The sciatic nerve is the largest nerve in your body. It begins in your lower back and travels all the way down to the heel of your foot. You may have heard of a condition called sciatica in which painful sensations radiate from your lower back and down your leg. This happens when the sciatic nerve is compressed or irritated. They can travel at a speed of up to meters per second. Your brain is divided up into different parts , each with different functions. Integration of these functions helps us to perceive and react to internal and external stimuli.
Your brain weighs about three pounds. This is small in comparison to your overall body weight, but according to the Smithsonian Institute, your brain gets 20 percent of your oxygen supply and blood flow. A special barrier called the blood-brain barrier prevents harmful substances in the blood from entering your brain. Since the first neurotransmitter was discovered in , more than substances have been implicated in signal transmission between nerves.
A couple that you may be familiar with are dopamine and serotonin. Researchers are hard at work to develop ways to repair damage to the nervous system. This is accomplished using a device that sends electrical signals to your vagus nerve. This, in turn, sends signals to specific parts of the brain. Vagus nerve stimulation can help to lower the number of seizures in people with some types of epilepsy.
Its effectiveness is being assessed for conditions like headaches and rheumatoid arthritis as well. A study in mice used imaging to visualize nerve cells surrounding fat tissue. Researchers found that stimulating these nerves also stimulated the breakdown of fat tissue. Additional research is needed, but this could have implications for conditions like obesity.
The system is able to collect information on applied pressure and convert it into electric impulses that can be integrated on a transistor.
This transistor then releases electrical impulses in patterns consistent with those produced by neurons. The majority of the nervous system is tissue made up of two classes of cells: neurons and neuroglia. Neurons, also known as nerve cells, communicate within the body by transmitting electrochemical signals. Neurons look quite different from other cells in the body due to the many long cellular processes that extend from their central cell body.
The cell body is the roughly round part of a neuron that contains the nucleus, mitochondria, and most of the cellular organelles. Small tree-like structures called dendrites extend from the cell body to pick up stimuli from the environment, other neurons, or sensory receptor cells.
Long transmitting processes called axons extend from the cell body to send signals onward to other neurons or effector cells in the body. Each neuron in the body is surrounded by anywhere from 6 to 60 neuroglia that protect, feed, and insulate the neuron. Because neurons are extremely specialized cells that are essential to body function and almost never reproduce, neuroglia are vital to maintaining a functional nervous system.
The brain , a soft, wrinkled organ that weighs about 3 pounds, is located inside the cranial cavity, where the bones of the skull surround and protect it. The approximately billion neurons of the brain form the main control center of the body. The brain and spinal cord together form the central nervous system CNS , where information is processed and responses originate. The brain, the seat of higher mental functions such as consciousness, memory, planning, and voluntary actions, also controls lower body functions such as the maintenance of respiration, heart rate, blood pressure, and digestion.
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. Optic Nerve II The optic nerve is essential for proper vision, and both of your eyes have one. Oculomotor Nerve III The word oculomotor is comprised of two parts: oculo , which relates to the eye, and motor , which can refer to movement or muscles. Trochlear Nerve IV The trochlear nerve is also involved in eye movement.
Trigeminal Nerve V The trigeminal nerve is the largest cranial nerve in the human body, and it has both motor and sensory functions. Motor Functions The trigeminal nerve assists you with chewing and clenching your teeth, and it provides sensation to muscles in your eardrum. Ophthalmic : Provides sensation for parts of the eye, nose, eyelid, and forehead Maxillary : Gives sensation to the middle third of the face, upper teeth, eyelid, and side of the nose Mandibular : Provides sensation to the lower third of the face, tongue, mouth, and lower teeth Abducens Nerve VI The abducens nerve also helps with eye movements, in particular, movements that involve your gaze moving outward.
It controls: Movement of muscles that produce facial expression Facial gland movement Taste Sensation in the external ear Vestibulocochlear Nerve VIII The vestibulocochlear nerve actually consists of two nerves in one, the vestibular nerve and cochlear nerve. The vestibular nerve helps your body sense changes in the position of your head, and your body uses this information to help it maintain its balance.
Glossopharyngeal Nerve IX As with other cranial nerves, the glossopharyngeal nerve has both sensory and motor functions. Vagus Nerve X Sensory Functions : Provides sensation to the outer ear, throat, heart, and abdominal organs Motor Functions: Gives movement to the soft palate and throat Parasympathetic Functions : Regulates heart rhythm and supplies nerves to smooth muscles in your gastrointestinal tract, lungs, and airway Doctors often use vagus nerve stimulation therapy to treat conditions such as epilepsy, depression, and anxiety.
Accessory Nerve XI This cranial nerve, the accessory nerve , provides motor function to some of the muscles in the neck. Spinal Nerves The spinal cord is part of your central nervous system.
Automatic Control Some nerves in the spinal cord are responsible for controlling automatic body functions, such as your heart rate, breathing, and other things your body does automatically.
For example, spinal nerves T1-L5, which are your thoracic and lumbar nerves, are partially responsible for controlling the functions of your: Heart Lungs Gastrointestinal system Kidneys Sweat glands The upper part of your sacral nerves, from L5-S3, are responsible for controlling bladder and bowel movements. Acupuncturists Carla Corkin, Lic. Joseph Goldfedder, Lic. Kathy A. Hoch, Lic. Justin Jaucian, MS, L. Scott Schulz, Lic. Margaret Sommeling, Lic. Cardiologists Faisal K.
Siddiqi, MD. Licensed Massage Therapist Sandra Roldan. Surgeons Dr. Nerve pathways of the PNS carry the incoming and outgoing signals. Twelve pairs of cranial nerves connect the brain to eyes, ears, and other sensory organs and to head and neck muscles. Thirty-one pairs of spinal nerves branch out from the spinal cord to tissues of the thorax, abdomen, and limbs. Each nerve is responsible for relaying sensory information, sending motor commands, or both.
All nervous tissue, from the brain to the spinal cord to the furthest nerve branch, includes cells called neurons. Neurons are charged cells: they conduct electrical signals to pass information through the body. A typical neuron consists of a cell body, dendrites, and an axon with an axon terminal. The dendrites receive signals from body tissues or other neurons and pass them into the cell body.
If an outgoing signal is produced, it zips down the axon to the axon terminal and passes to the next neuron or target cell. This conductive capability sends information up and down nerve pathways and through the central nervous system at incredible speed. Some billion neurons give the brain its awesome processing power. Nervous system messages travel through neurons as electrical signals.
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