TOPIC 8 : TRANSPORT IN ANIMALS Flashcards
2.2.1 CIRCULATORY SYSTEMS
Why do multicellular organisms need a transport system?
for multi-cellular organisms it is harder to supply all your cells with everything you need
these are relatively big and they have a low surface area to volume ratio and a higher metabolic rate
a lot of multicelluar oganims are also very active
this means that a large number of cells are all respiring very quickly, so they need a constant rapid supply of glucose and oxygen
CO2 also needs to be removed from cells quickly
to make sure that every cell has a good enough supply of useful substances and has its waste products removed, multicelluar organims need a transport system
the circulatory system in mammals uses blood to carry glucose and oxygen around the body
it also carries hormones, antibodies and waste products
2.2.1 CIRCULATORY SYSTEMS
What is a single circulatory system?
it is a system where blood passes through the heart once for each complete circuit of the body
2.2.1 CIRCULATORY SYSTEMS
How does the circulatory system for a fish work?
has a single circulatory system
the heart pumps blood to the gills (to pick up O2) and then on through the rest of the body ( to deliver the oxygen) in a single circuit
2.2.1 CIRCULATORY SYSTEMS
What is the difference between open and closed circulatory system?
both transport fluid but…
open: is not contained within vessels
closed: is contained within vessels
2.2.1 CIRCULATORY SYSTEMS
How does an incomplete double circulatory system work?
blood goes through the heart twice in one cycle
this means that blood can be pumped at a higher pressure to the lungs and to the body = its faster
however, as there is only one ventrilce, so oxygenated and deoxygenated blood are mixed
2.2.1 CIRCULATORY SYSTEMS
What is a double circulatory system?
a system that the blood passes though the heart twice for each complete circuit of the body
2.2.1 CIRCULATORY SYSTEMS
How does a double circulatory system work?
the right side of the heart pumps blood to the lungs
from the lungs it travels to the left side of the heart, which pumps it to the rest of the body
when blood returns to the heart, it enters the right side again
one sends blood to the lungs - this is called the pulmonary system and the other sends blood to the rest of the body - called systemic system
blood goes through the heart twice in one cycle
this means that blood can be pumped at a higher pressure to the lungs and to the body = it’s faster
there are two separate ventricles ensuring oxygenated and deoxygenated blood do not mix which maintains steep concentration gradients at exchange surfaces
2.2.1 CIRCULATORY SYSTEMS
What is the advantage of a double circulatory system?
can give the blood an extra push between the lungs and the rest of the body
this makes the blood travel faster, so oxygen is delivered to the tissues more quickly
2.2.1 CIRCULATORY SYSTEMS
What are the components of a double circulatory system
consists of the heart, blood vessels (arteries, veins, and capillaries), and blood
2.2.1 CIRCULATORY SYSTEMS
What are the limitations of a single closed circulatory system?
reduced blood pressure and slower circulation
2.2.1 CIRCULATORY SYSTEMS
What are the disadvantages of having an open circulatory system?
slower and less efficient oxygen delivery
Lower Metabolic Rates
2.2.1 CIRCULATORY SYSTEMS
How does a single celled organism such as an amoeba, gain the O2 and glucose required for aerobic respiration. Name the mechanisms involved
through their general body surfaces or cell membrane
2.2.1 CIRCULATORY SYSTEMS
What is a circulatory system?
it is an organ system that permits blood to circulate
2.2.1 CIRCULATORY SYSTEMS
What is blood and what are its functions/properties?
blood is a tissue which transports many vital components around the organisms : oxygen, carbon dioxide, hormones, blood cells to and from the cells in the body to enable respiration and help in fighting diseases, nutrients and maintains homeostasis
2.2.1 CIRCULATORY SYSTEMS
What does smaller organisms contain?
larger SA to volume ratio
smaller demand for O2
a cell surface membrane for diffusion of nutrients/ waste, no need for specialised surfaces for gas exchange to meet the demands of the organisms ( short distance )
2.2.1 CIRCULATORY SYSTEMS
What does larger organisms contain?
smaller SA to volume ratio
greater demand for O2
a larger distance between respiring cells of the organisms surface, so they have specialised exchange organs as diffusion across their surface is too slow to meet the demands of all the cells
2.2.1 CIRCULATORY SYSTEMS
What is a closed circulatory system?
all vertebrates have a closed circulatory system
in a closed circulatory system, the blood is enclosed inside blood vessels
2.2.1 CIRCULATORY SYSTEMS
How does a fish circulatory system work in a closed system?
theheart pumps blood into arteries
these branch to into millions of capilaries
substances like oxygen and glucose diffuse from the blood in the capilaries into the body cells, but the blood stays inside the blood vessels as its circulates
veins take the blood back to the heart
2.2.1 CIRCULATORY SYSTEMS
What is an open circulatory system?
where the blos isn’t enclosed in blood vessels all the time
instead it flows freely through the body cavity
2.2.1 CIRCULATORY SYSTEMS
How does an open circulatory system for an insect work?
an insects heart is segemented
it conracts in a wave, starting from the back, pumping the blood into a single main artery
that artery opens up into the body cavity
the blood flows around the insects’s organs, gradually making its way back into the heart segments through a series of valves
if the whole body cavity was bigger then it wouldn’t probably be able to supply all their cells
the circulatory system supplies the insect’s cells with nutrients and transports things like hormones around the body
it doesn’t supply the insects cells with oxygen through - this is done by a system of tubes called the tracheal system
2.2.1 CIRCULATORY SYSTEMS
Compare double and single circulatory systems
SINGLE:
can be found in what animal? - Fish
activity rate of animal? - Lower
Demand for glucose and oxygen? - Lower
Body temperature? - Lower - endotherm
Number of circuits? - 1
Speed of flow? - slower
Rate of material delivery? - Slower
DOUBLE:
can be found in what animal? - Mammal
activity rate of animal? - Higher
Demand for glucose and oxygen? - Higher
Body temperature? - Higher
Number of circuits? - 2
Speed of flow? - Faster
Rate of material delivery? - Faster
2.2.2 BLOOD VESSELS
What is the definition of arteries?
adapted to carrying blood away from the heart to the rest of the body,
thick walled to withstand high blood pressure, contain elastic tissue which allows
them to stretch and recoil thus smoothing blood flow, contain smooth muscle which
enables them to vary blood flow, lined with smooth endothelium to reduce friction
and eases the flow of blood
2.2.2 BLOOD VESSELS
What is the definition of arterioles?
branch off arteries, smaller than arteries
have thinner and less muscular walls,
have a layer of smooth muscle, but they have less elastic tissue
the smooth muscle allows them to expand or contract, thus controlling the amount of blood flowing to tissues
their role is to feed blood into capillaries
2.2.2 BLOOD VESSELS
What is the definition of venules?
larger than capillaries but smaller than veins
have very thin walls that can contain some muscle cells
vnules join together to form veins
2.2.2 BLOOD VESSELS
What is the definition of veins?
carry blood from the body to the heart, contain a wide lumen to maximise
volume of blood carried to the heart, thin walled as blood is under low pressure,
contain valves to prevent backflow of blood, no pulse of blood meaning there’s little
elastic tissue or smooth muscle as there is no need for stretching and recoiling
all veins carry deoxygenated blood (because oxygen has been used up by body cells) except for the pulmonary veins, which carry oxygenated blood to the heart from the lungs
2.2.2 BLOOD VESSELS
What is oncotic pressure?
the pressure generated by the plasma proteins in the capillaries
2.2.2 BLOOD VESSELS
What is hydrostatic pressure?
the pressure exerted by a liquid
2.2.2 BLOOD VESSELS
What is tissue fluid, and what is it made from?
It is the fluid that surrounds cells in tissues
It is made from substances that leave the blood plasma
2.2.2 BLOOD VESSELS
How is tissue fluid formed?
the formation of tissue fluid is the result of the interaction between hydrostatic pressure and osmotic pressure
hydrostatic pressure reduces as the blood moves from the arterole end of the venule end due to three reasons:
- increase in cross sectional area due to increasing number of vessels for blood to flow through
- increased friction/resistance between blood and capillary wall slows down blood flow
- reduction in volume of fluid in blood
oncotic/osmotic pressure is constant along the capillary
the tissue fluid has a higher water potential than the blood in capillaries
the water potential difference between the blood and the tissue fluid causes water to return to the capillary via osmosis -as the water potential in the capillares is lower than the water potential in thee tissue fluid
2.2.2 BLOOD VESSELS
What occurs in the aterial’s end?
hydrostatic pressure is greater than water potential (oncotic pressure) / solute potential = net outflow / tissue fluid is formed
plasma leaves the capillary to form tissue fluid making with it oxygen, amino acids, glucose, fatty acids ect.
2.2.2 BLOOD VESSELS
What occurs in the venous end?
water potential (oncotic pressure) / solute potential is greater than hydrostatic pressure = net inflow/water returns to the blood
plasma/water returns to capillary with carbon dioxide and urea
2.2.2 BLOOD VESSELS
How does lymph vessels work?
the capillaries at the vein end of the capillary bed - some excess tissue fluid is left over
this extra fluid eventually gets returned to the blood through the lymphatic system
the smallest lymph vessels are capillaries
excess tissue fluid passes into lymph vessels
once inside, its called a lymph
valves in the lymph vessels stop the lymph going backwards
lymph gradually moves towards the main lymph vessels in the thorax
here its returned to the blood near the heart
lymph fluid contains less oxygen and nutrients compared to tissue fluid, as its main purpose is to carry waste products.
The lymph system also contains lymph nodes which filter out bacteria and foreign material from the fluid with the help of lymphocytes
which destroy the invaders as part of the immune system defences.
2.2.2 BLOOD VESSELS
Compare tissue fluid, blood and lymph
BLOOD:
WHERE FOUND? - inside heart + vessels arteries, capilaries + veins
ROLE? - to transport the raw materials and products of respiration around the body
CELLS CONTAINED? - erythrocytes ( RBCs ), leucocytes ( WBCs ) and platelets
OXYGEN LEVEL? - more
CARBON DIOXIDE LEVEL? - little
PROTEINS CONTAINED? - hormones and plasma proteins
FATS CONTAINED? - lipoproteins
GLUCOSE CONTAINED? - 80 - 120MG / 100cm3
AMINO ACIDS CONTAINED? - more
TISSUE FLUID:
WHERE FOUND? - around the cells of individual tissue
ROLE? - the exchange of materials ( O2, CO2 + GLUCOSE ) by diffusion between blood + cells
CELLS CONTAINED? - same phagocytic ( WBCs )
OXYGEN LEVEL? - less ( absorbed by body cells )
CARBON DIOXIDE LEVEL? - more ( from body cells )
PROTEINS CONTAINED? - some hormones, large proteins, that one secreted by body cells but too big to pass into the capillary
FATS CONTAINED? - none
GLUCOSE CONTAINED? - less (absorbed by body cell )
AMINO ACIDS CONTAINED? - less ( absorbed by body cell )
LYMPH:
WHERE FOUND? - within the lymphatic vessels and then rejoins the blood in the chest cavity
ROLE? - supports the immune system, filter phatogens and any foreign materials to be destroyed by the lymphocytes ( produced in lymph nodes)
CELLS CONTAINED? - lymphocytes
OXYGEN LEVEL? - less ( absorbed by body cells )
CARBON DIOXIDE LEVEL? - more ( from body cells )
PROTEINS CONTAINED? - some proteins
FATS CONTAINED? - more that in the blood ( lacteals absorb the fats from the intestines )
GLUCOSE CONTAINED? - less (absorbed by body cell )
AMINO ACIDS CONTAINED? - less ( absorbed by body cell
2.2.3 HEART BASICS
What is the definition of systole?
cardiac muscle contracts and heart pumps blood out of aorta and pulmonary arteries ( happens in atria and ventricles )
2.2.3 HEART BASICS
What is the definition of diastole?
cardiac muscle relaxes and heart fills with blood ( happens in atria and ventricles )
2.2.3 HEART BASICS
What is the process of the cardiac cycle?
1) Atrial systole
blood returns to heart because of the breathing process
blood inder low presure flows into left and right atria from the pulmonary veins and vena cava
filling of atria (pressure) causes atrioventricular valves to open
blood leaks into ventricles
atria walls contract forcing more blood in ventricles
2) Ventricular systole
imemediately follows
ventricles contract increasing the pressure in them
blood pushed up and out of arteries –> semi-lunar valves
pressure of blood against atrioventricular valves closes and prevents backflow into atria
3) Diastole
atria and ventricles then relaxes
elastic recoil of the rellaxing heart lower pressure
blood drawn back towards ventricles
closing semi lunar valvas ( prevents back flow )
coronary arteries fill, low pressure in atria helps to draw blood into heart from veins
closing of atriventricular valves then semi lunar valves making th e LUB DUB
2.2.3 HEART BASICS
How long does the cardiac cycle last for and when does the event take place for?
0.8 seconds
it takes place for one heart beat
2.2.3 HEART BASICS
How does the cardiac cycle link to the chamber and blood flow in the heart?
deoxygenated blood enters under low pressure enters the right atrium and oxygenated blood under high pressure enters the left atrium
the bicuspid and trrcuspid valve intially stays closed
however the pressure in the atria increases it exceeds that of the ventricles and the valves open
this stage is called diastole
when the diastole ends,, the two atria contracts simultaneously thsi is called atrial systole
more bolld enters the ventricles
almost immediately ventricles contracr
this is called ventricle systole
when this occurs the tricuspid and bicuspid valves are closed
the ventricular pressure soon exceeds the pressure in the pulmonary arteries and the aorta
this forces the semi-lunar valves to open
during ventricular systole blood is forced against the atrio-ventricular valve and this produces the first heart sound of ‘LUBB’
ventricular systole ends with ventricular diastole
the high pressure in the aorta and pulmonary artery forces blood back towards the ventricles and this closed the semi-lunar valves
this produced the second heart sound of ‘DUBB’
one complete heartbeat consits of one systole and one diastole
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
How to control heart rate?
Heart can beat without any input form nervous system even when removed from body and placed in glucose and salt solution
myogenic contract without external nervous stimulation
cardiac muscle contraction initiated by small changes in electical charge of the cardiac mucle cells
When cell have slight postive charge on outside- polarised
when this charge is reversed they are depolarised
a change in polarity spreads like a wave and cause cells to contract
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
What is an ECG?
electodes attached to chest and limbs to record electrical current produced during cardiac cycle
when there is a change in polarisation of cardiac muscle, a small electrical signal is detected at the skins surface
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
How is a singnal generated?
Pacemaker generated wave of signals to contract
signals are delayed at AV node
signals pass to heart ape
signals spread throughout ventricles
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
Deciphering the ECG trace
‘P’ wave corresponds to atrial contraction
‘QRS’ complex relates to the contraction of the ventricles it is much larger than the ‘P’ wave due to the relative muscle masses of the atria and ventricles - and masks the relaxation of the atria
the relaxation of the ventricles can be seen in the form of the ‘T’ wave, the relaxation of the atrai being masked by the ‘QRS’ complex
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
What is ‘ cardiac outpu’? Units?
the volume of blood the heart pumps out over time
cm3/min
ml/ min
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
What is the stoke volume? Units?
the volume of blood the heart pumps per ‘pump’
ml/beat OR cm3/beat
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
What is the formula for cardiac output, stoke volume and heart rate?
Cardiac output = HR/ SV
Heart Rate = CO/ SV
Stroke Volume = CO/HR
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
What is the calculation for heart rate?
heart rate (bpm) = 60/ time taken for one heartbeat (s)
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
How can you tell on an ECG diagram that a patient has bradycardia and the symptoms?
less than 60bpm, common in athletes at rest, symptoms of heart problems, heart diseaase, hypothermia, medicine, drugs
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
How can you tell on an ECG diagram that a patient has tachycardia and the symptoms?
greater than 100 bpm, anxiety, fear, fever or exercise, symptoms of CHD, heart failur, medicine, drugs, fluid loss or anaemia
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
How can you tell on an ECG diagram that a patient has ischaemia and the symptoms?
heart muscle does not recieve blood due to atherosclerosis ( blocked coronary arteries )
the normal activity is distrupted
arrhythmias ( irregular beating caused by electrical disturbances ) can effect larger area of heart muscle than that affected by the intial (first diagram in booklet ) ischaemia
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
What is a sinus heartbeat?
underlying left atrial abnormality
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
What is eptopic heartbeat?
extra/slipped heartbeats
common causes include, lack of sleep, anxiety, alcohol. smoking + caffeine
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
Explain the cardiac cycle in terms of pressure graphs
At W (lowest point)
left atrium stop contracting and the left ventricle begin to contract ( ventricular systole)
pressure inside left ventricle increases
AV ( bicuspid ) valve closes ( ‘ LUBB ) as the pressure in the left ventricle > pressure in the left atrium
semi - lunar valve remains closed
aorta has low pressure, blood is moving through the circulatory system
At X ( increasing )
pressure inside left ventricle increases so much ( LV pressure > aortic pressure ), causing the semi-lunar valve to open
blood enters the aorta, aortic pressure increases
bicuspid valves are closed
the left atrium is filling up with blood from veins, which increases pressure
At Y ( after the peak )
as the LV empties, pressure inside aorta is higher than LV pressure, causing the semi-lunar valve to close (‘DUPP’)
ventricular daistole begins
At Z ( at the lowest after the peak )
as the LV empties, pressure inside left atrium is higher than LV causing the AV (bicuspid) valve to open
semi-lunar valves are closed
pressure increases above ventricular pressure in the left atrium
in the aorta pressure forces blood through the circulatory system
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
How can you check for a heart attack within a ECG graph and the cause of it?
look for higher S an T wave
the cardiac muscle, most of which is responsible for contracting the ventricles, is dying as the coronary artery has been blocked so no respiratory reactans (oxygen and fatty acids) are reaching the cardiac cells
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
How can you check for a atrial fibrillation within a ECG graph and the cause of it?
look for a distorted P wave
if the atria are in fibrillation the muscle is contracting out of synch with the cycle, it could be too fast, too slwo or at the wrong time
this prevents the ventricles from completely filling up so the efficiency of each heart beat is reduced
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
How can you check for a ventricular hypertrophy within a ECG graph and the cause of it?
look for a deep S wave
the muscle has thickened so there is more to contract therefore more elcetrical activity
this means that the volume of the chamber has decreased in size so the blood will be under even more pressure
2.2.4 ELECTRICAL ACTIVITY OF THE HEART
What does each wave tell us about the electricla activity in different chambers?
Wave P:
excitation of the atria ( both the left and right ) - atrial systole
Wave Q, R, S
excitation of the ventricles ( both left and right ) - ventricular systole
Wave T
relaxation of all chambers - diastole
2.2.5 HAEMOGLOBIN
What adaptations to RBCs have to ensure they can transport as much oxygen as possible?
Biconcave disc shape
no nucleus
large surface area to volume ratio
2.2.5 HAEMOGLOBIN
notes on haemoglobin and the word equation
haemoglobin as an example of conjugated protein ( globular protein with a prosthetic group )
haemoglobin has high affinity for oxygen
combines with oxygen to form oxyhaemoglobin
WORD EQUATION:
Haemoglobin + oxygen»_space; oxyhaemoglobin
«
2.2.5 HAEMOGLOBIN
Describe thhe structure of haemoglobin?
is a quaternary protein and consits of four subunits
each subunit is a polypeptide chain - 2 are alpha chains and 2 are beta chains
each subunit has a haem ( non-protein) group at the centre, in which a single iron atom is found . The Fe in haemoglobin is usually in the ferrous form ( Fe 2+)
each haem group binds to one oxygen molecule
2.2.5 HAEMOGLOBIN
How many atoms can one haemoglobin molecule carry?
4
2.2.5 HAEMOGLOBIN
How does red blood cells transport oxygen?
Red blood cells contains several hundered haemoglobin molecules which transports oxygen
oxygen binds to haem on the haemoglobin molecule
2.2.5 HAEMOGLOBIN
How does oxygen loading happen?
in the lungs, a steep concentration gradient is maintained due to blood flow & ventilation enabling efficent diffusion of oxygen
98% of the oxygen which diffuses into the plasma is taken up by haemoglobin in RBCs
The removal of oxygen out of blood plasma into RBCs, further maintains the steep concentration between blood plasma & alveolar space
2.2.5 HAEMOGLOBIN
How does oxygen dissociation occur?
When RBCs in capillaries pass respiring tissues, the oxygen must dissociate from the haemoglobin so it can diffuse into the cells which is needed for aerobic respiration
how much oxygen dissociates depends on the level of oxygen in the surrounding tissue
2.2.5 HAEMOGLOBIN
How is oxygen and partial pressure related?
The quantity of oxygen that can combine with Hb is determined by the ‘oxygen tension’ or ‘ partial pressure’
In Chemistry: partial pressure is the relative pressure that a gas exerts in a mixture of gases
in biology, think of it like concentration - a gas will move from an area where its partial pressure is higher to an area where its partial pressure is lower
If partial pressure of oxygen is high, oxyhaemoglobin is formed (oxygen is loaded)
If partial pressure of oxygen is low, oxygen is released
( dissociates ) from Hb
2.2.5 HAEMOGLOBIN
What does the oxygen dissociation curve suggest?
As oxygen dissociation curve shows how saturated the haemoglobin is with the oxygen at any given partial pressure
the affinity of haemoglobin for oxygen affects how saturated the haemoglobin is
2.2.5 HAEMOGLOBIN
What are the properties of oxygen loading and unloading in respiring tissue and alveoli in lungs?
ALVEOLI IN LUNGS:
- High in O2 concentration
- High partial pressure of O
- High affinity
- O2 loads
RESPIRING TISSUE
- Low O2 concentration
- Low partial pressure of O2
- Low affinity
- Oxygen unloads
2.2.5 HAEMOGLOBIN
What does the oxygen dissociation curve tell us?
Hb is saturated with O at a point called loading tension which gives 95% saturation
100% saturation is very rare
Over the steep part of the curve:
a small drop in the partial pressure of O2 results in a larger drop in the haemoglobin saturation
i.e a slight decreases in the partial pressure / oxygen level causes the haemoglobin to ‘give up’ lots of oxygen to the surrounding tissues
As haemoglobin loses molecules of oxygen the haemoglobin’s affinity for oxygen changes
2.2.5 HAEMOGLOBIN
What does the S shaped curve tell us?
When an oxygen molecule binds to the ferrous atom in Hb, it physically distorts ( aka conformational change) the haem group slightly making it easier for the next oxygen molecule to bind
this continues to happen each time the next oxygen binds and so on
therefore, at lower partial pressures of oxygen it is more difficult for oxygen to bind and it’s easier at higher partial pressures of oxygen
2.2.5 HAEMOGLOBIN
What does the foetal haemoglobin graph tell us?
At low pO2 in the placenta - foetal Hb has a high affinity for oxygen so O2 loads
At low pO2 in the placenta - adult Hb has a low affinity for oxygen so O2 unloads
foetal haemoglobin they need enough oxygen to survive
2.2.5 HAEMOGLOBIN
What does the O2 dissociation curve for foetal haemoglobin tell us?
Why is this important?
Foetal haemoglobin has a higher affinity for O2 than adult haemoglobin
Foetal haemoglobin will more readily load oxygen at lower PP i.e in the placenta, foetal haem will load the oxygen the mother’s haemoglobin is unloading
2.2.5 HAEMOGLOBIN
Why is it important that after birth foetal haemoglobin is replaced by adult haemoglobin?
This is important for easy release of oxygen in the respiring tissues of a more metabolically active individual
2.2.5 HAEMOGLOBIN
How does CO2 concentration work?
The partial pressure of CO2 is a measure of the concentration of CO2 in a cell
to complicate matters, pCO2 also affects O2 unloading
Hb gives up O2 more readily at higher pCO2
this ensures more O2 gets to cells during activity
When cells respire and produce CO2 this increases the pCO2 –> increases O unloading –> the dissociation curve shifts to the right –> the saturation of blood with oxygen is lower for a given pO2, meaning more oxygen is being given pO2, meaning more O2 is being released ( Bohr Effect )
2.2.5 HAEMOGLOBIN
What is the Bohr Effect?
The PP of Co2 also influences the affinity of haemoglobin for oxygen
2.2.5 HAEMOGLOBIN
What is the link between the Bohr effect and carriage of CO2?
Oxygen dissociation curve shifts to the right of the curve normal curve under higher partial pressures of carbon dioxide
the shift in the dissociation curve means that oxygen will dissociate from haemoglobin at a lower pO2, than normal
2.2.5 HAEMOGLOBIN
What is the explanation for the Bohr Effect?
The reason for Bohr effect is linked to how Co2 affects blood pH
most of the CO2 from respiring tissues diffuses in RBC
Here it reacts with water to form carbonic acid catalysed by the enzyme carbonic anyhydrase
the rest of the CO2, around 10% binds directly to the Hb and is carried to lungs
2.2.5 HAEMOGLOBIN
Explain the carbon dioxide carriage work in cells?
Most of the CO2 from respiring tissues diffuses in RBC
Here it reacts with warer to form carbonic acid catalysed by the enzyme carbonic anyhydrase
the carbonic acid dissociates to give H+ ions and HCO 3 -
this increases in H+ causes oxyhaemoglobin to unload its oxygen so Hb can take up the H+ to form haemoglobinic acid
this stops the H+ ions affecting the acidity of the cells ( Hb ‘mops’ H+ up )
the HCO3- ions diffuse out of the RBC and are transported to the blood plasma
to compensate for this loss of ions Cl- diffuses into RBC
this is called chlorine shift and maintains the balance of charge between the RBC and plasma
when the blood reached the lungs the low pCO2 causes some of the HCO3- ions and H+ ions to recombine into CO2 and water
the CO2 is diffused into the alveoli and breathed out
2.2.5 HAEMOGLOBIN
Word equation for the formation and splitting of carbonic acid
PLASMA:
Carbon dioxide + water –> carbonic acid –> hydrogen ions + hydrogencarbonate ions
2.2.5 HAEMOGLOBIN
Word equation for the chloride shift and the unloading of oxygen in red blood cells
hydrogen ions + oxyhaemoglobin –> haemoglobinic acid + oxygen
