Saturday, November 8, 2008



For this lab I had to create a working model of a limb and what transpires within the muscle of a limb.  I choose the upper arm as my limb and the bicep as my muscle.  The bone in the arm is the humerus and the bones in the forearm are the ulna and radius.  I will start by explaining what materials I used in my model of the limb, muscle, neuron, and the things that transpire with the muscle. 


I used Styrofoam for the limb along with pipe cleaners, also with the pipe cleaners for the sliding filaments.  I used the play- doh for the muscle, neuron, sarcoplasmic reticulum, and licorice for the t-tubules.  I also used, which I forgot to add into this picture, was little candies for my sodium and potassium gates.  The gates were made of play-doh also.   I used the plastic wrap from the poster board for my sarcolemma.  The poster board was used for my neuron.  I will have an explanation of each photo have taken for the lab. 





This is the photo of my working limb.  You can see the humerus, ulna, and radius.  At the bottom of the ulna and radius are the carpal's in which these bone articulate with.  Made with Styrofoam and pipe cleaners.



In this photo is the humerus with a muscle (red) and the tendons (yellow).  Made with Styrofoam, play-doh, and pipe cleaners.


This picture shows a neuron with all of its components.  The cell body, dendrites, axon terminal, the axon, schwann cells, nucleus, and the node of Ravier.   There are different types of neurons.  There are sensory neurons which are responsible for transmitting nerve impulses toward the Central nervous system (eg., getting poked by a rose thorn).  The other kind is a motor neuron and they are responsible for transmitting nerve impulses away from the central nervous system ( pulling your hand away from the rose thorn). Schwann cells act as a cushion around the neuron.  Axon is where action potential travel.  The cell body holds the nucleus.  The dendrites help carry a signal towards the cell body.  Node of Ravier are the bare green spots that help with saltatory conduction, which is the action potential jumping from node to node.   All made of play-doh.


This is a picture of a sarcomere which is contracted.  What that means is, this sarcomere is part of your muscle,  Just a small portion of your muscle.    The sarcomeres are what make the muscle shorten when it is contracted, with help of you flexing (eg., flex your arm).  As you can see I used pipe cleaners.


in this photo is a muscle (red play-doh) that is encased inside the sarcolemma (plastic wrap).  The myofibril (licorice) is a part of a sarcomere, which I explained above.  The sarcolemma is the plasma membrane of the muscle and contains t-tubules.


In this photo I tried to represent the sliding filaments.  The actin make up the thin filaments within a sarcomere and the myosin makes up the thick filaments.  Their purpose is to create a power stroke.  This is how the muscle works, or what is actually going on inside your muscle when you are exercising, walking, or just picking up a book.  The tropomyosin regulate myosin and actin interaction.  Myosin walks along the actin.  In the picture myosin (orange) has heads and the actin (blue/pink) have a binding site for myosin to fit.  It just keeps going and going until the muscle relaxes.  Made with play-doh and pipe cleaners.  The actin,myosin and tropomyosin are all proteins.


This is a picture of the sarcoplasmic reticulum (blue clay) with the t-tubule(licorice) going through it and calcium(candies) being released.  In order for your muscle to contract calcium needs to be released from the sarcoplasmic reticulum.  An action potential causes the release of the calcium.  An action potential is when the nerve cells carry a signal over a distance.


The is a picture a (close up) neuron just showing the axon portion with sodium and potassium gates releasing their product (ions) into and out of a cell.    This is a action potential that is propagated, meaning that these two ions are flowing and the cell is becoming polarized.  It must reach an equal balance on both side of the cell.    These gates open and close to allow these ions to pass through.   Made of play-doh  and candies.


This lab of building a working limb taught me how our bones are connected, how muscles work, and what transpires inside of a muscle.  It is hard to believe that all of this is actually going on while I am sitting here typing!!  It was hard to display all that I wanted to, but I hope I touched on the important stuff.   What I was trying to show with this model is the details of what is behind our skin and how a muscle works.  

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