Build A Limb Lab

Once again, because of the blog, the pictures are in "reverse" order. First picture is at bottom... then works it's way up. :)

Neurons- and Schwann Cell (Sorry, this was placed out of order by the blog... should come right above the first picture of the Neuron in Progress...)

Release of Calcium from Sarcoplasmic Reticulum, and it's Binding to Myosin.

Sarcomeres- Contracted

Muscle Cell w/ Labeled Parts: Sarcolemma, T-tubules, Sarcomere, Myosin Cross-Bridges, etc.

Muscle Cell- in progress

Action Potential Ends / Repolarization

Action Potential Begins

Movement of Charged Sodium and Potassium Ions Across Membrane:
Resting Potential

Propagation of Action Potential Along Axon

Neuron- In Progress

Emma's "Knee"- She was so proud. :)

Extended Knee: Quadricep Contracted

Bent Knee: Hamstring Contracted

Finished Knee: Tendons "peeled back" to see all labeled parts.

Finished Knee: Outside Labeled

Process: Building the Knee

My Materials: We always have a stockpile of play-do in our house. :)
1. Introduction: My assignment for this lab was to create a moving limb with neuron triggering muscle to pull on bone and make a joint move. I chose to make a model of the knee. The parts of the knee that I included in my model are as follows: Both the quadricep and hamstring muscles, that contribute to contracting the knee, fat, bursa, patella, artiulcar cartilage, patellar tendon, tibia, fibula, meniscus, synovial fluid, synovial membrane, and femur.
- The quadriceps and hamstring muscles move the knee joint.
- The femur (thigh bone), tibia (shin bone), and patella (knee cap) make up the knee joint.
- Meniscus: Covers the end of the bones and acts as "cushion". Helps absorb shock and allows the knee joint to move smoothly.
- Bursa: Fluid-filled sac that facilitates movement and reduces friction.
- Patella: the knee-cap. Triangular-shaped, covers and protects knee joint. Articulates with femur.
- Patellar Tendon: Attaches quad muscle to tibia.
- Articular Cartilage: Covers the ends of bones. It has a smooth, slippery surface, which allows the bones of the knee joint to slide over each other without rubbing.
- Synovial Fluid: Lubricates joints.
- Synovial Membrane: Secretes synovial fluid.
2. List of Limb Parts and Their Model Representations: I chose to use different colors of play-do for each part of the knee. They are labeled on the diagram itself, but I will list them here, as well.
- Quadricep and Hamstring Muscles: Red
- Bursa: Green
- Fat: Yellow
- Patella: Greenish "Mixed"
- Tibia: Light Yellow
- Femur and Fibula: White
- Tendons: Purple
- Synovial Fluid: Brown
- Meniscus: Pink
- Articular Cartilage: Orange
* I also built a sensory, inter, and motor nueron to show the propagation of action potential along an axon, a separate model demonstrating action potential, a skeletal muscle cell, the release of calcium from a sarcoplasmic reticulum and calcium binding to myosin.
3. The Models: Please see above pictures with corresponding captions.
4. Conclusion: Our bones are moved by muscle contractions. The way that a muscle contracts is as follows: A sensory neuron takes nerve impulses (action potential) from a sensory receptor to the Central Nervous System. An interneuron in the CNS receives the input from sensory neurons and from other interneurons, sums up the impulses, and communicates them to motor neurons. The motor neuron (whose axons are in the nerves) takes nerve impulses away from the CNS to an effector, in this case, the muscle fiber. When nerve impulses arrive at an axon terminal, the synaptic vesicles release ACh into the synaptic cleft. When ACh is released, it diffuses across the cleft and binds to receptors in the sarcolemma. Next, the sarcolemma generates impulses that spread over the sarcolemma and down T-tubules to the sarcoplasmic reticulum. The release of Ca2+ from the sarcoplasmic reticulum leads to sarcomere contraction. A single muscle fiber (cell) has many myofibrils that are each divided into sarcomeres, which contract. When the myofibrils of a muscle fiber contract, the sarcomeres shorten. The actin filaments slide past the myosin filaments toward the center, and the muscle pulls on the bone to move it.