Neurophysiology Drawings

In class we have been learning about the nervous system. Down below is a drawing of a neuron and all the parts labeled. Neurons are cells that transmit signals via action potentials. Located around neurons are supporting cells. The body of a neuron contains the nucleus and has no centrioles. The axon, which is the site for propagation of axon potentials covered in Myelin Sheath, arises in the axon hillock. At the top of the neuron, above the nucleus, are dendrites. Dendrites attract electrical signals and send them to the bottom of the axon. For a signal to be sent down to the bottom, you got to have a really big one or two that come at the exact same time. It all depends on the size and the timing. 

Located at the end of the axon is the axonal terminal, which is branched terminus of the axon. The axon is what transfers or emits the action potentials. An action potential is all or nothing electrical discharge. They produce and release neurotransmitters at the synapse. Synapse is the area of impulse transmission between axons (communication between axons). Movement can be sent towards the axonal terminal are sent away from it. The longest axon can be up to 1 M long. 

Myelin Sheath protects the axon. It is a whitish, fatty sheath that can be found along most axons. This sheath insulates fibers electrically. With this present, the speed of impulse transmission increases. There are gaps that are located in the sheath that allow for the propagation of impulses known as nodes of ranvier. Myelin sheath is formed by schwann cells and both myelinated and unmyelinated cells are present. 

                                                    

Down below is a picture of a protein membrane channel (doors). There are many different types of channels that all help out in a certain way. A potassium channel and sodium channel are two of the channels.There is voltage gated sodium channel and a voltage gated potassium channel. When the sodium channel opens and sodium rushes in, the voltage rises due to more positive charges going inside. The voltage or charge then triggers the potassium channel and the potassium, which is negative, starts flowing out causing the voltage to decrease and eventually even out. There is also a na+ and a K+ pump. Some channels only allow potassium and some only allow sodium.

                                                

Action potential is what is shown in the picture below. An action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. The channeled gates open and close really fast (micro seconds) to try and even out the charge as fast as possible. The potassium gate opens at 50- because the sodium is flowing in causing the voltage to rise and the potassium helps bring it back down and eventually even it out.

                             

The picture down below represents synaptic potential. This is when the charge is different on the inside and outside of the neuron. The outside is positive and the inside is negative. These channels are polarized due to more negatives located on the inside. When sodium rushes in (voltage rises), positives start to fill the inside causing depolarization to happen. When potassium starts to rush out (voltage drops), depolarization happens. Eventually the charge evens out again.

Resting potential is when there is the same amount of positives on the outside as there are negatives in the inside. You can stab the membrane with a pipet to measure the voltage. Sodium enters with calcium. 

Introduction to EMG (a.k.a. chewing lab)

This lab involves different varietys of food. My group was given different foods to chew. Electrodes were placed on Alexis's face along with wires to monitor her chewing of each food. The minimum and maximum transmitted through the wires was recorded. Down below is the information gathered during this lab. The food that we found was the hardest to chew was the gummy worm and required larger bites. The food that was the easiest to chew was a nilla wafer. When it was being chewed, it showed little muscle activity or electrical energy. The numbers you will see below show the minimum and maximum voltage transmitted through her masseter.

• Control- min: 0.9753mV max:1.131mV
• Apple- min: 0.2962mV max: 2.281mV
• Gummy Worm- min: 0.02083mV max: 4.006mV
• Marshmellow- min: 0.0208mV max: 3.053mV
• Nilla Wafers- min: 0.4115mV max: 1.924mV
• Oreo- min: 0.1567mV max: 2.484mV

The graph below was made from sutracting the minimum from the maximum.

Part 2- Muscle Anatomy and Physilogy Model Building

Down below is a link to my group's powerpoint that explains sliding filament theory and a poster we drew. This is a continuous project on muscles and part 1 was posted right before this. Enjoy!

Part 1 - Muscle Anatomy and Physiology Model Building

Down below are a couple notes over important words that have to do with muscle movement. Also below those notes is my explanation over muscle movement and my example.

Key Terms:

• Tendon- a flexible but inelastic cord of strong fibrous tissue attaching a muscle to a bone
• Fascia- connective tissue fibers, primarily collagen, that form sheets or bands beneath the skin to attach, stabilize, enclose, and separate muscles and other internal organs
• Epimysium- a layer of connective tissue, which ensheaths the entire muscle
• Perimysium- a sheath of connective tissue that groups muscle fibers into bundles or fascicles
• Fascicles- a bundle or a cluster
• Endomysium- a wispy layer of areolar connective tissue that ensheaths each individual muscle fiber, or muscle cell
• Muscle fibers- a long, multi-nucleated muscle cells, or myofibers, that make up skeletal muscle
• Myofibrils- a basic rod-like unit of a muscle
• Protein filaments- long chain of proteins
• Plasmalemma- a plasma membrane that bounds a cell, especially one immediately within the wall of a plant cell
• Mitochondria- a membrane bound organelle found in most eukarytoic cells
• Nucleus- the central and most important part of an object, movement, or grou, forming the basis for its activity and growth
• Sacroplasm- of a muscle fiber is comparable to the cytoplasm of other cells but it unusually contains large amounts of glycosomes.

Physiology

Skeletal, cardiac and smooth muscle all work together to create contractions. Contraction is stimulated by electrical impulses transmitted by the nerves. All skeletal muscle and many smooth muscle contractions are faciliated by the neurotransmitter acetylcholine. 

Function

The way a muscle functions is determined by its location. The cross-sectional area of a muscle determines the amount of force it can generate by defining the number sacromeres which can operate in parallel. When a sacomere contracts, the Z lines move close together, and the I band becomes smaller and the A band stays the same width. At full contraction, the thin and thick layers overlap.

My Project