Mass Transport Flashcards
What is mass transport?
The bulk movement of materials from exchange surfaces to cells
Whether an organism requires a mass transport system is depended on what?
Fick’s law
What do all efficient transport systems have?
Transport medium
Tubular vessels
Mechanisms for movement of tissue fluid
What is an example of a transport medium?
Blood
What are the state of transport mediums?
Liquids but can be a gas
What do tubular vessels do?
Contain/hold medium
Forms branches to all parts of organisms
Keeps medium close to cells
What is an example of a tubular vessel?
Blood vessel
What do mechanisms for movement of tissue fluid enable?
Medium to move
What is an example of a mechanism for movement of tissue fluid?
Heart
What do mechanisms for movement of tissue fluid require?
Pressure difference
What does it mean if an organisms has a double circulation?
They have a high metabolic rate
What is an example of a single circulation organism?
Fish (low metabolic rate)
What is an example of a double circulation organism?
Human (high metabolic rate)
Why is a double circulatory system required?
Small SA:Vol
High level of activity
Maintain temp via respiration
What is the pulmonary circulation?
Pumps blood from heart to lungs
Oxygenates blood/removes CO2
What is the systematic circulation?
Pumps blood to rest of the body
Increased pressure from heart
What are the two arteries connected to the heart?
Aorta
Pulmonary artery
What are the two veins connected to the heart?
Pulmonary vein
Vena cava
Where does the aorta take the blood to?
Head + body
Where does the pulmonary artery take the blood to?
Lungs
Where does the pulmonary vein deliver the blood from?
Lungs
Where does the vena cava deliver the blood from?
Head + body
What is the vena cava split into?
Superior and inferior
What are the valves called that separate the atrium and ventricle?
Atrio-ventricular valve
What are the two AV valves called?
Tricuspid
Bicuspid
Where is the tricuspid valve found?
Right side
Where is the bicuspid valve found?
Left side
What are the two valves called between the ventricles and arteries?
Semi-lunar valves
What does the right ventricle do?
Pump deoxygenated blood TO lungs
What does the left ventricle do?
Pump oxygenated blood FROM lungs to head + body
Do both ventricles fill at the same time?
YES
Describe the flow of blood
RA to RV through tricuspid valve
Out of pulmonary artery to lungs through semi-lunar valve
Lungs to pulmonary vein
LA to LV through bicuspid valve
Out of aorta to head + body through semi-lunar valves
Head + body to vena cava
What are the adaptations of the heart?
Coronary artery
Thick walls
Valves
Why do coronary arteries help?
As supply heart with O2
Why do thicker walls help?
As LV has to pump blood round all of body
Why do valves help?
As prevent backflow
What are the two main processes that the cycle is split into?
Contraction - systole
Relaxation - diastole
- Describe the diastole
Atria fills Pressure increases AV valves open NO CONTRACTION Cardiac muscles relax Low pressure in ventricles Semi-lunar valves close NO CONTRACTION
- Describe atrial systole
Cardiac muscles around atria contract
Pushes remaining blood into ventricles
Ventricle walls relax (ventricular diastole)
- Describe ventricular systole
Ventricles contract
Forces AV valves to shut
Pressure forces semi lunar valves to open
Blood pushes out of heart
Walls thicker so contract forcefully so push blood further
What is the equation for cardiac output?
Heart Rate X Stroke Volume
What is cardiac output measured in?
dm2 min-1
What is heart rate measured in?
Beats per min
What is stroke volume measured in?
Vol of blood pumped at each beat
How are the structure of the walls of arteries and arterioles related to their function?
Epithelium is smooth and reduces friction
Elastic tissue stretches under pressure and recoils to even out the pressure
Muscle contracts to reduce the diameter of the lumen to change the flow
What is haemoglobin?
A respiratory pigment used to transport oxygen
Describe the quaternary structure of haemoglobin?
Beta polypeptide
Alpha polypeptide
Each subunit has a haem group
What does each ahem group contain?
Ferrous ion (Fe*2+)
How many O2 molecules does each haemoglobin carry?
One
What is formed when O2 is combined with haemoglobin?
Oxyhaemoglobin
What must haemoglobin do to be efficient?
Readily associate
Readily dissociate
What is affinity?
The attractive force binding atoms together in molecules - chemical attraction
What does a haemoglobin with a high affinity have?
High attractive force
Readily associate with O2
What does a haemoglobin with a low affinity have?
Low attractive force
Readily dissociates
What are the factors that effect Hb affinity?
Metabolic rate
Environment
What is metabolic rate in terms of Hb affinity?
How much oxygen is required by the organism
What is environment in terms of Hb affinity?
How much oxygen is present (PO2)
What is partial pressure (PO2)?
The amount of a gas present in a mixture of gas (kPa)
What is the PO2 in the atmosphere?
21kPa
What is the PO2 in the lungs?
High
What does it mean that there is a high PO2 in the lungs?
High association/saturation
What is the PO2 in respiring tissues?
Low
What does it mean that there is a low PO2 in respiring tissues?
Low saturation
Why does haemoglobin change shape?
Difficult to attach first O2
So changed shape means it can easily associate
As bonds are disrupted
So fully saturated at high PO2
What is positive cooperativity?
Binding of the first molecules makes binding of the second easier
What is the shape of an oxygen dissociation curve?
S-shaped
What does the “S” shape of an oxygen dissociation curve reveal?
Difficult to attach first O2
As first attaches increases rapidly
What does an oxygen dissociation curve show?
At low PO2 saturation is low
As PO2 increases saturation increases
Which way does the curve shift when there is a high O2 affinity?
LEFT
Which way does the curve shift when there is a low O2 affinity?
RIGHT
What happens to the pH when the CO2 concentration increases?
Decreases
What happens to the affinity when the pH lowers?
Decreases
What happens in the lungs when oxygen is loaded?
CO2 constantly removed Low CO2 conc pH raised Protein shape changes Affinity of Hb increases O2 readily associates
Where is oxygen loaded?
Lungs
Where is oxygen unloaded?
Respiring tissues
What happens in respiring tissues when oxygen is unloaded?
CO2 is constantly produced High CO2 conc pH lowered Protein changes shape Affinity of Hb decreases O2 readily dissociates
What is the bohr effect?
CO2 rich environment (muscle cells)
More CO2 dissociates from oxyhaemoglobin
Oxygen dissociation curve shifts right
What do arteries do?
Carry blood away from the heart
What do arterioles do?
Control blood flow from arteries to capillaries
What do capillaries do?
Link arterioles to venules
What do venules do?
Control blood flow from capillaries to veins
What do veins do?
Carry blood back to the heart
What are similarities between arteries and veins?
Tough outer layer
Muscle layer
Elastic layer
Lumen (a cavity)
What is the function of the tough outer layer?
Resist pressure changes from within and outside
What is the function of the muscle layer?
Contract and control flow of blood
What is the function of the elastic layer?
Help to maintain blood pressure by stretching and recoiling
What is the function of the lumen (a cavity)?
A passage for the blood to travel through
Do veins have valves?
YES
Why are veins the only blood vessel with valves?
Because the pressure is very low so backflow is more likely
Order the blood vessels by thickness of muscle
Arteriole
Vein
Artery
Capillary (NONE)
Order the blood vessels by thickness of elastic
Artery
Arteriole
Vein
Capillary (NONE)
Order the blood vessels by size of lumen
Vein
Arteriole
Artery
Capillary
Order the blood vessels by blood pressure
Artery
Arteriole
Vein
Capillary
What are the cardiovascular diseases?
Strokes
Angina
Heart attack/failure
Atherosclerosis
What is correlation?
A change in one or two variables that is reflected by a change in the other
What does a correlation NOT indicate?
A cause
What is tissue fluid?
A watery liquid that bathes all the tissues in our body and allows for the exchange of substances between blood and cells
Where do substances in tissue fluid enter and leave?
Through capillary walls
What does tissue fluid contain?
Molecules required
eg. O2, glucose, ions, fatty acids + amino acids
Waste products
eg. CO2, urea + H2O
What does tissue fluid not contain?
Large molecules
eg. Red blood cells + plasma protein
What is the formation of tissue fluid a result of?
The balance of two pressures
What are the two pressures that form tissue fluid?
Hydrostatic pressure (blood pressure) Osmotic pressure (water potential)
What is hydrostatic pressure a result of?
The heart pumping
What happens to tissue fluid at the arteriole end?
Hydrostatic pressure is greater than osmotic pressure
So the NET movement is OUT
Why is the NET movement of tissue fluid OUT at the arteriole end?
H2O moves in + out but there is a greater hydrostatic pressure
What is it called when only small molecules move out?
Ultra-filtration
What happens to tissue fluid at the venule end?
Hydrostatic pressure is lower than osmotic pressure so the NET movement is IN
Why is the NET movement of tissue fluid IN at the venule end?
Higher water potential outside due to cells producing CO2 and proteins dissolving inside so water moves inwards
And lower hydrostatic pressure
Not all tissue fluid returns to the capillaries where does it go?
Into the lymphatic system
Is the lymphatic system separate to the circulatory system?
YES
What is the lymphatic system made up of?
Microscopic tubes called lymph capillaries
What does the lymphatic system contain?
Accumulated tissue
What is accumulated tissue called?
Lymph
How does lymph drain back into the blood?
Via two ducts that join to the veins close to the heart
What is lymph moved by?
Hydrostatic pressure of tissue fluid
Contract of body muscles squeezing lymph fluid
What is fluid in the blood called?
Plasma
What is fluid that surrounds the tissue called?
Tissue fluid
What is fluid in the lymphatic system called?
Lymph
Why do plants need a mass transport system?
Large
Multicellular
Small SA:Vol
Cannot rely on diffusion
What molecules are transported in plants?
Water
Sugar
What are two main vessels in plants that enable mass transport?
Xylem
Phloem
What is the leaf structure?
Waxy cuticle Epidermal layer Palisade cells Xylem Phloem Spongy mesophyll Air spaces Epidermal tissue Guard cells Stomata
What is transpiration?
The loss of water (evaporation) from the stomata
What happens to the H2O inside of the plant if the humidity of the atmosphere is less than the air spaces?
Water will leave
How does water move in the plant?
Mesophyll cells lose water to air spaces via evaporation due to heat from the sun
Cells have a lower water potential now
H2O enters via osmosis from neighbouring cells
They now have a lower water potential
In turn they take in H2O from neighbouring cells by osmosis
What is the force that moves water in the plant?
Water potential gradient
What are the factors that effect transpiration?
Light
Temperature
Humidity
Air movement
Why does light effect transpiration?
Stomata open in light + close in dark
Why does temperature effect transpiration?
H2O molecules gain more KE
Why does humidity effect transpiration?
More humid = less transpiration as more H2O in the air
Why does air movement effect transpiration?
Disperses humid layer of air = increases transpiration
How is the root hair cell adapted?
Large SA Thin cell wall No chloroplast Large vacuole Mitochondria
How is the xylem adapted?
Hollow open ended tubes
Walled lined with lignin
Lignin forms springs/spirals around the vessel
Cells die after mature
What is the cohesion tension theory?
The hypothesis is used to explain in how water can travel upwards against gravity in a plant
How is cohesion involved in the up movement of H2O in the xylem?
Forms H bonds between H2O molecules
Forms continuous H2O column
As H2O moves up, following molecule is pulled up
How is adhesion involved in the up movement of H2O in the xylem?
H2O attracted to lignin in xylem walls
Stops H2O column from breaking
Facilitates movement
What organic molecules are transported through the phloem?
Sucrose
Amino acids
What inorganic molecules are transported through the phloem?
Potassium
Chloride
Phosphate
Magnesium
How is the mechanisms of translocation explained?
Through the Mass Flow theory
What is the first part of the Mass Flow Theory?
Solute actively loaded from companion cells into sieve tubes
Lowers WP of sieve tubes so H2O enters via osmosis from xylem
So higher pressure inside sieve tubes at source end of phloem
What is the second part of Mass flow theory?
Solutes removed at sink end to be used up
Increases WP inside sieve tubes so water leaves via osmosis
Lowers pressure
What is the third part of the Mass Flow Theory?
Gradient pressure from source end to sink end
Gradient pushes solute along sieve tubes towards sink
At sink they used up or stored
What is the evidence FOR Mass Flow Theory?
If a ring of bark is removed a bulge would form above the ring and the fluid would have a higher conc of sugars above than below
EVIDENCE OF DOWNWARDS FLOW
Radioactive tracer can be used to track movement of organic substances
If a metabolic inhibitor is put into the phloem translocation stops
EVIDENCE ACTIVE TRANSPORT IS INVOLVED
How is a ring of bark being removed evidence of Mass Flow Theory?
If a ring of bark is removed a bulge would form above the ring and the fluid would have a higher conc of sugars above than below
EVIDENCE OF DOWNWARDS FLOW
What is the evidence AGAINST Mass Flow Theory?
Sugars travel to many different sinks not just the one with the highest WP
Sieve plates would create a barrier to mass flow
Lots of pressure needed for solutes to get through at a reasonable rate
How do you investigate translocation of solutes?
Using radioactive tracer
How do you use a radioactive tracer to investigate translocation?
Supply leaf with organic substance (radioactive label)
eg. CO2 pumped into container with leaf
CO2 incorporated into sugars
Movement can be traced by auto-radiography
Plant killed + placed on photographic film
Film black where sugar present
What is using a radioactive tracer evidence of?
Translocation of solutes from the source to the sink
What is translocation?
The movement of solutes to where they’re needed in the plant - it is an energy requiring process
What are sieve tubes?
Living cells that form the tubes for transporting solutes
How are sieve tubes adapted?
No nucleus
Few organelles
What do companion cells for each sieve tube carry out?
Living functions
How are enzymes involved in translocation?
Maintain conc gradient from source to sink by changing solutes at sink
This means there is always lower conc at sink
Where does translocation transport solutes to and from?
From the “source” (where it is made) to “sinks” (where it is used up)
