Gyri is a ridge or fold between two sets on the cerebral surface in the brain.Ģ. Sulci is a groove of furrow, especially on the surface of the brain. It is hard to imagine that this cycle is completed millions of times in a minute.ġ. The nervous system is an electrical conduction system sometimes we use such phrases as "sparks are flying." This could really be true. A simpler way of saying all this is that upon stimulation, a nerve cell goes from resting potential to depolarization and then to repolarization and back to resting potential.Īlthough this action occurs in just one part of the cell membrane, it spreads to _ membrane regions, continuing away from the original site of the stimulation, sending messages over the nerves. To restore order to this mess, the _-_ pump gets into act and _ the original concentrations of sodium and potassium ions. There are too many ions here, so the special potassium gates open and large amounts of potassium leave the cytoplasm of the cell, which results in the _ of the membrane. The membrane potential is reserved, and the gates close to additional sodium ions.
The sodium ions in the extracellular fluid line up and march through the gated channel into the cytoplasm. This is the special occasion that causes those gated channels to open, initiating the _-_. if it is strong enough, it will _ a portion of the cell membrane. This is where the fun begins! A sensory receptor picks up a message, a stimulus such as a sound, and the stimulus energy is converted to a(n) _ signal. This state of affairs is called resting membrane potential, and the membrane is said to be _. Now we have a situation in which the environment inside the cell is more negative than the environment outside the cell. The _ is true in the extracellular fluid that has more Na+ ions that K+ ions.ĭuring this time, some K+ cells sneak out through the membrane, which then makes the inside of the nerve cell more _. Inside the nerve cell are _ amounts of K+ and _ amounts of Na+. When the nerve cell is just hanging out, resting, the ion of _(potassium) and _ (sodium) are where they are supposed to be.
We have leaky ones that allow ions to flow in and out we have gated channels that are open only on special occasions, and we have the sodium-potassium pump. You may think you have a lot to worry about, but think about the special channel. It maintains the flow of ions from areas of _ concentration to _ concentration and serves to restore the cytoplasm and the _ fluid to their original states. Another special channel is called the sodium-potassium pump. Some of these openings are closed and _ only on special occasions.
Some of these channels are open and allow _ to move (leak) back and forth inside and _ during cell activity. Think of the nerve cell membrane as an envelope around the _ with lots of openings or _. To understand how impulses (_) are carried along nerves, we need to know about membrane _. We look here at just one of these incredible functions. we jog, talk, reason, and carry out activities of daily living. The heart pumps, blood circulates, and air moves in and out. In our day-to-day lives, we do not stop to think about all the processes going on in our magnificent machine, the body. Using the following words and symbols, complete the story on nerve functions.Ī STORY OF HOW A NERVE CELL FUNCTIONS (NERVES-R-US) Neurons that carry messages from the brain and spinal cord are called motor or (afferent, efferent) neurons.ĭ. The myelin sheath (speeds up, slows down) an impulse as it travels along the axon.ġ0. The two main communication systems of the body are the nervous system and the (endocrine, circulatory) system.ĩ. The extensions of the neuron that take messages to the cell body are called (axons, dendrites).Ĩ. Oligodendrocytes are (central nervous system, peripheral nervous system) structures that wrap around neuronal axons to form the myelin sheath.ħ. Neurons that carry messages to the brain and spinal cord are (afferent, efferent) neurons.Ħ. (Conductivity, irritability) is the ability of a neuron to react to stimuli.ĥ. The type of nervous tissue that insulates and supports the nerve is called "nerve glue" or (neuroglia, neuron).Ĥ. The extension of the neuron that carries the messages away from the away from the nerve cell body is the (axon, dendrite).ģ. (Associative neurons, efferent neurons) carry impulses from the sensory neurons to the motor neurons.Ģ. Circle the correct word or words in each following statements.ġ.