22 brain and nerves
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22 brain and nerves Document Transcript

  • 1. 22-1 BRAIN ANDNERVES
  • 2. 22-2 BRAIN AND NERVESThe Electrical System of Brain And NervesJust as you have electric wires trying to connect a switch on the wall to a electric bulb or a electricmotor, we have nerves connecting the brain to the hand or legs !Our Brain Controls AllAll that the brain has to do is to tell one Our Brain Can Sense Allpart of the body to move, and small elec- The brain is more than just a switchtric currents go from the brain to that part. to command. It also gets a second toIt orders some muscles to squeeze, the second feedback on every activityopposite group to relax, and magically, and has to be active at all times tothe order is followed. In fact there is no make corrections.part of the body that is not connected tothe brain. The brain is the most impor- So, you may have our eyes closed buttant part of the body and can command it can tell if someone is standing onthe heart to slow down or beat faster, can your toes. If a 50 paise coin is keptcommand the pancreas to secrete insulin in our hand, without even lookingwhen we have eaten too much of sugar,or can command the hand to move away at it, we would be able to tell it fromwhen it has touched a hot plate. a one-rupee coin. How Do You Tell A Banana From An Orange? Fine receptors on our skin can tell a feather touch from a rough cloth, hot from cold, a pointed needle from a solid bar and on our fingers can tell two points a mm apart. Other receptors can make us smell a orange differently from a lemon, can taste an apple differently from a banana and can help us make out the calls of a hundred different birds. The eyes of course are very specialised and its receptors can report all our surroundings to our brain in the dimmest of lights. PARTS OF OUR NERVOUS SYSTEM Brain1. BrainThe Brain weighs about a kilo and a half. Present inside the skull, itis as thick as soup or a raw egg. It is connected to every part of thebody at one place or the other, directly usually, but occasionallyindirectly also. It gets small electric signals from different parts ofthe body, tries to understand them, makes sense of them and thensends commands back to continue or alter the previous commands. Our Brains Has Departments That Do Different Jobs Our brain has different areas allocated to take care of different functions. The following two diagrams show where different signals from various parts of the body reach and where the commands for different parts of the body are sent from.
  • 3. 22-3 The Brain Wires Are Crossed The wires in our brains are crossed. All right-handed people have the left side of their brain that is ‘dominant’ (or more powerful). While in some left-handed people, the right side of the brain is dominant.What the Different Departments Do? Brains Need To Receive SignalsThe dominant side of the brain is responsi- We would commonly ask someone who doesble for language, and for understanding in- not pay heed to us if he is hard of hearing. Theformation in a logical sequence. The non- fact is that even though our ears may hear, un-dominant side of the brain looks after sig- less the areas of the brain were to receive thenals from seeing and also about the space signals properly, understand them and sendaround us. The non - dominant side takes them to another part of the brain, we wouldcare of recognition of faces, of music, or not be able to ‘know’ what we heard. Similarly,identification of things by their forms. even if our eyes were okay, but if the part ofIf for some reason, the dominant side gets the brain towards the back was not okay, wedamaged, the person is unable to speak. But wouldn’t ‘know’ what we saw and hence evenif the other side were to be damaged, she with wide open and healthy eyes, we wouldwould be able to speak, but may not be able not be able to move away from a car about toto pay attention to others emotions or her run us over!other side of the body. What Do Different Parts of the Brain Do? Different parts of the Brain Front of Brain Controls Behaviour: The front of controls different things the brain is associated imagine with learning that deter- mines how we behave. It talk helps us plan our future see Front Brain actions. If this part of ours were to get damaged, feel probably our neighbours hear would be shocked to hear walk-move Middle Brain us swear abuses or see us roaming nude! Learning heart beat/ how to socialise is also Lower Brain breathing controlled here.Lower Brain Controls Basic Body Functions : On the other hand, the lowest part of the brain- called the brain stem, has the most important and ‘basic’ centres. Even if the top parts of thebrain were to stop functioning – only the brain stem were to function, we would be ‘alive’because our breathing, our heart rate and our blood pressure is controlled from there.Middle Brain Control Our Sensations: Just above the brain stem is where our body receives allthe signals that warn it about danger, like those of pain. Just below this smell and sex signals arealso understood. Temperature regulation, hunger, sleep and thirst are also controlled here. Soalso are controlled here the emotions of fear and anger, and those of maternal instinct.
  • 4. 22-42. NervesNerves are like electrical wires that carry weak electric signals from one part of the body to an-other. While some of them may travel all the way from the periphery to the brain in one go, someof them may end in another nerve and then carry the signals through one or two more nerves. Our Nervous System Carriers of Sensations & SignalsDifferent types of nerves carry different signals Brainand sensations.a. Thick Nerves : Carry signals ofcommand from the brain to the peripheral Spinal Cordorgans.b. Medium Sized Nerves: Nerves carrying Nervestouch and pressureare of intermediate size.c. Thin Nerves : The thinnest nerves are usedfor carrying pain sensation. Across the Football Field in 1 Second ! The speed at which the sensation is carried also Sense receptors depends on the size of the nerve fibres. The thick- Nerves end in sense receptors which help us est nerves carry commands from the brain as fast identify different sensations. So we are able to as 120 metres a second, about the length of a foot- know hot, cold, pain, pleasure etc. These nerve ball field in one second. Pain sensation usually receptors are present on our skin or muscles at travels at 2 to 5 metres a second. various intervals. Nerves from these sense receptors carry the sig- nals to the brain. The brain then is able to choose what it is to do. For example, sense receptors on our tongue called “taste buds” tell our brain whether what we are eating is sweet or bitter. The brain then decides whether to continue eating or to stop.2. Spinal Cord SpinalThe spinal cord starts from where the brain stem ends at the skull Cordand it goes all the way just below the chest at the back. It goesthrough the hollow of the small bones of the backbone.Nerves carrying sensations up to the brain go in front of the spinalcord. And nerves that carry orders from brain to the body organsare in the back portion of the spinal cord. On the sides of the cordare a mixture of nerves that come down and those that go up. Somenerves are long. They carry signals through long nerve fibres allthe way up or down. But most nerves are not so long. They endhalfway and pass on their signal through other nerves.
  • 5. 22-5 Spinal Cord InjurySignals starting from one side usu- In people whose spinal cord is cut, many of the sensations from theally cross over to the other side ei- brain are unable to reach the ends and signals cannot reach from thether after reaching the brain or some- ends to the brain.where on the way in the spinal cord.So, if a person were to damage her In such cases, the muscles below the cut spinal cord waste away andspinal cord near the neck, some of get thin. Sensations are poor and the person may not even be able toher sensations would be lost on the know when to pass shit or urine. Considerable training needs to besame side while other sensations given to such people, and special care needs to be taken of their blad-would be lost from the other side. der and skin, or else they develop infections and die. AUTONOMIC NERVOUS SYSTEM The Control SystemIt is the autonomic system that controls the most Autonomic system controls the mostimportant organs inside our body. It adjusts the important organs inside our bodyheart rate, empties our stomach, squeezes out theurinary bladder when it is full and it throws outthe man’s semen during sex. It works all by itselflike a well-oiled machine with little or no guidancefrom the Brain. Many organs are controlled togetherThe autonomic system of the body can carry out functionsof different organs of the body all at the same time. We canbest see this in an emergency. In an emergency, there is notime for the body to carry out normal activities like shittingor urinating. Then, the body could carry out a well-coordinated ‘automatic ‘ range of actions.The palms start sweating (to improve the grip on a mis-sile or weapon), the eye pupils dilates to allow morelight to be able to see better and the heart would beatharder (to prepare for exercise like running away or us-ing the limbs). The lungs would breathe harder andquicker to get more oxygen and the liver would releasestores of stored glucose if required.Along with this, the speed of the intestine would slowdown and the ends of the stomach, rectum and bladderwould tighten to prevent diversion of attention toshitting and pissing that can be done later.
  • 6. 22-6 Know the Answers BRAIN & NERVESa. Please mark whether “right” ot “wrong”:1. The brain controls all parts of the body except heart and lungs.2. Each organ in the body sends signals to the different parts of the brain.3. The brain sends chemical fluids through the nerves to different parts of the body.4. The left side of the brain controls the right side of the body and the right side controls the left side.5. The autonomous nervous system controls the brain automatically.b. Please tick the right answer:The autonomic nervous system helps the body fight or take flight by affecting the working of thefollowing organs :1. Lungs by breathing harder / weaker and faster / slower.2. Eye pupils by becoming smaller / bigger.3. Heart by beating slower / faster.4. Liver by letting out stores of glucose / protein.c. Please fill in the blanks:1. The more powerful side of the brain helps us in our _______________ while the non-powerful side of the brain helps us think of _______________ and ____________________.2. A person with an injured spinal cord has the following problems: a. Hand and feet ______________________ b. Bladder ___________________________ c. Sex organs ________________________3. Nerves are of three types: a. Thick nerves carry ________________________ sensations. b. Medium sized nerves carry ______________________ sensations. c. Thin nerves carry _______________________ sensations.
  • 7. 22-7 Diseases of the BRAIN AND NERVES Page Number1. Meningitis 22-8 to 22-92. Encephalitis or Brain fever 22-103. Brain stroke 22-104. Polio and related illnesses 22-115. Head injury 22-116. Spinal cord injury 22-127. Mental illnesses 22-12 to 22-13
  • 8. 22-8 DISEASES OF THE BRAIN AND SPINAL CORDThe Brain is such an important part of the body that any disorder affecting it would affect theperson’s life very seriously. The same is about disorders of the spinal cord.As a health worker, you will be called to deal with some diseases of the brain and spinal cord,such as: 1. Meningitis 5. Head injury 2. Encephalitis or Brain fever 6. Spinal cord injury 3. Brain stroke 7. Mental illnesses 4. Polio and related illnesses1. Meningitis (me-nin-jye-tis)Membranes called meninges cover the brain to hold its porridge like mass of nerves together. Dueto infections, these meninges may swell and get inflamed. This is meningitis ans it may get severeto lead to death.Many types of germs may cause meningitis. Meningitis due to the TB germ and some types offungus have a very slow progression. However, the intensity of problems with most otherbacteria and viruses is quick and can kill without giving much time.Usually meningitis is seen as:The illness very often starts with a sore throat or a cold with high fever. However, other signs asmentioned below come up rapidly and can get very serious. 1. Fever – high and at 2. Headache: The person times with chills. How- complains of severe headache ever, TB and some fungi and may even vomit because can also cause meningitis of it. The vomiting is worth that has very low fever noting because often the force although other signs are of vomiting is very high and present. gets thrown very far from the body. 3. Neck stiffness: Test for Meningitis The neck is stiff and To test further, ask the person to one can feel it to be lie down and straighten the so. Ask the person knees and the hip. Now try to to touch her chin to bend forward the neck towards her chest. She will the chest. The hips and the knees not be able to. Even automatically tend to bend – this if you try to force such touching, you is an important sign of meningitis. will experience severe restriction.
  • 9. 22-94. Rashes: Some 6. Fits: Any infection of the meninges also af-children may fects the nearby brain tissues. Hence, fits or con-show rashes on vulsions in which the person becomes uncon-the face or chest, scious and throws about his jaws, arms and legsbut is difficult to in repetitive motions are also important signs ofsee in dark peo- meningitis. especially in a person who has beenple. complaining of headache for a few hours or days.5. Unconsciousness: Unconscious-ness may appear within a few hoursof the beginning of the headache. InTB meningitis, the period may be afew days or weeks away.However, if treatment is not started Fits is also a sign ofwithin minutes, it may lead to death. meningitis Treatment for Meningitis: A test done by removing some fluid from the lower area of the spinal cord can tell if the offending germ is bacteria, TB or a virus. In the last case, there is no cure. Refer urgently any child or elder who shows headache and neck stiffness as explained above. If the doctor is far, start Amoxycillin or Ciprofloxacin and ask the relatives to urgently take the patient to a hospital. Unconscious patients may need injections. Prevention of Meningitis Meningitis can often spread from one person to another very fast as can be seen in school hostels and soldiers’ barracks. If more than one patient is seen who stay in the same room or hall, open all windows and doors and sun the room/ hall. Increase the distance between the beds and prevent crowd- ing. Those who have already been staying with the patients may be started on Amoxycillin to prevent meningitis. BCG in children can help avoid TB meningitis.
  • 10. 22-102. Encephalitis (en-kef-e-lye-tis) or Brain feverEncephalitis means swelling of the brain (not just the covering!) and can lead to death. Althoughsigns of meningitis can be the same as that of encephalitis, the neck stiffness and headache areconsiderably less in encephalitis, also called Brain fever by lay people. On the other hand, fits,unconsciousness, inability to move one or both eyes, inability to swallow or speak or to moveher hands or legs are signs that one or more areas of the brain have been affected.Starting with mild or high fever, cold or cough, the illness is caused only by viruses (not bacte-ria) like that of Polio, Measles, Rabies or Herpes. As such, we still do not have any effective germkillers that may be used easily. Refer immediately if encephalitis We need to provide support systems to help the per- son survive the three to seven days period, while the effects of the virus get over. These can be possible only at hospitals and hence it is important to identify the illness early enough and refer immediately to a doc- tor/hospital.3. Brain strokeA Brain Stroke means that suddenly the blood supply of one or both sides of the brain has beencut off. One or more parts of the brain stops working because of this. Usually this happens inpeople above the age of forty and those known to be having high blood pressure and/or highblood sugar (Diabetes).How strokes happen?It can happen by two methods.a. In the first type, a blood clot blocks the brain’s blood b. In the second type of stroke, one supply slowly. People can experience this type of stroke of the tubes that supply blood in two ways. For example, an old person gets up from to the brain bursts suddenly. sleep with an inability to speak. This keeps worsening This could be because of high in the next few hours. He will reach a state when she blood pressure or some weak- cannot even move her arm, then legs, etc. This usually ness in its wall. The person happens only the left or the right side of the body, not both. suddenly loses consciousness Unconsciousness is also typical of a stroke. and collapses. The chances of death in such patients areIn other people, the person gets a sudden feeling of weak- very high unless they reachness on one side of the face or hand or leg. And this keeps and get a good standard ofworsening. Usually, if the person survives the first two days, medical care in the first fewthe person gradually gets better and regains most – though hours of illness.not all – functions of different parts of his body. Treatment for strokes In both the illnesses, if the person is still alive and can swallow, give one tablet of Aspirin before sending her off to a hospital. To an un- conscious patient, put her in the Recovery position (see First Aid of Unconsciousness) and send her immediately to the hospital.
  • 11. 22-114. Polio and related illnessesPolio may affect the spinal cord (and brain as discussed earlier). The virus enters throughour food and water into the intestines and slowly reaches the brain and spinal cord.There are other similar illnesses also that behave like Polio. (We will learn more aboutPolio when we learn Immunisation Diseases).There is no cure for Polio once it has attacked the body. So, children must be given Polio drops to drink to prevent them from getting Polio. Leg affected by Polio virus5. Head injuryFalls & other accidents can lead to injury of the brain inside. This is called head injury. Also, RoadTraffic Accidents (RTAs) are common and injuries to the brain can be serious enough to lead todeath. Signs to look out for in a head injurya. Loss of Consciousness: One of the most important b. Abnormal behaviourthings to note is loss of consciousness. Even if the person is Another important sign to conscious when you get to see note is the presence of signs her, if she or other people like irrelevant talking, ag- present at the accident site say gressive behaviour, fits, that she had lost consciousness unconsciousness, etc. Diffi- for some time, it is serious culty in swallowing or talk- enough. If so, ENSURE that the ing after a head injury is person is close to a hospital /sur- another danger sign. geon for at least 24 hours afterthe accident. There are two other signs that you can test to predict danger: If present, SEND TO A HOSPITAL IMMEDITELY.* Shine a torch in one eye Check for brain damage * Take a key or a blunt pointedat a time and check the thing and rub it hard on the solespupil size and its move- brain of the injured person’s feet. Rubment. Slow movement or damage from the heel to base of the big toea lack of movement in (when toe via the base of the small toe. If onethe pupil is dangerous. goes up) or both the big toes bend up-Also, if the size of the two wards towards the head, it tellspupils is different, it can be us that the brain signals are notdangerous. Quickly send reaching the legs. Once again, normalthe patient to a hospital. (when toe send the patient to the hospital at goes down) the earliest. IMPORTANT Such patients may need an operation on the brain at the earliest. Do not allow them to eat or drink anything and rush them to a hospital that has facilities for operations.
  • 12. 22-12 Spinal 6. Spinal cord injury Cord The Spinal Cord may get injured if the spine or backbone gets injured in an accident or a fall from the roof/tree. Depending on how badly the injury has taken place, the spinal cord may be partially or fully cut. What happens in A different kind of paralysis spinal cord injury? Unlike the inability to move legs- paraly- The person may be unable to sis — that can also happen in a head (brain) move her legs. She may lose con- injury, here the legs when moved by an- trol over her bladder and lose the other person feel like soft rubber that is capacity to hold back her shit and loose. On the other hand, paralysis (pa – urine. If it is a man, he may be ra- li-sis) due to head injury makes the legs and arms very stiff when someone tries to unable to perform sex with his move them. partner.If the person does not recover any movement of the toes or feet at the end of two full days of theinjury, there is little hope for it later. In most cases however, the Spinal Cord does not get fully cutand some movement does recover very early. Treatment for Spinal Cord Injury First Aid is all that one must try at the health work- er’s level. Refer such a person to a hospital but make sure that the person’s spine is not damaged further while sending to a hospital. If the injury is in the neck, place sand bags on both sides of the neck to prevent it from turning. For lower injuries of the spine, see the section on First Aid on Fractures. 7. Mental illnessesIf one goes by definitions provided by doctors who specialise in mental illnesses, these illnessesare common. Three types of mental illnesses are commonly seen : 1. Anxiety (ang-zye-ti) 2. Depression (dep-re- shun) 3. Psychosis (sy-ko-sis) 1. AnxietyAnxiety means that someone is extra worried about one or more thingsin life. It could simply be due to poverty or an illness of a relative oroneself, or due to an important event coming up.Anxious people are: unable to sleep properly may have palpitations (conscious of her heart beats) hands may tremble. The pulse may be higher than ninety per minute.What to do in people with anxiety? Talking to the person and assuring her of support from you and other people around her is very helpful. Ensuring that she gets a noiseless place to sleep also is important. For a week or so, you may help her sleep by asking her to take CHLORPHENIRAMINE. If the person is unable to sleep well for more than a week despite your help, refer her to a doctor.
  • 13. 22-13 2. DepressionDepression means that a person is unusually sad. Although many peo-ple may feel sad due to the passing away of a person or by failure, theyget back to work very fast and can be made to get interested in day today work.What are the signs of depression?People who do not get back to work, are unable to mix around, keep to them-selves and do not cook or take bath when left to themselves are said to be havingDepression. They may oversleep and show no interest in getting out of bed. unusual sadnessVery often they are seen to keep crying and weeping for long periods. is depression Such a patient also needs to be talked to. Make friends with her and gradu- ally try to talk more and more with her. Try to make her speak out her fears and her problems. Without speaking much or commenting whether what she thinks is right or wrong, try to understand her feelings and then try to engage her in some small work that may interest her. However, if the person talks about her desire to die using words like ‘ I wish I were dead’ or ‘I should have died along with so and so’ it is im- portant to refer the person to a doctor. Until then inform a person close to her to keep a watch on her and take care of her as such people may actually commit suicide. Doctors can give medicines that may help pa- Suicidal thoughts tients with Depression to see more positively and get over the suicidal tendency. 3. PsychosisUsually a person who is seen as ‘mad’ is actually suffering from Psychosis.A person is said to have psychosis if he / she behaves abnormally : o like undressing in public o talking on topics without any reference o talking to no one in particular o very fearful or suspicious of someone without reason o claims to see and hear things that others cannot. Abnormal behaviour are signs of psychosis. Refer to a doctor! bizarre behaviour seeing & hearing things talking to self (like undressing in when there are none public)Why psychosis happens? What to do in Psychosis ?Psychosis may be temporary due to medicines or Refer all such patients to a doctordrugs or even due to an illness. These people are who has specialised in mental ill-likely to get better when the illness or the effect of nesses – a psychiatrist. However,the drug wears off. However, those who have such if the person has a tendency to bebehaviour since long will take a long time to im- violent or hurt some one else,prove but require regular medicines and counsel- send enough people with her to take care ofling by someone trained for such a thing. her and others who can be at risk.
  • 14. 22-14 Know the Answers Eye Diseasesa. Please fill in the blanks:1. Meningitis is due to an infection of the covering of the ___________.2. Signs of meningitis are ________________, _________________, ______________ and _______________________.3. To avoid meningitis among family members of a patient, we can _____________, ________________, and _____________________.4. Brain stroeks may happen because of __________________ or _______________ of the blood tubes going to the brains.5. If you find _________________________________________________ on shining a torch in the eye of a patient with head injury OR if the big toe goes _____________ when the sole of the foot is stroked, you must URGENTLY refer the patient to the hospital.b. Please mark if “right” or “wrong”:1. People with mental illnesses are mad.2. People with a fall from a tree may have liver injury because of which they cannot move their legs.3. If the pupil of the eye becomes small in both eyes when you shine a torch in a person with head injury, it is important to rush to the hospital.4. Brain strokes due to a clot in the blood supply may cause early death.5. BCG given to children can avoid TB of the meninges (covering of brain).