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Transport Systems
Transport Systems in Plants
• Fossils and other evidence indicate that the first land
plants probably evolved from green algae about 430
million years ago.
• Life out of water posed a new challenge: loss of
moisture to the air.
• The first adaptations included a cuticle (waxy
coating) and protective structures for reproductive
organs.
The Mycorrhizae Connection
• Most plants have a symbiotic fungi associated with
their roots.
• The fungi helped to absorb water and essential
minerals from the soil and provide these materials to
the plant.
• The sugars produced by the plant nourish the fungi.
• Mycorrhizae are evident on some of the oldest plant
fossils, indicating that they were key to the plant’s
early survival on land.
Other Land Adaptations
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Roots – to draw up water and minerals from the soil
Shoots – to hold leaves for photosynthesis
Stomata – for gas exchange
Lignin – a chemical that hardens the cell walls so that
the plant can maintain posture
• Vascular tissue – conducting network of tubes
Xylem – transports water
Phloem – distributes sugars
Reproductive Adaptations
• Plants produce their
gametes in protective
structures called
gametangia to protect
them from dehydration.
• Most plants rely on
wind or animals to
disperse pollen or seeds
for fertilization.
Water Transport
• There are two types of
water-conducting cells:
– tracheids
– vessel elements
• These two make up the
xylem tissue of a plant
Water Restoration
• Tremendous amounts of water evaporate every day
through the stomata as a plant exchanges gases with
the air.
• This water must be replaced if the plant is to survive.
• Water must be transported great distances to reach
the higher stems and leaves.
• Plants do not have a pumping mechanism like the
hearts of animals.
Cohesion-Tension Hypothesis
• Due to cohesion, every water molecule that leaves
the plant during transpiration tugs on the next water
molecule behind it.
• This tugging is transmitted from one water molecule
to the next, resulting in a long chain of water
molecules continually being pulled through the
xylem from root to leaf.
• This requires NO ENERGY EXPENSE
• See page 645
How stomata regulate water
• They help adjust the plant’s transpiration rate to
changing environmental conditions.
• Stomata are usually open during the day and closed
at night. By opening stomata to allow CO2 to enter, a
plant also loses water through transpiration.
• Stomata may also close during the day if a plant is
losing water too fast.
Nutrient Transport
• Nutrients travel through living phloem cells joined
end to end.
• There are pores at the ends of these cells that
resemble tiny strainers or sieves, so the phloem
channels are often called sieve tubes.
• Sugars and amino acids move through the phloem
cells from the leaves to other parts of the plant.
Pressure-Flow Hypothesis
• Water and dissolved
sugars move through
the phloem from
sources (areas of higher
pressure) to sinks (areas
of low pressure).
Plant Nutrition
• Essential plant nutrient – a plant must obtain this
substance in order to complete its life cycle
– There are 17 essential nutrients
– Macronutrients are required in large amounts
– Micronutrients are required in smaller amounts
Macronutrients
• 98% of the plant’s dry weight consists of 6 major
macronutrients: carbon, oxygen, hydrogen, nitrogen,
sulfur, and phosphorus.
• Calcium, potassium and magnesium make up 1.5%.
Micronutrients
• Iron, chlorine, copper, manganese, zinc, boron, nickel
and molybdenum.
• These elements function as components of enzymes.
• Any deficiency can cause a plant to die.
Nutrient Deficiencies
Other Plant Cells
• Parenchyma cells – most abundant type of cell;
provide food storage and perform photosynthesis
• Collenchyma cells – provide support in parts of the
plant that are actively growing
• Sclerenchyma cells – hardened with lignin, provide
support in parts of the plant that have stopped
growing
Tissue Systems
• Dermal tissue – first line of defense against physical
damage and infectious organisms
• Vascular tissue – transports water, nutrients and food
throughout the plant
• Ground tissue – makes up the bulk of a plant’s tissue;
functions in photosynthesis, storage of nutrients and
support
TRANSPORT IN ANIMALS
2, 3, & 4-chambered hearts
The Cardiac Cycle
• When the heart relaxes, the chambers fill with blood.
• The relaxation phase is known as diastole.
• When the heart contracts, it pumps blood.
• The contraction phase is known as systole.
• Cardiac Cycle simulation
Blood Vessels
Arteries
• Carry blood away from the
heart
• Diameter is smaller
• Lined by thin layer of
smooth epithelium
• Outer layer of elastic
connective tissue
• Middle layer of smooth
muscle
• No backflow valves
Veins
• Carry blood back to the
heart
• Diameter is larger
• Lined by thin layer of
smooth epithelium
• Outer layer of elastic
connective tissue
• Middle layer of smooth
muscle
• Backflow valves
Blood Flow Through Arteries
• Blood pressure – the force that blood exerts against
the walls of your blood vessels
• Normal blood pressure for adults is below 120
systolic and below 80 diastolic.
• The first number is blood pressure during systole;
the second number is the blood pressure that
remains in the arteries during diastole.
Blood Flow Through Veins
• By the time blood exits the capillaries and into the
veins, the pressure originating from the heart has
dropped to zero.
• The blood still moves through the veins against
gravity because veins are sandwiched between
skeletal muscles.
• When the skeletal muscles contract, the blood is
forced along by the squeezing action.
Types of Blood Cells
Common Name
Science Name
Function
Red Blood Cells
erythrocytes
transport oxygen
White Blood Cells
leukocytes
fight infections
Platelets
thrombocytes
blood clotting
Distribution of Blood Supply
Body at Rest
Body Exercising
27 %
Digestive tract
64 %
Skeletal muscle
22 %
Kidneys
14 %
Skin
20 %
Skeletal muscle
5%
Digestive tract
14 %
Brain
5%
Brain
7%
Bone
4%
Kidneys
6%
Skin
4%
Bone
4%
Heart
4%
Heart
Homeostasis of the Cardiovascular System
• Helps to control chemical balance of the fluid in
which cells live by exchanging nutrients and wastes.
• Helps to control the composition of blood by
continuously moving it through organs that regulate
the blood’s contents, such as the lungs, liver and
kidneys.
• Helps to regulate body temperature.
• Helps to distribute hormones throughout the body.
• Helps to defend against foreign invaders.
Cardiovascular Disease
• Encompasses a set of diseases that affect the heart
and blood vessels.
• Accounts for 40% of all deaths in the United States.
• Kills one million people each year.
• The leading cause of death in the United States is
heart attack.
Coronary Arteries
• Heart muscle cells require oxygen-rich blood to
function and survive.
• From the aorta, several coronary arteries branch off
to supply the heart muscle.
• If one or more of these arteries becomes blocked,
heart muscle cells quickly die from lack of oxygen.
• Approximately one-third of heart attack victims die
almost immediately.
Atherosclerosis
• Cholesterol and other substances accumulate into
buildups called plaques that form in the walls of
arteries, narrowing the passages through which
blood flows.
Other Circulatory Diseases
• Hypertension – high blood pressure, usually above
140/90.
• Varicose veins – leg veins that stretch and enlarge,
allowing blood to pool under the surface of the skin
• Anemia – an abnormally low amount of hemoglobin
or a low number of red blood cells
Genetic Disorders
• Sickle-cell disease – disorder that
causes red blood cells to be
uncharacteristically shaped
• Hemophilia – excessive bleeding
caused by a mutation in clotting
proteins
• Leukemia – cancer of the leukocytes that affects how
the bone marrow produces healthy blood cells
Decreasing Your Risk
• Do not smoke. Smoking doubles your risk of heart
attack and increases the severity if one does occur.
The chemicals in cigarettes constrict the diameter of
your blood vessels.
• Exercise. Exercise can cut the risk of heart disease in
half. Exercising promotes blood flow and does not
allow plaques to form easily inside your arteries.
• Eat a heart healthy diet. Your diet should be low in
cholesterol, trans fat, and saturated fat, reducing the
risk of developing atherosclerosis.
Remedies for Cardiovascular Disease
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Cholesterol lowering drugs
Balloon angioplasty
Stents (new plumbing)
Bypass surgery
Heart transplant