Mass transport Flashcards
(27 cards)
What is haemoglobin and describe the structure
a globular protein with 4 polypeptide chains
it has a quaternary structure
each polypeptide has a haem group with an Fe2+ ion
it has 4 oxygen binding sites so it carries oxygen through the blood to respiring cells
describe the shape of a standard oxyhaemoglobin dissociation curve
graph begins shallow at low partial pressures of oxygen until the first O2 molecule binds
upon the binding of the first oxygen molecule a conformational shape change of haemoglobin is causes so the 2nd and 3rd binding oxygen is much easier, this causes the curve to become very steep very quickly
the graph then begins to plateau as there is a decrease in binding site availability so it is harder for oxygen to bind
What is the Bohr effect
During exercise, rate of respiration increases which increases blood concentration of carbon dioxide
CO2 dissolves in blood to form carbonic acid which lowers blood pH
this causes a change in haemoglobins tertiary structure, lowering oxygen affinity
this means more oxygen is dissociated from haemoglobin at respiring tissues which will compensate for the increased rate of respiration
How does haemoglobin differ in different organisms
Organisms that live in low partial pressures of oxygen have a higher affinity so haemoglobin is more readily loaded at these low partial pressure
Organisms that live in high partial pressures have myoglobin, which has a lower affinity for oxygen, so oxygen can be more readily dissociated
3 Blood vessels surrounding the liver
Hepatic artery
Hepatic vein
Hepatic portal vein
2 Blood vessels surrounding the kidneys
Renal artery
Renal vein
4 blood vessels surround heart
vena cava
aorta
pulmonary artery and vein
Flow of blood through the heart to lungs
through vena cava into right atrium
through tricuspid valve into right ventricle
through semilunar valve to pulmonary artery to lungs
Flow of blood through heart to body
Through pulmonary vein into left atrium
through bicuspid valve into left ventricle
through semilunar valve into aorta and out to the whole body
Adaptations of the heart
left ventricle walls are much thicker than the right ventricle walls as blood has to be pumped much further
Aorta is much thicker than any other artery as has to withstand the highest pressure of blood
valves to prevent backflow
septum to prevent mixing of oxygenated and deoxygenated blood
1st Step of cardiac cycle
Cardiac diastole
- both atria and ventricles are relaxed and blood enters the atria
- As pressure rises atrioventricular valves will open and blood moves down pressure gradient
2nd step of cardiac cycle
Ventricular diastole and atrial systole
- atria contract to ensure all blood enters ventricles
- as pressure increases in ventricles, atrioventricular valves shut to prevent backflow
3rd step of cardiac cycle
Ventricular systole
- ventricles contract, increasing pressure further so semilunar valves open
-blood flows into pulmonary artery and aorta
Why is double circulatory system a good adaptation and why would a single system not work
it allows a high pressure to be maintained
Large surface area of lung capillaries would decrease pressure so less oxygenated blood will be delivered to tissues
Structure of artery
Thick muscular layer so constriction and dilation can control blood volume
Thick elastic layer to allow to stretch and recoil
Thick wall to withstand high pressures
Structure of arterioles
thick muscular layer to restrict blood flow into capillaries
thinner elastic wall to arteries
Structure of veins
thin muscular layer
thin elastic layer due to lower pressure
valves to prevent backflow at lower pressure
Capillary structure
1 cell thick wall for short diffusion pathway
no muscle or elastic layer
form capillary beds which have narrow diameter
Formation and return of tissue fluid
- Blood enters capillaries from arterioles resulting in a high hydrostatic pressure at arteriole end
- molecules like glucose, amino acids, fatty acids, ions, water and oxygen are forced out to form tissue fluid
- larger molecules such as proteins will remain in capillaries, which lower water potential at venule end
- at venule end, low hydrostatic pressure and water potential means that water re - enters by osmosis ( NOT ALL OF IT )
- REMAINING TISSUE FLUID ABSORBED INTO LYMPHATIC SYSTEM
How is water moved through the plant
Water absorbed via root hair cells by osmosis
water reaches xylem and travels against gravity in continuous columns
transpiration occurs so water vapour evaporates through stomata
Describe the cohesion tension theory
Water is dipolar so hydrogen bonds form between molecules (cohesion)
results in a continuous water column created in the xylem
water evaporates out of stomata, so the column is pulled up the xylem (transpiration pull)
Tension on the xylem is created, causing its diameter to decrease
Adaptations of the xylem to form a column
Made of dead cells so are hollow
have no end walls so a column can form
Function of the phloem
transport of organic substance by translocation by mass flow
Structure of the phloem
sieve tube element
sieve tube plates
companion cells
