Fysiologie les 3

What are the two types of membrane transport proteins?

Channels and carriers.

What are channels in membranes?

Proteins with a pore that can be either open or gated, allowing specific ions to pass.

How do carriers facilitate diffusion?

By changing shape to allow ions to pass through the cell membrane.

What triggers the conversion from graded potential to action potential?

Sufficient depolarization reaching the threshold potential of -55 mV.

What is the resting membrane potential of a neuron?

Approximately -90 mV.

What happens during depolarization?

The membrane potential becomes less negative, making the neuron more sensitive to activation.

What occurs during hyperpolarization?

The membrane potential becomes more negative, making the neuron less likely to be activated.

What is the role of the axon hillock?

It decides if the graded potential will convert into an action potential.

Define action potential.

A short-term reversal of membrane potential that propagates along the axon.

What is the significance of lidocaine in medical applications?

It blocks sodium channels to prevent action potentials, temporarily numbing sensation.

What is the graded potential?

A local change in membrane potential that can be depolarizing or hyperpolarizing.

How does the size of a stimulus affect graded potential?

The larger the stimulus, the greater the electrical change and the number of channels that open.

What is meant by 'temporal and spatial summation' in neural activity?

The cumulative effect of multiple signals over time or across different locations on a neuron.

What are excitatory and inhibitory changes in the context of neuronal signaling?

Excitatory changes make a neuron more active, while inhibitory changes make it less likely to fire.

What is the function of a synapse?

To connect an axon to another neuron or target cell to transmit signals.

What characterizes the 'all or nothing' principle of action potentials?

There are no varying sizes of action potentials; they are either fully generated or not.

What ion concentrations are involved in the action potential process?

Higher sodium (Na+) concentration outside the cell and higher potassium (K+) concentration inside.

How do graded potentials differ from action potentials?

Graded potentials are local and vary in magnitude, while action potentials are uniform and propagate along the axon.

What is the role of kationkanalen and anionkanalen in membrane dynamics?

Kation channels allow positive ions to flow in, while anion channels let negative ions flow out, affecting membrane potential.

What is the function of dendrites in a neuron?

They receive stimuli from the environment and convert them into graded potentials.