Action Potentials In A Giant Alga Lab Report

b. What phenomena must take place for the small postsynaptic potentials to reach threshold and produce action potentials?

Action potentials can occur more frequently as long there is a continued source of stimulation, as long as the relative refractory period has been reached, which in experiment 2 the refractory period was complete.

Extracellular recording electrodes were used to measure the compound action potentials (CAPs) in a cockroach leg nerve. CAPs are the summations of all present action potentials (APs) in the individual axons of the nerve. When an AP is conducted along an axon, sodium channels open and positively charged sodium ions enter the axon. Therefore the inside and the outside voltage changes. The voltage changes in the extracellular fluid were measured. A depolarisation of the axonal membrane causes a local negative charge in the extracellular fluid. The summation of all the voltage changes in the extracellular fluid at a specific position is measured by the recording electrodes.

-Sarcoplasmic Reticulum (SR) then releases Calcium which binds to troponin in the thin filament, exposing myosin-binding sites;

As well as these there are also the axon of the cell which is covered in myelin sheaths which carried information away from the cell body and hands the action potentials, these are small short bursts of change in the electrical charge of the axon membrane through openings of ion channels, off to the following neurons dendrites through terminal buttons at the end of the axons. Whenever an action potential is passed through these terminal buttons it releases a chemicals that pass on the action potential on to the next neuron through the terminal button and dendrite connection. The chemicals that are

Wischusen, William, Jolissaint, Ann, Reiland, Jane, and Pomarico, Steven. 2012. Biology 1208/1209: Biological Laboratories for Science Majors. Hayden McNeil, Plymouth,

Water will move out of the cell. The high water potential means there is little solute in the cell and more in the outside environment. In order to balance these concentrations, water moves out of the cell and creates equilibrium with the environment.

Both electrical and chemical forces combine to determine the resting membrane potential of the cell. Although the resting membrane potential of most cells is normally negative, the selective permeability of the membrane allows certain ions in and out, causing the neuronal membrane voltage to become depolarized (more positive), or hyperpolarized (more negative). Key ions involved in muscle membrane potential are sodium, potassium, and chloride, which move via passive or active diffusion through ion channels and transporter pumps (Baierlein et al. 2011). The Nernst equation predicts the membrane voltage based on the assumption that the membrane is only permeable to one type of ion. In this investigation, we are seeking to understand the basis for how different ions interact to produce the membrane potential of DEM, DEL1, and DEL2 crayfish muscle

Explain why increasing extracellular K+ causes the membrane potential to change to a less negative value. How well did the results compare with your prediction? ___

Shutting down cell 18 will lead to Swimmy moving its tail to the left constantly; its left tail will be more overly active compared to the right tail. Although cell 11 is no longer inhibited and will continue firing in its normal bursting pattern, it will only sometimes inhibit cell 13 because it is an endogenous burster. With this in mind, the stimulation on cell 2 would be weaker (since it is only sometimes excited by cell 13) than the stimulation on cell 1 (since it is constantly excited by cell 12). Cell 1 would be less inhibited by cell 25 due to cell 2’s inactiveness, and cell 2 would be more inhibited by cell 24 due to cell 1’s activeness. Because cell 12 is always excited and thus constantly excites cell 1, it can be inferred that motor

Depolarization in membrane potential triggers an action potential because nearby axonal membranes will be depolarized to values near or above threshold voltage.

The findings of this experiment reinforced the hypothesis that the resting membrane potential is most influenced by the ion potassium. We were able to deduce this through the collection of a multitude of intracellular and extracellular recordings, such as the one shown below in Figure 1. This shows how this experiment was able to record every single resting membrane potential in all three different muscle groups under all six solutions.

In animal cells, the movement of water into and out of the cell is influenced by the relative concentration of solute

Whenever the balance is altered, the process of transmitting electrical signals, which is called action potential initiates by carrying information across a neuron’s axon; which is called resting membrane potential. This process occurs as uneven ions distribution flow across cell membrane, creating electrical potential. As a result, the duration of active potential can be as fast as 1 ms. Similarly, the average resting membrane is between -40 mV and -80 mV. Since the membrane from inside is more negatively charged than the outside, it reflected on the negative average voltage readings of the resting membrane.

1984). This is due in part to a decrease of the transient K+ current (IA), a decrease in