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THE NERVOUS SYSTEM PHYSIOLOGY AND ANATOMY OF BODY CONTROLING SYSTEM Created by: Yasmeen Hani Arafsha GOALS AND OBJECTIVES Select the objective to view… NEURONS: The structural components of the nervous system… Neuroanatomy and an introduction to the Nervous system. Structural classification… The skull: home of the brain division of the brain. Brain structures. She brain – He brain. Differences in the total brain sizes. Brain fitness: your guide to good brain health. How the nervous system interacts with other body systems. Nervous system diseases.. Central nervous system.. Peripheral nervous system.. The Brain… Structure and mechanism of a neuron (nervous cell). Types of neurons. Alzheimer’s disease. Parkinson’s disease. Huntington's disease. References and Closure.. NEURONS: The structural components of the nervous system… Objectives: Structure and mechanism of a neuron (nervous cell). Types of neurons. NEURONS: The structural components of the nervous system… Structure and mechanism of a neuron (nervous cell). Click here to view Types of neurons. Click here to view Structure and mechanism of a neuron (nervous cell). The human body is made up of trillions of cells. Cells of the nervous system, called nerve cells or neurons, are specialized to carry "messages" through an electrochemical process. The human brain has about 100 billion neurons that carry out the nerve impulses through a process called action potential. A real view showing a neuron (nerve cell) Next Structure and mechanism of a neuron (nervous cell). Neurons are similar to other cells in the body because: 1. Neurons are surrounded by a cell membrane. 2. Neurons have a nucleus that contains genes. 3. Neurons contain cytoplasm, mitochondria and other "organelles". 4. Neurons carry out basic cellular processes such as protein synthesis and energy production. However, neurons differ from other cells in the body because: 1. Neurons have specialized extensions called dendrites and axons. Dendrites bring information to the cell body and axons take information away from the cell body. 2. Neurons communicate with each other through an electrochemical process. 3. Neurons contain some specialized structures (for example, synapses) and chemicals (for example, neurotransmitters). Next Structure and mechanism of a neuron (nervous cell). Neurons are the oldest and longest cells in the body! You have many of the same neurons for your whole life. Although other cells die and are replaced, many neurons are never replaced when they die. In fact, you have fewer neurons when you are old compared to when you are young. On the other hand, data published in November 1998 show that in one area of the brain (the hippocampus), new neurons CAN grow in adult humans. Neurons can be quite large - in some neurons, such as corticospinal neurons (from motor cortex to spinal cord) or primary afferent neurons (neurons that extend from the skin into the spinal cord and up to the brain stem), can be several feet long! Next Structure and mechanism of a neuron (nervous cell). A single neuron consist of: CELL BODY: is the metabolic center of the neuron, contains the Nucleus and Mitochondrion. DENDRITES: convey incoming messages to the cell body. AXON HILLOCK: a cone like region from where an axon arises. AXONS: generates nerve impulses and topically conduct them away from the cell body." A nerve is a group of axons”. Presynaptic terminals: The swollen, distal end of an axon; contains a neurotransmitter substance within synaptic vesicles. Also called synaptic ending or synaptic bouton. Next Structure and mechanism of a neuron (nervous cell). There are several differences between axons and dendrites: Axons Take information away from the cell body Smooth Surface Generally only 1 axon per cell No ribosomes Can have myelin Branch further from the cell body Dendrites Bring information to the cell body Rough Surface (dendritic spines) Usually many dendrites per cell Have ribosomes No myelin insulation Branch near the cell body Next Structure and mechanism of a neuron (nervous cell). What is inside of a neuron? A neuron has many of the same "organelles," such as mitochondria, cytoplasm and a nucleus, as other cells in the body. Nucleus - contains genetic material Components of a neuron Click here (chromosomes) including information for cell development and synthesis of proteins necessary for cell maintenance and survival. Covered by a membrane. Nucleolus - produces ribosomes necessary for translation of genetic information into proteins Nissl Bodies - groups of ribosomes used for protein synthesis. Endoplasmic reticulum (ER) - system of tubes for transport of materials within cytoplasm. Can have ribosomes (rough ER) or no ribosomes (smooth ER). With ribosomes, the ER is important for protein synthesis. Golgi Apparatus - membrane-bound structure important in packaging peptides and proteins (including neurotransmitters) into vesicles. Microfilaments/Neurotubules - system of transport for materials within a neuron and may be used for structural support. Mitochondria - produce energy to fuel cellular activities. Types of neurons. Neurons come in many different shapes and sizes. Some of the smallest neurons have cell bodies that are only 4 microns wide. Some of the biggest neurons have cell bodies that are 100 microns wide. (Remember that 1 micron is equal to one thousandth of a millimeter!!). Next Types of neurons. One way to classify neurons is by the number of extensions that extend from the neuron's cell body (soma). Next Bipolar neurons have two processes extending from the cell body (examples: retinal cells, olfactory epithelium cells). Multipolar neurons have many processes that extend from the cell body. However, each neuron has only one axon (examples: spinal motor neurons, pyramidal neurons, Purkinje cells). Pseudounipolar cells (example: dorsal root ganglion cells). Actually, these cells have 2 axons rather than an axon and dendrite. One axon extends centrally toward the spinal cord, the other axon extends toward the skin or muscle. Types of neurons. Neurons can also be classified by the direction that they send information: Sensory (or afferent) neurons: send information from sensory receptors (e.g., in skin, eyes, nose, tongue, ears) TOWARD the central nervous system. Motor (or efferent) neurons: send information AWAY from the central nervous system to muscles or glands. Interneurons: send information between sensory neurons and motor neurons. Most interneurons are located in the central nervous system. objectives Neuroanatomy and an introduction to the Nervous system. Introduction Neuroanatomy and an introduction to the Nervous system. Neuroanatomy is the structure of the nervous system. To learn how the nervous system functions, you must learn how the nervous system is put together. the nervous system maintains body homeostasis with electrical signals; provides for sensation, higher mental functions, and emotional response; and activates muscles and glands. Next the nerves system is the master controlling and communicating system of the body. Every thought, action and emotion reflects its activity. Its signaling device, or means of communicating with body cells, is electrical impulses, which are rapid and specific and cause almost immediate responses. Neuroanatomy and an introduction to the Nervous system. To carry out its normal role, the nervous system has three over lapping functions: 1) Much like a sentry, it uses its millions of sensory receptors to monitor changes occurring both inside and outside the body. These changes are called stimuli, and the gathered information is called sensory input. 2) It processes and interprets the sensory input and makes decisions about what should be done at each moment – a process called integration. 3) It then effects a response by activating muscles or glands (effctors) via motor output. objectives Structural classification of the nervous system Objectives: Central Nervous system (CNS) Peripheral Nervous system (PNS) Structural classification of the nervous system The nervous system can be divided into several connected systems that function together. Let's take the simple division: The Nervous System is divided into: First: The Central Nervous System Second: The Peripheral Nervous System Click here to view Click here to view Structural classification of the nervous system The Central Nervous System The central nervous system is divided into two parts: the brain and the spinal cord. The average adult human brain weighs 1.3 to 1.4 kg (approximately 3 pounds). The brain contains about 100 billion nerve cells (neurons) and trillions of "support cells" called glia. The spinal cord is about 43 cm long in adult women and 45 cm long in adult men and weighs about 35-40 grams. The vertebral column, the collection of bones (back bone) that houses the spinal cord, is about 70 cm long. The Central Therefore, the spinal cord is much Nervous System shorter than the vertebral (Brain and Spinal column. Cord) Click here Structural classification of the nervous system The Peripheral Nervous System The peripheral nervous system is divided into two major parts: the somatic nervous system and the autonomic nervous system. 1. Somatic Nervous System The somatic nervous system consists of peripheral nerve fibers that send sensory information to the central nervous system AND motor nerve fibers that project to skeletal muscle. The picture on the left shows the somatic motor system. The cell body is located in either the brain or spinal cord and projects directly to a skeletal muscle. 2. Autonomic Nervous System The autonomic nervous system is divided into three parts: the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system. The autonomic nervous system controls smooth muscle of the viscera (internal organs) and glands The preganglionic neuron is located in either the brain or the spinal cord. This preganglionic neuron projects to an autonomic ganglion. The postganglionic neuron then projects to the target organ.. Notice that the somatic nervous system has only one neuron between the central nervous system and the target organ while the autonomic nervous system uses two neurons. The enteric nervous system is a third division of the autonomic nervous system that you do not hear much about. The enteric nervous system is a meshwork of nerve fibers that innervate the viscera (gastrointestinal tract, pancreas, gall bladder). Next Structural classification of the nervous system In the Peripheral Nervous System, neurons can be functionally divided in 3 ways: 1 Sensory (afferent) - carry information INTO the central nervous system from sense organs. OR Motor (efferent) - carry information away from the central nervous system (for muscle control). 2 Cranial - connects the brain with the periphery. OR Spinal - connects the spinal cord with the periphery. 3 Somatic - connects the skin or muscle with the central nervous system. OR Visceral - connects the internal organs with the central nervous system. Click here Structural classification of the nervous system Some differences between the Peripheral Nervous System (PNS) and the Central Nervous System (CNS): In the CNS, collections of neurons are called nuclei. In the PNS, collections of neurons are called ganglia. In the CNS, collections of axons are called tracts. In the PNS, collections of axons are called nerves Next Structural classification of the nervous system The following table shows how the nervous system can be divided. The bottom row of the table contains the names of specific areas within the brain. Divisions of the Nervous System objectives The Brain… Objectives: The skull: home of the brain division of the brain. Brain structures. She brain – He brain. Brain fitness: your guide to good brain health. the Brain… Although some people may think that the brain is like a bowl of jell-O, the brain is NOT a bowl of jell-O. Unlike a bowl of jell-O, the brain is not a uniform material. Rather, the brain is made up of many different areas, each having a particular structure and function. Next The skull: home of the brain Your brain is protected by several bones. There are eight bones that surround your brain: one frontal bone; two parietal bones, two temporal bones, one occipital bone, one sphenoid bone and one ethmoid bone. These eight bones make up the cranium. Another 14 bones in the face make up the entire skull. There are also 3 small bones in each ear. Also protecting your brain are 3 layers of tissue called the meninges. A few of the bones have been colored in the diagram to the right. Next The skull: home of the brain There is a large opening, called the foramen magnum, located in the back of the occipital bone. This is where the medulla ends and projects out of the skull. Smaller holes in the skull, called foramina, allow nerves and blood vessels to enter and leave the cranium. The picture in the bottom shows the base of the skull. The places in the skull where the bones come together are called sutures. These sutures are flexible in young children, but become fixed as you age. Next Divisions of the Brain Divisions of the Brain Major Division Subdivision Structures Telencephalon Neocortex; Basal Ganglia; Amygdala; Hippocampus; Lateral Ventricles Diencephalon Thalamus; Hypothalamus; Epithalamus; Third Ventricle Mesencephalon Tectum; Tegmentum; Cerebral Aqueduct Metencephalon Cerebellum; Pons; Fourth Ventricle Myelencephalon Medulla Oblongata; Fourth Ventricle Prosencephalon (Forebrain) Mesencephalon (Midbrain) Rhombencephalon (Hindbrain) Next Division of the brain The subdivisions of the brain Telencephalon Diencephalon Myelencephalon Mesencephalon (Midbrain) Metencephalon Next Division of the brain Lobes of the brain The average human brain weighs about 1,400 grams (3 lb). When the brain is removed from the skull, it looks a bit like a large pinkish-gray walnut. The brain can be divided down the middle lengthwise into two halves called the cerebral hemispheres. Each hemisphere of the cerebral cortex is divided into four lobes by various sulci and gyri...the sulci (or fissures) are the grooves and the gyri are the "bumps" that can be seen on the surface of the brain. The folding of the cerebral cortex produced by these bumps and grooves increases the amount of cerebral cortex that can fit in the skull. (In fact, the total surface area of the cerebral cortex is about 324 square inches - about the size of a full page of newspaper!). Although most people have the same patterns of gyri and sulci on the cerebral cortex, no two brains are exactly alike. Next Division of the brain Lobes of the brain FRONTAL LOBE Located in front of the central sulcus. Concerned with reasoning, planning, parts of speech and movement (motor cortex), emotions, and problem-solving. PARIETAL LOBE Located behind the central sulcus. Concerned with perception of stimuli related to touch, pressure, temperature and pain. TEMPORAL LOBE Located below the lateral fissure. Concerned with perception and recognition of auditory stimuli (hearing) and memory (hippocampus). OCCIPITAL LOBE Located at the back of the brain, behind the parietal lobe and temporal lobe. Concerned with many aspects of vision. Next Division of the brain A top view of the brain From a top view, notice how the brain is divided into two halves, called hemispheres. Each hemisphere communicates with the other through the corpus callosum, a bundle of nerve fibers. (Another smaller fiber bundle that connects the two hemispheres is called the anterior commissure). Next Brain structures Click on one of the question marks beside each structure to view its characteristics… hypothalamus Next Brain stem Brain structures Cerebral Cortex Functions: Thought Voluntary movement Language Reasoning Perception Return to structures The word "cortex" comes from the Latin word for "bark" (of a tree). This is because the cortex is a sheet of tissue that makes up the outer layer of the brain. The thickness of the cerebral cortex varies from 2 to 6 mm. The right and left sides of the cerebral cortex are connected by a thick band of nerve fibers called the "corpus callosum." In higher mammals such as humans, the cerebral cortex looks like it has many bumps and grooves. A bump or bulge on the cortex is called a gyrus (the plural of the word gyrus is "gyri") and a groove is called a sulcus (the plural of the word sulcus is "sulci"). Lower mammals, such as rats and mice, have very few gyri and sulci. Brain structures Cerebellum Functions: Movement Balance Posture Return to structures The word "cerebellum" comes from the Latin word for "little brain." The cerebellum is located behind the brain stem. In some ways, the cerebellum is similar to the cerebral cortex: the cerebellum is divided into hemispheres and has a cortex that surrounds these hemispheres. Brain structures Brain stem Functions: Breathing Heart Rate Blood Pressure Return to structures The brain stem is a general term for the area of the brain between the thalamus and spinal cord. Structures within the brain stem include the medulla, pons, tectum, reticular formation and tegmentum. Some of these areas are responsible for the most basic functions of life such as breathing, heart rate and blood pressure. Brain structures Hypothalamus Functions: Body Temperature Emotions Hunger Thirst Circadian Rhythms Return to structures The hypothalamus is composed of several different areas and is located at the base of the brain. Although it is the size of only a pea (about 1/300 of the total brain weight), the hypothalamus is responsible for some very important functions. One important function of the hypothalamus is the control of body temperature. The hypothalamus acts as a "thermostat" by sensing changes in body temperature and then sending signals to adjust the temperature. For example, if you are too hot, the hypothalamus detects this and then sends a signal to expand the capillaries in your skin. This causes blood to be cooled faster. The hypothalamus also controls the pituitary. Brain structures Thalamus Functions: Sensory processing Movement Return to structures The thalamus receives sensory information and relays this information to the cerebral cortex. The cerebral cortex also sends information to the thalamus which then transmits this information to other areas of the brain and spinal cord. Brain structures Midbrain Functions: Vision Audition Eye Movement Body Movement Return to structures The midbrain includes structures such as the superior and inferior colliculi and red nucleus. There are several other areas also in the midbrain. Brain structures Pons Functions: Cardiovascular and respiratory control center. Return to structures The pons are continuous with the medulla Brain structures Medulla Functions: Heart rate Breathing. Blood pressure. Swallowing and vomiting Return to structures She brain – He brain Bigger - Stronger - Faster...are there really any differences between female brains and male brains? Differences between the brains of men and women have generated considerable scientific and public interest. If there are differences in the way that men and women behave, then it is reasonable to suppose that their brains have something to do these behavioral differences. Just what are these differences and where in the brain might these differences be located? For hundreds of years, scientists have searched for differences between the brains of men and women. Early research showing that male brains were larger than female brains was used to "prove" that male brains were superior to female brains. Of course, this "proof" is NOT so simple and straight forward as you will see. Nevertheless, even today, there is plenty of controversy about the differences in the brains of men and women. Not only from an anatomical point of view, but also from a functional point of view - in other words, just what do the differences in the brains mean? Next She brain – He brain Hormones that are present during a baby's development will affect the brain and determine whether the brain will be female or male. Studies that have looked at differences in the brains of males and females have focused on: Total Brain Size The Corpus Callosum The Hypothalamus Women and Men - Boys and Girls The behavioral and neurological differences between men and women require further study. Perhaps new studies will find neuroanatomical differences that explain some of the complex differences between male and female behavior. However, from a review of the current scientific evidence, it appears that differences in many cognitive behaviors (for example, memory) are related more to individual differences between people than to whether people are female or male. Next Brain fitness: your guide to good brain health You are born with just about all the neurons (nerve cells) that your brain will ever have. Damaged brains are NOT easy to fix. Here are some suggestions for good brain health. 1. Wear your seat belt! In a car, truck or airplane, your seat belt will help protect your head and brain from injury. Motor vehicle accidents are by far the greatest causes of brain injuries, accounting for 37-50% of all brain injuries 3. Stay away from illegal drugs! Next Drugs alter brain function, no question about that. Although damage done by some drugs can be reversed, some drugs may change brain function permanently. Why take the chance? 2. Wear your helmet! Whether you are biking, skating or skateboarding, your helmet will protect your head if you fall. Head injury is the most common cause of death in bicycle crashes accounting for 62% of all bicycle-related deaths. 4. Know the risks involved with sports! This applies mainly to boxing, football and the martial arts. However, even soccer, climbing, horseback riding, diving and skiing have risks. Always wear your safety equipment properly and be in good physical condition for your sport. Brain fitness: your guide to good brain health 5. Look before you leap! I know it sounds impossible, but people DO dive into swimming pools without water. Dive only in the deep end of the pool and make sure that the water in the lake and at the beach is deep enough to dive in head first. Also, be aware of any objects, such as large rocks, that may be hidden under the water. 6. Look both ways before crossing the street! I know that you have heard this one before, but accidents do happen and you can't be wearing your helmet all the time. 7. Stay away from guns! I don't think I have to explain 8. Make sure you have a "good" surface around your playground equipment! Just in case you fall off of a climber, a soft impact-absorbing surface will cushion your drop. this one. 9. Dispose of chemicals properly! Many chemicals, such as pesticides and cleaners, contain neurotoxins that can kill nerve cells and damage nerves. These dangerous chemicals can be found in your home or at places of work. Dispose of these materials properly! objectives 10. Eat right! Your brain needs energy to work its best. How the nervous system interacts with other body systems. Objectives: skeletal system cardiovascular system muscular system endocrine system lymphatic system respiratory system digestive system reproductive system urinary system How the nervous system interacts with other body systems. All of the systems within the body interact with one another to keep an organism healthy. Although each system has specific functions, they are all interconnected and dependent on one another. The nervous system controls various organs of the body directly. The brain also receives information from many organs of the body and adjusts signals to these organs to maintain proper functioning. Next How the nervous system interacts with other body systems. The Skeletal system Function of the skeletal system.. The skeletal system makes up the framework of the body and allows us to move when our muscles contract. It stores minerals (e.g. calcium, phosphorous) and releases them into the body when they are needed. The skeletal system also protects internal organs and produces blood cells. Next Interaction with the nervous system.. Bones provide calcium that is essential for the proper functioning of the nervous system. The skull protects the brain from injury. The vertebrae protect the spinal cord from injury. Sensory receptors in joints between bones send signals about body position to the brain. The brain regulates the position of bones by controlling muscles. How the nervous system interacts with other body systems. The Cardio vascular system Function of the cardiovascular system… The cardiovascular system delivers oxygen, hormones, nutrients and white blood cells around the body by pumping blood, and it removes waste products. Next Interaction with the nervous system… Endothelial cells maintain the blood-brain barrier. Baroreceptors send information to the brain about blood pressure. Cerebrospinal fluid drains into the venous blood supply. The brain regulates heart rate and blood pressure. How the nervous system interacts with other body systems. The muscular system Function of the muscular system… Different types of muscles enable motion, generate heat to maintain body temperature, move food through digestive tract and contract the heart. Next Interaction with the nervous system… Receptors in muscles provide the brain with information about body position and movement. The brain controls the contraction of skeletal muscle. The nervous system regulates heart rate and the speed at which food moves through the digestive tract. How the nervous system interacts with other body systems. The Endocrine system Function of the endocrine system… The endocrine system secretes hormones into blood and other body fluids. These chemicals are important for metabolism, growth, water and mineral balance, and the response to stress. Next Interaction with the nervous system… Hormones provide feedback to the brain to affect neural processing. Reproductive hormones affect the development of the nervous system. The hypothalamus controls the pituitary gland and other endocrine glands. How the nervous system interacts with other body systems. The Lymphatic system Function of the lymphatic system… The lymphatic system protects the body from infection. Interaction with the nervous system… The brain can stimulate defense mechanisms against infection Next How the nervous system interacts with other body systems. The Respiratory System Function of the respiratory system… The respiratory system supplies oxygen to the blood and removes carbon dioxide. Interaction with the nervous system… The brain monitors respiratory volume and blood gas levels. The brain regulates respiratory rate. Next How the nervous system interacts with other body systems. The Digestive system Function of the digestive system… The digestive system stores and digests foods, transfers nutrients to the body, eliminates waste and absorbs water. Next Interaction with the nervous system… Digestive processes provide the building blocks for some neurotransmitters. The autonomic nervous system controls the tone of the digestive tract. The brain controls drinking and feeding behavior. The brain controls muscles for eating and elimination. The digestive system sends sensory information to the brain. How the nervous system interacts with other body systems. The Reproductive system Function of the reproductive system… The reproductive system is responsible for producing new life. Interaction with the nervous system… Reproductive hormones affect brain development and sexual behavior. The brain controls mating behavior. Next How the nervous system interacts with other body systems. The Urinary system Function of the urinary system… The urinary system eliminates waste products and maintains water balance and chemical balance. Interaction with the nervous system… The bladder sends sensory information to the brain. The brain controls urination. objectives Diseases of the Nervous system Objectives: Alzheimer’s disease Parkinson’s disease Huntington's disease Diseases of the nervous system Alzheimer’s Disease Dementia is a brain disorder that seriously affects a person’s ability to carry out daily activities. The most common form of dementia among older people is Alzheimer’s disease (AD), which initially involves the parts of the brain that control thought, memory, and language. Although scientists are learning more every day, right now they still do not know what causes AD, and there is no cure. AD is named after Dr. Alois Alzheimer, a German doctor. In 1906, Dr. Alzheimer noticed changes in the brain tissue of a woman who had died of an unusual mental illness. He found abnormal clumps (now called amyloid plaques) and tangled bundles of fibers (now called neurofibrillary tangles). Today, these plaques and tangles in the brain are considered signs of AD. Next Diseases of the nervous system Alzheimer’s Disease Next What Causes AD? Scientists do not yet fully understand what causes AD. There probably is not one single cause, but several factors that affect each person differently. Age is the most important known risk factor for AD. The number of people with the disease doubles every 5 years beyond age 65. Family history is another risk factor. Scientists believe that genetics may play a role in many AD cases. For example, early-onset familial AD, a rare form of AD that usually occurs between the ages of 30 and 60, is inherited. The more common form of AD is known as late-onset. It occurs later in life, and no obvious inheritance pattern is seen in most families. However, several risk factor genes may interact with each other and with non-genetic factors to cause the disease. The only risk factor gene identified so far for late-onset AD is a gene that makes one form of a protein called apolipoprotein E (ApoE). Everyone has ApoE, which helps carry cholesterol in the blood. Only about 15 percent of people have the form that increases the risk of AD. It is likely that other genes also may increase the risk of AD or protect against AD, but they remain to be discovered. Scientists still need to learn a lot more about what causes AD. In addition to genetics and ApoE, they are studying education, diet, and environment to learn what role they might play in the development of this disease. Scientists are finding increasing evidence that some of the risk factors for heart disease and stroke, such as high blood pressure, high cholesterol, and low levels of the vitamin folate, may also increase the risk of AD. Evidence for physical, mental, and social activities as protective factors against AD is also increasing. Diseases of the nervous system Alzheimer’s Disease Next How is AD Diagnosed? An early, accurate diagnosis of AD helps patients and their families plan for the future. It gives them time to discuss care while the patient can still take part in making decisions. Early diagnosis will also offer the best chance to treat the symptoms of the disease. Today, the only definite way to diagnose AD is to find out whether there are plaques and tangles in brain tissue. To look at brain tissue, however, doctors usually must wait until they do an autopsy, which is an examination of the body done after a person dies. Therefore, doctors can only make a diagnosis of “possible” or “probable” AD while the person is still alive. At specialized centers, doctors can diagnose AD correctly up to 90 percent of the time. Doctors use several tools to diagnose “probable” AD, including: questions about the person’s general health, past medical problems, and ability to carry out daily activities, tests of memory, problem solving, attention, counting, and language, medical tests—such as tests of blood, urine, or spinal fluid, and brain scans. Sometimes these test results help the doctor find other possible causes of the person’s symptoms. For example, thyroid problems, drug reactions, depression, brain tumors, and blood vessel disease in the brain can cause AD-like symptoms. Some of these other conditions can be treated Diseases of the nervous system Parkinson’s Disease Parkinson's disease (PD) belongs to a group of conditions called motor system disorders, which are the result of the loss of dopamine-producing brain cells. The four primary symptoms of PD are tremor, or trembling in hands, arms, legs, jaw, and face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slowness of movement; and postural instability, or impaired balance and coordination. As these symptoms become more pronounced, patients may have difficulty walking, talking, or completing other simple tasks. PD usually affects people over the age of 50. In some people the disease progresses more quickly than in others. As the disease progresses, the shaking, or tremor, which affects the majority of PD patients may begin to interfere with daily activities. Other symptoms may include depression and other emotional changes; difficulty in swallowing, chewing, and speaking; urinary problems or constipation; skin problems; and sleep disruptions. There are no blood or laboratory tests available to diagnose PD. Next Diseases of the nervous system Parkinson’s Disease Is there any treatment? At present, there is no cure for PD, but a variety of medications provide dramatic relief from the symptoms. Usually, patients are given levodopa combined with carbidopa. Carbidopa delays the conversion of levodopa into dopamine until it reaches the brain. Nerve cells can use levodopa to make dopamine and replenish the brain's dwindling supply. Although levodopa helps at least three-quarters of parkinsonian cases, not all symptoms respond equally to the drug. Bradykinesia and rigidity respond best, while tremor may be only marginally reduced. Problems with balance and other symptoms may not be alleviated at all. Anticholinergics may help control tremor and rigidity. Other drugs, such as bromocriptine, pergolide, pramipexole, and ropinirole, mimic the role of dopamine in the brain, causing the neurons to react as they would to dopamine. An antiviral drug, amantadine, also appears to reduce symptoms Next Diseases of the nervous system Huntington’s Disease In 1872, the American physician George Huntington wrote about an illness that he called "an heirloom from generations away back in the dim past." He was not the first to describe the disorder, which has been traced back to the Middle Ages at least. One of its earliest names was chorea,* which, as in "choreography," is the Greek word for dance. The term chorea describes how people affected with the disorder writhe, twist, and turn in a constant, uncontrollable dance-like motion. Later, other descriptive names evolved. "Hereditary chorea" emphasizes how the disease is passed from parent to child. "Chronic progressive chorea" stresses how symptoms of the disease worsen over time. Today, physicians commonly use the simple term Huntington's disease (HD) to describe this highly complex disorder that causes untold suffering for thousands of families. Next Diseases of the nervous system, Parkinson’s disease What Causes Huntington's Disease? HD results from genetically programmed degeneration of nerve cells, called neurons,* in certain areas of the brain. This degeneration causes uncontrolled movements, loss of intellectual faculties, and emotional disturbance. Specifically affected are cells of the basal ganglia, structures deep within the brain that have many important functions, including coordinating movement. Within the basal ganglia, HD especially targets neurons of the striatum, particularly those in the caudate nuclei and the pallidum. Also affected is the brain's outer surface, or cortex, which controls thought, perception, and memory. What are the Major Effects of the Disease? Early signs of the disease vary greatly from person to person. A common observation is that the earlier the symptoms appear, the faster the disease progresses. Family members may first notice that the individual experiences mood swings or becomes uncharacteristically irritable, apathetic, passive, depressed, or angry. These symptoms may lessen as the disease progresses or, in some individuals, may continue and include hostile outbursts or deep bouts of depression. The disease can reach the point where speech is slurred and vital functions, such as swallowing, eating, speaking, and especially walking, continue to decline. Some Next individuals cannot recognize other family members. Diseases of the nervous system, Parkinson’s disease Is There a Treatment for HD? Physicians may prescribe a number of medications to help control emotional and movement problems associated with HD. Antipsychotic drugs, such as haloperidol, or other drugs, such as clonazepam, may help to alleviate choreic movements and may also be used to help control hallucinations, delusions, and violent outbursts. Antipsychotic drugs, however, are not prescribed for another form of muscle contraction associated with HD, called dystonia, and may in fact worsen the condition, causing stiffness and rigidity. These medications may also have severe side effects, including sedation, and for that reason should be used in the lowest possible doses. For depression, physicians may prescribe fluoxetine, sertraline, nortriptyline, or other compounds. Tranquilizers can help control anxiety and lithium may be prescribed to combat pathological excitement and severe mood swings. Medications may also be needed to treat the severe obsessive-compulsive rituals of some individuals with HD. Most drugs used to treat the symptoms of HD have side effects such as fatigue, restlessness, or hyperexcitability. Sometimes it may be difficult to tell if a particular symptom, such as apathy or incontinence, is a sign of the disease or a reaction to medication. objectives references * Books: - Essentials of human anatomy and physiology by: Elain N. Marieb. * Websites: - http://faculty.washington.edu/chudler/sagittal.html - www.alzheimers.org/pubs/adfact.html - http://www.ninds.nih.gov/disorders/parkinsons_disease/parkinsons_disease.htm - http://www.ninds.nih.gov/disorders/huntington/detail_huntington.htm#17353137 - http://www.wekipedia.org * Essential of interactive physiology CD. Closure I hope that you have enjoyed this material.. Thank you Created by: Yasmeen Hani Arafsha Collage: Applied Medical Science College number: 425201717 PS.: I would be appreciative if you call me for commentary Phone: 0502997548