Mass Transport Flashcards
What are the adaptations of a red blood cell
No nucleus so more room for haemoglobin
Bi concave shape
Pits the capillary perfectly so there is a short diffusion pathway
Protein structure of haemoglobin (primary - quaternary)
Primary - two alpha and two beta polypeptide chains
Secondary - each polypeptide chain folds into a helix
Tertiary - polypeptide chain is folded into a precise shape
Quaternary- all 4 polypeptides are linked to make a spherical shape each associated with a haem group with iron
How many oxygen molecules can each human haemoglobin molecule Carry
4
How many oxygen atoms can two haemoglobin molecule carry and why
16 because there would be 8 oxygen molecules with two atoms each
Describe the role of oxygen affinity in haemoglobin
Affinity must be high where oxygen loads (lungs )
But it decreases at the respiring tissue so that oxygen can unload
What factors effect the type of haemoglobin present in an organism
Amino acid sequence
Shape of molecule
Why is only one of the 4 oxygen molecules released when the body is at rest
So that more oxygen can be delivered to tissue when they become more active
What is a erythrocyte
Red blood cell
What is partial pressure
In a mixture of gasses the pressure of one gas if it alone filled the container
What does cooperativity mean in terms of loading oxygen
When one oxygen binds the structure of the haemoglobin changes shape slightly making it easier for future oxygen molecules to bind
Explain the shape of the oxygen dissociation curve
At the beginning oxygen struggles to bind with the haemoglobin once one sxygen has bound to the haem group the gradient of the line increases because the quaternary structure of the haemoglobin moves slightly. This is cooperative and allows three other oxygens to load easily
Describe how partial pressure affects oxygen association
Haemoglobin slightly saturated with oxygen at higher partial pressure
Drop in partial pressure leads to rapid decrease in % saturation of haemoglobin
This favours loading oxygen in the lungs and unloading in the tissue
Describe the Bohr shift
In Actively respiring tissue carbon dioxide concentration increases which dissolves in the blood plasma. This forms carbonic acid so there is an increase in H+ ions causing a decrease in blood pH
More oxygen is more easily unloaded because of the lower affinity of oxygen due to the pH reduction. This means more oxygen is available for respiration at the same partial pressure
The Bohr effect is reversed in the alveoli because carbon dioxide conc is low , so loading of oxygen is easier because higher affinity of haemoglobin for oxygen bought about by pH increase
What is the oxygen dissociation curve for lug worms and llama ( and which way does it move)
Moves to the far left
They have a higher affinity for oxygen because they live in low partial pressure areas
What does the foetal oxgyen dissociation curve look like (and where does it move )
Moves slightly left
It has a higher affinity for oxygen because partial pressure at placenta can associate more oxygen from the mother
What does the oxygen dissociation curve look like for small mammals as birds (and where does it move)
Moves to the right
They are highly metabolically active so are adapted to release oxygen more readily
Lower affinity for oxygen
How do simple animals transport things and why
Diffusion because of their small surface area to volume ratio
How do larger animals transport stuff and why
Transport systems
Because they have a smaller surface area to volume ratio and diffusion would be to slow
What determines if a transport system needs a pump
The surface area to volume ratio
How active it is
Distance to the centre
Why is it important Mammels have a double closed circulatory system
Because when blood passes the lungs its pressure decreases and if it then went straight to the body it wouldn’t have enough pressure to get all the way round so it must return to the heart to increase the pressure
Why does the aorta have the highest pressure
It is coming from the left ventricle which is muscular as it contracts
Why does the vena cava have the lowest pressure
It is returning to the right atrium and has travelled the furthest around the body
How to describe data
Double data quote ( x and y ) and units
Then quantify with trends
Describe how blood flows through the heart
The right atrium receives deoxygenated blood in the vena cava from the body and the right ventricle pumps through the pulmonary artery to the lungs
The left atrium receives oxygenated blood through the pulmonary vein and and the left ventricle pumps it to the body through the aorta
What are the functions of the valves in the heart
Atrioventricular valves are attached to the ventricles by pupillary muscles which prevent the valves from inverting under high pressure
Describe diastole
Heart muscle is relaxed
Atria and ventricles fill with blood
Semi lunar valves close
Pressure in atrium exceeds ventricle so atrioventricular valves open
Describe atrial systole
Walls of atria contract and blood is forced into the ventricle
Ventricle walls are relaxed
Describe ventricular systole
After a short delay the ventricules fill with blood and walls contract
Atrioventricular valves shut
Pressure in ventricle exceed that of blood vessels so blood forces through the semilunar valves
Pressure in blood vessels increase so semilunar valves shut
What is cardiac output
Volume of blood pumped by both ventricles in one minute
What is the function of the artery
Carries blood away from the heart and into smaller blood vessels
What is the function of the atrioles
Smaller than an artery and controls blood flow into the capillary
What is the function of a capillary
Tiny blood vessels that link the atrioles to the vein
What is the function of a vein
Carries blood from the capillaries back to the heart
Describe the structure of the artery from inside out
Lumen
Tunica media - contains smooth muscle and elastic tissue - does vasoconstriction and vasoconstriction
Tunica externa - contains collagen to protect from internal pressure
Describe the structure of the vein from inside out
Lumen
Tunica media - contains smooth muscle and elastic tissue - does vasoconstriction and vasoconstriction
Tunica externa - contains collagen to protect from external
pressure
Semi lunar valves
Describe the structure of a capillary
Lumen
Endothelium
Fenstrations - gaps which allow substances out
What is good about the thick muscle in the arteries
Constriction and dilation controls volume of blood
What is good about thick elastic layer in arteries
Maintain blood pressure
What is good about the thick wall in the artery
Prevents it bursting under pressure
What is good about semi lunar valves
Prevents back flow
What is good about thick muscle in atrioles
Contracts to restricts blood flow into capillaries
Why do atrioles have thinner elastic
Blood is at a lower pressure
Why is it good capillaries are only one cell thick
Short diffusion distance
Why is it good that there are so many capillaries
Large surface area for exchange
Why is it good capillaries have a small lumen
The blood cells are pushed flat to decrease diffusion distance
Why are there spaces between the capillaries endothelial cells
So white blood cells can escape into infected tissue
What is tissue fluid
Yellowish liquid made from blood plasma and acts as a transport medium
What is the difference between plasma and tissue fluid
Plasma is found in blood
Tissue fluid is found around tissues
Plasma has proteins tissue fluid does not
What is the difference between lymph and tissue fluid
Lymph doesn’t have glucose , co2 , amino acids or minerals
What is hydrostatic pressure
Pressure that builds up forcing water out of the blood plasma
Describe how tissue fluid is formed
The arterial end of the capillary has a higher concentration of amino acids , glucose , h2o , blood cells etc so has a high hydrostatic pressure
All of these things (plasma ) are forced out of the capillary to the lower hydrostatic pressure and becomes tissue fluid
The minerals are used in the tissue cells and the RER turns amino acids into large proteins
Then water , urea , minerals and co2 move by osmis back into the capillary
But the large proteins act as a solute increasing the water potential so not all water moves back into the capillary
The rest of the water and large proteins move into the lymph as lymph fluid
How is lymph moved around the body
Contraction of body muscles
Where are xylem found
On the inside of the vascular bundle in the plant stem
Describe how water is taken up by the xylem
Water evaporates from the leaves
Water forms hydrogen bonds by cohesion
This forms a continuous column of water down the xylem
As the water evaporates molecules are drawn up the xylem
This places the xylem under negative pressure so their is tension
Why does the diameter of the tree trunk decrease during the day
Transpiration is greatest at mid day so their is more tension in the xylem which pulls in the walls of the xylem
Describe how water moves across cells in a leaf
Water is lost from the mesophyll by evaporation
It is replaced by water from the xylem
Some is lost from the mesophyll by evaporation from the sun meaning they have a lower water potential causing water to move by osmosis
Neighbouring cells then have a lower water potential so water moves there
What does a potometer measure
Water uptake
How does a potometer work
Cut the end of a shoot off under water and put it in a rubber tube connected to a capillary tube
Using the tap and a syringe trap one bubble in the tube and measure how far it travels in a certain period of time on a millimetre scale
Describe the structure of the phloem
Sieve tube elements- not a proper cell , no nucleus or ribosomes and very little cytoplasm
They have sieve plates in which are pores to allow sap through
Companion cells - small cells in between sieve tubes with large nucleus, dense cytoplasm, lots of mitochondria , small vacuole
Cytoplasm is linked to sieve tube elements by plasmodesmata
What is the source
Where sucrose is loaded
What is the sink
Where sucrose is removed
How is sucrose transported from the source to the sieve tube
ATP made in the mitochondria used to active transport H+ ions out creating a high concentration in the source
H+ ions then move via facilitated diffusion and co transport of sucrose into the source
Sucrose diffuses through plasmodesmata into sieve element
Describe how organic matter moves through phloem by mass transport
Water moves into phloem from xylem by osmosis due to pits in xylem and high sucrose making low water potential but then creating high hydrostatic pressure
It then moves down to phloem to lower hydrostatic pressure at the sink
Sucrose is actively transported from the companion cell to the sink causing increase water potential and lower hydrostatic pressure so water moves back to the xylem
Describe the ringing experiment
A ringing of bark containing the phloem is removed
The bark above swells and the liquid collected from the swelling was found to be containing sugars
Proving sugar goes down the phloem
Describe the aphid experiment
Probis from aphid penetrates the phloem
Their head is cut off leaving the probis in the tree
Phloem continued to come out without the sucking motion proving the phloem is under pressure and mass flow is likely
