Transport System Flashcards
What do animals need to take in from the external environment?
food and oxygen
What do plants need to take in from the external environment?
the raw materials necessary to carry out photosynthesis mineral nutrients and oxygen
What do both animals and plants have to do?
get rid of waste products from their bodies to the exterior
How does a simple unicellular organism like Amoeba carry out material exchanges?
through its external body surface by diffusion
Up to what size can Amoeba effectively exchange materials by diffusion?
a certain limit
What happens when Amoeba increases in size beyond its diffusion capacity?
it stops growing and divides into two
What happens as the Amoeba increases in size?
the surface area to volume ratio decreases
What is the ability of the Amoeba to exchange materials in a given time related to?
its surface area
How are the needs of Amoeba like oxygen intake and carbon dioxide excretion related to its size?
the larger the volume the greater the needs
What happens to Amoeba’s ability to exchange materials as it increases in size?
it cannot cope with its needs
What limits material exchange as an organism increases in size?
the S.A./V ratio
What multicellular organisms increased their S.A./V ratio by developing structures like the gut?
Hydra and flatworm
Beyond what size could Hydra and flatworm not grow?
a certain size
What becomes a limiting factor preventing the development of larger and more complex bodies?
diffusion
How close are all the body cells to the material exchange surfaces in Hydra and flatworm?
very near
How are materials transported between exchange surfaces and cells in Hydra and flatworm?
Diffusion
Over what distance is diffusion efficient?
1 mm or less
What happens to diffusion as the distance between body cells and exchange surface increases?
it becomes slow and inefficient
What does an increase in body size mean for the distance between body cells and exchange surfaces?
an increase
What arose due to the inability of diffusion to transport materials over long distances?
a need for a transport system to carry materials rapidly between the material exchange surfaces and the body cells
How did large multicellular organisms overcome the limiting factors of size and complexity?
by developing structures for material exchange and a transport system where a fluid carries materials throughout the organism
Name examples of structures with large surfaces for material exchange
gills lungs intestines and leaves (in plants)
What does the transport system use to carry materials throughout the organism?
a fluid
What provides the driving force to keep the fluid moving continuously?
Certain mechanisms
How do suspensions and solutes in the fluid flow?
at the same speed
What is this type of transport system called?
a mass flow system
What organisms have a mass flow system?
all higher plants and animals
Do simple multicellular animals have transport systems?
No
Why dont simple multicellular animals need transport systems?
They are small and have a large S.A./V ratio so diffusion is sufficient to meet their needs
What do other animals have to transport and distribute materials?
a mass flow system
Name the main materials that are transported in animals
digested food water and other nutrients oxygen excretory products and hormones
In what form are all materials transported within an animal?
an aqueous solution
What are transport media?
fluids
What acts as transport media in simple animals?
cytoplasm and water
What is the main medium of transport in most animals?
blood
What are part of blood and play an important role in transport to individual body cells?
Intercellular fluid and lymph
What is the basic function of a transport system?
to bring about rapid mass flow of materials such as soluble food excretory products and oxygen throughout the body
Where must materials be able to leave the transport system?
at appropriate sites and enter the cells and tissues that either use them or excrete them
What must be able to enter the transport system?
materials from various cells and tissues to be carried to their destinations
What are the features of a transport system (also called a circulatory system in most animals)?
a circulating fluid (usually blood) a pumping device or heart and a system of branched tubes or vessels connected to the heart through which the fluid can circulate
What are the two types of circulatory systems in animals?
open and closed circulatory systems
Where is the open circulatory system found?
in some animals like insects and molluscs
What happens in an open circulatory system?
the heart pumps blood out into a blood vessel which branches and opens into spaces in the body cavity called haemocoels The organs and tissues are bathed in blood and exchange of materials occurs between the body cells and the blood Blood in spaces eventually flow into vessels leading to the heart
What does the Paramecium use for the distribution of materials within its body?
continuous streaming movements of the cytoplasm
What does the Hydra’s two-layered body enclose?
a huge gut cavity
What circulates digested food and oxygen within the Hydra’s gut?
movements of the gut wall
What helps the cells lining the gut to absorb materials?
the circulation of materials
What do some cells in the gut have to circulate materials?
flagella
What are arteries?
Blood vessels leading away from the heart
What do arteries branch into?
smaller vessels called arterioles
What do arterioles branch into?
fine vessels called capillaries
Where are capillaries found?
in between all body cells
How does exchange of materials occur between cells and capillaries?
through the walls of the vessels and cell membranes by diffusion
What do capillaries unite to form?
venules
What do venules join together to form?
veins
What are veins?
the blood vessels that transport blood back to the heart
How is blood distribution controlled in a closed circulatory system?
well controlled
How does blood leave the heart in a closed circulatory system?
at high pressure
How does blood return to the heart in a closed circulatory system?
at low pressure
What is the body cavity of an insect like the grasshopper called?
haemocoel
What does the haemocoel consist of?
a network of blood-filled spaces where the internal organs are immersed in blood
Describe the insect heart
a dorsal tubular heart with several chambers stretching from the thorax into the abdomen and extending towards the head as a single blood vessel the aorta which opens into the haemocoel
What does each chamber of the insect heart have?
a pair of slit-like openings at its side with valves that only allow blood to enter the heart
What makes the insect heart contract and relax rhythmically?
Muscles attached to the heart chambers
What happens when the insect heart contracts?
the slits close and blood is pushed forward into the aorta and out into the haemocoel
What happens when the insect heart relaxes?
the slits open and blood that has passed through various parts of the body enters the heart
What ensures that blood flows forward towards the head in insects?
Valves between the heart chambers
What ensures that blood flows in a definite backward direction in the spaces in the thorax and abdomen of insects?
thin walls partitioning the haemocoel
What helps to make the blood flow into the heart in insects?
the movements of the abdominal walls
Describe blood movement in an open circulatory system
slow
What is the main function of blood in an open circulatory system?
to transport digested food from the gut to body cells and collect wastes from cells to the Malpighian tubules for excretion
How is oxygen transported in insects?
by a network of air tubes
Why is insect blood colorless?
because it does not contain haemoglobin
Is the open circulatory system efficient?
No
Why is the open circulatory system adequate for insects?
because they have a well-developed system of air tubes for transporting oxygen to all parts of their body
What type of circulatory system do vertebrates have?
closed circulatory systems
Describe the vertebrate heart
a well-defined muscular heart lying ventrally in the body
What do arteries and veins do in vertebrates?
Arteries carry blood away from the heart and veins bring blood back to the heart
What does the closed circulatory system show?
distinct modifications as the vertebrates evolved from fishes to mammals
How is the fish heart divided?
into two main chambers an atrium and a ventricle
Where does blood from the general body circulation enter in a fish?
the atrium
Where does blood go after the atrium in a fish?
the ventricle
How does the ventricle compare to the atrium in a fish?
it is more muscular
What happens when the ventricle contracts in a fish?
it forces blood out into the aorta at high pressure
What prevents backflow of blood in a fish?
Valves guard the opening between the atrium and the ventricle and the ventricle and the aorta
What propels blood towards the gills in a fish?
the elastic walls of the aorta
What do the aorta branch into at the gills?
arterioles and capillaries
What occurs at the gills?
Gaseous exchange oxygen enters the blood from the surroundings while carbon dioxide leaves the blood and diffuses into the surroundings
Where does oxygenated blood go after leaving the gills in a fish?
in arteries which branch out to all parts of the body
What do arteries form at organs and tissues in a fish?
a network of capillaries
What diffuses into and out of body cells at the capillaries in a fish?
Oxygen and digested food diffuse into the body cells while waste materials diffuse out of them
What do capillaries rejoin to form in a fish?
veins
Where do veins return blood in a fish?
back to the heart
How many times does blood pass through the heart in one complete circuit in a fish?
once
What is this type of circulation in a fish known as?
single circulation
Is single circulation efficient?
No
Where do arteries form capillary networks in a fish?
at the gills and again at the various organs and tissues
What happens to blood pressure each time blood passes through capillary networks?
it decreases
How does blood move in veins in a fish?
sluggishly at low pressure
What helps blood flow in veins leading to the heart in a fish?
valves in veins and some veins replaced by blood spaces
What does sluggish blood movement tend to do to fish?
slow down their activities
What circulatory system do higher land vertebrates have?
double circulation
What changes occurred in the vertebrate circulatory system during the evolution of higher land vertebrates?
changes in the structure of the heart related to the change from gills to lungs
How is the atrium of the heart divided in an amphibian like a frog?
completely into a left chamber and a right chamber with no opening connecting the two sides
How is the ventricle divided in a reptile?
partially divided
How is the ventricle divided in mammals and birds?
completely partitioned into a left chamber and a right chamber just like the atrium
How many chambers does the heart have in mammals and birds?
four-chambered
Where is deoxygenated blood pumped from the heart in land vertebrates?
to the lungs where gaseous exchange occurs
Where is oxygenated blood from the lungs returned in land vertebrates?
to the heart from where it is pumped to the other organs and tissues of the body
What happens to oxygen in the body of land vertebrates?
it is used up and the deoxygenated blood is then returned to the heart before it is sent to the lungs
How many times does blood pass through the heart in one complete circuit through the body of land vertebrates?
twice
What is this circulation known as in land vertebrates?
double circulation
What is the blood circulation from the heart to the lungs and back to the heart known as?
the pulmonary circulation
What is the circulation from the heart to all other parts of the body and back to the heart known as?
the systemic circulation
How many capillary networks does blood go through in each circulation?
only one
How is blood pressure maintained in double circulation?
at a high pressure
What is the result of high blood pressure in double circulation?
efficient and rapid transport
Where does oxygenated blood flow in mammals?
always through the left side of the heart
Where does deoxygenated blood flow in mammals?
always through the right side of the heart
Is blood completely separated in the frog’s ventricle?
No
What is the result of the incomplete separation of oxygenated and deoxygenated blood in the frog’s ventricle?
there is a tendency for them to mix
What structures help to keep oxygenated and deoxygenated blood separate and channel them to the correct circulations in the frog?
ridges and valves
What kind of circulation does the frog exhibit?
a partial double circulation
Why is the frog’s circulation called partial double circulation?
because oxygenated and deoxygenated blood are not completely separated as in mammals
Describe the efficiency of the mammalian transport system
rapid and efficient
What are the main features of the mammalian transport system?
blood lymph and intercellular fluid a muscular four-chambered heart arteries veins and capillaries and a double circulation
What does blood consist of?
liquid plasma in which float a mixture of blood cells
Describe plasma
a pale yellow liquid made up mainly of water with many dissolved substances including plasma proteins antibodies hormones enzymes gases salts digested food materials and waste materials
What is the main function of plasma?
to transport the substances that are dissolved in it as well as the cells that float in it
What are the blood cells made up of?
red blood cells or erythrocytes white blood cells or leucocytes and platelets
How many red blood cells are in one cubic millimeter of blood?
about five million
Describe red blood cells
flat and circular with a depression on each side and no nucleus in a mature cell surrounded by an elastic membrane
What does the elastic membrane of a red blood cell enable it to do?
squeeze through narrow capillaries whose internal diameters are smaller than its own
What is the inside of a red blood cell filled with?
the oxygen-carrying pigment haemoglobin
What does haemoglobin give to a clump of red blood cells?
its characteristic red color although each cell looks yellow when viewed singly
What is the lifespan of red blood cells?
about three months
Where are new red blood cells formed?
in the red marrow of most bones in adults
What happens to worn-out red blood cells?
they are ingested by phagocytes in the spleen and broken down to bilirubin and ferritin
What does the liver do with ferritin and bilirubin?
stores the iron in ferritin for new red blood cell production and gets rid of the bilirubin via the bile
What is the main function of red blood cells?
to transport oxygen from the lungs to the body cells
What adaptations do red blood cells have for their function?
their shape gives them a high S.A./V ratio for absorbing large amounts of oxygen and they contain haemoglobin which has a high affinity for oxygen
How many white blood cells are in one cubic millimeter of blood?
about 7000
How do white blood cells compare to red blood cells?
they are much larger and are nucleated
Where are white blood cells formed?
in some lymph nodes and in bone marrow
What is the lifespan of most white blood cells in the bloodstream?
only a few days
What are the two main groups of white blood cells?
granulocytes and agranulocytes
Describe granulocytes
white blood cells with a granular cytoplasm and a lobed nucleus
Describe agranulocytes
white blood cells with a clear cytoplasm and an oval or bean-shaped nucleus
What movement do most white blood cells exhibit?
amoeboid movement allowing them to squeeze between cells in capillary walls and enter intercellular spaces
What is the function of white blood cells?
to help defend the body against diseases
Describe platelets
tiny irregular cell fragments which are non-nucleated
How many platelets are in one cubic millimeter of blood?
about 250 000
Where are platelets formed?
in large bone marrow cells
What do platelets produce?
an important factor which initiates the blood clotting process
What are the two important functions of blood in mammals?
It is the transport medium carrying various substances and it protects the body against disease-causing micro-organisms
What do red blood cells transport?
oxygen from the lungs to all the cells in the body
What does haemoglobin do?
It has a high affinity for oxygen and combines with it to form oxyhaemoglobin
Describe oxyhaemoglobin
an unstable compound which gives blood a bright red colour
When does the reaction between haemoglobin and oxygen occur readily?
when blood flows through regions where the oxygen concentration is high as in the capillaries of the lungs
How is oxygen transported to body cells?
in the form of oxyhaemoglobin
When does oxyhaemoglobin break down to liberate oxygen?
when blood flows through capillaries surrounding the body cells where the oxygen concentration is low
What color is deoxygenated blood?
dark red
What does the oxygen-dissociation curve show?
the behavior of haemoglobin at varying oxygen concentrations
What is carbon dioxide?
a metabolic waste constantly produced by all the body cells as they respire
How is carbon dioxide transported?
It diffuses out of the cells into blood which transports it to the lungs for excretion
What happens to most of the carbon dioxide?
it enters the red blood cells reacts with water and is rapidly converted to carbonic acid which dissociates to form hydrogen ions and hydrogencarbonate ions
What do hydrogen ions combine with?
haemoglobin
What does haemoglobin act as?
a buffer to maintain the acid-base balance in the cell
Where do hydrogencarbonate ions diffuse?
out of the red blood cells into the plasma
How are hydrogencarbonate ions transported?
in the plasma to the lungs
What ions move from the plasma into the red blood cells?
chloride ions
Why do chloride ions move into red blood cells?
to maintain ionic concentrations and replace the hydrogencarbonate ions that diffused out
What does some carbon dioxide combine with to form carbamino-haemoglobin?
haemoglobin
How is carbamino-haemoglobin transported?
to the lungs
What happens to a small amount of carbon dioxide?
it does not enter the red blood cells and forms hydrogen ions and hydrogencarbonate ions
What buffers the hydrogen ions formed in the plasma?
the plasma proteins
What happens to hydrogencarbonate ions and carbamino-haemoglobin in the lungs?
they break down to release carbon dioxide
What speeds up the release of carbon dioxide in the lungs?
the high oxygen concentration and the formation of oxyhaemoglobin
How is urea transported?
as a solution in the plasma from the liver to the kidneys
How are digested soluble foods transported?
from the small intestine to the liver in the plasma
What does the liver do with the digested food?
releases the required amount into the blood for distribution to all parts of the body
How are hormones transported?
by the plasma from the glands that produce them to the target organs
How does blood help with temperature control?
it distributes heat uniformly and regulates body temperature by getting rid of excess heat through the skin or reducing heat loss
How does blood protect the body?
from foreign agents and proteins such as disease-causing micro-organisms in three ways
What do phagocytes do?
ingest and destroy harmful micro-organisms and remove broken-down dead tissues
What happens to some white blood cells during phagocytosis?
they are killed forming pus around wounds
What do lymphocytes produce?
antibodies
How do antibodies destroy micro-organisms?
by causing them to clump together or dissolving their outer coats
What do some micro-organisms produce and what neutralizes them?
toxins which are neutralized by anti-toxins
What do antibodies and anti-toxins provide?
immunity against diseases
What constitutes the bodys immune system?
white blood cells that produce protective substances
What does the AIDS virus do?
attacks and destroys certain white blood cells in the immune system
What is the result of AIDS?
the infected person is left without a defence against disease-causing microorganisms and suffers from microbial infections which cause death
What do arterioles branching from arteries divide into?
capillaries with one-cell thick walls
What is the blood pressure like in capillaries at the arteriole end?
high
What does high capillary blood pressure cause?
plasma most dissolved substances and some white blood cells to filter out into intercellular spaces
What cannot filter through capillary walls?
plasma proteins and erythrocytes
What is intercellular or tissue fluid?
plasma that filters out and occupies the spaces between the cells
What does intercellular fluid contain?
water dissolved oxygen dissolved food and hormones
How are materials transported between blood and cells?
via the intercellular fluid
What role does intercellular fluid play?
a middleman in the transport and exchange of materials between the blood and the cells
How is intercellular fluid returned to the blood?
in two ways
Describe the first way intercellular fluid is returned to the blood
blood in capillaries at the venule end is highly concentrated with mainly plasma proteins and little water while intercellular fluid near venules is a weak solution so some intercellular fluid is absorbed into the blood in the capillaries
Describe the second way intercellular fluid is returned to the blood
unabsorbed intercellular fluid passes into blindly ending lymphatic vessels near the capillaries becoming lymph which flows through fine lymphatic vessels joining to form large vessels that empty into veins in the neck region
What fluids are in continuous circulation in the body?
intercellular fluid lymph and blood
What makes lymph flow along lymphatic vessels?
movements of the body muscles
What prevents backflow of lymph?
valves in the lymphatic vessels
What are lymph nodes?
bean-shaped structures along the lymphatic vessels that produce white blood cells filter out micro-organisms foreign particles and cell fragments and engulf them with phagocytes
Describe the human heart
a conical hollow muscular organ that works continuously throughout life is about the size of a clenched fist and weighs about 300 grams
Where is the heart located?
in the chest just behind the breastbone and between the two lungs
What are lymph nodes?
bean-shaped structures along the lymphatic vessels that produce white blood cells filter out micro-organisms foreign particles and cell fragments and engulf them with phagocytes
Describe the human heart
a conical hollow muscular organ that works continuously throughout the life of a person is about the size of a clenched fist and weighs about 300 grams
Where is the heart located?
in the chest just behind the breastbone and between the two lungs
What is the heart enveloped in?
a two-layered tough membranous bag the pericardium
What is between the two layers of the pericardium?
fluid
What does the fluid between the pericardium layers do?
reduces the friction caused by the pumping movements of the heart between the heart wall and the surrounding tissues
How often does the average human heart contract and relax at rest?
about 70 times per minute
How much blood does the average human heart pump per day at rest?
about 14 000 litres
What happens to the heart rate during exercise?
it goes up to over 100
What does increased heart rate during exercise do?
increases the supply of oxygen and food to the body cells
What is the heart wall made of?
a special muscle the cardiac muscle found only in the heart
Describe cardiac muscle
contracts and relaxes rhythmically and can work continuously without becoming tired like the skeletal muscles
What does cardiac muscle need to work hard and continuously?
a good supply of blood to provide oxygen and nutrients and remove its wastes
What supplies the heart muscle with blood?
coronary arteries and veins which spread all over the heart wall
What are the chambers of the heart?
two upper thin-walled atria or auricles and two lower thick-walled ventricles
What separates the right and left sides of the heart?
a wall called the septum
What veins open into the right auricle?
two large veins the superior (anterior) and inferior (posterior) venae cavae bringing dark red deoxygenated blood from the various parts of the body (except the lungs)
What veins open into the left auricle?
pulmonary veins bringing bright red oxygenated blood from the lungs
What controls the openings of the veins into the auricles?
rings of muscles found in the vein
What do the muscles controlling the openings of the veins into the auricles do when they contract and relax?
contraction closes the openings while relaxation opens them
What guards the opening between the right auricle and the right ventricle?
the tricuspid valve
Describe the tricuspid valve
has three flaps attached by cord-like tendons (chordae tendinae) to the walls of the right ventricle
What do the chordae tendinae do?
only allow the flaps to open outwards into the ventricle allowing unidirectional blood flow from the auricle into the ventricle
What guards the opening of the left auricle into the left ventricle?
the bicuspid or mitral valve
How is the bicuspid or mitral valve similar to the tricuspid valve?
structurally and functionally except that it has two flaps instead of three
What does the right ventricle open out into?
the pulmonary artery which branches into two one leading to the right lung and the other to the left lung
What do the branches of the pulmonary artery carry?
deoxygenated blood to the lungs
What does the left ventricle open into?
the large aorta which branches to distribute oxygenated blood to all parts of the body except the lungs
What prevents backflow of blood from the arteries into the ventricles?
Semi-lunar valves in these arteries
How does the thickness of the left ventricle wall compare to that of the right ventricle?
it is at least three times thicker
Why is the left ventricle wall thicker?
because its contraction must send blood round the much longer systemic circulation while the right ventricle only needs to send blood round the shorter pulmonary circulation
What is the blood pressure of blood entering the aorta and pulmonary artery?
about 105 mmHg in the aorta and about 16 mmHg in the pulmonary artery
What happens during diastole?
Veins and auricles contract forcing blood into relaxed ventricles semi-lunar valves close and cuspid valves open
What happens during systole?
Ventricles contract forcing blood into aorta and pulmonary artery Backflow of blood into the auricles is prevented by the closing of the cuspid valves which we hear as a loud lub sound Blood from the ventricles enters the arteries After fully contracting the ventricles start to relax The blood in the arteries tend to flow back into the ventricles This is prevented by the closing of the semi-lunar valves which we hear as a soft dub sound
What is one heartbeat?
one contraction (systole) and one relaxation (diastole) of the ventricles and lasts for about 0.8 second
What happens to the heart chambers during diastole?
they especially the ventricles relax or rest
What happens to the heart chambers during systole?
they especially the ventricles contract
What happens when the ventricles contract?
they force blood into the arteries at high pressure causing the elastic walls of the arteries to dilate suddenly
