7. mass transport Flashcards
describe the structure of hemoglobin
four polypeptide chains (two a two b), each polypeptide is associated with a ‘heam’ group, containing Fe, which can associate with an 02 molecule
what effect does CO2 concentration have on the association of oxygen? why?
high concentration of CO2 = oxygen is DISSOCIATED
high conc of CO2 = lower PH
lower PH affects the shape of hemoglobin, oxygen is unloaded more readily
explain the shape of an oxygen dissociation curve
- the shape of hemoglobin makes the first oxygen molecule the hardest to bind to an oxygen
- after the first oxygen associates, the hemoglobin changes shape, making it easier for the rest of the heam groups to associate with an oxygen
this is called positive cooperativity - fourth heam group however has a low probability of associating, as there are fewer binding sites
if the oxygen dissociation curve is further to the left, what does this suggest?
hemoglobin has a higher affinity for oxygen, loading easier but unloading less easily,
ideal for lungs
if hemoglobin has a low affinity for oxygen, what does this suggest? what is this ideal for?
loads oxygen less readily but unloads it more easily
respiring tissue
how is the rate of respiration linked to the affinity of hemoglobin in respiring tissue
increased rate of respiration = more concentration of CO2 = lower PH = more change in shape = lower affinity
which blood vessel delivers blood from the body to the heart
the vena cava
what blood vessel delivers blood from the heart to the body
the aorta
what is special about the pulmonary artery
it is the only artery that carries deoxygenated blood
how do the roles of veins and arteries differ?
veins transport blood toward the heart, arteries carry blood away from the heart
what blood vessels supply the heart (muscles) with oxygen
the coronary arteries
what does diastole mean
relaxation of the heart
describe the three stages of the cardiac cycle, and make mention of the heart’s valves.
- diastole
blood enters the heart via the vena cava and pulmonary vein, and relaxation of tri/bicuspid valves m
allow blood to flow to the ventricles.
semi-luna valves are shut. - atrial systole
atria contract, pushing blood into the ventricles.
semi-luna valves remain shut. - ventricular systole
ventricles contract, pushing blood through the atria and out of the aorta and pulmonary artery
bi/tri are shut and semi-luna is now open
Explain how and when valves open and close.
valves have a cusp shape. when blood is of high pressure on the convex side (fat), blood moves the valve open and travels through.
when blood is of high pressure on the concave side, blood collects in the ‘bowl’ of the cusp. this pushes the valves together, closing them
What is the equation for cardiac output
CO = HR x SV
Why do arteries have a thick elastic layer?
Why do arteries have a thick muscle layer?
Why do arteries have a thick wall?
elastic layer keeps blood at high pressure
muscle layer allows vasoconstriction and dilation.
stop vessels from bursting due to high pressure
how is the structure of capillaries adapted for their function?
- extremely thin, short diffusion pathway.
- highly branched, large SA.
- narrow lumen, cell squeezed flat against the side of capillary, a smaller distance of diffusion.
- gaps for white blood cells.
describe the hearts role in the formation of tissue fluid
contraction of heart ventricles produces high hydrostatic pressure,
forcing water and dissolved substances out of capillaries into tissue fluid
High blood pressure leads to an accumulation of tissue fluid. Explain how. (3)
high blood pressure = higher hydrostatic pressure
increase in outward presssure at the atrole end
so more tissue fluid is formed and less is re-absorbed
how is tissue fluid re-absorbed into capillaries?
Large molecules remain in the capillaries, lowering water potential.
As hydrostatic pressure decreases towards the venule end of capillaries, water re-enters by osmosis.
+ lymphatic system - back to bloodstrem
how can diet increase risk of heart disease? (2)
- high levels of salt raises blood pressure
- high levels of saturated fat = high blood cholesterol
Where are atrioventricular valves found?
What is their role?
between the left and right atrium and ventricle, preventing blood from moving to the aorta and pulmonary artery (when closed)
Where are Semi-lunar valves found?
What is their role?
in the aorta and pulmonary artery, prevent backflow of blood into ventricles
Name the two arteries connected to the heart.
Pulmonary artery
Aorta
Name the two veins connected to the heart.
Vena Cava
Pulmonary Vein
What two vessels connect the heart and lungs?
pulmonary vein/ artery
What is the septum?
What is its role?
tissue that separates the deoxy and oxy blood.
maintaining concentration gradient between oxygenated blood and respiring cells.
Compare the pressure in the arteries, arterioles and veins.
most pressure in arteries, slightly lower in arterioles and much lower in veins
What is meant by ‘Diastole’?
atria and ventricular muscles are relaxed, blood enters heart.
Identify the vessels at which blood enters the heart.
vena cava and pulmonary vein.
What is tissue fluid?
Fluid containing water, glucose, amino acids ect that ‘bathes’ tissue cells
What is transpiration?
loss of water from the stroma evaporation
Explain how Wind affects transpiration.
positive correlation, more wind will blow away air with water in it. maintaining water potential.
Explain how Humidity affects transpiration.
negative correlation,
more water in air, reduces water potential gradient.
Explain cohesion’s role in transpiration
water is dipolar, hydrogen bonds form (between hydrogen and oxygen)
water molecules stick together = continuous water column through xylem
Explain capillarity in the xylem.
adhesion of water to the xylem wall, narrower the xylem the bigger impact of capillarity.
What evidence is there for the transpiration stream?
tension is created by water being pulled up the xylem, pulling the xylem narrower.
During daytime, trunk of tree is thinner due to collective pressure of xylems.
Describe the cells that make up phloem tissue.
- sieve tube cells, living cells, no nucleus, few organelles
- companion cells, provide ATP for active transport.
Explain the role of root pressure in transpiration.
As water moves into roots, volume increases and therefore pressure.
positive pressure forces water upwards
Explain the ‘source to sink’ mass transport process.
explanation of transport of sucrose not necessary
Draw it if poss.
sucrose (made by photosynthesis) lowers water potential of sieve tubes.
water enters the sieve tube by osmosis
Sucrose into respiring (sink) cells, decreasing its water potential, water into the sink cell, out of sieve tube + into xylem.
high hydrostatic pressure at the source cell, low pressure at the sink.
How does sucrose enter seive cells in translocation
Draw if poss
sucrose diffuses into companion cell (fac)
active transport of H+ ions from companion cells into cell walls,
H+ diffuse into sieve tube, co-transport of sucrose with H+ ions
sucrose is actively transported into sieve cell.
In simple terms, what causes the movement of sucrose from the source to the sink end of the sieve tube elements?
differences in hydrostatic pressure.
How can tracers be used to investigate translocation?
Plants provided with radioactively labeled carbon = sugars made in photosynthesis contain radioactive carbon
Thin slices of stems are cut and placed in X-ray film, black when exposed to x ray
can be used to highlight of pathway of sugars across stem sample
How can the ringing experiment be used to investigate translocation?
ring of bark and phloem removed, trunk swells above removed section.
liquid in swelling contains sugar, proves that without phloem, sugars cannot be transported around plant.
definition of tidal volume
volume of air that enters the lungs each breath
definition of cardiac output
blood the heart pumps through circulatory system in one minute
definition for stroke volume
volume of blood pumped out of left ventricle in one contraction
