3.1.2 Transport in animals Flashcards
why do large multicellular organisms need transport systems
3.1.2(a)
small SA:V ratio, large diffusions distance, high metabolic rate
-they have a high metabolic rate so demand for oxygen and glucose is high to supply aerobic respiration
What happens in a double circulatory system
3.1.2(b)
the blood passes through the heart twice and travels through two separate circuits
what is pulmonary circulation
3.1.2(b)
blood flows from the heart to the lungs and back
what is systemic circulation
3.1.2(b)
where blood flows from the heart to the body and back
what happens in a single circulatory system
3.1.2(b)
the blood flows through the heart once for each circuit of the body
what is an advantage of a double circulatory system for organisms with a high metabolic rate
3.1.2(b)
higher blood pressure can be achieved in the systemic circuit (where blood flows from the heart to the body and back) meaning the rate of oxygen and glucose delivery and carbon dioxide removal from respiring tissues is high.
what is an open circulatory system and how can fluid be moved
3.1.2(b)
the blood or fluid is not enclosed within the vessels it can be moved around by contraction of body muscles
what is a disadvantage of an open circulatory system
3.1.2(b)
as the fluid is not contained withing vesicles pressure is lowered
describe the circulatory system in fish
3.1.2(b)
single and closed
heart has 2 chambers
blood is pumped from heart to the gills to the rest of the body and back to the heart
heart->gills->body->back to heart
describe the circulatory system in insects
3.1.2(b)
they have a tube shaped heart that pushes haemolymph around the body cavity called haemocoel
what happens at the haemolymph
3.1.2(b)
exchange of substances like ions and glucose takes place between haemolymph and cells of the organ
What is a closed circulatory system and where is this present
3.1.2(b)
in larger animals blood is contained within vesicles
tissue fluid bathes the tissues and cells
what is an advantage of a closed circulatory system
3.1.2(b)
higher blood pressure can be maintained
so rate of delivery of oxygen and glucose is higher
describe the circulatory system in insects, fish and mammals
3.1.2(b)
insects-open single
fish-closed single
mammals-closed double
function of the arteries
3.1.2(c)
carry high pressure blood away from the heart
structure of the arteries
3.1.2(c)
-thin layer of collagen to provide structural support
-layer of smooth muscle provides strength to withstand high pressure
-elastic fibres allow stretch and recoil. This is so the arteries can stretch when ventricles contract and recoil when ventricles relax. This maintains the high pressure
-small lumen maintains high pressure
function of the arterioles
3.1.2(c)
distribute blood from arteries to capillary beds
structure of the arterioles
3.1.2(c)
-Arteriole walls contain a higher proportion of smooth muscle than artery walls do.
This smooth muscle can contract or relax to decrease or increase the blood flow to a particular area. For example, during the fight or flight response, arterioles supplying the digestive system contract to reduce blood flow to the digestive organs, instead prioritising blood flow to the muscle
function of the capillaries
3.1.2(c)
allow the exchange of materials between the blood and the tissue fluid
structure of the capillaries
3.1.2(c)
· Capillary walls are made only of a single layer of endothelial cells, reducing the diffusion distance
· The walls do not contain any other substances that would increase the diffusion distance e.g. collagen, smooth muscle, elastin
· The lumen is only wide enough to allow one red blood cell through at a time, giving more time for oxygen to diffuse out of red blood cells and into the tissue fluid
function of the venule
3.1.2(c)
carry blood under low pressure from capillary beds to veins
structure of the venule
3.1.2(c)
venules have a thin wall and collagen for structural support
function of the vein
3.1.2(c)
carry low pressure blood back to the heart
structure of the vein
3.1.2(c)
· Lumen is relatively large to reduce friction against the slow flow of low-pressure blood
· Very thin layers of elastic fibres and smooth muscle
· More collagen than arteries to provide structural support
· Valves prevent backflow of low-pressure blood due to gravity
Explain why tissue fluid forms at the arteriole end of a capillary bed
3.1.2(d)
Hydrostatic pressure > oncotic pressure
why is hydrostatic pressure high at the arteriole end
3.1.2(d)
as it closest to the heart and the powerful contraction of the left ventricle
Explain why tissue fluid returns to the capillaries at the venule end of a capillary bed
3.1.2(d)
Hydrostatic pressure < oncotic pressure
What causes oncotic pressure in capillaries?
3.1.2(d)
Large negatively charged plasma proteins that are too big to leave the capillary
how do large negatively charged plasma proteins affect the water potential
3.1.2(d)
makes the bloods water potential slightly negative
What happens to excess tissue fluid that doesn’t get drawn back into capillaries?
3.1.2(d)
drains into lymph vessels
what molecules can enter tissue fluid
3.1.2(d)
Only very small molecules are able to be squeezed out of the capillaries and enter the tissue fluid.
For example, blood plasma contains the large negatively charged plasma proteins these cannot enter the tissue fluid.
For small molecules like oxygen and ions, the composition of blood plasma and tissue fluid is similar. Most cells are unable to enter tissue fluid, but some white blood cells with immune functions (lymphocytes) can, including neutrophils.
Describe the composition of tissue fluid vs blood plasma
3.1.2(d)
Tissue fluid does not contain any large plasma proteins
Describe the composition of lymph vs tissue fluid
3.1.2(d)
-It contains less oxygen and more wastes as it’s made of excess tissue fluid.
-lymph also contains more lipids and has an important immune function so contains white blood cells and antibodies.
what order does the cardiac cycle take place
3.1.2(f)
diastole
atrial systole
ventricular systole
Describe the events during diastole
3.1.2(f)
Atria and ventricles relax. Volumes increase. Pressures decrease. Semilunar valves close. Blood flows from vena cava and pulmonary vein into atria.
Describe the events during atrial systole
3.1.2(f)
once atria are filled with blood
Atria contract. Volumes decrease. Pressures increase. Tricuspid and bicuspid valves are pushed open. Blood flows from atria into ventricle
Describe the events during ventricular systole
3.1.2(f)
once ventricles are filled with blood
Ventricles contract. Volumes decrease. Pressures increase. Tricuspid and bicuspid valves shut. Blood flows from ventricles into aorta and pulmonary artery.
equation for cardiac output
3.1.2(f)
cardiac output=stroke volume x heart rate
what are the units for cardiac output
3.1.2(f)
cm^3min-1
what are the units for stroke volume
3.1.2(f)
cm^3 beat-1
what are the units for heart rate
3.1.2(f)
beats min-1
how is the heart muscle myogenic
3.1.2(g)
as it can initiate it own wave of excitation
what does the S.A.N (sinoatrial node) do
3.1.2(g)
sends a wave of cardiac action potentials across both atria causing them to contract simultaneously which causes atrial systole
where are cardiac action potentials then sent
3.1.2(g)
cardiac action potentials are then sent to the AVN. There is then a short delay where no cardiac action potentials are sent. This allows time for the atria to contract and empty into the ventricles
where does the AVN (atrioventricular node) then send cardiac action potentials
3.1.2(g)
the AVN send cardiac action potentials down to the bundle of his.
the bundle of his is insulated so that the surrounding muscle does not contract as action potentials are conducted down to the apex of the heart
what happens at the apex
3.1.2(g)
from the apex, purkyne fibres conduct cardiac action potentials up the walls of the ventricles. This causes ventricular systole-the ventricle wall contract.
the contraction starts at the apex to ensure the ventricles completely empty into the aorta and pulmonary artery
what happens after blood empties into the aorta and pulmonary artery
3.1.2(g)
electrical activity in the heart stops briefly-this is diastole
The atria and ventricles re-fill with blood from pulmonary vein and vena cava.
What stage of the cardiac cycle causes a P wave on an ECG?
3.1.2(h)
Atrial systole
What stage of the cardiac cycle causes the QRS complex on an ECG?
3.1.2(h)
Ventricular systole
What stage of the cardiac cycle causes the T wave on an ECG?
3.1.2(h)
Diastole
Describe how you would identify bradycardia on an ECG
3.1.2(h)
defined P, QRS and T waves, but increased time between beats
Describe how you would identify tachycardia on an ECG
3.1.2(h)
defined P, QRS and T waves, but decreased time between beats
Describe how you would identify atrial fibrillation on an ECG
3.1.2(h)
Atrial – lack of normal P waves, multiple distorted P waves between QRS complexes
Describe how you would identify ventricular fibrillation on an ECG
3.1.2(h)
Ventricular – multiple malformed QRS waves with no obvious P or T wave
what is bradycardia
3.1.2(h)
abnormally) slow heart rate. Aerobically fit people can have a lower heart rate as their heart is much more efficient – the stroke volume is higher and the heart muscle is stronger and thicker.
what is tachycardia
3.1.2(h)
(abnormally) high heart rate
what is atrial fibrillation
3.1.2(h)
there is a lack of clear P waves as the atria are beating quickly and irregularly.
what is Ventricular fibrillation
3.1.2(h)
results in a loss of definition to the QRS complex as the ventricles beat quickly and irregularly
Describe how you would identify ectopic heartbeats on an ECG
3.1.2(h)
QRS complexes out of place
How many oxygen molecules is one haemaglobin molecule carrying
3.1.2(i)
4 o2 molecules
What does haemoglobin do at high pO2?
3.1.2(i)
Associate with oxygen to form oxyhaemoglobin
What does haemoglobin do at low pO2?
3.1.2(i)
Dissociate with oxygen to form deoxyhaemoglobin
Where in the body has a high pO2
3.1.2(i)
Lungs
theres a high oxygen concentration in the surrounding medium
so theres a high partial pressure of oxygen
at high partial pressure haemglobins affinity for oxygen is high so oxygen will associate with haemaglobin
Where in the body has a low pO2?
3.1.2(i)
Respiring tissues
oxygen is being taken up by respiring tissues so there’s a low partial pressure
haemaglobin will have a low afinity for oxygen
so haemaglobin dissociates from oxygen
Describe co-operative binding of oxygen to haemoglobin
3.1.2(i)
The first oxygen molecule is difficult to bind to haemoglobin. It causes a conformational change so that the second and third oxygen bind more easily. The final oxygen is difficult to add because haemoglobin is becoming saturated and can only bind at high partial pressures.
this gives it the sigmoidal shape
what are the three ways co2 is transported in the blood
3.1.2(i)
·-Directly dissolved in the water in the blood plasma (5%)
- Combined directly with haemoglobin to form carbaminohaemoglobin (10%)
-As hydrogencarbonate ions, HCO3- (85%
how are hydrogen carbonate ions formed
3.1.2(i)
Carbon dioxide in enters the tissue fluid by diffusion, then diffuses into the blood plasma and into an erythrocyte. Here, it reacts with water to form a weak acid called carbonic acid, catalysed by the intracellular enzyme carbonic anhydrase
The carbonic acid dissociates, to release hydrogen ions and hydrogencarbonate ions:
what are the two problem from this
3.1.2(i)
- A lot of negative charges, HCO3-, are leaving the erythrocyte, which could affect the water potential of the cell or cause an electrical imbalance
- H+ are building up inside the erythrocyte, making the pH more acidic (lower), which could cause proteins (e.g. haemoglobin!) to denature by breaking hydrogen or ionic bonds in their tertiary structure
Describe the chloride shift
3.1.2(i)
HCO3- diffuse out of an erythrocyte and Cl- diffuse in to restore the charge inside the cell
How does haemoglobin buffer the pH inside an erythrocyte?
3.1.2(i)
Excess H+ from carbonic acid associate with haemoglobin to form haemoglobinic acid
once the erythrocyte arrives at the lungs what happens next
3.1.2(i)
the process is reversed
-h+ dissociates from haemoglobonic acid
-HCO3- diffuses back into erythrocyte and reacts with H+ to form carbonic acid
-Cl- ions diffuse back into erythrocyte
-carbonic acid breaks down into co2 and h2o
-co2 diffuses out of erythrocyte into air in the alveoli where it is exhaled
once the erythrocyte arrives at the lungs what happens next
3.1.2(i)
the process is reversed
-h+ dissociates from haemoglobonic acid
-HCO3- diffuses back into erythrocyte and reacts with H+ to form carbonic acid
-Cl- ions diffuse back into erythrocyte
-carbonic acid breaks down into co2 and h2o
-co2 diffuses out of erythrocyte into air in the alveoli where it is exhaled
what happens as PCO2 increases in the surroundings and what do we do to counteract this
3.1.2(j)
as Pco2 increases H+ accumulates inside cells
-haemoglobinic buffers this by combining with H+ to form haemoglobin acid
what occurs as a result of haemoglobin binding to H+
3.1.2(j)
it reduces haemoglobins affinity for O2 as it cant combine with both H+ and o2
-this means o2 dissociates from haemoglobin
what is the bohr effect
3.1.2(j)
the decreased affinity for oxygen at high Pco2
why is the bohr effect important
3.1.2(j)
as it increases the dissociation of oxygen from hb near respiring tissues
-so they have a high pCO2 but also high demand for oxygen
when the bohr effect is present where does the oxygen dissociation curve shift
3.1.2(j)
rightwords
describe the affinity of oxygen with foetal vs adult
3.1.2(j)
foetal haemaglobin has a higher affinity for oxygen than adult haemaglobin at the same po2
describe the Po2 in the placenta and what occurs as a result of that
3.1.2(j)
low Po2 in the placenta
at low Po2 maternal hb dissociates
O2 diffuses from maternal to foetal hb
what does foetal hb do at low Po2
3.1.2(j)
at low po2 in their placenta foetal hb still has a high enough affinity for oxygen to associate with oxygen in the placenta
-this ensures it can respire aerobically to produce ATP for growth by mitosis
describe the oxygen dissociation curve for foetal hb
3.1.2(j)
shifts left
