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Human Body Systems Project Nicholas Bien. Digestive System.

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1 Human Body Systems Project Nicholas Bien

2 Digestive System

3 Digestive System: Function The function of the digestive system is to convert the food we eat into smaller molecules that can be used for energy in cells. The unusable substances are then excreted from the body. http://img.webmd.com/dtmcms/live/webmd/consumer_assets/site_images/articles /health_and_medical_reference/digestive_disorders/yourdigestivesystem_Digestive System.jpg

4 Digestive System: Drawing

5 Digestive System: Mouth Digestion starts at the mouth. Food is broken down physically by chewing and chemically by enzymes in saliva. http://microbewiki.kenyon.edu/images/2/2d/ITeeth_mouth.jpg

6 Digestive System: Pharynx The pharynx (throat) the passage between the mouth and the esophagus. When food is swallowed, a flap called the epiglottis closes over the trachea (part of the respiratory system) to prevent choking. http://upload.wikimedia.org/wikipedia/commons/thumb/d/d4/Illu01_head_neck.jp g/250px-Illu01_head_neck.jpg

7 Digestive System: Esophagus The esophagus is a long tube extending from the pharynx to the stomach. Muscle movements (peristalsis) propel food down the tube into the stomach. http://www.prajnayoga.net/wp-content/uploads/2012/03/esophagus_front.jpg

8 Digestive System: Stomach The stomach is a sac-like organ with muscular walls that mix and grind food. The walls also secrete strong acids (gastric acid) and enzymes that further break down food. By the time the food leaves the stomach, it is an acidic, mostly liquid substance called chyme. http://www.umm.edu/graphics/images/en/19223.jpg

9 Digestive System: Small Intestine The small intestine moves food through over 20 feet of tubes through peristalsis. The small intestine is made up of three parts: In the duodenum, acids and enzymes continue to break down food. Bile, which helps to digest fats, is added to the food mixture. The lining of the jejunum absorbs amino acids, sugar, fatty acids, vitamins, and minerals into the blood stream. These molecules soak into the tiny projections (villi) of the jejunum. The ileum has more villi that absorb the remaining nutrients, especially salts and vitamin B. http://microbewiki.kenyon.edu/images/c/c3/Small_inte stine.jpg

10 Digestive System: Large Intestine Billions of bacteria inhabit 5 feet of the large intestine and aid in digestion. Excess water is absorbed into the blood and the waste is mixed with dead cells to form feces. The large intestine is made up of five parts: The cecum is connected to the ileum of the small intestine. The ascending colon and the transverse colon absorb water and salts. The descending colon stores food before it enters the sigmoid colon. The loop-like sigmoid colon connects to the rectum. http://home.comcast.net/~wnor/colon.jpg

11 Digestive System: Rectum Solid waste is stored in the rectum before it is excreted. The rectum is about 5 inches in length. http://www.jacksonregionalsurgery.com/Resources/10502/FileRepository//Rectal- Surgery.jpg

12 Digestive System: Anus When the rectum becomes full, waste is excreted through the anus. The anus is the end of the gastrointestinal tract. http://www.cancerresearchuk.org/prod_consump/groups/cr_common/@cah/@gen /documents/image/crukmig_1000img-12111.jpg

13 Digestive System: Salivary Glands The salivary glands, which are located in the mouth, secrete saliva for digesting food. In humans, there are three main salivary glands: the parotid gland, the sublingual gland, and the submandibular gland. http://www.baileybio.com/plogger/images/anatomy___physiology/12._powerpoint _-_digestive_system/salivary_glands_2.jpg

14 Digestive System: Liver The liver makes bile, which it then secretes through the cystic duct into the gallbladder. The liver also purifies the blood that contains nutrients coming from the small intestine. http://www.umm.edu/graphics/images/en/19261.jpg

15 Digestive System: Gallbladder When food is eaten, the gallbladder contracts and pumps bile into the duodenum for use in digesting fats. The bile travels down the common bile duct into the duodenum. http://medicalimages.allrefer.com/large/digestive-system-organs.jpg

16 Digestive System: Pancreas The pancreas is a gland organ that secretes enzymes whose destination is the duodenum. The enzymes reach the duodenum through the pancreatic duct. http://miamitransplant.com/images/pancreas02.jpg

17 Digestive System: Sphincters Sphincters are circular muscles that regulate the passage of substances by expanding and contracting. In the digestive system, the primary sphincters are: The lower esophageal sphincter, which prevents acid from moving up from the stomach into the esophagus. The pyloric sphincter, which forms the boundary between the stomach and the small intestine. The ileocecal sphincter, which stops colon contents from entering the ileum. The internal and external anal sphincters, which regulate the excretion of feces from the body. http://studydroid.net/imageCards/0k/lg/card-21676774-front.jpg http://digestivedisease.uthscsa.edu/stomach2.jpg

18 Digestive System Alimentary Organs Gastrointestinal tract Continuous tube Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus Accessory Organs Aid in digestion Physical (chewing) Chemical (secretions) Teeth, tongue, gallbladder, salivary glands, liver, pancreas http://encyclopedia.lubopitko- bg.com/images/Accessory%20organs%20of%20digestion.jpg http://legacy.owensboro.kctcs.edu/gcaplan/anat2/notes/Image489.gif

19 Digestive System Physical Digestion Done by teeth, tongue, and muscles in the stomach Breaks food into smaller pieces Chemical Digestion Done by enzymes and acid in stomach and intestines Breaks food down into simpler molecules

20 Digestive System: Digestion of Carbs, Proteins, Lipids Carbohydrates Amylase in saliva and stomach breaks down starch into oligosaccharides Other enzymes such as lactase and sucrase in stomach and small intestine convert oligosaccharides into monosaccharides Proteins The enzyme pepsin in stomach breaks some of the peptide bonds Other enzymes such as trypsin in small intestine break down polypeptides into oligopeptides Amino peptidase and other enzymes convert oligopeptides into individual amino acids Lipids Lingual lipase in saliva begins digesting lipids In small intestine, bile helps break down fats Pancreatic lipase converts fats into monoglycerides Lipid digestion is most difficult because lipids not water-soluble

21 Digestive System: Crohn’s Disease Crohn’s Disease is an inflammatory disease of the gastrointestinal tract. The symptoms include abdominal pain, bloody stool, and ulcers anywhere from the mouth to the anus. There are an average of 7 cases per 100,000 people. The disease is slightly more common among women. Treatment options include anti- inflammatory therapies, biological therapies, or surgery to remove the affected area of the tract. http://www.healingwell.com/images/illustrations/crohns.gif

22 Digestive System: GERD Gastroesophageal Reflux Disease (GERD) is inflammation of the esophagus due to reflux of acidic contents from the stomach. It is caused by an incompetent lower esophageal sphincter. The symptoms include heartburn, acidic taste in the mouth, chest pain, abdominal pain, cough, and hoarseness. 10% of Americans experience GERD on a daily basis. The increasing prevalence is likely correlated to the obesity epidemic. Treatments include eating smaller and more frequent meals, weight loss, and acid-suppression with histamine blockers or proton-pump inhibitors. http://images.medicinenet.com/images/illustrations/gast roesophageal_reflux.jpg

23 Digestive System: Bibliography http://digestive.niddk.nih.gov/ddiseases/pubs/yrdd/ http://www.enchantedlearning.com/subjects/anatomy/digestive/ http://www.webmd.com/heartburn-gerd/your-digestive-system http://science.nationalgeographic.com/science/health-and-human- body/human-body/digestive-system-article/ http://science.nationalgeographic.com/science/health-and-human- body/human-body/digestive-system-article/ http://home.comcast.net/~wnor/largeintestine.htm http://classes.midlandstech.com/carterp/Courses/bio211/chap23/chap23.htm http://www.lrn.org/Content/Lessons/digestive.html http://www.mbc.edu/faculty/pdeeble/BIO151/Web/151Notes/Chapter%2017.ht m http://www.mbc.edu/faculty/pdeeble/BIO151/Web/151Notes/Chapter%2017.ht m http://www.livestrong.com/article/366300-the-digestion-of-carbohydrates- lipids-and-proteins/ http://www.livestrong.com/article/366300-the-digestion-of-carbohydrates- lipids-and-proteins/ http://www.mayoclinic.com/health/crohns-disease/DS00104 http://www.ccfa.org/what-are-crohns-and-colitis/what-is-crohns-disease/ http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001311/ http://www.mayoclinic.com/health/gerd/DS00967

24 Endocrine System

25 Endocrine System: Function The endocrine system is a system of glands that secrete hormones into the bloodstream. The hormones function to generate changes within cells. The system regulates functions such as metabolism, development, sleep, and mood. Exocrine glands such as sweat glands, salivary glands, and digestive glands excrete their products outside of the body. They are not part of the endocrine system. http://www.ama- assn.org/resources/images/atla s/endocrinesystematlas.gif

26 Endocrine System: Homeostasis Homeostasis (Greek for “standing still”) is the property of organisms to maintain a stable internal environment. Mechanisms such as positive feedback and negative feedback respond to cellular needs. Stable temperatures and stable pH levels are necessary for the proper functioning of enzymes. The endocrine system is the regulator of homeostasis. It secretes hormones in order to control cellular processes and maintain homeostasis.

27 Endocrine System: Negative Feedback The end product of a cellular pathway functions to switch off the pathway. Often, the end molecule binds to the allosteric site of an enzyme in the pathway, deactivating that enzyme and the pathway. In this way, the cell manages to avoid overproducing certain substances. For example, the hypothalamus secretes TRH, which causes the thyroid gland to secrete T4. The presence of T4 then “feeds back” to turn off the secretion of TRH in the hypothalamus. http://www.emc.maricopa.edu/faculty/farabee/bio bk/metabolfbk.gif

28 Endocrine System: Drawing

29 Endocrine System: Diabetes Diabetes mellitus is a disease characterized by high blood sugar due to the inability to break down glucose. Type 1 diabetes occurs when the pancreas fails to produce insulin. Insulin is a peptide hormone that moves glucose into cells for cellular respiration. Individuals with type 1 diabetes lack beta cells, the producers of insulin, in their pancreases. Type 1 diabetes accounts for about 10% of diabetes cases and begins most commonly in childhood. Type 2 diabetes is a problem not in the production of insulin but in its function. Individuals with type 2 diabetes have cells that have developed resistance to insulin. Their cells no longer respond properly to insulin. Type 2 diabetes accounts for about 90% of diabetes cases and is more likely in overweight individuals.

30 Endocrine System: Hyperthyroidism Hyperthyroidism, or “overactive thyroid,” is a disorder that occurs when the thyroid produces and secretes excessive amounts of thyroid hormone. Since thyroid hormones regulate the pace of nearly all cellular activities, an excess of thyroid hormones speeds up processes. Symptoms include weight loss, fast heart beat, anxiety, weakness, and fatigue. 2-5% of women in the United States have hyperthyroidism. Women are ten times more likely than men to have hyperthyroidism. Treatment options include antithyroid drugs, which inhibit thyroid hormone production, and beta blockers, which offset the anxiety and trembling side effects of hyperthyroidism. http://upload.wikimedia.org/wikipedia/commons/thumb/e/e 0/Triiodothyronine.svg/664px-Triiodothyronine.svg.png Triiodothyronine (T3) – a thyroid hormone

31 Endocrine System: Bibliography http://kidshealth.org/parent/general/body_basics/endocrine.html http://www.ama-assn.org/ama/pub/physician-resources/patient- education-materials/atlas-of-human-body/endocrine-system.page http://www.ama-assn.org/ama/pub/physician-resources/patient- education-materials/atlas-of-human-body/endocrine-system.page http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookendo cr.html http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookendo cr.html http://www.emedicinehealth.com/anatomy_of_the_endocrine_syst em/article_em.htm http://www.emedicinehealth.com/anatomy_of_the_endocrine_syst em/article_em.htm http://www.nlm.nih.gov/medlineplus/endocrinesystem.html http://www.hormone.org/Endo101/page3.cfm http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001350/ http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001356/ http://www.webmd.com/a-to-z-guides/hyperthyroidism-topic- overview http://www.webmd.com/a-to-z-guides/hyperthyroidism-topic- overview http://www.endocrine.niddk.nih.gov/pubs/Hyperthyroidism/

32 Excretory System

33 Excretory System: Function The function of the excretory system is to remove waste from the body. The waste products of chemical processes such as metabolism must be excreted from the body. The primary products for excretion are nitrogenous wastes such as ammonia, urea, and uric acid. The components of the excretory system are limited to those that function only for excretion. http://www.newyoungworld.com/images/body/excretory_system.jpg

34 Excretory System: Major Parts The two kidneys eliminate waste from the bloodstream and produce urine. They regulate: Volume of extracellular fluid Ion concentration in extracellular fluid pH of extracellular fluid Toxicity of extracellular fluid The uterers are two 10- to 12-inch tubes that connect each kidney to the urinary bladder. Valves prevent backflow of urine. The urinary bladder is an organ that stores urine from the kidneys before excretion through the urethra. The urethra carries urine from the urinary bladder to the outside of the body. It has a specific orientation for each gender. http://www.sci.sdsu.edu/class/bio100/Lect ures/Lect16/Image270.gif

35 Excretory System: Kidney Drawing

36 Excretory System: Nitrogenous Waste 1 nitrogen atom per molecule Amino groups are released when proteins are converted into carbohydrates. Ammonia is then formed by the oxidation of amino groups. Ammonia is toxic and must be excreted. Marine organisms excrete ammonia directly into water because they have no shortage of water. 2 nitrogen atoms per molecule Ammonia is converted into the less-toxic urea. Urea can be tolerated in higher concentration in the body. Mammals and amphibians excrete urea to conserve water. Urea is the primary waste product excreted in human urine. 4 nitrogen atoms per molecule. Uric acid is formed from urea. Uric acid requires more energy to make than urea. Uric acid is much less toxic than urea. Reptiles excrete uric acid because doing so requires very little water. Ammonia (NH 3 )Urea (CH 4 N 2 O)Uric acid (C 5 H 4 N 4 O 3 ) http://upload.wikimedia.org/wikip edia/commons/9/9b/Harns%C3% A4ure_Ketoform.svg http://upload.wikimedia.org/wikipedia/common s/3/3d/Harnstoff.svg http://0.tqn.com/d/che mistry/1/0/S/S/1/Amm onia.jpg

37 Excretory System: Nephron Drawing

38 Excretory System: Nephron Processes Filtration – Filtration of blood occurs in the renal corpuscles. Plasma in the glomeruli flows into Bowman’s capsules. Water, ions, salts, glucose, and ammonia are absorbed. Reabsorption – Reabsorption occurs when materials move from the renal tubules back into the blood in peritubular capillaries. The primary substances reabsorbed are water, glucose, sodium ions, and other ions. Secretion – Secretion occurs when substances move from capillaries into distal tubes and collecting tubes. Hydrogen ions, potassium ions, ammonia, and other toxic substances are secreted. Excretion – The fluid resulting from filtration, reabsorption, and secretion flows through the collecting duct to the uterers, destined to be excreted as urine. http://www.nsbri.org/humanphysspace/focus4/f 4-148.jpg

39 Excretory System: Kidney Stones Kidney stones result when salt crystals form around particles of foreign matter, such as bacteria. These stones prevent fluid from leaving the kidneys through the uterers. Symptoms include pain in the side or back and pain during urination. The yearly incidence of kidney stones in the United States is 0.5% of the population. 80% of those with kidney stones are men. Most smaller stones pass out of the body spontaneously through urine a few weeks after occurrence. Pain-relief is often necessary during stone excretion. Sometimes, surgery is necessary to remove larger stones. http://img.webmd.com/dtmcms/live/webmd/con sumer_assets/site_images/articles/health_and_m edical_reference/miscellaneous/kidney_stone.jpg

40 Excretory System: Nephritis Nephritis is inflammation of the nephrons in the kidney. Glomerulonephritis is inflammation of the glomeruli. Interstitial nephritis is inflammation of the spaces between the renal tubules. Nephritis can be caused by infection or by disorders that affect the major organs, such as lupus. Symptoms include decreased urine output, fever, drowsiness, vomiting, nausea, swelling, and weight gain. Nephritis can cause loss of a protein that stops blood from clotting, which can result in a stroke. About 4 in 100,000 people develop acute interstitial nephritis each year in the United States. There were 61,423 people with primary glomerulonephritis in the United States in 1996. Treatment includes a diet low in salt and fluid, as well as anti- inflammatory medications and corticosteroids.

41 Excretory System: Bibiliography http://www.sciencedaily.com/articles/e/excretory_system.htm http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookexcre t.html http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookexcre t.html http://biology.clc.uc.edu/courses/bio105/kidney.htm http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Excretor y_system.html http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Excretor y_system.html http://shs.westport.k12.ct.us/mjvl/anatomy/MandalaWeb/excretory.htm http://shs.westport.k12.ct.us/mjvl/anatomy/MandalaWeb/excretory.htm http://www.bio.miami.edu/dana/dox/nitrogenouswaste.html http://www.nsbri.org/humanphysspace/focus4/ep-urine.html http://www.rpi.edu/dept/chem-eng/Biotech- Environ/Projects00/memfilt/kidneys.htm http://www.rpi.edu/dept/chem-eng/Biotech- Environ/Projects00/memfilt/kidneys.htm http://www.webmd.com/kidney-stones/understanding-kidney- stones-basics http://www.webmd.com/kidney-stones/understanding-kidney- stones-basics http://www.nlm.nih.gov/medlineplus/ency/article/000464.htm

42 Immune System

43 Immune System: Function The function of the immune system is to protect the body from disease. The immune system identifies and attacks foreign invaders and substances that are harmful to the body. http://www.dynavax.com/images/immunesys.jpg

44 Immune System: Organs Bone Marrow (technically a tissue) – creates stem cells that differentiate into cells necessary to the immune system, such as white blood cells, B cells, and thymocytes. Thymus – operates mostly during adolescence to cause thymocytes to mature into T cells that can identify between “self” and “non-self.” Spleen – filters blood while its specialized cells, such as T cells, look for invaders Lymph nodes – filter lymph, a cellular fluid, and identifies foreign matter with specialized cells Adenoids – present only in children, looks for infection-causing material as it passes through the back of the nasal cavity Tonsils – trap bacteria and viruses that enter the body through the air http://images.emedicinehealth.com/imag es/healthwise/medical/hw/n5551350.jpg

45 Immune System: Recognition Antigens are foreign substances that enter the body. Certain B lymphocyte cells recognize specific antigens. B cells produce antibodies that attach to antibodies. T cells then use antibodies to locate antigens and destroy them. http://www.dynavax.com/images/immunesys.jpg

46 Immune System: Innate & Acquired Immunity Innate Immunity Have from birth Passed on to offspring General Examples: Skin Cough reflex Mucus Stomach acid Acquired (Adaptive) Immunity Changes over time Not passed on Specific Examples: B lymphocytes T lymphocytes Specific antibodies http://www.seakylin.net/wp- content/uploads/2012/11/rituxan1.jpg

47 Immune System: Active & Passive Immunity Active Immunity Antibodies created in own body Permanent Examples: People become immune from chicken pox after becoming sick once Vaccinations for the flu create active immunity Passive Immunity Antibodies created elsewhere Temporary Examples: Developing fetus receives antibodies from mother Injections of antibodies for hepatitis or tetanus

48 Immune System: Humoral & Cell-mediated Immunity Humoral Immunity B lymphocytes primarily involved Pathogens in body fluid recognized Antibodies specific to antigen Cell-mediated Immunity T lymphocytes primarily involved Invaded cells and tumor cells recognized Antibodies not specific http://jeeves.mmg.uci.edu/immunology/Architecture/La rgeLymph.jpg

49 Immune System: B & T Lymphocytes B Lymphocytes Mature in bone marrow Secrete antibodies Slower to respond T Lymphocytes Mature in thymus gland Attack antigens directly Faster to respond Originate in bone marrow Can recognize invaders the second time http://upload.wikimedia.org/wikipedia/commons/thumb/d/df/T- dependent_B_cell_activation.png/300px-T-dependent_B_cell_activation.png

50 Immune System: Antibiotics Antibiotics affect bacteria by: Destroying the cell walls Destroying the plasma membrane Disrupting DNA replication Disrupting protein synthesis Viruses, however, use their hosts’ cellular processes to reproduce, so antibiotics are ineffective. Antiviral drugs affect viruses by: Disrupting DNA synthesis in host cells Disrupting reverse transcriptase Inhibiting protease http://www.ou.edu/class/phei dole/General%20Bacteria.jpg http://facstaff.cbu.edu/~seise n/Viruses_files/image003.jpg

51 Immune System: HIV/AIDS Acquired immunodeficiency syndrome is a disorder causes by the human immunodeficiency virus. The virus severely and chronically weakens the immune system. HIV is spread through sexual contact, blood transfer, pregnancy, or breastfeeding. Symptoms include a fever-like illness complete with fever, soreness, rash, headache, joint pain, and sore throat. In the United States, about 1.2 million people are infected with HIV. 17,000 people dies each year in the United States. Worldwide, about 33 million people are infected. There is no cure for HIV/AIDS, but certain drugs (such as reverse transcriptase inhibitors) can control the virus. http://ronewoldcnews.files. wordpress.com/2012/06/wo rld_aids_day_ribbon.png

52 Immune System: Lupus Lupus is a disorder in which the immune system mistakenly attacks the bodies own necessary tissues. Lupus can damage joints, the skin, the kidneys, the heart, the lungs, blood vessels, and the brain. The cause of lupus has not been determined, but the disorder has been linked to the use of certain medications. Some of the symptoms of lupus include rash on cheeks, red patches on skin, oral ulcers, seizures, and sensitivity to sunlight. The number of people in the United States who have lupus is estimated to be between 270,000 and 1.5 million. There is no cure for lupus, but the severity f the symptoms may be decreased by treating them individually.

53 Immune System: Bibliography http://kidshealth.org/parent/general/body_basics/immune.html http://uhaweb.hartford.edu/bugl/immune.htm http://medicalcenter.osu.edu/patientcare/healthcare_services/infec tious_diseases/immunesystem/Pages/index.aspx http://medicalcenter.osu.edu/patientcare/healthcare_services/infec tious_diseases/immunesystem/Pages/index.aspx http://www.niaid.nih.gov/topics/immunesystem/Pages/default.aspx http://www.nlm.nih.gov/medlineplus/ency/article/000821.htm http://curiosity.discovery.com/question/antibiotics-immune-to- viruses http://curiosity.discovery.com/question/antibiotics-immune-to- viruses http://www.mayoclinic.com/health/hiv-aids/DS00005 http://www.diseasesandconditions.net/lupus.html http://www.niams.nih.gov/Health_Info/Lupus/lupus_ff.asp

54 Nervous System

55 Nervous System: Function The function of the nervous system is to transmit signals throughout the body. The nervous system receives information in the form of sensory input or internal condition, processes that information, and then responds by stimulating a change in the body. http://stevegallik.org/sites/histolog yolm.stevegallik.org/images/nervou ssystem2.jpg

56 Nervous System: CNS & PNS Central Nervous System Processes information Coordinates activity Consists of: Brain Spinal cord Peripheral Nervous System Connects CNS to outer body Consists of: Nerves Ganglia http://www.umm.edu/graphics/images/en/ 8679.jpg

57 Nervous System: Neuron Drawing

58 Nervous System: Reflex Arc Drawing

59 Nervous System: Brain Drawing

60 Nervous System: Impulses When a neuron is not transmitting a signal, the electric potential difference across its membrane (its membrane potential) is between -60 and -80 mV. This is called its resting potential. At this state, there are 30 times more K + ions inside the cell than outside, and there are 10 times more Na + outside the cell than inside. Overall, there is more positive charge outside. http://faculty.irsc.edu/FACULTY/TFischer/AP1/rest ing%20membrane%20potential2.jpg

61 Nervous System: Impulses A stimulus triggers depolarization, which if it reaches a certain threshold can create an action potential. This action potential occurs when a decrease in membrane potential causes voltage-gated K + channels and voltage-gated Na + channels to open. http://www.bio.miami.edu/tom/courses/protected/ECK/CH05/figure-05-22.jpg

62 Nervous System: Impulses At the height of the action potential, there membrane potential is positive rather than negative. During the falling phase, the membrane potential returns to its original level. During this period, the refractory period, another stimulus cannot be transmitted. http://www.mindcreators.com/Images/NB_IonFlow.gif

63 Nervous System: Neurotransmitters Neurotransmitters are released by neurons into the synaptic cleft. Neurotransmitters bind to receptors on the postsynaptic membrane to stimulate an action potential. Neurotransmitters are an example of a chemical messengers that accompanies a membrane potential. Excitatory postsynaptic potentials (EPSPs) are depolarizations that occur when neurotransmitters activate ligand-gated ion channels that allow both K + and Na + ions to pass. Inhibitory postsynaptic potentials (IPSPs) occur wen neurotransmitters active ligand-gated K + channels only, which causes a hyperpolarization of the postsynaptic membrane. http://capone.mtsu.edu/studskl/s ynapse2.GIF

64 Nervous System: Multiple Sclerosis Multiple sclerosis (MS) is a disease that involves damage to the myelin sheathes surrounding axons in neurons. MS limits communication between cells of the brain and spinal cord. Symptoms include loss of sensitivity, numbness, muscle spasms, difficulty in speech, vision problems, and cognitive impairment. The number of people per 100,000 with MS in a given country varies from 2 to 150. MS is more common farther from the equator. MS is three times more common in women than in men. There is no cure for MS, but several drugs have been developed to prevent MS attacks and prevent disability.

65 Nervous System: Alzheimer’s Disease Alzheimer’s disease is a type of dementia (a significant loss in cognitive ability) associated with tangles and plaque in the brain. Alzheimer gradually worsens and eventually results in death. Symptoms include memory loss, confusion, irritability, and mood swings. About 27 million people worldwide have Alzheimer’s, but the proportion of sufferers is likely to increase to 1 in 85 by 2020. There is no cure for Alzheimer’s, and alleviation is primarily concerned with caregiving, including physical and psychological assistance.

66 Nervous System: Bibliography http://www.emc.maricopa.edu/faculty/farabee/biobk/biobooknerv.htm l http://www.emc.maricopa.edu/faculty/farabee/biobk/biobooknerv.htm l http://hes.ucfsd.org/gclaypo/nervoussys.html http://faculty.washington.edu/chudler/chnt1.html http://people.eku.edu/ritchisong/301notes2.htm http://webspace.ship.edu/cgboer/actionpot.html http://faculty.washington.edu/chudler/ap.html http://www.cliffsnotes.com/study_guide/Reflexes.topicArticleId- 277792,articleId-277641.html http://www.cliffsnotes.com/study_guide/Reflexes.topicArticleId- 277792,articleId-277641.html http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%201 02/bio%20102%20lectures/nervous%20system/neurons.htm http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%201 02/bio%20102%20lectures/nervous%20system/neurons.htm http://www.nlm.nih.gov/medlineplus/multiplesclerosis.html http://www.medicalnewstoday.com/articles/37556.php http://www.alz.org/alzheimers_disease_what_is_alzheimers.asp http://www.nia.nih.gov/alzheimers/publication/alzheimers-disease- fact-sheet http://www.nia.nih.gov/alzheimers/publication/alzheimers-disease- fact-sheet


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