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2021-05-14

In which of the following lobes would you find the primary visual cortex?

In which of the following lobes would you find the primary visual cortex?

The primary visual cortex (V1) is located in and around the calcarine fissure in the occipital lobe. Each hemisphere’s V1 receives information directly from its ipsilateral lateral geniculate nucleus that receives signals from the contralateral visual hemifield.

Which of the following is the part of the neuron that carries messages to other parts of the body?

Dendrites

Which part of a neuron is attached to the soma and carries messages out to other cells?

Axon

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When a neuron’s resting potential is occurring the neuron is charged on the inside?

A neuron at rest is negatively charged because the inside of a cell is approximately 70 millivolts more negative than the outside (−70 mV); this number varies by neuron type and by species.

What is the first step in an action potential?

depolarization

What is the sequence of an action potential?

The action potential can be divided into five phases: the resting potential, threshold, the rising phase, the falling phase, and the recovery phase. We begin with the resting potential, which is the membrane potential of a neuron at rest.

What starts an action potential?

Action potentials are caused when different ions cross the neuron membrane. A stimulus first causes sodium channels to open. Because there are many more sodium ions on the outside, and the inside of the neuron is negative relative to the outside, sodium ions rush into the neuron.

What is the difference between graded potential and action potential?

Graded potentials are brought about by external stimuli (in sensory neurons) or by neurotransmitters released in synapses, where they cause graded potentials in the post-synaptic cell. Action potentials are triggered by membrane depolarization to threshold.

What is action potential example?

The most famous example of action potentials are found as nerve impulses in nerve fibers to muscles. Neurons, or nerve cells, are stimulated when the polarity across their plasma membrane changes. These cells are self-excitable, able to generate an action potential without external stimulation by nerve cells.

Which of the following is a sensory stimulus?

The stimulus can come in many forms such as light, heat, sound, touch, as well as from internal factors. Sensory stimuli can be perceived by the auditory, tactile, visual, gustatory, proprioceptive, and vestibular systems.

Why are fewer action potentials recorded at R2 when lidocaine is applied between R1 and R2 How well did the results compare with your prediction?

If a nerve, rather than an axon, had been used in the lidocaine experiment, the responses recorded at R1 and R2 would be the sum of all the action potentials (called a compound action potential). Fewer action potentials were recorded at R2 because the voltage gated sodium channel is blocked.

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Why must a sushi chef go through years of training to prepare puffer fish?

Why must a sushi chef go through years of training to prepare puffer fish for human consumption? Proper preparation to remove the toxin. If depolarizing membrane potentials open voltage-gated sodium channels, what closes them?

What is TTX?

Tetrodotoxin (TTX) is a potent toxin that specifically binds to voltage gated sodium channels. TTX binding physically blocks the flow of sodium ions through the channel, thereby preventing action potential (AP) generation and propagation. TTX has different binding affinities for different sodium channel isoforms.

What happens when voltage gated K+ channels open?

A set of voltage-gated potassium channels open, allowing potassium to rush out of the cell down its electrochemical gradient. These events rapidly decrease the membrane potential, bringing it back towards its normal resting state.

What happens if you block potassium channels?

These drugs bind to and block the potassium channels that are responsible for phase 3 repolarization. Therefore, blocking these channels slows (delays) repolarization, which leads to an increase in action potential duration and an increase in the effective refractory period (ERP).

What happens when Na+ channels open?

Role in action potential. Voltage-gated sodium channels play an important role in action potentials. If enough channels open when there is a change in the cell’s membrane potential, a small but significant number of Na+ ions will move into the cell down their electrochemical gradient, further depolarizing the cell.

Are potassium leak channels always open?

Sodium leak channels further enhancing the influx of sodium ions, while potassium leak channels allow potassium ions to diffuse out of the cell. It doesn’t matter if the neuron is at the resting membrane potential, depolarizing, repolarizing, or hyperpolarizing; the leak channels are always open.

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How do potassium leak channels work?

The leak channels allow Na+ and K+ to move across the cell membrane down their gradients (from a high concentration toward a lower concentration). With the combined ion pumping and leakage of ions, the cell can maintain a stable resting membrane potential.

Why does potassium leak out of the cell?

At the peak action potential, K+ channels open and the cell becomes (c) hyperpolarized. When the membrane is at rest, K+ ions accumulate inside the cell due to a net movement with the concentration gradient. Therefore, potassium diffuses out of the cell at a much faster rate than sodium leaks in.

What are K+ leak channels?

Tandem pore domain potassium channel – are constitutively open or possess high basal activation, such as the “resting potassium channels” or “leak channels” that set the negative membrane potential of neurons.

What is the purpose of the Na K pump?

It acts to transport sodium and potassium ions across the cell membrane in a ratio of 3 sodium ions out for every 2 potassium ions brought in. In the process, the pump helps to stabilize membrane potential, and thus is essential in creating the conditions necessary for the firing of action potentials.

What do K+ channels do?

K+ channels are membrane proteins that allow rapid and selective flow of K+ ions across the cell membrane, and thus generate electrical signals in cells. Upon changes in transmembrane potential, these channels open and allow passive flow of K+ ions from the cell to restore the membrane potential.

What ion is Na+?

sodium ion