9. Describe the structure of the human nervous system. Living is taking information from the world to make decisions and send back information. This is needed in order to send information to our body to help make us function properly. The nervous system is composed of two different parts. The first is the central nervous system (CNS) which is made up of the brain and spinal cord. This is what makes up the decisions for our bodies. The second part is the peripheral nervous system (PNS). This system is responsible for gathering information and it also transmits CNS decisions to other parts of the body. Nerves, are bundles of axons which links the CNS with sensory receptors, muscles, and glands. Information travels through the nervous system on three different types of neurons. The first type of neuron is sensory neurons they carry messages from the sensory receptors inward to the brain and spinal cord to be processed. The second type is motor neurons. These neurons bring messages from the central nervous system out to our body’s muscles. Finally our body had interneurons. The interneurons are located between the sensory input and motor output neurons, this is where the brain processes information. There are only a few million of both sensory and motor neurons, while interneurons there are billions and billions of neurons. Because of so many interneurons this is where our complexity resides. The peripheral nervous system has two parts, somatic and autonomic. The somatic nervous system allows for voluntary control of skeletal muscles. Autonomic system is also like an automatic pilot where it can operate usually on its own although it can at some points in time be consciously over ridden. This system has control over gland and muscles of internal organs, which influence simple functions such as glandular activity, digestion and heartbeat. The autonomic system also controls the sympathetic and parasympathetic nervous systems. The sympathetic system makes you ready for something to happen. This will cause your heartbeat to accelerate, raise blood sugar and blood pressure, and also make your digestion become slower. The parasympathetic nervous system gives off the exact opposite of the sympathetic system. It helps to calm you instead of excite you like the sympathetic system does. These two systems work with each other to keep your internal state at regular levels.
The central nervous system in way are even more complex than the idea of neurons working with each other to communicate. The brain is what allows us to be known as humanity because of it allowing us to think, have feeling and a sense of the way we behave. Work groups of neurons in the brain cluster together to form neural networks. They groups in networks to make the connection between each other shorter and faster. The spinal cord is also a part of the CNS. This two-way information pathway connects the peripheral nervous system and the brain. The neural fibers that climb up send up sensory information while the descending fibers release back motor control information. These neural pathways have control over our reflexes. Simple spinal reflexes are made up of one sensory neuron and one motor neuron, which they communicate through a single interneuron. Information travels back and forth because of the neurons sent to the spinal cord. To be able to feel pain or pleasure information from the sensory neurons must reach the brian. This is how the human nervous system is set up and works to allow us to lead everyday actions.
Artifact#1 This image shows the main parts that compose the nervous system.
Artifact #2 This image gives a description of each part of the nervous system.