Download ch 7 test-transport systems

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Adaptations for Life on Land
-fossils and other evidence indicate that the first plants probably evolved from green algae
-the challenge of life out of water: loss of water
-so the first adaptations included a cuticle and protective structures for the gametes and embryos
-2 types of plants emerged:
1. vascular plants- had specialized vascular tissue and a tubing system
-the ancestors of all plants except mosses and their relatives
2. nonvascular plants- complex tissues didn’t evolve
-mosses and their relatives
-are restricted to damp environments and don’t grow very large
-other challenges of life on land: soil contains water and minerals but the light and carbon dioxide
needed for photosynthesis must be obtained above ground
-vascular plants adapted by having an underground root system that absorbs water and minerals
and a different aerial system of stems and leaves that makes food
-more challenges:
-the sections of roots that absorb water lack a cuticle
-root hairs greatly increase the root’s water-absorbing surface are
-how does a plant shoot stand upright
-lignin: a hard material embedded in the cellulose matrix of the cell walls which support trees
and other vascular plants
-water and minerals must be conducted upward from the roots to the leaves (xylem)
-the products of photosynthesis must be distributed from the leaves to the roots (phloem)
-xylem tubes carry water up from the roots
-mature xylem cells are nonliving hollow tubes
-phloem tubes carry sugars and the products of photosynthesis throughout the plants
Water Transport
-xylem consists of 2 types of water-conducting cells, plus strong weight bearing fibers
1. tracheids- have pointed ends and thick walls with pits that connect them to nearby cells
-water moves from cell to cell through these pits
2. vessel elements- wider, shorter, thinner walled, and less tapered
-the ends of vessel elements are perforated or missing and water can flow freely through these
openings
-columns of vessel elements form the xylem vessels that water moves throughout the plant in
-a lot of water evaporates everyday through the stomates as a plant exchanges gases with the air
-this water must be replaced if the plant is to survive
-this water is transported upward to reach the higher stems and leaves
1. cohesion-adhesion—capillary action
-the rise of water by capillary action isn’t very rapid
2. root pressure- high concentration of water from the soil moves into the roots
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3. transpiration- plants also lose a large amount of water through the stomates in their leaves when
the stomates open
-this evaporation of water “pulls” water upward from the roots to the leaves
-it is the primary and most significant method of water transport in plants
Nutrient Transport
-in vascular plants, sugar and nutrients travel through phloem cells joined end to end
-tiny pores in the walls at the ends of the phloem cells allow the contents of the cell to mix
-the porous areas at the ends of these cells 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
-the rate that this fluid moves is thousands of times faster than what diffusion can account for
-best explanation: pressure-flow hypothesis
-water and dissolved sugars move through the phloem from sources (areas of higher pressure) to
sinks (areas of lower pressure)
-sources include cotyledons and endosperm during germination, leaves during spring and summer,
and some storage roots in early spring
-sinks are found in the many areas of a plant where waters and sugars are used, including foodstorage areas and growing leaf buds, root tips, flowers, fruits, and seeds
-the process begins at a source, like a leaf, where photosynthesis occurs  the sucrose is actively
transported into the sieve tubes from the mesophyll cells  the companion cells produce a key protein
involved with this transport  the resulting high concentration of sucrose draws water into the phloem
cells  produces higher pressure which forces the sucrose solution to move toward the lower pressure
at the sinks
-so sucrose molecules move from phloem cell to phloem cell, from source to sink, through sieve tubes
-at a sink, active transport removes sucrose from the phloem to be used or stored
-as this occurs, water also leaves the phloem cells by osmosis, and most of it returns to the xylem
-the entire process depends on the uptake of sucrose and water by phloem cells in the leaves and active
removal of sucrose and water from phloem cells in sink tissues
An overview of transport in plants
-plants take up water through roots only (not stomates)
-xylem transports water by capillary action
1) cohesion
2) adhesion
-high concentration of water from soil moves into the roots = root pressure
-no sugar in the roots because there’s no sunlight or chloroplasts  can’t carry out photosynthesis
 depend on leaves to make sugars
-all parts of the plant need oxygen for cellular respiration
-loose soil allows oxygen to reach the roots
-earthworms help to aerate soil
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-cellular respiration = C6H12O6 + O2  CO2 + H2O + ATP (energy)
-water is transported by xylem tubes to the leaves for photosynthesis
-photosynthesis
air
roots
CO2 + H2O
sunlight
chlorophyll
glucose
C6H12O6 + O2
- C6H12O6 is transported throughout the plant by phloem
-plants also lose a large amount of water through the stomates in their leaves = transpiration
-this evaporation of water “pulls” water upward from the roots to the leaves
-it is the primary and most significant method of water transport in plants
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Transport Systems in Animals
Circulatory Systems
-unicellular organisms, like paramecium:
-no specific transport structures
-food vacuole
-the food in the vacuole is broken down by enzymes
-the food then diffuses into the cytoplasm
-multicellular microscopic organisms, like hydra
-no specific transport structures
-simple diffusion
-fluid containing food, oxygen, and carbon dioxide passes into and around its body as the hydra
moves
-its tentacles catch the food and the food goes in the mouth into the gastrovascular cavity where it
is broken down. It then diffuses into the endoderm and ectoderm
-insects, crabs, and other arthropods, like grasshoppers
-open circulatory system
-there is no separation between blood and other intercellular fluid
-transports hemolymph, not blood
-the movement of the insect moves and circulates the fluid
-there is no pumping mechanism to keep the fluid flowing and moving
-organisms with this kind of system tend to be smaller or more sluggish because it’s less efficient
-insects distribute oxygen through microscopic air ducts with branches that reach every part of
their body which works well because of their small size
-invertebrate organisms, like earthworms
-closed circulatory system
-blood is confined to vessels
-major vessels branch into smaller vessels that carry blood to or from the various organs
-blood is transported in blood vessels by aortic arches also known as “hearts” to circulate the blood
-more efficient at delivering food and oxygen
Circulation in Vertebrates
-closed circulatory system called the cardiovascular system
-consists of a heart with chambers, blood vessels, and blood
the heart
-has chambers
-one or more atria (singular: atrium)- chambers that receive blood returning to the heart
-one or more ventricles- chambers that pump blood out of the heart
3 types of blood vessels
1. arteries- carry blood away from the heart
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2. veins- carry blood to the heart
3. capillaries- connect arteries to veins
Types of hearts
fish
-2 chambers
-1 atrium
-1 ventricle
-called a single loop circulation
amphibians and reptiles
-3 chambers
-2 atria
-1 ventricle
*least efficient:
-because there’s only one ventricle, deoxygenated blood comes in through one atrium and oxygenated
blood come in through the other atrium into the same ventricle
-deoxygenated blood and oxygenated blood mix  these organisms’ blood is partially deoxygenated
-because organisms need oxygen for cellular respiration (which produces energy), these organisms don’t
have much energy
birds and mammals
-4 chambers
-2 atria
-2 ventricles
-the septum divides the two ventricles, and allows the deoxygenated blood to be pumped out into the
lungs
the path of the blood:
-deoxygenated blood enters the right atrium and flows into the right ventricle
-it goes to the lungs through the pulmonary artery where it is enriched with oxygen
-the newly oxygenated blood comes back to the heart through the pulmonary veins
-it enters the left atrium and flows into the left ventricle
-it then leaves the heart through the aortic arch and flows to the rest of the body
Arteries, Veins, and Capillaries
arteries- carry blood away from the heart
-carry oxygenated blood (which is bright red)
-larger in diameter
-thicker – more smooth muscle tissue that allows blood vessels to contract and move blood
-able to constrict on their own
-found deep (closer to the bone)
-coronary arteries: carry blood to the heart
-pulmonary arteries: carry blood to the lungs from the heart
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-biggest artery = aorta – leads from the heart and supplies blood to the body
-large arteries have walls made up of smooth muscle and other elastic tissue
-when the heart contracts (systole): it forces blood into these arteries under high pressure,
stretching their walls which allows more blood to enter and prevents the pressure from being too
great
-during the relaxed phase of the heartbeat (diastole): the stretched artery walls contract, helping to
push the blood along and maintain blood pressure
-signals from the nervous system can cause smaller arteries to contract and expand
veins- carry blood to the heart
-carry deoxygenated blood
- smaller in diameter
-less smooth muscle tissue
-superficial (closer to the surface)
-valves prevent blood from flowing backwards—blood is flowing upwards, against gravity
-lower pressure
-veins have thinner walls with less muscle and elastic tissues than arteries
capillaries- connect arteries to veins
-drops of oxygen and picks up carbon dioxide
-thinnest, tiniest tubes- can be 1 cell layer thick
-connect arterioles to venuoles = where the blood deoxygenates
-found everywhere in the body
-thin capillary walls allow chemicals to be exchanged between the blood
-thin capillary walls also allow the intracellular fluid surrounding the cells and oxygen and carbon
dioxide to be exchanged with air in the lungs
-blood flows from:
the heart
arteries
High pressure
arterioles
capillaries
venuoles
veins
the heart
Lowest pressure
Highest pressure
Heart Anatomy
-the circulatory system is made of 2 parts:
-cardiovascular system- circulates the blood
-lymphatic system- removes foreign substances
-oxygen, carbon dioxide, nutrients and waste are transported by the body’s circulatory system
-93,000 miles of blood vessels in the human body
-36 gallons or 6,000 quarts of blood in the body
-the heart is the size of your fist
-pericardium: the membrane that surrounds and protects the heart
-tough
-a little translucent
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-pulmonary circulation: supplies blood to the lungs
-systemic circulation: supplies blood to the rest of the body
-autonomic system- the nervous system that controls the heartbeat
-the cardiac cycle: each heartbeat is a sequence of muscle contraction and relaxation
-in each cycle, the four chambers of the human heart go through phases of systole and diastole
-diastole: heart at rest
-the ventricles are filling
-systole: heart at work pumping blood
-ventricular contraction
-the atria contract slightly before the ventricles
-when the atria are relaxed and filling, the ventricles are also relaxed
-as the pressure rises in the atria, the valves between the atria and ventricles (AV valves) are forced
open and the ventricles start to fill
-then the atria contract (atrial systole), forcing additional blood into the ventricles
-next, the ventricles contract (ventricular systole), causing the AV valves to snap shut and the pressure
inside the ventricles rises sharply
-valves to the aorta and the pulmonary arteries open and blood flows out of the heart
-then the ventricles relax and the cycle starts again
-AV valves prevent blood in the ventricles from backing up into the atria
-leaks in these valves cause the condition known as heart murmur
-although the heartbeat starts in the heart itself, changes in the rate of the heartbeat are controlled by
nerves outside the heart
Molecular Basis of Muscle Contraction
-the heart is made of cardiac muscle
-it is very similar to skeletal muscle: they both contract
-cardiac muscle contracts involuntarily
-skeletal muscle contracts voluntarily
-the heart is myogenic: it doesn’t need nerve pulses to make it contract
-this pushes the blood along
-the contractions of the heart are produced by a molecular motor, the pacemaker
-this motor is composed of two proteins called actin and myosin
Blood Pressure
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-a healthy blood pressure is maintained through complex interactions involving hormones and the
nervous, excretory, and circulatory systems
-nerves connect pressure receptors in the aorta and the artery leading to the brain
-other cardiac things respond to sensory input like emotions and chemical input like carbon dioxide
-when someone’s blood pressure falls below normal, for example due to danger or exercise, the brain
sends signals to increase blood pressure
-to increase blood pressure:
-increase the heart rate and constrict the blood vessels
-to decrease blood pressure:
-decrease the heart rate and don’t constrict the blood vessels
-tissues that are most important during activity, like the heart and skeletal muscles, receive more
oxygen and nutrients
benefits of exercise that move large skeletal muscles
-brings more oxygen to muscles
-increases the flow of blood to the heart
-reduces the oxygen need of muscles
-reduces cholesterol and blood pressure
-helps with weight loss
hypertension
-hypertension: having blood pressure higher than normal
-20% of the adult population has hypertension
-it causes serious health problems, even death
-it forces the heart to work harder which can damage heart muscles
-it can damage blood vessels in the brain so they rupture which can cause a stroke
-it contributes to atherosclerosis
-its exact causes aren’t known
-it can be prevented or controlled by medication, regular physical examinations, proper diet, and
exercise
-1 in 5 Americans is most likely to die of heart disease
Composition of Blood
-blood is the only fluid tissue in the body
-total volume of blood in the body = 5-6 quarts
-blood is made of 4 parts:
erythrocytes- red blood cells
-contains hemoglobin
-hemoglobin binds to oxygen
-oxygen is released from blood when the blood passes through capillaries
-oxygen diffuses out into surrounding tissues
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-carbon dioxide is transported by the blood plasma back to the lungs
leukocytes- white blood cells
-protect against foreign substances
-defend again bacteria and viruses
-an infection results in more white blood cells
thrombocyte- platelets
-allows the blood to clot or coagulate
-platelets become “sticky”
-fibrin (a protein produced by a series of chemical reactions) forms a network of fibers to trap red blood
cells
-abnormal clotting when blood flow to heart is blocked = heart attack
-abnormal clotting when blood flow to brain is blocked = stroke
plasma
-the “watery” part of the blood
-it transports blood cells (red blood cells, white blood cells, and platelets)
-it helps to regulate body temperature
-consists of water, dissolved ions (electrolytes), amino acids, sugars, and hormones
-transports carbon dioxide back to the lungs
-maintains the pH of the blood and water balance in the body
The Lymphatic System
-it protects against disease
-it’s the “pollution control system” of your body
-the lymphatic system returns only white blood cells
-these cells collect at lymph nodes where bacteria and viruses are destroyed before returning to the
blood
-lymph is the fluid in the lymphatic system that returns the white blood cells to the lymph nodes
-since the lymphatic system has no pump of its own, the flow of lymph is a lot slower than the flow of
blood
-muscle contractions from body movement help push lymph through the lymphatic system
The Circulatory System and Homeostasis
-even though organisms live in an external environment that is constantly changing, the internal
environment of living things must be kept stable
-an organism’s ability to maintain homeostasis depends on its transport system
-different systems regulate the amount of hormones that are released, the level of sugar in your blood,
and your metabolic rate
-the transport system is essential in maintaining homeostasis because it carries hormonal signals and
needed materials to all parts of the body
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-organisms develop responses to maintain homeostasis
-to stay cool:
-blood vessels dilate so excess heat energy can radiate out of the blood
-chemical messages carried in the blood stimulate you to sweat
-the gas exchange system is also important in maintaining homeostasis
-the rate of breathing and amounts of oxygen and carbon dioxide are important
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