Mass Transport Flashcards
Mass transport system
movement of a huge number of substances in the same direction at the same time
Double circulatory system
confined to vessels and blood passes through the heart tissue twice for each complete circuit- from heart to lungs and heart to body
Haemoglobin structure
quaternary protein made up of 4 polypeptide chains each with a haem group containing an iron ion
each iron ion can bind with an oxygen molecule so hb can bind with 4 o2 molecules- oxyhaemoglobin
Haemoglobin function
transports o2 around the body by associating with o2 in the lungs and dissociating at the tissues
it has a chemical attraction/ affinity for o2
Dissociation curve
s shaped curve which shows the binding of o2 to hb
1st o2 is hard to bind so curve is not steep
2,3rd o2 easily taken up by hb as the quaternary structure is affected when the first o2 binds
-allows o2 to be taken up quickly in lungs
4th is hard to bind as it has to find empty iron ion so curve is flatter
Dissociation curve shift
curve shifts to right- lower affinity for o2 so it will unload more readily and load at higher po2- smaller animals or those who respire more, have greater SA:V so lose heat (maintain temp)
curve shift to left- higher affinity for o2 so it doesn’t unload as easily, o2 binds at low po2- animals who live in environments with little o2 (high altitude) + lugworms
Bohr shift
during exercise co2 levels rise (carbonic acid) which lowers the ph of blood making it more acidic which changes the shape of hb - has a lower affinity and unloads o2 more readily at respiring tissues
curve shifts to the right known as bohr effect
Cardiac cycle
sequence of events that occur in one heart beat
atrial systole- ventricular systole- diastole
AS- atria are full of blood and contract, higher pressure in atria than ventricles, AV valves open and blood flows to ventricles
VS- ventricles are full of blood and contract, higher pressure in ventricles so AV valves shut and SL valves open and blood flows to arteries
D- atria and ventricles relax (low pressure), blood trickles into atria, blood trickles into atria from vena cava and pul vein, pressure higher in atria, AV valves open, pressure higher in arteries, SL valves shut
Cardiac output
stroke volume x heart rate
stroke volume= highest volume-lowest volume
calculating bpm- find out time of one heart beat
look when volume of blood repeats itself
work out how many beats in one minute- 60/time of one heart beat
higher pressure in ventricles as more muscle
Blood vessels
arteries, arterioles and veins have layered structure surrounding lumen of endothelium, elastic layer (stretch to receive blood at high pressure, recoil when blood pressure decreases), muscle layer (controls blood flow by contracting and relaxing vasoconstriction + vasodilation ),
tough fibrous layer to resist pressure
blood in veins keeps moving by contraction of skeletal muscles, valves preventing back flow, wide lumen
capillaries- surround cells and tissue fluid and assist with exchange of substances
Tissue fluid
surrounds the cells in the body and provides a medium that allows o2 and glucose etc to travel out of capillaries
formed:
high hydrostatic pressure at arteriole end
forces water (+glucose) out through capillary walls
large proteins and RBC remain in capillary
lowers water potential
water moves back in at venous end by osmosis
from high wp outside to low wp inside
low pressure at venous end due to loss of fluid
lymph system collects excess tissue fluid which links with vena cava and returns tf to circulatory system
Capillaries
structures that aid their function;
walls consist of endothelium so short diffusion path
narrow lumen so rbc up tight against capillary wall meaning they are closer to body cells
highly branched increasing surface area and rate of diffusion
Cardiovascular disease
weakens the heart, reduces cardiac output and increases the risk of heart attack
risk factors- excess saturated fat leads to build up of atheroma causing atherosclerosis
smoking- carbon monoxide binds with hb
high cholesterol levels
genetics, age, sex
Transpiration
evaporation of water from leaves through open stomata
transpiration pull/stream moves water up from root to leaf
-water molecules evaporate from mesophyll cells then move through air spaces in the leaf and diffuse out of stomata
-lowers wp of mesophyll cells so water moves from high to low wp from neighbouring cells into mesophyll cells by osmosis
-lowering wp is repeated back to xylem
-the wp gradient across the leaf to the atmosphere pulls water up from the xylem- transpiration pull
(cohesion tension theory)
Xylem
carry water
xylem vessels are dead cells with no end walls
form continuous tubes from roots to leaves
lined with lignin to prevent cells collapsing under tension
connected through pits which allow lateral movement of water if pathway is blocked
have no organelles to allow water travel without being blocked