometer cuff was
placed around his upper left arm at heart level. The cuff was then pumped to 200mm Hg,
which is safely higher than the blood pressure of the subject. The stethoscope was then
placed in the well of the subject’s elbow, where the brachial artery is located, and