Excitatory Signals and Inhibitory Signals

What ion concentration is high outside the cell?

Calcium (Ca²⁺) and Sodium (Na⁺) concentrations are high outside the cell.

What ion concentration is high inside the cell?

Potassium (K⁺) concentration is high inside the cell.

What is the main anion outside the cell?

Chloride ions (Cl⁻) are the main anion outside the cell.

What serves as the main anion inside the cell?

Negatively charged proteins serve as the main anion inside the cell.

What is the typical resting membrane potential?

The resting membrane potential is typically around -60 to -70 millivolts.

What does a resting membrane potential indicate?

It indicates that the inside of the cell is slightly negative compared to the outside.

What triggers the generation of action potentials?

The differences in ion concentration help initiate nerve impulses and muscle contractions.

What happens to the membrane potential during an action potential?

There is a rapid change in membrane potential when the cell is stimulated.

What ion entry is crucial for depolarization?

The entry of Sodium (Na⁺) into the cell is crucial for depolarization.

What is facilitated diffusion?

Facilitated diffusion is the process by which ions move through the cell membrane via special protein channels.

What occurs during depolarization?

During depolarization, positive ions (like Na⁺ and Ca²⁺) enter the cell, making the inside less negative.

What occurs during hyperpolarization?

Hyperpolarization happens when negative ions (like Cl⁻) enter or when positive ions (like K⁺) leave the cell, making the inside more negative.

How do neurons communicate at synapses?

Neurons communicate at synapses by action potentials triggering the release of neurotransmitters into the synaptic cleft.

What is the role of excitatory neurotransmitters?

Excitatory neurotransmitters, like Acetylcholine, help depolarize the next neuron.

What is the role of inhibitory neurotransmitters?

Inhibitory neurotransmitters, such as GABA, cause hyperpolarization in the next neuron.

What type of channels do excitatory signals utilize?

Sodium and calcium channels support excitatory signals.

What type of channels do inhibitory signals utilize?

Chloride channels (activated by GABA) lead to inhibitory signals.

What is the significance of the resting membrane potential?

It is essential for setting up the conditions required for nerve impulses and muscle contractions.

How does the entry of Calcium (Ca²⁺) affect action potentials?

Calcium (Ca²⁺) can enhance depolarization needed to generate an action potential.

Why is hyperpolarization significant?

Hyperpolarization makes it harder for the cell to trigger an action potential, affecting neuron communication.

What factors influence whether a next neuron will fire an action potential?

The type of neurotransmitter released and the resulting ion flow influence whether the next neuron fires.

Who proposed the concept of action potentials?

The concept of action potentials was developed through work in neurobiology by various scientists.

What is the role of synaptic cleft?

The synaptic cleft is the space where neurotransmitters are released to transmit signals between neurons.

What process is crucial for reversing membrane potential during action potentials?

The rapid influx of Sodium (Na⁺) ions is crucial for depolarization during action potentials.

How does a neuron return to resting potential after an action potential?

The neuron returns to resting potential by the outflow of Potassium (K⁺) ions after depolarization.

What are neurotransmitters?

Neurotransmitters are chemical messengers that transmit signals across synapses between neurons.

How does the movement of ions occur during action potentials?

Ions move across the cell membrane through gated channels, initiated by changes in membrane potential.

What happens when a neuron is stimulated?

When a neuron is stimulated, it can lead to changes in membrane potential, generating an action potential.

What is the effect of Sodium (Na⁺) influx on membrane potential?

The influx of Sodium (Na⁺) decreases negativity inside the cell, pushing the membrane potential closer to zero.

What type of signals do excitatory neurotransmitters create?

Excitatory neurotransmitters create signals that increase the likelihood of the next neuron firing an action potential.

What is the outcome of inhibitory neurotransmitter activation?

Inhibitory neurotransmitter activation leads to the hyperpolarization of the receiving neuron.

Which ion's movement is primarily responsible for repolarization?

The movement of Potassium (K⁺) ions primarily repolarizes the cell after depolarization.

What does the term 'ion distribution' refer to?

Ion distribution refers to the varying concentrations of ions inside and outside the cell affecting its electrical properties.

What role do ion channels play in membrane potential?

Ion channels regulate ion movement, significantly influencing the membrane potential and action potential generation.

How does the selective permeability of the membrane affect ion distribution?

Selective permeability of the membrane restricts certain ions from passing, maintaining the distinct concentrations inside and outside the cell.

What effect does increased K⁺ outflow have?

Increased K⁺ outflow results in hyperpolarization, making the inside of the cell more negative.

What is the result of high Na⁺ concentration outside the cell?

A high Na⁺ concentration outside the cell creates a driving force for Na⁺ influx during stimulation.

How does GABA affect neuronal signaling?

GABA activates chloride channels, leading to hyperpolarization and inhibition of neuronal firing.

What is the typical duration of an action potential?

An action potential typically lasts for a few milliseconds.

What happens to membrane potential at the peak of an action potential?

At the peak of an action potential, the membrane potential briefly becomes positive before repolarization.

What factors can alter resting membrane potential?

Factors such as ion concentration changes or permeability alterations can lead to changes in resting membrane potential.

In what circumstance does hyperpolarization occur in terms of preceding potential?

Hyperpolarization occurs following a repolarization phase after an action potential.

What physiological processes rely on resting membrane potential?

Nerve impulses, muscle contractions, and signal transmission in neurons rely on resting membrane potential.

What is the relationship between neurotransmitters and ion channels?

Neurotransmitters bind to receptors that control the opening of ion channels, affecting neuronal excitability.

How do depolarization and action potentials relate to nerve impulse propagation?

Depolarization leading to action potentials facilitates the rapid propagation of nerve impulses along axons.

Why is it important to maintain the resting membrane potential?

Maintaining the resting membrane potential is crucial for ensuring that neurons can respond to stimuli appropriately.

What does an action potential represent in neural communication?

An action potential represents an all-or-nothing response that transmits information along the neuron.

What can happen if action potentials fail to occur appropriately?

If action potentials fail to occur, it can lead to impaired communication between neurons and muscle cells.

What technique is often used to measure membrane potential?

Techniques such as patch-clamp or intracellular recording are used to measure membrane potential.

In which part of the neuron do action potentials typically initiate?

Action potentials typically initiate at the axon hillock.

What eventual impact can excitatory and inhibitory neurotransmitters have?

They can modulate the likelihood of a neuron firing action potentials.

What does the term 'electrical excitability' refer to in neurons?

Electrical excitability refers to a neuron's ability to respond to stimuli and convert it into electrical impulses.

What effect does a high concentration of Ca²⁺ have on neurons?

A high concentration of Calcium (Ca²⁺) can enhance neurotransmitter release and signal transduction.

What is the role of the action potential in muscle contraction?

Action potentials stimulate muscle fibers to contract by triggering calcium release from the sarcoplasmic reticulum.

What happens when the synaptic cleft is flooded with neurotransmitters?

The likelihood of the next neuron firing an action potential increases with more neurotransmitter in the synaptic cleft.

How do changes in ion concentration influence cellular activities?

Changes in ion concentration can influence cell activation, signaling, and responses to external stimuli.

What is the significance of the sodium-potassium pump?

The sodium-potassium pump helps maintain resting membrane potential by actively transporting Na⁺ out of the cell and K⁺ into the cell.

What would happen if the sodium-potassium pump ceased functioning?

If the sodium-potassium pump ceases functioning, it could disrupt resting membrane potential and lead to cell dysfunction.