Question

How does the Nervous System work? And what is CNS and PNS?

Answer 1

I'll start with the simplest question first - the difference between the CNS and the PNS. The CNS, or central nervous system, consists of the brain and spinal cord. The CNS is able to process different kinds of sensory information incoming from all over your body, and most nerve impulses attached to muscles and glands originate in the CNS. Since it contains the brain, it's also responsible for memory, emotions, and active thinking.

The PNS, or peripheral nervous system, includes all nervous tissue existing outside the brain and spinal cord. This nervous tissue includes (but is not limited to) your cranial nerves, spinal nerves, ganglion, and various sensory receptors for pain, blood pressure, and much more.

Before I address your first question, it's helpful to know basic nervous system anatomy. I just described what your brain does, but it's important to note your 12 pairs of cranial nerves extend from the brain.
- Your spinal cord is a mass of nerve tissue located in your vertebral canal. The 31 pairs of spinal nerves originate here.
- A neuron is a single nervous cell, consisting of a cell body, dendrites, and an axon. Neurons are electrically excitable, which means that they respond very well to electrical signals from receptors.
- Receptors are specialized nervous cells (or the distal portion of a neuron). These respond to specific stimuli such as touch, pressure, temperature, light, sound, etc. It takes these stimuli and converts them into an electrical signal that the rest of your nervous system is able to respond to in an appropriate manner.

The nervous system as a whole has a long list of tasks it accomplishes. Olfactory senses (otherwise known as your sense of smell), speech, memory, motor signals, and organ operation are just a few of these tasks. However, the different activities your nervous system performs can be broken down into three groups: sensory, integrative, and motor.

SENSORY: Sensory receptors are able to detect internal stimuli (such as an increase in blood pressure) or external stimuli (such as receiving a cut). Neurons called sensory, or afferent, neurons carry whatever information your body receives into the brain and spinal cord through your cranial and spinal nerves.

INTEGRATIVE: The nervous system itself is able to process, or integrate, sensory information by both analyzing and storing it. It also chooses the appropriate response to stimuli. (For instance, if your blood pressure increases, your brain will send a signal to release a vasodilator hormone). There's a specific type of neuron that aids your nervous system in integration - these neurons are called interneurons, which means they are able to communicate very effectively with nearby neurons to send an accurate message through your nervous system. The integrative portion is also responsible for perception, or the constant awareness of sensory stimuli/information. Perception occurs in the brain.

MOTOR: Once your sensory information has been integrated, or processed, the nervous system is able to accurately respond to the stimulus through muscle contraction, gland secretion, etc. The neurons that perform this job are called motor, or efferent, neurons. Motor neurons then deliver the information from the brain to the spinal cord, or OUT of the brain and outside of the spinal cord where they act as messengers to effector sources (i.e. your muscles and glands). They carry the messages outside of the spinal cord through cranial and spinal nerve branches. Once the motor neurons have reached the effector sources, they cause the muscles to contract or the glands to secrete depending on the appropriate response to the stimulus in question.

The nervous system itself is FAR more involved than what I have explained here, but this is a good, basic overview. Hope this helped!

Answer 2

thank you so much! that is really helpful!

Answer 3

The nervous system is a network of cells called neurons which transmit information in the form of electrical signals. Your brain has around 100 billion neurons, and each communicates with thousands of others – as many connections as in the world's telephone system, the biggest machine on the planet. Neurons communicate with each other at special junctions where chemicals help to bridge the gap between one neuron and the next.