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Question Description

Lab report and must have the sensors to check heart rate to do this lab.

Effect of Coughing on Heart Rate

Involuntary coughing is the result of irritation of special sensory nerves in the respiratory tract.

This helps to clear potentially damaging substances from the lungs (water, foreign bodies, dust,

infection, mucous, etc.). Coughing can be more deleterious than helpful, causing discomfort,

preventing sleep, or leading, in some cases, to dizziness or loss of consciousness (known as

cough syncope).

The physiologic effects resulting from a cough are numerous. There is marked increase in

intrathoracic pressure just prior to expulsion of air. When blood pressure is normal, this leads to

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

other hand, a cough-induced increase in intrathoracic pressure may provide a form of “internal

cardiopulmonary resuscitation” in a heart attack victim whose blood pressure is falling

dangerously low. In this case, coughing can be as effective as the external chest compressions of

CPR in raising blood pressure and providing better blood circulation to vital tissues.

Coughing, and the resulting wide fluctuations in intrathoracic pressure it produces, causes reflex

stimulation of the autonomic nervous system. The sympathetic nervous system is an “activating

system,” preparing the body for a “flight or fight response” by increasing heart rate and blood

pressure. The parasympathetic nervous system acts through the vagus nerve to slow the heart and

to lower blood pressure. Both the sympathetic and parasympathetic systems may be stimulated or

inhibited by physiologic stimuli or medications.

The following table shows potential heart rate response to stimulation or inhibition of the

sympathetic or parasympathetic nervous systems:

Branch of Autonomic

Nervous System

Heart Rate Response to

Stimulation Inhibition

Sympathetic ? ?

Parasympathetic ? ?

In this experiment, you will observe the response of heart rate to coughing, and correlate this

response to activity in the autonomic nervous systems.

Important: Do not attempt this experiment if you suffer from asthma or any condition that may

be aggravated by repeated coughing


1. In what direction did your heart rate change in this experiment? According to the table in the

Introduction, what are the possible explanations for this change?

2. There are medications that can selectively block the action of either sympathetic or

parasympathetic influences on the heart. How could such medications be used to determine

which of these systems is responsible for a change in heart rate such as was seen in this


3. Compare the response and recovery times recorded in Table 1. List possible survival

advantages of the differences you see.

4. The parasympathetic and sympathetic nerve supplies are severed during heart transplantation

and are not surgically repaired. Would a heart transplant recipient’s heart rate change with

coughing (or with a severe fright)?

5. You are in a remote location and a member of your party complains of chest pain and

dizziness. You find that his pulse is 35 bpm. You immediately call 911 and are told that it

will take 15 minutes for the helicopter to arrive. You know that CPR should not be performed

on conscious individuals. Drawing from the knowledge you have gained from this

experiment, what might be done to improve your patient’s pulse and blood pressure?

6. Perform the experiment with different coughing frequencies and intensities.