Friday, March 4, 2011

EKG Lab

Different ways of monitoring the heart:

Auscultation: The act of using a stethoscope to listen to sounds made by the heart, blood, and lungs.

Echocardiography: A technique that uses ultrasound to visualize the details of the heart.

Electrocardiography (ECG or EKG): A graphic representation of the heart's electrical activity over time.

Magnetic Resonance Imaging (MRI): A technique to obtain high-resolution images of organs within the human body. This is done by mapping the distribution of hydrogen nuclei.

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EKG LAB

Objective: To obtain a graphical representation of the electrical activity of the heart.

Materials:

  • Computer
  • Computer Interface
  • Logger Pro
  • EKG Sensor
  • Electrode Tabs
Procedure:
  1. We first connected the EKG Sensor to the computer interface, and opened the file "12 Analyzing Heart EKG" in Logger Pro.
  2. Next we attached three electrode tabs to our arms. On a right arm we placed two tabs - one on the inside of the upper forearm and the other on the wrist. On the left arm we only placed one tab - on the inside of the upper forearm. 
  3. Then we connected the EKG clips to the electrode tabs. We then had our test subjects sit in a relaxed position with their forearms resting on their legs. Once the subjects were in the proper position we began to collect data.
Data/Analysis:


An example of a normal EKG:




















The P Wave represents atrial contraction.
The QRS Wave represents ventricular contraction.
The T Wave represents ventricular repolarization, or the recovery period of the heart.


My own EKG




This shows that I have a small QRS wave and a long T wave, or a long recovery period.

Overall this lab showed that everyone's heart beat is different, but there are certain things (P, QRS, and T wave) that are constant.

Anatomy of the Heart: Sheep, Pig, and Cow Heart Dissection

In this lab the class was divided into several groups, and each group dissected either a sheep, pig, or cow heart. After the dissection was complete, each group moved around the room and collected data on all three different types of heart.


  1. The basic structure of each heart is pretty much the same throughout each heart specimen. Each heart has four chamber (two atriums and two ventricles) and contains an aorta and pulmonary trunk. The only difference between the hearts is the size of each structure.
  2. There were many differences between each heart specimen. The cow heart was very fatty and firm. Both the pig and sheep heart were softer and did not have as much fat surrounding them. Also the overall size each heart and its structures differed from each other.
  3. Adaptive reasons for the difference in size would probably be due to the actual size of each animal. A sheep does not need a heart the size of a cow because it is considerably smaller than a cow.



A picture of the cow heart my group dissected. It was the best one. :)

Reflex Lab

Purpose: 
To see the difference between voluntary and involuntary movements of the body. Why are reflexes faster than voluntary movement?

Materials:
  • Computer
  • Reflex Hammer
  • Accelerometer 
  • Logger Pro
  • Electrode Tabs
Procedure:
  1. In this lab we recorded different people's reflexes. First, two electrode tabs were placed on the subject's legs, across the muscle.
  2. The reflex hammer, with the accelerometer strapped to it and plugged into the computer using Logger Pro, was hit against the desk. As soon as the subject heard the hammer being hit, they were to voluntarily kick their leg.
  3. The next test was just a simple reflex test. The reflex hammer was used to hit the subject's reflex, and it was recorded on the computer.
  4. Next, the subject's reflexes were recorded while resistance was happening in another part of the body. The subject locked their hands together and tried to pull them apart as hard as they could. During this time their reflexes were being tested and recorded.
  5. The final test was another simple reflex test. The data was taken right after the resistance test, expect the subject was to relax and not have resistance.
Data/Analysis :



This is a graph of the average time our test subject's reflexes took. In the resistance tests it is shown that with resistance the subject's reflexes were much slower than without resistance. The first bar shows that the voluntary test took much longer than the involuntary test. 
  • In the voluntary test the subject kicked their leg an average of .426 seconds after they heard the sound of the hammer hitting. While in the involuntary test, it took an average of .076 seconds for the leg to react after being hit with the reflex hammer. The difference in time is due to the actions in the body. In the voluntary test the brain had to process the hitting of the hammer before the subject could kick their leg. However, in the involuntary test, a circuit from the leg to the spinal cord was used, kicking out the use of the brain completely. This made the action of the involuntary test much faster because it was an automatic response, without the need to travel all the way to the brain and back to the leg.