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Biology - HOT Science Lab

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Student<br />

a decrease in venous return to the right side of the heart and a decrease in cardiac output. On<br />

the other hand, a cough-induced increase in intrathoracic pressure may provide a form of<br />

―internal cardiopulmonary resuscitation‖ in a heart attack victim whose blood pressure is falling<br />

dangerously low. In this case, coughing can be as effective as the external chest compressions<br />

of CPR in raising blood pressure and providing better blood circulation to vital tissues.<br />

Coughing, and the resulting wide fluctuations in intrathoracic pressure it produces, causes reflex<br />

stimulation of the autonomic nervous system. The sympathetic nervous system is an ―activating<br />

system,‖ preparing the body for a ―flight or fight response‖ by increasing heart rate and blood<br />

pressure. The parasympathetic nervous system acts through the vagus nerve to slow the heart<br />

and to lower blood pressure. Both the sympathetic and parasympathetic systems may be<br />

stimulated or inhibited by physiologic stimuli or medications.<br />

The following table shows potential heart rate response to stimulation or inhibition of the<br />

sympathetic or parasympathetic nervous systems:<br />

Branch of Autonomic Nervous<br />

System<br />

Heart Rate Response to Stimulation<br />

Inhibition<br />

Sympathetic ↑ ↓<br />

Parasympathetic ↓ ↑<br />

Purpose or Problem Statement: In this experiment, you will observe how the heart responds<br />

to two different stimuli: cold stimulus applied peripherally and coughing. In both cases, cold and<br />

coughing will act as noxious stimuli, activating the ―fight or flight‖ response through the<br />

sympathetic nervous system. The purpose of this lab is to evaluate how sympathetic stimuli alter<br />

the heart rate.<br />

Safety: Do not attempt this experiment if physical exertion will aggravate a health problem.<br />

Inform your instructor of any possible health problems that might be exacerbated if you<br />

participate in this exercise. Do not attempt this experiment if you suffer from asthma or any<br />

condition that may be aggravated by repeated coughing.<br />

Vocabulary: baroreceptors, sympathetic nervous system, parasympathetic nervous system,<br />

resting heart rate, maximum heart rate, homeostatic mechanisms, blood pressure, heart rate,<br />

stroke volume, intrathoracic pressure<br />

Materials (individual or per group):<br />

CBL2 with TI 83 calculator<br />

ice water bath<br />

towel<br />

DataMate App<br />

Vernier Respiration Rate Monitor<br />

Vernier Hand-Grip Heart Rate Monitor or Vernier Exercise Heart Rate Monitor<br />

saline solution in dropper bottle for the exercise heart rate monitor<br />

<strong>Biology</strong> HSL Page 272<br />

Curriculum and Instruction

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