Resting Membrane Potential Of Orconectes Lab Report

A voltage-gated sodium ion channel opens when there is a change in the voltage of the membrane and allows sodium ions to flow across its electrochemical gradient. These voltage-gated channels are made up of amino acids and they aid in generating and moving an action potential down a membrane or axon (Brooker, Robert, 106).

Resting potentials require ions as they play a vital role in the process. In the surface membrane of a cell there are protein carriers. These actively pump Na+ ions out of the cytoplasm to the outside of the cell. At the

The conceptual overview, along with the experimental procedures are found in the NPB 101L Physiology Lab Manual 2nd Edition. More specifically, pages 55 to 63 provided a full insight to all the experiments in the respiratory lab. In addition, a list of required materials was given for every experiment. The authors of this lab manual were Erwin Bautista and Julia Korber. As for data acquisition, the BIOPAC software was used to collect and record data for all the trials. Furthermore, the teaching assistants had calibrated each station prior to initiating the lab exercises. For the entirety of the respiratory lab, a human subject was used in all the experiments. A 22-year-old female was the participant for the first two experiments regarding

When a membrane is excited depolarization begins. When the membrane depolarizes the resting membrane potential of -70 mV becomes less negative. When the membrane potential reaches 0 mV, indicating there is no charge difference across the membrane. the sodium ion channels start to close and potassium ion channels open. By the time the sodium ion channels finally close. The membrane potential has reached +35 mV. The opening of the potassium channels allows K+ to flow out of the cell down its electrochemical gradient ( ion of like charge are repelled from each other). The flow of K+ out of the cell causes the membrane potential to move in a negative direction. This is referred to as repolarization. ( Marieb & Mitchell, 2009). As the transmembrane potential comes back down towards its resting potential level and the potassium channels begins to close, the trasmembrane potential level goes just below -90mV, causing a brief period of hyperpolarization (Martini, Nath & Bartholomew, 2012). Finally, as the potassium channels close, the membrane turns back to its resting potential until it is excited or inhibited again.

1. Chamberlain et al. Effects of Tonicity on Cell Membrane . Human Physiology Labratory Manual, 8th Edition, Expt 6 part C and D

2. 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? _______________________________________________________________________

Increasing extracellular K+ causes the membrane potential to change to a less negative value because the K+ ions diffuse out across the membrane. My results went well compared to my prediction because I predicted that the resting membrane potential would become less negative.

The resting membrane potential is the difference between the outside and the inside cell membrane polarity. It is called a resting potential because it occurs when a membrane is not being stimulated or conducting impulses (Ritchison n.d.). This polarity can be measured and it is about -70mv. In the resting membrane potential, outside the cell has a more positive polarity and inside the cell has more negative polarity. There are more Na+ and Cl- on the outside and larger negative proteins (because they cannot go through the tiny pores to outside) and more K+ inside the cell (Ceballos, 2016).

Na+ , K+ and Cl- cotransporter is envolved in electroneutral transport at apical surface, which is driven by low concentration of these ions. This low concentration of ions is achieved by basolateral Na+ and K+ contertransporter (sodium-potassium adenosine triphosphatase) and basolateral chloride ion channel by facilitated diffusion (CLC-kb). Potassium ion is capable of diffusing back to lumen through apical potassium channel (ROMK) and returns net positive charge to lumen, this is important for reabsorption of calcium and magnesium

The fluid mosaic model developed by S.J Singer and Garth Nicolson in 1972 explains the structure of the membrane. It shows this through the explanation of the phospholipid bilayer which contains hydrophobic tails and a hydrophilic heads as well as the peripheral and integral proteins which help to hold the structure. The fluid mosaic model also says how the membrane is in a fluid form rather than solid because of the constant movement within the membrane (Biology Online, 2008).

The purpose of this experiment was to test the hypothesis that the crayfish resting membrane potential is primarily dependent on the potassium ion concentration gradient. Our approach to testing this hypothesis involves taking intracellular recordings using an IWX/214 interface, iWorx and LabScribe software, and a Model 3100 electrometer complete with a head stage, ground electrode, glass microelectrodes, and micromanipulator. The study organism used for this experiment involved the abdominal extensor muscles of adult Orconectes rusticus. One-sample t-tests were conducted on the resulting membrane potentials and their corresponding predicted values, taken from the Nernst Equation. The results of the statistical analysis rejected the null hypothesis only for some potassium gradient concentrations, and while there might be enough evidence to suggest that there is a relationship between the potassium gradient concentration and crayfish resting membrane potential, we cannot conclude from this experiment a primarily dependent relationship.

The Ryanodine receptors (RyRs) are membrane proteins that are located in the sarcoplasmic and endoplasmic reticulum of the cells. The key role of the receptors is to mediate the release of calcium ions (Ca2+) from intracellular storages in either reticulum into the cytoplasm during excitation-contraction coupling in muscles. Intracellular Ca2+ regulation is important for secondary messenger for signal transduction and is essential for certain cellular processes. Ryanodine is named after the plant alkaloid ryanodine, which binds to the receptors and displays preferential interactions with the open state of the channel. At nanomole concentrations, they lock the Ca2+ channel in an open sub-conductance state and at higher concentration, they inhibit the channels completely. For mammalian organisms, there are three distinct RyRs are the largest known ion channels and three isoforms have been identified, RyR1, RyR2 and RyR3 each of which is encoded by a distinct gene on different chromosomes (Lanner, Georgiou, Joshi, &

Cell membranes regulate the chemicals that go out or stay inside a cell. This lab tested these functions to see how the cell membrane regulates the chemicals that pass through it. The membrane tries to achieve equilibrium on both sides by sending some chemicals to the outside or inside to get the same amount of each chemical. Dialysis tubing was used as a cell membrane.

To osmo- regulate properly in a marine habitat, physiological mechanisms intended to conserve fresh water and thus avoid dehydration are required. Marine mammals are well adapted to their hyper-osmotic environment. Their cells need to maintain both a water balance and an ion balance and life depends on the maintenance of the transmembrane potential. The concentration of potassium ions is higher in cells than on the extracellular fluid (ECF) and the concentration of sodium ions is higher in the extracellular fluid. Osmolarity is describes the total solute concentration.

Under resting conditions, all cells will have an electrical potential difference across the membrane so that the inside of the cell is negatively charged and the outside of the cell is positively charged. This RMP must be established before a neuron is able to conduct an electrical signal. The difference in charge across a membrane establishes a cell’s RMP. When the membrane is at rest, potassium ions collect inside the cell due to the net movement within the concentration gradient. The negative resting membrane potential is maintained by the increased concentration of cations outside the cell compared to the inside environment (cytoplasm) of the cell. The overall negative charge of the cell is due to the accumulation of more sodium ions outside