nickHumanBodySystemsProject

Report
Human Body
Systems Project
Nicholas Bien
Digestive System
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
Digestive System: Drawing
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
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
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
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
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
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
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//RectalSurgery.jpg
Digestive System: Anus
• When the rectum becomes full, waste is excreted through the
anus.
• The anus is the end of the gastrointestinal tract.
http:[email protected][email protected]
/documents/image/crukmig_1000img-12111.jpg
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
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
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
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
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://digestivedisease.uthscsa.edu/stomach2.jpg
http://studydroid.net/imageCards/0k/lg/card-21676774-front.jpg
Digestive System
Alimentary Organs
• Gastrointestinal tract
• Continuous tube
• Mouth, pharynx,
esophagus, stomach,
small intestine, large
intestine, rectum, anus
http://legacy.owensboro.kctcs.edu/gcaplan/anat2/notes/Image489.gif
Accessory Organs
•
•
•
•
Aid in digestion
Physical (chewing)
Chemical (secretions)
Teeth, tongue,
gallbladder, salivary
glands, liver, pancreas
http://encyclopedia.lubopitkobg.com/images/Accessory%20organs%20of%20digestion.jpg
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
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
Lipids
• 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
• 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
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 antiinflammatory therapies, biological
therapies, or surgery to remove the
affected area of the tract.
http://www.healingwell.com/images/illustrations/crohns.gif
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
Digestive System: Bibliography
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•
•
•
•
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-humanbody/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.livestrong.com/article/366300-the-digestion-of-carbohydrateslipids-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
Endocrine System
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.amaassn.org/resources/images/atla
s/endocrinesystematlas.gif
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.
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
Endocrine System: Drawing
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.
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
Triiodothyronine (T3) – a thyroid hormone
hyperthyroidism.
• Women are ten times more likely than
men to have hyperthyroidism.
• Treatment options include antithyroid
drugs, which inhibit thyroid hormone
http://upload.wikimedia.org/wikipedia/commons/thumb/e/e
0/Triiodothyronine.svg/664px-Triiodothyronine.svg.png
production, and beta blockers, which
offset the anxiety and trembling side
effects of hyperthyroidism.
Endocrine System: Bibliography
• http://kidshealth.org/parent/general/body_basics/endocrine.html
• http://www.ama-assn.org/ama/pub/physician-resources/patienteducation-materials/atlas-of-human-body/endocrine-system.page
• 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.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-topicoverview
• http://www.endocrine.niddk.nih.gov/pubs/Hyperthyroidism/
Excretory System
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.
http://www.newyoungworld.com/images/body/excretory_system.jpg
• The components of the excretory
system are limited to those that
function only for excretion.
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
Excretory System: Kidney Drawing
Excretory System: Nitrogenous Waste
Ammonia (NH3)
Urea (CH4N2O)
Uric acid (C5H4N4O3)
• 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.
http://0.tqn.com/d/che
mistry/1/0/S/S/1/Amm
onia.jpg
http://upload.wikimedia
.org/wikipedia/common
s/3/3d/Harnstoff.svg
http://upload.wikimedia.org/wikip
edia/commons/9/9b/Harns%C3%
A4ure_Ketoform.svg
Excretory System: Nephron Drawing
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
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
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 antiinflammatory medications and corticosteroids.
Excretory System: Bibiliography
• http://www.sciencedaily.com/articles/e/excretory_system.htm
• 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://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/BiotechEnviron/Projects00/memfilt/kidneys.htm
• http://www.webmd.com/kidney-stones/understanding-kidneystones-basics
• http://www.nlm.nih.gov/medlineplus/ency/article/000464.htm
Immune System
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
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
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
Immune System: Innate &
Acquired Immunity
Innate Immunity
Acquired (Adaptive) Immunity
• Have from birth
• Passed on to offspring
• General
• Changes over time
• Not passed on
• Specific
• Examples:
• Examples:
•
•
•
•
• B lymphocytes
• T lymphocytes
• Specific antibodies
Skin
Cough reflex
Mucus
Stomach acid
http://www.seakylin.net/wpcontent/uploads/2012/11/rituxan1.jpg
Immune System: Active &
Passive Immunity
Active Immunity
Passive Immunity
• Antibodies created in
own body
• Permanent
• Antibodies created
elsewhere
• Temporary
• Examples:
• Examples:
• People become immune
from chicken pox after
becoming sick once
• Vaccinations for the flu
create active immunity
• Developing fetus receives
antibodies from mother
• Injections of antibodies for
hepatitis or tetanus
Immune System: Humoral &
Cell-mediated Immunity
Humoral Immunity
Cell-mediated Immunity
• B lymphocytes primarily
involved
• Pathogens in body fluid
recognized
• Antibodies specific to
antigen
• T lymphocytes primarily
involved
• Invaded cells and tumor
cells recognized
• Antibodies not specific
http://jeeves.mmg.uci.edu/immunology/Architecture/La
rgeLymph.jpg
Immune System: B & T
Lymphocytes
B Lymphocytes
T Lymphocytes
• Originate in bone marrow
• Can recognize invaders the
second time
• Mature in bone marrow
• Secrete antibodies
• Slower to respond
• Mature in thymus gland
• Attack antigens directly
• Faster to respond
http://upload.wikimedia.org/wikipedia/commons/thumb/d/df/Tdependent_B_cell_activation.png/300px-T-dependent_B_cell_activation.png
Immune System: Antibiotics
• Antibiotics affect bacteria by:
•
•
•
•
Destroying the cell walls
Destroying the plasma membrane
Disrupting DNA replication
Disrupting protein synthesis
http://www.ou.edu/class/phei
dole/General%20Bacteria.jpg
• 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://facstaff.cbu.edu/~seise
n/Viruses_files/image003.jpg
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
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.
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://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-toviruses
• 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
Nervous System
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
Nervous System: CNS & PNS
Central Nervous System
Peripheral Nervous System
• Processes information
• Coordinates activity
• Consists of:
• Connects CNS to outer
body
• Consists of:
• Brain
• Spinal cord
• Nerves
• Ganglia
http://www.umm.edu/graphics/images/en/
8679.jpg
Nervous System: Neuron Drawing
Nervous System: Reflex Arc Drawing
Nervous System: Brain Drawing
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
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
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
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
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.
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.
Nervous System: Bibliography
• 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.topicArticleId277792,articleId-277641.html
• 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-diseasefact-sheet

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