Transcript Human Biology II - Care and Maintenance

Hewitt/Lyons/Suchocki/Yeh
Conceptual Integrated
Science
Chapter 20
HUMAN BIOLOGY II—
CARE AND MAINTENANCE
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This lecture will help you
understand:
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Integration of Body Systems
The Circulatory System
Integrated Science—Hemoglobin
Respiration
Digestion
Nutrition, Exercise, and Health
Integrated Science—Diets
Excretion and Water Balance
Keeping the Body Safe: Defense Systems
Technology: Transplanting Bone Marrow
Science and Society: What Are the Odds?
Science and Society: The Placebo Effect
Science and Society: AIDS
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Integration of Body Systems
The body’s systems rarely act alone.
Bodily functions usually require two or more
organ systems.
Example: Obtaining oxygen for the cells
requires the coordination of the respiratory
and circulatory systems.
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Integration of Body Systems
CHECK YOUR NEIGHBOR
What body systems are involved in
disposing cellular wastes?
Explain your answer to your neighbor.
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Integration of Body Systems
CHECK YOUR ANSWER
Three systems work together to dispose of
cellular wastes:
The circulatory system collects wastes from
the tissues. The respiratory and excretory
systems remove them from the body.
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The Circulatory System
The circulatory system consists of three
components:
• Heart
• Blood vessels
• Blood
The circulatory system is the body’s system
for moving things around.
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The Circulatory System
The right side of the heart pumps blood to
the lungs to pick up oxygen. The left side
pumps blood to the rest of the body.
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The Circulatory System
Every heartbeat begins in the pacemaker—the sinoatrial
node. The pacemaker initiates an action potential that
causes the right and left atria to contract simultaneously.
The signal also passes to the atrioventricular node and
then to the two ventricles, which also contract
simultaneously.
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The Circulatory System
Blood vessels are tubes that carry blood:
• Arteries carry blood away from the heart into
arterioles and then into capillaries.
• Capillaries are thin walled and do not have
smooth muscle surrounding them. In the
capillaries, materials move between tissues and
blood.
• Venules carry blood back to veins, which return
the blood to the heart.
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The Circulatory System
When we move, our muscle contractions squeeze
blood along the veins. Valves ensure that blood
does not flow backwards.
When we sit for a long time, what happens to our
blood?
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The Circulatory System
Our blood is composed of:
• Plasma
—Water, salts, proteins, hormones, glucose, other
nutrients, wastes
• Cells
—Red blood cells—carry oxygen, do not have a
nucleus or mitochondria. Red blood cells die and
must be replaced frequently.
—White blood cells—immune cells, defend our bodies
against disease
—Platelets—function in blood clotting
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Integrated Science—Hemoglobin
Hemoglobin protein carries the oxygen in our red blood
cells. Hemoglobin consists of four subunits.
Each subunit contains a heme group that includes one iron
atom. The iron binds oxygen. Each hemoglobin molecule
can carry up to four molecules of oxygen.
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Integrated Science—Hemoglobin
When one of the heme groups binds to an
oxygen molecule, the other three heme
groups are altered to make them more
likely to bind oxygen as well.
The reverse occurs, too. When one heme
group unloads an oxygen molecule, the
other groups are altered to be more likely
to give up their oxygen.
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Respiration
Through breathing, the respiratory
system moves oxygen to the
circulatory system from the air.
Gas exchange occurs through
diffusion in the alveoli of the
lungs. Oxygen diffuses into
capillaries, and carbon dioxide
diffuses from capillaries into the
alveoli.
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Respiration
As air passes the larynx, it vibrates the
vocal cords, generating sound waves. We
control the muscles that stretch the vocal
chords to produce the sounds of speech.
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Respiration
We move air in and out of our lungs using a set of muscles:
• The diaphragm and muscles between our ribs contract,
the chest cavity expands, air pressure drops, and air is
sucked into the chest.
• The diaphragm and rib muscles relax, decreasing the
volume of the thoracic cavity, forcing air out.
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Digestion
We rely on food:
• To supply us with organic molecules for
energy
• To provide essential molecules that we
cannot produce on our own
• To help us maintain a stable body
temperature
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Digestion
The digestive system consists of several parts:
• The mouth—teeth, saliva, taste
buds, tongue
• Esophagus—moves food via
peristalsis until it reaches a
sphincter leading to the stomach
• Stomach—gastric juice and
churning action reduce food to
chyme
• Small intestine—breaks down
proteins, fats, carbohydrates,
and nucleic acids and conducts
absorption of nutrients
• Large intestine—absorbs water
and minerals and produces feces
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Nutrition, Exercise, and Health
For good health, the human body needs
• An adequate number of calories
• Essential nutrients such as amino acids
that the body cannot produce
• Vitamins and minerals that the body
cannot produce
• Exercise!
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Integrated Science—Diets
Both low carb and low calorie diets help us
lose weight because we consume fewer
calories. However, low carb diets:
• Reduce water retention
• Tend to be high in saturated fats and
cholesterol
• Are low in whole grains and fruit
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Excretion and Water Balance
The excretory system:
• Filters our blood, removing wastes
• Controls the retention or excretion of ions and
water
Excretion begins in the kidneys.
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Excretion and Water Balance
Fluid enters the nephron from the
circulatory system.
The loop of Henle reabsorbs
water from the filtrate.
In the distal convoluted tubule,
additional wastes are added to
the filtrate. In the collecting
duct, water may be reabsorbed.
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Excretion and Water Balance
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Excretion and Water Balance
From the collecting duct, urine flows into the
renal pelvis, down the ureter, and into the
bladder. It is excreted out the urethra.
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Keeping the Body Safe: Defense
Systems
The immune system consists of two parts:
• Innate immunity—nonspecific—works against a
wide variety of pathogens
• Acquired immunity—specific—cells recognize
certain very specific features of pathogens
Acquired immunity is found only in vertebrates
(probably).
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Keeping the Body Safe: Defense
Systems
Our immune systems consists of many tissues and organs,
including:
• Bone marrow—produces all immune cells (“white” blood
cells)
• Thymus
• Lymphatic system
• Spleen
• Skin
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Keeping the Body Safe: Defense
Systems
The innate immune system relies on:
• The skin (tough outer layer, shedding of cells,
acidic secretions from hair follicles)
• Saliva, tears, sweat, milk
• Mucous membranes
• Response from innate immune cells
• Inflammatory response
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Keeping the Body Safe: Defense
Systems
The inflammatory response occurs when damaged
tissues release histamines, which increase
blood flow to the site, cause capillaries to leak,
and attract innate immune cells.
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Keeping the Body Safe: Defense
Systems
Each cell of the acquired immune system has
receptors that recognize a single antigen—a
molecule or part of a molecule belonging to a
pathogen.
The acquired immune system takes longer to
deploy but retains a memory of pathogens so
that it can respond more quickly and
aggressively the next time the pathogen is
encountered.
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Keeping the Body Safe: Defense
Systems
There are two types of acquired immune
cells:
B cells target pathogens in body fluids.
T cells target pathogens inside the body’s
cells.
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Keeping the Body Safe: Defense
Systems
B cells divide and release antibodies. Some
clones become memory cells that stay in
the body.
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Keeping the Body Safe: Defense
Systems
Helper T cells organize the acquired immune
response.
They stimulate B cells and killer T cells to divide.
Killer T cells kill infected cells in the body.
Helper T cells also make suppressor T cells that
inhibit the action of killer T cells and B cells
when they are no longer needed.
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Keeping Your Body Safe: Defense Systems
CHECK YOUR NEIGHBOR
How do vaccines protect us from disease?
Explain your answer to your neighbor.
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Keeping Your Body Safe: Defense Systems
CHECK YOUR ANSWER
Vaccines make use of the acquired immune
system’s “memory.” They expose the body
to antigens of a particular pathogen
without introducing the pathogen itself.
Vaccines contain dead or weakened
pathogens or parts of pathogens that
stimulate the immune response.
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Keeping the Body Safe: Defense
Systems
Autoimmune diseases occur when a
malfunction in the immune system causes
it to attack certain body cells.
Examples:
• Type I diabetes
• Multiple sclerosis
• Lupus
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Keeping the Body Safe: Defense
Systems
HIV—the virus that causes AIDS—attacks
immune cells, particularly helper T cells.
With the immune system compromised,
many infections and cancers can
overwhelm the body.
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Technology: Transplanting Bone
Marrow
Bone marrow transplants allow patients to survive
after aggressive cancer treatments.
A patient may have his or her own stem cells
harvested before cancer treatment or receive
donor cells from another person. Replacing the
damaged bone marrow stem cells allows the
patient to continue to generate red and white
blood cells and platelets after cancer treatment.
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Science and Society: What Are the
Odds?
In the United States,
heart disease is
still the leading
cause of death,
followed by cancer
and strokes.
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Science and Society: The Placebo
Effect
Placebos may operate through the release
of endorphins, natural opiates that prevent
a patient from feeling pain, or from stress
reduction, allowing the immune system to
function more effectively. A patient’s
expectations also affect the outcome.
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Science and Society: AIDS
CHECK YOUR NEIGHBOR
Which of the following groups is acquiring AIDS at
an increasingly high rate?
A. Women
B. East Asians
C. Eastern Europeans
D. Central Asians
Explain your answer to your neighbor.
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Science and Society: AIDS
CHECK YOUR ANSWER
The answer is all of these groups. Women,
and people from East Asia, Central Asia,
and Eastern Europe, are increasingly
becoming infected with HIV.
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