Lab Description

LAB WRITE - UP

This model represents a movable, flexible limb. This model also shows the knee joint, and how it makes the leg move. Neurons and muscle cells are also depicted in this model, as well as their specific function in the leg. The essential elements presented in this model include neurons carrying action potentials that trigger muscle (neurotransmitter), actin-myosin sliding filaments, a bony element that muscle attaches to and moves, and a joint that allows for movement.The neurons presented in this model include axon with schwann cells, movements of charged sodium and potassium ions across the membrane (action potential), and the propagation of action potential along the axon. There are also several aspects of the muscle cells included in this model, such as sarcolemma and T-tubule membranes, a sarcomere, the release of calcium from the Sarcoplasmic reticulum, calcium binding to myosin, and myosin cross-bridges that bring actin filaments together. All of these things put together make a simple limb movement.Knee Cap joint – This joint is considered a hinge joint in the body, in which this joint only moves in one direction. Neurotransmitters – These chemicals are used in order to amplify and relay electrical signals between a neuron and another cell. Within the cell, small neurotransmitter molecules are usually found in vesicles. When action potential occurs, and travels to the synapse, depolarization causes the calcium ion channels to open, which leads to the process of exocytosis.Actin-myosin sliding filaments – These filaments are responsible for many types of movement in the muscle. Myosin is the prototype of a protein that converts chemical energy in the form of ATP to mechanical energy, in order to create enough force to make the arm move.Bony element that muscle attaches to – The two ends of the muscle belly are attached to a bone by a muscle tendon. The bone that remains stable during movement is known as the origin, and the bone that moves when the muscle belly contracts in known as insertion. A muscle can make a leg move when insertion occurs, and moves toward the origin, as the muscle belly shortens.Axon with Schwann cells – Schwann cells speed up and save energy for the processes of action potentials. This variety of neuroglia mainly provides myelin insulation to axons in the peripheral nervous system of our bodies.Action potential – This process of electrical discharge is very important in order to carry information within and between tissues. This charge travels along the membrane of a cell, and essential in animal and some plant life.Propagation of action potential – Propagation is the interaction between membrane depolarization and sodium channels. Action potential will propagate in unmyelinated axons, and let sodium ions enter the cell by facilitated diffusion.Sarcolemma – This is the cell membrane of a muscle cell which receives and conducts stimuli. This membrane is extendable, and encloses different substances from muscle fiber.Sarcomere – This is the basic unit of a muscle’s myofibril. Sarcomeres are multi-protein complexes which are composed of three different filament systems. The different bands in the sarcomeres allow muscle contraction to occur, and expand and contract in order make the muscle move.Release of Calcium – This process is important because it lets ATP hydrolysis occur, which supplies energy in the actin-myosin complex. When the action potential triggers a myocyte to contract, calcium ions are able to enter. This calcium actually triggers the release of more calcium ions that are stored in the sarcoplasmic reticulum.Calcium binding to myosin – This calcium is then able to bind to myosin, after the energy is supplied in the actin-myosin complex. This is needed in order to trigger a contraction of the muscle.Myosin cross-bridges – During this cycle, actin combines with myosin, and ATP is used to produce force. This ATP first disconnects the actin from the myosin, and is then hydrolyzed by the myosin in order to produce the energy needed for muscle contraction.