Pathology

1
Pathology

• Diseases and Defenses

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Section One

• Pathogens

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Disease

• Disease is a condition in which the body or one
  of its parts is not functioning normally.
• Pathogens are the agents that cause disease.
• Parasites cause many different diseases. They
  are pathogens.
• A parasite is an organism or a virus that is
  dependent on another organism (the host) and
  causes damage in the process.
• Lets look at some of the parasites that affect
  humans.

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Parasites

• Parasites can be passed from one person to
  others.
• Parasites that invade the body can cause
  infections.
• Lets look at some of the parasites that can
  cause infectious diseases

5
Bacteria

• Most of these one-celled protists are extremely
  small and some are pathogenic.
• They have a variety of shapes and sizes.
• Bacteria usually have one of three general
  shapes
• Round (cocci)
• Coil-shaped (spirilla)
• Rod-shaped (bacilli)

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Cocci

• Some cocci bacteria can cause rheumatic fever,
  gonorrhea, scarlet fever and many other diseases.

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Bacilli

• Some bacilli bacteria can cause tetanus,
  diphtheria and many other diseases.

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Spirilla

• Some spirilla bacteria can cause Asiatic cholera
  and syphilis.

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Bacterial Growth

• What conditions favor the growth of bacteria that
  invade the body? Think about it!
• In the laboratory, bacteria grow on nutrients in
  petri dishes to form colonies that you can see.
• One bacterium can produce a colony of millions of
  identical bacteria.
• With the proper living conditions, bacteria can
  divide every 20 to 60 minutes.

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Bacterial Growth

• Bacterial growth increases as temperature
  increases up to an optimal temperature of 38C.
• The rate of bacterial growth is zero at 5C and
  50C.
• Bacterial growth is greatest when the amount of
  light is low or zero (absolute dark).
• Bacterial growth is also dependent upon water
  moist conditions are best.
• The amount of available nutrients also affects
  the growth rate more concentrated (higher)
  nutrient levels promotes more growth.

11
Information

• The interior of the human body is warm, dark,
  very moist and has a concentrated food supply.
• Based on this information and what we discovered
  on the previous slide, you can conclude that when
  bacteria enter the body they often grow rapidly.

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Information

• The optimum conditions for the growth of most
  bacteria are found in the interior of the human
  body.
• Some bacteria destroy body cells.
• Other bacteria cause harm by secreting toxins
  (poisonous chemicals).
• Food poisoning and tetanus are examples of
  diseases caused by toxins.
• Lets look at viruses next

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Viruses

• Viruses are so small that you cannot see them
  with ordinary light microscopes.
• Some viruses can cause colds, measles, mumps,
  influenza, polio and other diseases.
• Some scientists do not consider viruses to be
  living. They do not contain protoplasm and
  depend upon other living organisms to reproduce.

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Viruses

• This is how viruses enter the body
• By inhalation.
• By ingestion.
• Through a wound.
• Viruses travel in the body until they reach a
  specific type of cell.
• Different viruses attack different cells.
• Some viruses enter the cells. Others attach
  themselves to the surface of a cell.

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Viral Infection

• Some viruses inject their nucleic acid (either
  DNA or RNA) into a cell.
• The viral nucleic acid directs the infected cell
  to manufacture more viruses.
• As many as 100 viruses can be produced.
• The virus also directs the cell to produce an
  enzyme that breaks the cell open.
• This kills the cell and releases new viruses.
• Many more viruses can now attack other cells.
• This is how a viral infection spreads.

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Protozoa

• Protozoa are one-celled animals that cause
  malaria and dysentery.

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Fungi

• Fungi are organisms that lack chlorophyll.
• They can cause ringworm, athletes foot and lung
  infections.

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Worms

• Several species of nematodes (round worms) and
  annelids (segmented worms) cause disease.
• Hookworm, tapeworm and trichinosis are examples.

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Parasites

• How do parasites enter the body?
• Bacteria and fungi typically enter through cuts
  in the skin.
• Viruses, bacteria and some kinds of fungi spores
  can be inhaled.
• Bacteria and protozoa can enter with our water.
  Bacteria, fungi and worms can enter with our
  food.
• Lets examine a parasite the enters the body in
  this third manner.

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Tapeworm

• There are two main parts to a tapeworm
• The head with hooks and suckers.
• Many small square sections.
• A tapeworm grows within the host by adding new
  sections behind its head.
• It can become ten meters long.
• Mature sections containing self-fertilized eggs,
  break off and leave the host during excretion.
• The next host, a pig or a cow, may eat the
  section with its food.

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Tapeworm

• The next host, a pig or a cow, may eat the
  section with its food.
• Larvae hatch from the eggs and burrow into the
  animals muscles to form cysts.
• Each cyst contains a fully developed tapeworm
  head.
• Tapeworms enter the human body when they are
  eaten.
• If infected meat is not properly cooked,
  tapeworms emerge from the cysts as the meat
  passes through the intestines.
• Tapeworms have no digestive system. They absorb
  food directly from the digested material in the
  intestines.

22
Review

• Some bacteria, viruses, protozoa, fungi and worms
  are parasites that cause infectious diseases.
• Bacteria grow best in warm, dark, moist places
  that have concentrated nutrients.
• Parasites, such as tapeworms, can have more than
  one host.
• Viruses direct affected cells to produce more
  viruses.
• Fungi cause skin infections.

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Select The Letter Of The Correct Answer From The
List Below
A. infectious D. host B. bacterial E. virus C. genetic F. fungi

• A parasite that infects the body causes a(n)
  __________________ disease.
• A parasite can have more than one
  _________________.
• Skin infections are most frequently caused by
  __________________.
• A(n) __________________ reproduces by directing
  an invaded cells genetic material.

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Answers
infectious

• A parasite that infects the body causes a(n)
  __________________ disease.
• A parasite can have more than one
  _________________.
• Skin infections are most frequently caused by
  __________________.
• A(n) __________________ reproduces by directing
  an invaded cells genetic material.

host
fungi
virus
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Section Two

• The Bodys Defenses

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The Three Lines of Defense

• How does the body fight off pathogens?
• There are three lines of defense.
• First Line Unbroken Skin
• The skin acts as a barrier to pathogenic
  organisms.
• Second Line White Blood Cells
• A phagocyte is a type of white blood cell that
  destroys pathogens after they invade the body.
• Third Line The Immune System
• The immune system produces chemicals that
  deactivate pathogens in the body. The immune
  system is most important when there are more
  pathogens than the phagocytes can destroy.

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Examples

• Unbroken skin is the line of defense that would
  protect you against bacteria that grow in shoes.
• Unbroken skin is also the line of defense that
  would defend against soil bacteria touched while
  gardening.
• White blood cells would be the line of defense
  that fights bacteria that enter a small cut on
  your finger.
• The immune system would be the line of defense
  that would fight an invasion by millions of
  measles viruses.

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Information

• Fungi often compete with bacteria for nutrients.
• Fungi produce antibodies to inhibit or kill
  bacteria.
• Refined antibodies are used to inhibit or kill
  bacteria in an infected person.

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Antibiotics

• Antibiotics kill or inhibit dividing bacteria.
  Why arent antibiotics useful for killing
  viruses? Think about it!
• Remember what a virus is a nucleic acid
  surrounded by a protein coat. It is not a cell
  and therefore does not divide. It enters a
  living cell to make more viruses.
• Bacteria are cells and reproduce by cell
  division.
• Since viruses function only in living cells, the
  only way to chemically destroy them is to kill
  infected cells. This method destroys too many
  cells.

Virus
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Viruses

• Since antibiotics are ineffective in destroying
  viruses, how do you suppose the body fights
  viruses?
• A) By the immune system and white blood cells.
• B) By digestion in the stomach.
• C) Competition from bacteria kills them.
• D) Body heat destroys them.

The second and third lines of the bodys defenses
are designed to destroy all types of pathogens.
Your body heat is too low to kill a virus.
Answer A
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Immune System

• Antigens are foreign substances in the blood.
  Antigens have special shapes. They are found on
  the surfaces of viruses or bacteria.
• Lymphocytes are white blood cells with antibodies
  that interact with antigens.
• The interaction causes the lymphocyte to grow and
  divide.
• Memory cells rapidly respond to the antigen if it
  is encountered again.
• Plasma cells secrete antibodies that attack
  antigens.
• Lets examine how antibodies interact with
  antigens.

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Antibodies

• Antibodies form weak bonds with antigens.
• Antibodies can bond with two antigens.
• This causes clumping (sticking together) of the
  antigens and antibodies.
• The antigen-antibody clump can then be engulfed
  by a white blood cell called a phagocyte.

Clumping
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Information

• Immunity is the ability to resist and fight off
  infection.
• In the body, immunity is due to the presence of
  antibodies and lymphocytes.
• After a pathogen is destroyed, memory cells
  remain in the body.
• These cells, as well as free (unattached)
  antibodies, attack pathogens that can invade the
  body in the future.

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Immunity

• There are two ways to become immune to a disease
  without catching the disease.
• One way is to stimulate antibody formation in the
  body by injecting it with dead or weakened germs.
  This is called active immunity.
• Another way is to inject antibodies into the
  blood. This is called passive immunity because
  the body does not produce its own antibodies.
• Giving an individual immunity without catching
  the disease is called vaccination.

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Review

• These are the three lines of defense against
  disease
• Unbroken skin.
• White blood cells.
• Immune system.
• Antibodies inhibit or destroy bacteria.
• Antigens are any foreign matter that enters the
  body.
• Antibodies are chemicals that bond with the
  special shapes of antigens.

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Review

• White blood cells called lymphocytes attach to
  specific antigens.
• Lymphocytes divide to form memory cells and
  plasma cells.
• Plasma cells release antibodies.
• Antibodies attach to antigens and cause clumping.

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Select The Best Matching Choice

• Antibody

Answer Column Has plasma cells A red blood cell First line of defense Any foreign matter Engulfs clumps Inhibits bacteria Has antigens Attaches to antigens
Correct Answer H

• Antigen

Correct Answer D

• Antibiotic

Correct Answer F

• Unbroken skin

Correct Answer C

• Virus

Correct Answer G

• Phagocyte

Correct Answer E
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Section Three

• Genetic Disorders

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Information

• Mutations are changes in the genetic material
  that can be inherited.
• Mutations can cause genetic disorders.
• Sometimes mutations occur when gamete (sperm and
  egg) producing cells divide.
• Lets see how this occurs

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Gamete-Producing Cell

• The gamete-producing cell produces gametes with
  one-half the number of chromosomes (meiosis).
• The gametes pass the chromosomes to the next
  generation.

Chromosomes
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Nondisjunction

• Sometimes chromosomes do not separate properly
  during meiosis.
• This is called nondisjunction.

Chromosomes
Notice that the distribution of chromosomes is
uneven one gamete has more than the correct
number of chromosomes one has less than the
correct number.
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Downs Syndrome

• Observe the way Downs syndrome begins in this
  simplified gamete-producing cell.
• Nondisjunction results in two abnormal gametes
  C D.

Chromosomes
A
B
C
D
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Normal Fertilization

• Observe the fertilization of a normal female
  gamete (egg) by a normal male gamete (sperm).

Normal Gamete
Sperm
Egg
Normal Zygote
Correct Chromosome Number
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Downs Syndrome Fertilization

• Observe the fertilization of a abnormal female
  gamete (egg) by a normal male gamete (sperm).

Normal Gamete
Sperm
Egg
Abnormal Zygote
Incorrect Chromosome Number
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Normal vs. Abnormal Zygotes
Normal Zygote
Correct Chromosome Number
Abnormal Zygote
Incorrect Chromosome Number

• The zygote (fertilized egg) with the correct
  number of chromosomes develops into a normal
  individual.
• The zygote (fertilized egg) with the incorrect
  number of chromosomes develops into an individual
  with Downs syndrome.

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Information

• Nondisjunction of a chromosome pair (usually
  number 21) during egg formation causes the egg to
  receive an extra chromosome.
• The total chromosome number in victims of Downs
  syndrome is usually 47 as opposed to 46 in most
  people.
• About 0.2 of newborn children suffer from Downs
  syndrome.
• These children are mentally retarded and are
  highly susceptible to many diseases.

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Other Types of Chromosomal Mutations

• Sometimes chromosomes break and are altered.
• Lets look at some common chromosome alterations
  such as
• Deletions
• Translocations
• Inversions

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Deletions

• When a chromosome breaks, a piece can be lost.
  This form of alteration is a deletion.
• The genes in this deleted piece can be lost.
• In humans, one form of leukemia is associated
  with a deletion in the white blood cells.

(Deleted)
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Translocations

• Sometimes part of a chromosome transfers to
  another chromosome that is not homologous with
  it. This is a translocation.
• Translocations are found in parents who have many
  stillbirths, or in children who have serious
  defects in development.

(End Product)
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Review

• Chromosome mutations often occur when an egg
  (female gamete) or a sperm (male gamete) is
  produced.
• Nondisjunction, inversion, deletion and
  translocation can cause genetic disorders such
  as
• Stillbirth
• Sterility
• Leukemia
• However, not all mutations result in genetic
  disease.

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Inversions

• An inversion is another common alteration. A
  portion of a chromosome breaks out, and fuses
  back in its original position with its ends
  reversed.
• Inversion can cause sterility or defects in the
  offspring of affected individuals.

(End Product)
52
Select The Best Matching Choice

• Nondisjunction

Answer Column Fertilized egg Reversed segment Downs syndrome Lost chromosome piece Male gamete Translocation Meiosis Female gamete
Correct Answer C

• Inversion

Correct Answer B

• Deletion

Correct Answer D

• Sperm

Correct Answer E

• Egg

Correct Answer H

• Zygote

Correct Answer A
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Changes In A Gene Can Cause Problems

• Genes contain the genetic code for the production
  of specific enzymes.
• Enzymes regulate chemical reactions in a cell.
  Each step in a chemical reaction requires the
  presence of a specific enzyme.

Chemical A
Chemical B
Enzyme A
Chemical C
Enzyme B
End Product
Enzyme C
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Changes In A Gene Can Cause Problems

• If an enzyme is missing, the reaction stops.
• For example, if Enzyme B is missing, Chemical B
  cannot be converted into Chemical C.

Chemical A
Chemical B
Enzyme A
No Chemical C
No Enzyme B
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A Question

• What is the effect of missing Enzyme B?
• A) Chemical A builds up in the body.
• B) Chemical B builds up in the body.
• C) Chemical C is converted to the end product.
• D) End Product is produced in great amounts.

Answer B

• If Chemical B cannot be converted to Chemical C,
  then it remains in the cell. The reaction stops
  at Chemical B and no end product is produced.

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Phenylketonuria (PKU)

• Phenylketonuria (PKU) is an example of a disease
  caused by a defective gene.
• The accumulation of phenylalanine (an amino acid)
  causes PKU.
• A gene controls the synthesis of an enzyme that
  converts phenylalanine into tyrosine.
• Tyrosine is converted into skin and hair pigments
  as well as the hormone thyroxin.

Phenylalanine
Tyrosine
Enzyme
-Pigment -Thyroxin -Other Chemicals
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PKU

• PKU is caused by a defective gene that does not
  produce the enzyme responsible for the conversion
  of phenylalanine to tyrosine.
• Phenylalanine builds up in the blood and damages
  the nervous system.
• Phenylalanine eventually oxidizes to form
  phenylpyruvic acid.
• Phenylpyruvic acid is then excreted by the
  individual with PKU.
• Phenylpyruvic acid is not present in the blood of
  normal people.

X
Phenylalanine
Tyrosine
Enzyme
-Pigment -Thyroxin -Other Chemicals
Phenylpyruvic Acid
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Select The Best Matching Choice

• Enzyme

Answer Column Phenylalanine Phenylketonuria Regulates a reaction Hormone Codes, enzymes End product Gamete Phenylpyruvic acid
Correct Answer C

• PKU

Correct Answer B

• Amino Acid

Correct Answer A

• Gene

Correct Answer E

• Thyroxin

Correct Answer D

• PKU Excretion

Correct Answer H
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Section Four

• Noninfectious Diseases

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Noninfectious Diseases

• Noninfectious diseases are those that are not
  caused by pathogens.
• These are some of the causes of noninfectious
  diseases
• Genetic defects.
• Damage to the body.
• Poor or insufficient diet.
• Substances that promote allergic reactions.
• Congenital (birth) defects.

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Noninfectious Diseases

• The heart and the lungs are the sites frequently
  affected by noninfectious diseases.
• Lets remove a section of a heart to study some
  of these diseases.

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Lungs

• The alveoli are sac-like structures, in the
  lungs, through which oxygen and carbon dioxide
  pass during respiration.
• A person with emphysema, a respiratory disease,
  has a great deal of difficulty exchanging oxygen
  and carbon dioxide.
• Emphysema is linked to cigarette smoking.
• Smoking causes the alveoli to break down and the
  remaining walls to thicken.

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Aorta

• The aorta is the large artery that supplies blood
  to the body. It is composed of several layers of
  muscle and connective tissue.
• Several diseases can weaken an arterial wall.
  This is called an aneurysm.
• The aneurysm can suddenly burst, resulting in
  internal bleeding or death. An aneurysm in the
  brain can cause a stroke.

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Heart Valve

• The heart valves keep the blood flowing in one
  direction.
• Rheumatic fever can produce abnormalities in the
  heart valves.
• These abnormal valves can permit the backward
  flow of blood.
• This can produce heart murmurs and insufficient
  blood flow to the head and the body.

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Septum

• The septum separates the right side of the heart
  from the left side.
• This prevents deoxygenated (oxygen-poor) blood
  from mixing with oxygenated (oxygen-rich) blood.
• Some people have an opening in the septum.
• This can cause a condition in infants known as
  blue baby.
• These infants have a blue color in their skin due
  to a general lack of oxygen in their tissues.
• Blood in these infants, as in other people, is
  red. Blood is never blue.

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Heart Walls

• The walls of the heart are composed of cardiac
  muscle cells.
• A blocked artery leading to an area of the heart
  can cause the cells in that area of the heart to
  die.
• This is called an infarct.
• As dead cells break down, a tough scar tissue
  covers the area.
• This causes the remaining heart muscles to work
  harder.

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Coronary Artery

• The coronary artery supplies the hearts muscles
  with nutrients and oxygen.
• A person with atherosclerosis has a reduced blood
  supply to the muscles of the heart due to plaque.
• The build up of plaque is linked to saturated
  fats in the diet.
• Clots can form on the plaque, break off and block
  a smaller artery in the heart.
• This can cause a heart attack.

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Quiz Fill In The Blanks
Many noninfectious diseases attack the heart and
the lungs. A disease that breaks down the
alveoli in the lung is called ______________.
The build up of plaque in the coronary artery is
characteristic of the disease _______________.
This condition may cause a heart attack. A
weakened arterial wall that balloons outward
produces a(n) ________________. Heart valves are
also subject to disease. A leaking valve often
produces a heart sound called a ______________.
emphysema
atherosclerosis
aneurysm
murmur
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Section Five

• Testing Your Knowledge

70
This Is A Test of What You Have Learned

• There are 10 questions on this test.
• Try to correctly answer all of the questions.
• If you miss a question, watch the screen for an
  explanation of the correct answer.

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Select The Best Matching Choice

• Protozoa

Answer Column Forms plasma cells Invades living cells Causes emphysema Produces antibodies Causes dysentery Causes trichinosis Causes ringworm Forms memory cells
Correct Answer E Protozoa are responsible for
causing dysentery. This is a disease that
affects the large intestine. During excretion,
victims of the disease pass large quantities of
blood and mucus.

• Virus

Correct Answer B A virus invades a living cell
in order to reproduce. Once in the cell, the
viral nucleic acid directs the cell to create
more viruses.
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Select The Best Matching Choice

• Worm

Answer Column Forms plasma cells Invades living cells Causes emphysema Produces antibodies Causes dysentery Causes trichinosis Causes ringworm Forms memory cells
Correct Answer F A worm in poorly cooked meat
causes trichinosis. The trichina (trichinosis
worm) invades the victims muscles and uses them
for food.

• Fungus

Correct Answer G A fungus causes the disease
called ringworm. The fungus grows from a central
point in an ever-expanding ring. There are no
worms in ringworm.
73
Select The Best Choice To Complete Each Analogy

• 46 chromosomes are to most people as 47
  chromosomes are to most victims of
  ___________________.
• A. heart attacks
• B. PKU
• C. measles
• D. tapeworm
• E. Downs syndrome

Downs syndrome
Since most people have 46 chromosomes in their
body cells, the best analogy is victims of
Downs syndrome, most of whom have 47 chromosomes
in their body cells.
74
Select The Best Choice To Complete Each Analogy

• Many alveoli are to healthy lungs as few alveoli
  are to lungs with _______________.
• A. tapeworms
• B. emphysema
• C. viruses
• D. bacteria
• E. PKU

emphysema
Since healthy lungs have many alveoli, the best
analogy is lungs with emphysema that have few
alveoli. These alveoli also have thick walls
that slow down gas exchange in the lung.
75
Fill In The Blanks
There are many diseases that affect people. A
pathogenic disease that can be passed from one
person to another is called a(n) ____________
disease. The ability of an individual to resist
such a disease is called ____________. A genetic
disease is one that can be ____________ from a
parent. Diseases that are not infectious, and
therefore cannot be passed from one person to
another, are called ______________ diseases.
infectious
immunity
inherited
noninfectious
76
Pathology
Biology Basics
Review!
You Have Completed...

• Diseases and Defenses