The human nervous system consists of billions of nerve cells (or neurons)plus supporting (neuroglial) cells. Neurons are able to respond to stimuli (such as touch, sound, light, and so on), conduct impulses, and communicate with each other (and with other types of cells like muscle cells).

Neurons can respond to stimuli and conduct impulses because a membrane potential is established across the cell membrane. In other words, there is an unequal distribution of ions (charged atoms) on the two sides of a nerve cell membrane.

The membranes of all nerve cells have a potential difference across them, with the cell interior negative with respect to the exterior (a). In neurons, stimuli can alter this potential difference by opening sodium channels in the membrane. For example, neurotransmitters interact specifically with sodium channels (or gates). So sodium ions flow into the cell, reducing the voltage across the membrane.

Once the potential difference reaches a threshold voltage, the reduced voltage causes hundreds of sodium gates in that region of the membrane to open briefly. Sodium ions flood into the cell, completely depolarizing the membrane (b). This opens more voltage-gated ion channels in the adjacent membrane, and so a wave of depolarization courses along the cell - the action potential.

As the action potential nears its peak, the sodium gates close, and potassium gates open, allowing ions to flow out of the cell to restore the normal potential of the membrane.

Membranes are polarized or, in other words, exhibit a RESTING MEMBRANE POTENTIAL. This means that there is an unequal distribution of ions (atoms with a positive or negative charge) on the two sides of the nerve cell membrane. This POTENTIAL generally measures about 70 millivolts (with the INSIDE of the membrane negative with respect to the outside). So, the RESTING MEMBRANE POTENTIAL is expressed as -70 mV, and the minus means that the inside is negative relative to (or compared to) the outside. It is called a RESTING potential because it occurs when a membrane is not being stimulated or conducting impulses (in other words, it's resting).

Source : Internet.

The space between neurons is called the synaptic cleft. It is where neurotransmitters are released by the presynaptic neuron, travel across the cleft, and bind to receptors on the postsynaptic neuron to transmit chemical messages.

Yes, sound waves travel through the external auditory canal and cause the eardrum to vibrate. These vibrations are then transmitted through the middle ear bones to the inner ear, where they stimulate hair cells in the cochlea. The hair cells convert the vibrations into electrical signals that are sent to the brain via the auditory nerve.

The cell body of a neuron contains the nucleus and organelles involved in protein synthesis and metabolism. It integrates incoming signals from dendrites and generates electrical signals known as action potentials that travel along the axon to communicate with other neurons or cells.

Neurons communicate with each other through electrical and chemical signals. When an action potential is generated in one neuron, it travels down the axon and releases neurotransmitters at the synapse, which then bind to receptors on the neighboring neuron, causing either excitation or inhibition of the receiving neuron.

1. Sensory neurons: Transmit sensory information from the body to the brain.
2. Motor neurons: Control muscles and glands, enabling movement and bodily functions.
3. Interneurons: Process information within the central nervous system, facilitating communication between sensory and motor neurons.

A neuron transmits signals from its cell body, where the nucleus is located, to other neurons or target cells through its axon. The axon carries the electrical impulses away from the cell body towards the synapse, where communication with other cells occurs.

Nociceptors are the neurons in the skin that are responsible for detecting pain. They are specialized sensory receptors that respond to potentially damaging stimuli by sending signals to the brain, alerting the body to the presence of tissue-damaging stimuli like heat, pressure, or chemicals.

Yes, the brain continues to create new neurons through a process called neurogenesis, particularly in regions like the hippocampus which is involved in memory and learning. This process can be influenced by factors such as physical exercise, diet, and mental stimulation.

Afferent nerves carry sensory information from the body to the brain, allowing us to sense touch, temperature, pain, and other stimuli. Efferent nerves, on the other hand, transmit signals from the brain to the muscles and glands, enabling movement and physical responses.

The term for inflammation of a nerve is neuritis.

A nerve is one or more bundles of fibers forming part of a system that conveys impulses of sensation, motion, etc., between the brain or spinal cord and other parts of the body.

Neurology is the science of the nerves and the nervous system, especially of the diseases affecting them.

cephalization

No, you're thinking of Neuroglia

Chemical synapses are specialized junctions through which neurons signal to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow neurons to form interconnected circuits within the central nervous system. They are thus crucial to the biological computations that underlie perception and thought. They provide the means through which the nervous system connects to and controls the other systems of the body, for example the specialized synapse between a motor neuron and a muscle cell is called a neuromuscular junction. The adult human brain has been estimated to contain from 1014 to 5 × 1014 (100-500 trillion) synapses.[citation needed] The word "synapse" comes from "synaptein", which Sir Charles Scott Sherrington and colleagues coined from the Greek "syn-" ("together") and "haptein" ("to clasp"). Chemical synapses are not the only type of biological synapse: electrical and immunological synapses exist as well. Without a qualifier, however, "synapse" commonly refers to a chemical synapse. Wikipedia

Motor neurons are neurons which carry impulses from the Central Nervous System to muscles or glands. When an action potential is conducted by a motor neuron a muscle contracts or a product is released from a gland.

The second cranial nerve is the optic nerve, which tells the brain what the eye is seeing

The high-speed signals that pass along the axon are called action potentials. They spread in a wave of depolarization.

They process and relay sensory input from your nose.

Neurotransmitters are chemicals that send messages from one cell to another.

Cranial nerves

You have a really good question. Studying the nervous system can be overwhelming and quit confusing. Preganglionic Neurons come from the CNS to the Ganglion ( mass of neuron cell bodies and dendrites) and Postganglionic neurons leave the ganglion and head toward the effector organ ( smooth muscle, glands, etc..).

In simplest terms, the five stages of action potential are...

A. Action Potential

B. Depolarization

C. Recovery Phase

D. Refractory Period

E. Hyper-polarization

We can be thankful that they go in only one direction; otherwise brain activity would be nothing but chaos. Neurotransmission begins at the synapse. At the synapse, only one of the two corresponding neurons has receptor locations that determine whether or not the receiving neuron will fire. The other neuron at the synapse is responsible for producing the neurotransmitters that attach to the receptors. There is sometimes a re-uptake of neurotransmitters when there are no more receptors for them to attach to. Some psychotropic drugs work to inhibit this re-uptake.

There are the Mixed Nerves in the spinal column that carry both sensory and motor nerves, but these neurons have 2 different jobs that they do,& I know of no neurons doing both as the impulses travel to 2 different locations which couldn't be done at the same time.