Cells use electrical signals to talk to each other. They do this mainly through two types of signals: action potentials and graded potentials. These signals are super important for things like moving our muscles and how our brain sends messages.

1. Action Potentials:

   • Action potentials are quick changes in a cell's electrical charge. For a short time, the cell becomes positively charged, reaching about +30 mV.
   • This happens when the cell reaches a certain level, usually around -55 mV, called the threshold.
   • In neurons (the cells in our brain and nervous system), the number of action potentials can change. On average, they can fire off about 10 to 100 times every second, depending on the type of cell and what’s happening around it.

2. Graded Potentials:

   • Graded potentials are smaller changes in a cell's electrical charge. These changes can either make the cell more positive (depolarize) or more negative (hyperpolarize).
   • They can be different strengths and can build up together. This buildup can decide if an action potential happens or not.
   • The strength of a graded potential gets weaker the farther it moves from where it started, making them very important for local signaling.

3. Neurotransmission:

   • When electrical signals happen, they trigger the release of special chemicals called neurotransmitters.
   • These neurotransmitters travel across small gaps (called synapses) and attach to receptors on other cells, helping to continue sending the message.
   • The human brain has about 100 billion neurons. They form complex networks that communicate using these electrical signals, which affect every single thing our body does.