Excitatory neurotransmitters stimulate electrical signals in other neurons and encourage responses from body cells. Inhibitory transmitters discourage signals and cellular responses. Through these chemicals, the nervous system regulates the activity of muscles, glands, and its own nerve pathways. The spinal cord is an elongated cylinder of neuron cell bodies, bundles of axons and other cells, protected by connective tissue and bone.
It connects to the brain at the medulla oblongata and runs down the vertebral column, the hollow tunnel enclosed within the vertebrae of the spine. The spinal cord is part of the central nervous system and serves as a kind of superhighway.
Sensory information and motor commands travel up and down, heading to and from the brain. Some incoming signals demand a simple, immediate response. The spinal cord can shoot out a reflex command without bothering the brain. The nervous system does more than route information and process commands. Why do certain smells immediately raise particular memories? The answer appears to lie in the limbic system. The limbic system forms two paired rings within the brain, consisting of the hippocampus, the amygdala, the cingulate gyrus, and the dentate gyrus, along with other structures and tracts.
As with other brain segments, the limbic system is involved in multiple nervous system functions and levels of activity.
It helps to process both memory and olfaction—our sense of smell—and it manages a range of emotions. The aroma rising from a pot on the stove may send your hand reaching for a spoon.
Source: aboutcancer. The olfactory nerve is responsible for your sense of smell. It sends information to your brain about smells you encounter. When you smell something pleasant, such as bread baking, the aromatic molecules dissolve at the roof of your nasal cavity, which stimulates receptors to generate nerve impulses. These nerve signals are then sent to the areas of your brain that deal with memory and smell recognition.
When light first enters your eye, it comes in contact with receptors in your retina, called rods, which help you see black and white images and in the dark, and cones, which are responsible for color vision. Your rods and cones receive this information and pass it along to your optic nerve. The signal continues traveling along this optic nerve pathway until it reaches the visual cortex in your brain, which processes the information and ensures you can see clearly. The word oculomotor is comprised of two parts: oculo , which relates to the eye, and motor , which can refer to movement or muscles.
The trochlear nerve is also involved in eye movement. It controls the muscle in the eye that enables it to point downward and inward. The trigeminal nerve is the largest cranial nerve in the human body, and it has both motor and sensory functions. The trigeminal nerve assists you with chewing and clenching your teeth, and it provides sensation to muscles in your eardrum.
The abducens nerve also helps with eye movements, in particular, movements that involve your gaze moving outward. Like the trigeminal nerve, the facial nerve also has motor and sensory functions. It controls:. The vestibulocochlear nerve actually consists of two nerves in one, the vestibular nerve and cochlear nerve. As with other cranial nerves, the glossopharyngeal nerve has both sensory and motor functions. Its sensory function receives incoming information from the back of your mouth, including the tongue, tonsils, and throat.
It is also involved with taste sensation for the back of your tongue. Doctors often use vagus nerve stimulation therapy to treat conditions such as epilepsy, depression, and anxiety.
The vagus nerve is also the longest of all the cranial nerves because it begins in the medulla in the brain and extends all the way to the abdominal area.
This cranial nerve, the accessory nerve , provides motor function to some of the muscles in the neck. The last of the cranial nerves is the hypoglossal nerve. It provides necessary motor functions to the tongue muscles.
The spinal cord is part of your central nervous system. It begins at the bottom of the brain stem and continues down to your lower back. There are 31 pairs of spinal nerves, and they control sensory, motor, and other functions of your body. They transmit messages between your spinal cord and the rest of the body, including skin, muscles, and internal organs.
Each spinal nerve is responsible for providing sensation to a different area of your body. Source: neuroxcel. Each group of spinal nerves is involved with movements in certain parts of your body, including your hands, fingers, arms, upper back, hips, and abdominal muscles.
Some spinal nerves are even responsible for ensuring you can walk and run properly. The spinal cord is a long, thin mass of bundled neurons that carries information through the vertebral cavity of the spine beginning at the medulla oblongata of the brain on its superior end and continuing inferiorly to the lumbar region of the spine.
The white matter of the spinal cord functions as the main conduit of nerve signals to the body from the brain. The grey matter of the spinal cord integrates reflexes to stimuli. Nerves are bundles of axons in the peripheral nervous system PNS that act as information highways to carry signals between the brain and spinal cord and the rest of the body.
Each axon is wrapped in a connective tissue sheath called the endoneurium. Individual axons of the nerve are bundled into groups of axons called fascicles, wrapped in a sheath of connective tissue called the perineurium. Finally, many fascicles are wrapped together in another layer of connective tissue called the epineurium to form a whole nerve. The wrapping of nerves with connective tissue helps to protect the axons and to increase the speed of their communication within the body.
The meninges are the protective coverings of the central nervous system CNS. They consist of three layers: the dura mater, arachnoid mater, and pia mater. CSF is formed from blood plasma by special structures called choroid plexuses. The choroid plexuses contain many capillaries lined with epithelial tissue that filters blood plasma and allows the filtered fluid to enter the space around the brain.
Newly created CSF flows through the inside of the brain in hollow spaces called ventricles and through a small cavity in the middle of the spinal cord called the central canal. CSF also flows through the subarachnoid space around the outside of the brain and spinal cord.
CSF is constantly produced at the choroid plexuses and is reabsorbed into the bloodstream at structures called arachnoid villi. What are known as the special senses—vision, taste, smell, hearing, and balance—are all detected by specialized organs such as the eyes , taste buds , and olfactory epithelium.
Sensory receptors for the general senses like touch, temperature, and pain are found throughout most of the body. All of the sensory receptors of the body are connected to afferent neurons that carry their sensory information to the CNS to be processed and integrated. Did you know that DNA testing can help you discover your genetic risk of acquiring certain health conditions that affect the organs of our nervous system? The brain and spinal cord together form the central nervous system, or CNS.
The CNS acts as the control center of the body by providing its processing, memory, and regulation systems. The CNS is also responsible for the higher functions of the nervous system such as language, creativity, expression, emotions, and personality. The brain is the seat of consciousness and determines who we are as individuals. The peripheral nervous system PNS includes all of the parts of the nervous system outside of the brain and spinal cord.
These parts include all of the cranial and spinal nerves, ganglia, and sensory receptors. The SNS is the only consciously controlled part of the PNS and is responsible for stimulating skeletal muscles in the body.
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