EKG Lab

Yet again, we had some more fun tests to perform in the lab.  This time it was an EKG lab.  In this lab we got to play around a lot with different ways of taking blood pressure.  Everything from blood pressure cuffs to more accurate hand grips that hooked up to a recording program on a computer.  I’m really not a fan of blood pressure cuffs…they just freak me out…claustrophobia…ew, ew.  So, I decided to watch rather than volunteer my scrawny arm! 

An EKG is first and foremost, a graphical recording of the events occurring within the heart.  It records the natural pace and movement of the heart and can give good insight into the health of the heart and thus the rest of the body.  There are five parts to a single heartbeat, the P wave or atrial contraction, the QRS or ventricular contraction and finally the T wave which is the ventricular repolarization.  Viewing the EKG tracing of the heart can prove disorders or abnormalities in the heart.  For our lab we recorded for five seconds the electrical activity of the heart.  We then switched the red and green leads to simulate the change in electrical activity.  We started by connecting a green(negative) and black(ground) cords to the right arm and red(positive) cord to the left forearm.  The cords were connected to the recording program on the computer, we then collected the data from the model.  We then exchanged the clips with the other arm and recorded again.  Here is our data.

Interval                       Time

P-R                         .089s  .104s

QRS                        .079s  .069s

Q-T                         .257s  .140

R-R                         .666s  .562

Heart Rate (BPM)            39.96   33.72

After researching this data we could explore further on what a healthy/average heart rate would be for different ages, genders etc.  This may be something I will be looking into further for another post.  

This lab taught quite a bit on simply how to record heart rate and how to analyze it afterwards.  I think it's a skill that's a bit more likely to be used in daily life.  I think our previous heart dissection lab really helped close the gap with this one.  The dissection lab discussed what everything was, and this EKG lab showed what those parts did and how they relate to the proper functions of the rest of the body.  For me it really made the connection.  I think this is also something that could be explored further.  I may be looking back at this post for an outside research blog.  We'll see!

Reflex Lab

This quarter we’ve been doing a lot of work in the lab.  Recently, we performed a reflex lab.  This was probably one of my favorite labs because I got to smack my best friend with a mallet!  Fun fun!  The purpose of this lab was to see how long it took the reflexes of the body to react to the hit of mallet on the reflex point of their knee.  We first connected adaptor cords to various parts of the leg and body that then connected to a computer with a recording program.  The first step was to hit the mallet on a hard surface and have the model kick their leg according to the timing of the hit.  The computer would then record the exact timing of the hit in comparison to the reflex kick of the model’s leg.  After the given number of hits had been made and recorded we moved on to direct reflex.  This consisted of literally locating and hitting the reflex point on the knee cap of the model.  The computer would record the accuracy of the kick in response to the hit.  It was clear just how accurate a direct hit was in comparison to a hit to the table.  Here are our results:

1st Recording of mallet on table.

2nd Recording of mallet on knee.

After reviewing the results it's easy to see that the direct hit to the reflex point on the knee is much more accurate than the hit to the table.  This would be because the direct hit only takes time to connect to the spinal cord back to the knee point.  Whereas the hit to the table takes more time to connect with thought before running down the body to the reflex point.  

BRAINS!!

We recently performed a brain dissection lab in class.  It was a fairly quick lab but reeked of formaldehyde nonetheless. Each group received a lamb brain.  Some groups, such as ours, received a brain that still had the tough outer layer protecting it called the dura mater, or outer meninges.  We first had to remove this protective outer layer.  We then were assigned to cut the brain horizontally.  This took quite a bit of time because none of us could agree on the right size cut.  Once we had accomplished this we sliced the brain into various pieces and identified them.  

Here is a shot of the final outcome.

These are the parts identified on the brain itself. 

Eat Your Hearts Out!

Rawr.

We recently performed another dissection lab and oddly enough it didn't reek of formaldehyde!  This time we performed our dissections on hearts, on Valentine's day nonetheless!  There were three hearts to choose from sheep, cow, and pig.  Our group decided to go with the smallest of the three, the sheep. 

Throughout the lab we were required to measure various sections and pieces of the heart to compare to the other animals hearts.  Once the outer parts were recorded we sliced the heart open "clam shell" style and inspected the inside.  

Here are our records:

Aorta- 1.5cm
Pulmonary Trunk- 1cm and 2.5 Length
Right Atrium Diameter-4cm
Left Atrium Diameter- 3.5cm
Right Ventricle Diameter-1.5cm and 5cm in length
Left Ventricle Diameter-1.5cm and 5.5 in length
Outer Wall thickness- 1cm

Some of the areas identified.

We then compared our results to other group's results of the cow and pig.  Here are the results.

Pig:                                    
Right Atrium: 4.5cm
Left Atrium: 4cm
Right Ventricle: 3cm
Left Ventricle: 2.5cm
Outer Wall:  .5-1cm
Aorta: 5x3cm
Pulmonary Trunk: 4cm

Cow

Right Atrium: 3cm

Left Atrium: 3cm

Right Ventricle: 3cm

Left Ventricle: 4.5cm

Outer Wall:  1-1.5cm

Aorta: 3cm

Pulmonary Trunk: 2.5cm

After reviewing the three hearts we agreed that the three hearts are all the same in structure, the only major difference was the size.  This is obviously due to the size of the animal and what is needed to carry out basic functions.  After we performed the dissection we reviewed an assortment of slides relating to sections and parts of the heart.  After comparing the slides of artery and vein, we agreed the artery has the thickest wall because more blood passes through more quickly. The cardiac muscle was next which we discovered was indeed striated.  We decided that having atherosclerotic plaque on the coronary artery could possibly lead to the heart clogging and thus heart attacks due to build up.