THE NERVOUS SYSTEM The nervous system and endocrine system work together to control and coordinate the workings of the components of the body. All actions and thoughts are coordinated by a complex group of organs and nerves that enable man to receive stimuli. The nervous system is like a communication network that transmits information by electrical signals called nerve cells or neurons. The Nerve and Nerve Cell • The basic cell of the nervous system is the neuron. It carries nerve impulses, or action potential, from one part of the body to another. • A typical neuron has three parts: a cell body, which controls the growth of the nerve cell; dendrites, which are short-branched fibers that carry impulses or messages toward the cell body; and the axon, which is typically long, thin fibers that carries messages away from the cell body. • The axon is also known as nerve fibers. The fibers are made up of connective tissue bundles. Parts and Functions of the Nervous System A. The Central Nervous System The Central Nervous System (CNS) consists of the brain and the spinal cord. It is where the interneurons receive and pass on messages. The brain is the control center of the CNS while the spinal cord relays sensory and motor information to and from the brain and other parts of the body. The Brain It is a moist and spongy organ with an average of 3 pounds in weight. It consists of 10 billion neurons that control everything a person does, such as thoughts, movements, memory, and sense. The brain produces waves of electrical impulses that differ in length and frequency, depending upon the type of activity performed by the body. Every person has a different brain wave pattern, just as every person has a unique set of fingerprints and footprints. 1. The Brain The skull protects the brain. Beneath the skull are three distinct layers of membranes that cover the entire brain. The entirety of these membranes of these membranes is call meninges. The cerebrospinal fluid substance is located between the middle and inner meninges and in some spaces within the brain. This fluid helps cushion and protect the brain and the spinal cord. The brain is divided into three parts: the cerebrum, cerebellum, and the brain stem. • Brain Stem – located below the cerebellum at the base of the skull, which serves as the body’s life support system. It controls the heartbeat, breathing, and blood pressure. 1. The Brain • Cerebellum – located beneath the back part of the cerebrum. It coordinates muscle movement. It has an outer layer of gray matter and white matter in the brain’s interior. The cerebellum produces signals that stimulate reactions in other parts of the nervous system. • Cerebrum – the large upper region of the brain. It consists of deep folds, which are divided into many ridges and depressions just like the surface of a walnut. 1. The Brain • Corpus callosum – a broad band of nerve fibers joining the two hemispheres of the brain. • Hippocampus – a small organ located within the brain’s medial temporal lobe, which is associated mainly with the memory, in particular long-term memory. • Hypothalamus - regulates the body’s temperature, use of water, blood pressure, and release of regulatory chemicals. • Medulla – controls breathing, heart rate, and swallowing. 1. The Brain • Midbrain - also linked to vision and controls the movement of the eye and constriction and dilation of the pupil. • Pituitary gland – a pea-sized structure located at the base of the brain. It is part of endocrine system that produces critical hormones that control various body functions. • Pons – regulates breathing and helps control eye movement. • Thalamus – one of the smaller parts of the brain, which serves a relay station for senses. It is responsible in processing the information from the sense organs. Spinal Cord • The spinal cord is a rod of brain tissue that extends about two-thirds of the way down the back, just below the ribs. It is covered with three meninges and cerebrospinal fluid. The spinal cord is protected by a spinal column, which allows the trunk to bend. The Peripheral Nervous System • The Peripheral Nervous System (PNS) is made up of cranial and spinal nerves. There are 12 pairs of cranial nerves in the body that emerge from the brain that connect with the eyes, ears, and nose. • The cranial nerves contain mostly sensory nerve fibers. • Some cranial nerves are made up of sensory and motor nerve fibers. The PNS is divided into two: • The Somatic Nervous System (SNS) is responsible for actions that a person can control such as skeletal muscles and sensory neurons of the skin. This is under conscious voluntary control. • The Autonomic Nervous System (ANS) controls autonomic functions that do not require a person to think. For example, involuntary muscles help digest food, heartbeat, and breathing. The ANS is important in maintaining homeostasis, just like the endocrine system. • There are two subdivisions of the autonomic nervous system – the sympathetic nervous system that prepares the body for action and stress, and the parasympathetic nervous system that helps the body to conserve energy. Common Diseases of the Nervous System • Meningitis is an inflammation of the meninges of the brain or spinal cord caused by bacterial infection or a virus. The infection occurs most often in children and young adults. Those who have weakened immune system and long-term health problems are at risk to this disease. Meningitis can be deadly if not treated immediately. Symptoms: Stiff and painful neck, fever, headache, vomiting, seizures, trouble breathing, and slight headache Treatment: Treated with antibiotics • Cerebral Palsy is a disorder resulting in a lack of full control of physical movement and muscle tightness that affect almost all parts of the body. Some people have little or no control over their arms and legs or other parts of their body. For example, they cannot control the movement of their mouth and tongue, which can cause problems with eating and speaking. • Symptoms : Seizures, intellectual disability, slight limp, and difficulty in walking • Treatment: Surgery • Parkinson’s disease is a disorder of the nervous system that affects the movement of a person. It develops gradually and tremors start in the hands. In early stages, the face shows little or no expression. The arms do not swing when one walks. • Symptoms: Tremors, slow movement, impaired posture and balance, penmanship changes, speech changes, emotional changes and depression, difficulty swallowing, sleep disorder, blood pressure changes, inability to smell, and constipation. • Treatment: Cannot be cured, but symptoms can be improved through surgery to regulate the region of the brain. • Brain Tumor an adult brain tumor is called meningeal tumor. The tumor is formed in the meninges that cover the brain and the spinal cord. Another type is the metastatic brain tumor. It develops cancerous cells from another tumor is called metastasis. Not all brain tumors are cancerous. The term cancer is for a malignant tumor, while a benign tumor is less serious. • Cancer refers to any disease that is characterized by the uncontrolled growth and spread of useless abnormal cells. Cancer cells form a mass of tissue called a malignant tumor. The tumor has no sheath or membrane enclosing it; thus, the cancer cells invade the surrounding tissue. On the other hand, a benign tumor is a mass of tissue formed from non-cancerous cells. It is enclosed within a sheath so that it does not spread nearby tissues. This occurs as the cancer cells grow out into the neighboring tissues and are carried elsewhere in the body. • Symptoms: Trouble walking and change of mental status. • Treatment: Surgery, radiation therapy, and chemotherapy. • Epilepsy is a brain disorder in which clusters of nerve cells or neurons act abnormally. The action potential activity becomes disturbed causing strange sensation and emotions, convulsions, and muscle spasms. • Symptoms: Loss of muscle tone, jerking movements, brief loss of consciousness, muscle stiffness • Treatment: Epileptic seizures are controlled through drug therapy and anticonvulsant drugs Keeping the Nervous System Healthy • Ensure adequate intake of healthy fats such as oil and vegetable oil. Adequate vitamin d and vitamin B-12 is essential to maintain optimal myelin in the neurons. • Exercise the nervous system on daily basis by stretching the arms and reading in order for the motor and sensory pathways to be used. This type of exercise plays a role in regulating blood circulation through your brain and also reduces the risk of many diseases. • Spend a minimum of 15 minutes per day writing on paper as legibly as you can. • Engage yourself in social activities to keep your brain active. Socialization helps to reduce stress and promote emotional health. Reporters: Baguhin, Frema M. Napala, Gwyn Berry D. Raniel, Nina Dominique B.
