3. Increasing frequency of stimulation to the trigger zone: DOES NOT increase the production of action potentials.…
F. David has lost blood volume, resulting in a drop in blood pressure. His automatic nervous system countered the dropping blood pressure by stimulated vasoconstriction. How does…
Smooth muscle contractions are affected by calcium and potassium ions. Calcium ion influx into the smooth muscle cell initiates a contraction. Potassium ion concentration in the extracellular medium affects the resting membrane potential of the cell, bringing it closer to or farther away from its threshold voltage. Neurotransmitters affect different types of smooth muscle differently, depending on the association of the smooth muscle with excitable cells. In general, acetylcholine increases the muscle cell’s permeability to calcium, while epinephrine decreases the cell’s permeability to calcium.…
-Increasing extracellular K+ reduces the net diffusion through the leak channels because if there are an increased amount of K+ ions outside of the cell, the amount coming from the leak channels needs to decrease so it can be balanced.…
The stimulus is measured in volts, and its role is to cause depolarization of the muscle…
a. The opening of voltage-gated K+ channels cause the membrane to repolarize. b. Does K+ move into or out of the cell? Out of c. If the membrane potential becomes more negative than –70 mV, this is called hyperpolarization. d. This potential is caused by what characteristic of K+ permeability?…
A greater stimulus is required because voltage-gated K+ channels that oppose depolarization are open during this…
Experiment Results Predict Question: Predict Question: Predict what will happen to the resting membrane potential if the extracellular K+ concentration is increased. Your answer : b. The resting membrane potential will become less negative. Stop & Think Questions: What is the polarity of the resting membrane potential (voltage)? You correctly answered: b. negative What does it mean that the voltage just inside the membrane is negative? You correctly answered: b. There are more negative charges than positive charges just inside the membrane. The membrane of most cells, including neurons, contains passive, open, K+ leak channels. Given the normal K+ concentrations and the resultant concentration gradient, which direction would K+ be expected to move (diffuse) through these leak channels? You correctly answered: b. out of the cell What effect does increasing extracellular K+ have on the net diffusion of K+ out of the cell? You correctly answered: b. It decreases the net diffusion of K+ . Which way would Na+ move across the membrane if there were open Na+ channels? You correctly answered: a. Na+ would diffuse into the cell. The membrane has open K+ channels, and changing extracellular K+ concentration results in a change in membrane potential. Changing the extracellular Na+ concentration does not significantly change the membrane potential. What do your results suggest about the number or state (open or closed) of Na+ channels in the resting membrane of a neuron? You correctly answered: b. Na+ channels are mostly closed. Experiment Data: Extracellular Fluid (ECF) Control Control Control Control High K+ High K+ High K+ High K+ Low Na+ Low Na+ Low Na+ Low Na+ Microelectrode Position Cell body extracellular Cell body intracellular Axon extracellular Axon intracellular Axon intracellular…
a. What acts as a chemical force that pushes K+ out of the cell? ___________…
17. The sodium-potassium pump in the neuron cell membrane uses the energy of ATP to pump Na+ out of the cell and, at the same time to pump K+ in.…
Sensory neurons have a resting membrane potential based on the efflux of potassium ions (as demonstrated in Activity 1.) What passive channels are likely found in the membrane of the olfactory receptor, in the membrane of the Pacinian corpuscle, and in the membrane of the free nerve ending?…
Which way would Na+ move across the membrane if there were open Na+ channels? Na+ would diffuse into the cell. 75. Why did the free nerve ending respond to several different modalities?…
The rate of active transport of sodium potassium pumps will decrease dramatically due to the lessened concentration of pumps.…
Primary disturbances in magnesium balance, especially magnesium depletion, create auxiliary potassium depletion. Magnesium hinders potassium, which then magnesium pushes the potassium out the cells through renal excretion causing hypokalemia. In order for the cell to keep up the typically high intracellular grouping of potassium the expansion in the membrane permeability to potassium as well as the restraint of Na+-K-ATPase needs to take place.…
“(3) Specific enzymes that drive active pumps that promote concentration of certain ions, particularly potassium (K+), within the cell while keeping concentrations of other ions, for example sodium (Na+), below concentrations found in the extracellular environment…” (McCance &Huether, pg. 12).…