mass transport Flashcards
Haemoglobin
quaternary structure protein
2 alpha chains
2 beta chains
4 associated haem groups in each chain containing Fe2+
transports oxygen
affinity of haemoglobin
the ability of haemoglobin to attract/ bind to oxygen
saturation of haemoglobin
when haemoglobin is holding the maximum amount of oxygen it can hold
loading/ unloading of haemoglobin
binding/ detachment of oxygen to haemoglobin
also known as association and disassociation
oxyhaemoglobin dissociation curve
oxygen is loaded in regions with high partial pressures
unloading in regions of low partial pressure
oxyhaemoglobin dissociation curve shifting left
Hb would have a higher affinity for oxygen
load more at the same partial pressure
becomes more saturated
adaptations in low-oxygen environments
cooperative binding
Hbs affinity for oxygen increases as more oxygen molecules are associated with it
when one binds. Hb changes shape meaning others bind more easily
explaining S shape of curve
how CO2 affects haemoglobin
When carbon dioxide dissolves
in liquid, carbonic acid forms
decreases pH causing Hb to
change shape
affinity decreases at respiring
tissues
more oxygen is unloaded
Bohr effect
High carbon dioxide partial pressure
causes oxyhaemoglobin curve
to shift to the right
oxyhaemoglobin dissociation curve shifting right
Hb has lower affinity for oxygen
unloads more at the same
partial pressures
less saturated
present in animals with faster
metabolisms that need more
oxygen for respiration
e.g. birds/rodents
closed circulatory system
Blood remains within blood
vessels
name different types of blood vessels
Arteries, arterioles, capillaries,
venules and veins
structure of arteries
Thick muscular layer
thick elastic layer
thick outer layer
small luman
no valves
capillary endothelium
Extremely thin
one cell thick
contains small gaps for small
molecules to pass through (e.g.glucose, oxygen)
capillaries
Form capillary beds
narrow diameter (1 cell thick) to slow blood flow
red blood cells squashed
against walls shortens diffusion pathway
small gaps for liquid / small
molecules to be forced out
arterioles
Branch off arteries
thickest muscle layer to restrict
blood flow
thinner elastic layer and outer
layer than arteries as pressure
lower
tissue fluid
Liquid bathing all cells
contains water, glucose, amino
acids, fatty acids, ions and
oxygen
enables delivery of useful
molecules to cells and removal
of waste
tissue fluid formation
At arteriole end, the smaller
diameter results in high
hydrostatic pressure
small molecules forced out
(ultrafiltration)
red blood cells / large proteins
too big to fit through capillary
gaps so remain
reabsorption of tissue fluid
Large molecules remaining in
capillary lower its water
potential
towards venule end there is
lower hydrostatic pressure due to loss of liquid
water reabsorbed back into
capillaries by osmosis
role of lymph in tissue fluid reabsorption
Not all liquid will be reabsorbed by osmosis as equilibrium will
be reached
excess tissue fluid (lymph) is
absorbed into lymphatic system and drains back into
bloodstream and deposited
near heart
cardiac muscle
walls of heart having thick muscular layer
unique because it is:
myogenic - can contract and
relax without nervous or
hormonal stimulation
never fatigues so long as
adequate oxygen supply
coronary arteries
Blood vessels supplying cardiac muscle with oxygenated blood
branch off from aorta
if blocked, cardiac muscle will
not be able to respire, leading to myocardial infarction (heart
attack)
adaptation of left ventricle
Has a thick muscular wall in
comparison to right ventricle
enables larger contractions of
muscle to create higher
pressure
ensures blood reaches all body
cells
veins that connect to the heart
Vena cava - carries
deoxygenated blood from body to right atrium
Pulmonary vein - carries
oxygenated blood from lungs to left atrium
arteries connected to the heart
Pulmonary artery - carries
deoxygenated blood from right ventricle to lungs
Aorta - carries oxygenated blood from left ventricle to rest of the body
valves within the heart
ensure unidirectional blood flow
semilunar valves are located in aorta and pulmonary artery near the ventricles
atrioventricular valves between atria and ventricles
opening and closing valves
Valves open if the pressure is
higher behind them compared
to in front of them.
AV valves open when pressure
in atria > pressure in ventricles
SL valves open when pressure in ventricles > pressure in arteries
the septum
Muscle that runs down the
middle of the heart
separates oxygenated and
deoxygenated blood
maintains high concentration
of oxygen in oxygenated blood
maintaining concentration
gradient to enable diffusion to
respiring cells
cardiac output
Volume of blood which leaves one ventricle in one minute.
heart rate = beats per minute
heart rate x stroke volume
stroke volume
Volume of blood that leaves the heart each beat
measured in dm^3
cardiac cycle
Consists of diastole, atrial
systole and ventricular systole
diastole
Atria and ventricular muscles
are relaxed
when blood enters atria via
vena cava and pulmonary vein
increasing pressure in atria
atrial systole
Atria muscular walls contract,
increasing pressure further.
pressure atria > pressure
ventricles
atrioventricular valves open and blood flows into ventricles
ventricular muscle relaxed
ventricular systole
After a short delay (so ventricles fill), ventricular muscular walls contract
pressure ventricle > atria
pressure and artery pressure
atrioventricular valves close
and semi-lunar valves open
blood pushed into artery
transpiration
Loss of water vapour from
stomata by evaporation
affected by:
light intensity
temperature
humidity
wind
can be measured in a lab using
a potometer
how light intensity affects transpiration
As light intensity increases, rate of transpiration increases
more light means more stomata open
larger surface area for
evaporation
how temperature affects transpiration
As temperature increases, rate
of transpiration increases
the more heat there is, the more kinetic energy molecules have
faster moving molecules
increases evaporation
how humidity affects transpiration
As humidity increases,
transpiration decreases
the more water vapour in the
air, the greater the water
potential outside the leaf
reduces water potential
gradient and evaporation
how wind affects transpiration
As wind increases, rate of
transpiration increases
the more air movement, the
more humid areas are blown
away
maintains water potential
gradient, increasing
evaporation
cohesion in plant transport
Because of the dipolar nature of water, hydrogen bonds can form - cohesion
water can travel up xylem as a
continuous column
adhesion in plant transport
Water can stick to other molecules (xylem walls) by forming H-bonds
helps hold water column up
against gravity
cohesion-tension theory
As water evaporates out the
stomata, this lowers pressure
water is pulled up xylem (due to negative pressure)
cohesive water molecules
creates a column of water
water molecules adhere to walls of xylem pulling it upwards
this column creates tension,
pulling xylem inwards
root pressure in plant transport
as water moves into roots by osmosis, the volume of liquid inside the root increases
therefore the pressure inside the root increases
this forces water upwards
translocation
Occurs in phloem explained by mass flow hypothesis
transport of organic substances through plant
sieve tube elements
Living cells
contain no nucleus
few organelles
this makes cell hollow
allowing reduced resistance to
flow of sugars
companion cell
Provide ATP required for active
transport of organic substances
contains many mitochondria
mass flow hypothesis
Organic substances, sucrose,
move in solution from leaves
(after photosynthesis) to
respiring cells
source -> sink direction
how is pressure generated for translocation
Photosynthesising cells
produce glucose which diffuses into companion cell
companion cell actively
transports glucose into phloem
this lowers water potential of
phloem so water moves in from xylem via osmosis
hydrostatic pressure gradient
generated
what happens to sucrose after translocation
Used in respiration at the sink
stored as insoluble starch
investigating translocation
Can be investigated using
tracer and ringing experiments
proves phloem transports
sugars not xylem
tracing
Involves radioactively labelling
carbon - used in photosynthesis
create sugars with this carbon
thin slices from stems are cut
and placed on X-ray film which
turns black when exposed to
radioactive material
stems will turn black as that is
where phloem are
ringing experiments
Ring of bark (and phloem) is
peeled and removed off a trunk
consequently, the trunk swells
above the removed section
analysis will show it contains
sugar
when phloem removed, sugar
cannot be transported
how do small organisms exchange gases
Simple diffusion
across their surface
why dont small organisms need breathing systems
They have a large surface area
to volume ratio
no cells far from the surface
how alveoli structure relates to its function
Round shape & large number in - large surface area for gas
exchange (diffusion)
epithelial cells are flat and very
thin to minimise diffusion
distance
capillary network maintains
concentration gradient
how fish gas exchange surfaces provide a short diffusion distance
Thin lamellae epithelium means short distance between water and blood
capillary network in every
lamella
how fish gas exchange surface maintains diffusion gradient
Counter-current flow
mechanism
circulation replaces blood
saturated with oxygen
Ventilation replaces water with
oxygen removed
name of gas exchange system in terrestrial insects
tracheal system
structure of spiracles
Round, valve-like openings
running along the length of the
abdomen
trachea and tracheoles structure
Network of internal tubes
have rings of cartilage adding
strength and keeping them
open
trachea branch into smaller
tubes - tracheoles
tracheoles extend through all
tissues delivering oxygen
how tracheal system provides short diffusion distance
Tracheoles have thin walls so
short diffusion distance to cells
how tracheal system maintains concentration gradient
Body can be moved by muscles to move air - ventilation
Use of oxygen in respiration and production of CO2 sets up steep concentration gradients
amylase
Produced in pancreas &
salivary gland
hydrolyses starch into maltose
enzymes involved in protein digestion
endopeptidases
exopeptidases
membrane-bound dipeptidases
products of protein digestion
larger polymer proteins are hydrolysed to amino acids
Double circulatory system
Blood passes through heart twice
pulmonary circuit delivers blood to/from lungs
systemic circuit delivers blood
to the rest of the body
coronary arteries
Supply cardiac muscle with
oxygenated blood
for continued respiration and
energy production for contraction
Blood vessels entering/ exiting the kidneys
Renal artery carries oxygenated
blood to kidney
renal vein carries deoxygenated
blood to heart
Blood vessels entering/ exiting the lungs
Pulmonary artery carries deoxygenated blood to lung
pulmonary vein carries
oxygenated blood to heart
describe the structure of the veins
Thin muscular layer
thin elastic layer
thin walls
valves
explain role of elastic layer in arteries
Thick elastic layer
to help maintain blood pressure
by stretching and recoiling
Describe the elastic layer in veins
Thin elastic layer as pressure lower
cannot control the flow of blood
explain the role of valves in veins
Due to low pressure in veins skeletal muscle usually used to flatten walls of veins for blood flow
valves prevent the backflow of blood
unidirectional flow
What causes the AV valves to open
Higher pressure in the atria
than in the ventricles
what causes the semi-lunar valves to open
Higher pressure in the
ventricles than in the arteries
