Neurons, as with other excitable cells in the body, have two major physiological properties: and . A neuron has a positive charge on the outer surface of the cell membrane due in part to the action of an active transport system called the . This system moves out of the cell and into the cell. The inside of the cell membrane is negative, not only due to the active transport system but also because of , which remain negative due to the intracellular pH and keep the inside of the cell membrane negative.

Neurons, as with other excitable cells in the body, have two major physiological properties: irritability and conductivity. A neuron has a positive charge on the outer surface of the cell membrane due in part to the action of an active transport system called the sodium potassium pump. This system moves sodium (Na+) out of the cell and potassium (K+) into the cell. The inside of the cell membrane is negative, not only due to the active transport system but also because of intracellular proteins, which remain negative due to the intracellular pH and keep the inside of the cell membrane negative.

Explanation:

Neurons are cells with the capacity to transmit information between one another and also with other tissues in the body. This information is transmitted thanks to the release of substances called neurotransmitters, and this transmission is possible due to the electrical properties of the neurons.

For the neurons (and other excitable cells, such as cardiac muscle cells) to be capable of conducting the changes in their membranes' voltages, they need to have a resting membrane potential, which consists of a specific voltage that is given because of the electrical nature of both the inside and the outside of the cell. The inside of the cell is negatively charged, while the outside is positively charged - this is what generates the resting membrane potential. When the membrane voltage changes because the inside of the cell is becoming less negative, the neuron is being excited and - if this excitation reaches a threshold - an action potential will be fired. But how does the voltage changes? This happens because the distribution of ions in the intracellular and extracellular fluids is very dissimilar and when the sodium channels in the cell membrane are opened (because of an external stimulus), sodium enters the cell rapidly to balance out the difference in this ion concentration. The sudden influx of this positively-charged ion is what makes the inside of the neuron become less negative. This event is called depolarization of the membrane.

one characteristic that is shared by all is a soft body. many

of these invertebrate animals also have an outer shell to protect their

body. oysters, clams, snails, and mussels are all mollusks. so are octopuses, squids, and slugs. mollusks live on land and in freshwater.