List two anatomical areas where graded potentials occur in a post synaptic neuron.
The correct answer and explanation is:
Correct Answer:
- Dendrites
- Cell body (soma)
Explanation:
Graded potentials are changes in membrane potential that vary in magnitude depending on the strength of the stimulus. They occur in specific areas of a neuron that are involved in receiving and integrating incoming signals. In a postsynaptic neuron, two primary anatomical regions where graded potentials occur are the dendrites and the cell body (soma).
Dendrites are the branched extensions of a neuron that receive signals from other neurons. When neurotransmitters are released into the synaptic cleft, they bind to receptors located on the dendritic membrane. This interaction leads to the opening of ligand-gated ion channels, causing localized changes in membrane potential called graded potentials. These potentials can be either depolarizing (making the membrane less negative) or hyperpolarizing (making it more negative), depending on the type of ion channel opened.
The cell body (soma) also contains receptors and ion channels that contribute to the generation of graded potentials. These signals received in the dendrites and soma are added together in a process known as summation. The combined effect of multiple graded potentials determines whether the neuron will reach the threshold to fire an action potential at the axon hillock.
Graded potentials differ from action potentials in several key ways. They are localized and do not travel long distances. Their strength decreases with distance from the point of origin due to the leaky nature of the neuronal membrane. They are also variable in amplitude, meaning that stronger stimuli result in larger graded potentials.
In summary, graded potentials in a postsynaptic neuron occur primarily in the dendrites and the cell body. These electrical changes are essential for integrating synaptic inputs and determining whether a neuron will initiate an action potential, thereby continuing signal transmission within the nervous system.