mass transport

Question 1

what is the role of haemoglobin

Answer 1

pick up and transport oxygen around an organism

Question 2

how does haemoglobin function

Answer 2

picks up oxygen in areas where it is most plentiful and releases it into areas where it is needed

Question 3

what is the structure of haemoglobin

Answer 3

globular protein
-4 polypeptide chains
-two alpha and two beta
-each chain contains a haem group and a Fe ^2+ ion group the iron is responsible for the colour

Question 4

how is the binding of oxygen a reversible process

Answer 4

the binding of oxygen is known as association or oxygen loading
the release of oxygen is known as dissociation or oxygen unloading

Question 5

how does haemoglobin bind to oxygen

Answer 5

Each molecule has binding sites
there is a different conc of oxygen in the blood which enables it to change its affinity
in areas where there is a high oxygen partial pressure there is a high affinity for oxygen and oxygen is associated for example in the lungs- this means that lots will be picked up to transport
in areas where there is low oxygen and high carbon dioxide there is a low affinity for oxygen so oxygen is dissociated to the blood for example in active respiring tissue

Question 6

why does the DNA effect the affinities of haemoglobin

Answer 6

-different sequences in the bases on the DNA code for different amino acids so different primary structure
-this then leads to a different folding of the chain thus a different tertiary structure
-different genes have different affinities for example alpha has a higher affinity than beta which means that in fetal blood the maternal haemoglobin is lower

Question 7

what happens when haemoglobin binds to oxygen

Answer 7

oxyhaemoglobin is formed

Question 8

what is the graph that shows % Hb sat and ppO2 called

Answer 8

oxygen dissociation curve

Question 9

what is the shape of the graph

Answer 9

an s-shape

Question 10

what is an explanation for the shape of the graph - oxygen dissociation curve

Answer 10

at a low ppO2 - the one molecule enables the quaternary structure to change slightly- so oxygen will bind to the haemoglobin
when the 2nd and 3rd molecule binds - the binding sites become more accessible, as the shape begins to get looser and the graph increases steeper as it is more easy to gain O2
at the 4th molecule - graph is more constant - as the chance of the oxygen binding is reduced via probability

Question 11

what happens in the body due to oxygen dissociation curve

Answer 11

active tissue - low sat and ppO2- tertiary structure is very tight so oxygen binding sites are small, this means that at a low saturation of haemoglobin there is a low affinity for oxygen - this causes the oxygen to be unloaded from Hb eg 25% sat so 75% oxygen released
in the lungs - high sat and high ppO2- high affinity for oxygen so oxygen loaded on Hb eg 98% sat so 2% released

Question 12

what is the process in which the1 molecule helps the 2nd + 3rd molecule

Answer 12

positive cooperativity - gradient increases

Question 13

what is the Bohr effect

Answer 13

in a high conc of carbon dioxide the oxygen dissociation curve is shifted to the right

Question 14

why does the bohr effect happen

Answer 14

in high activity situations
high level of carbon dioxide, the CO2 and H2O produced in respiration react to form carbonic acid
carbonic acid lowers the pH which releases more H+ ions
this reduces the O2 affinity of Hb
which promotes the unloading of oxygen into the active tissues enabling them to gain more oxygen

Question 15

why is the bohr process important

Answer 15

-haemglobin mops up hydrogen ions so blood doesn’t become acidic - buffer
-CO2 leads to the release of 02 into actively respiring tissues

Question 16

how is fetal haemoglobin different from adult

Answer 16

it has a higher affinity at any given partial pressure
this is bc it needs to gain O2 from the mothers blood which is lower

Question 17

which way does the graph shift in the case a fetal haemoglobin

Answer 17

left
due to fact that it will pick up more oxygen at lower pp02
maternal haemoglobin dissociates and fetal associates

Question 18

in what other condition does the curve shift left

Answer 18

in anaerobic conditions
as the demand for oxygen increases so organisms have a high affinity at lower pressure to gain more oxygen

Question 19

what other conditions affect the dissociation curve

Answer 19

-size and SA:V ratio - small have large SA:V so less O2 needed so shift right
-conditions - availability of oxygen
-activity levels - more respiration = more demand for o2 at higher sat as more CO2

Question 20

which molecule stays binded to haemoglobin

Answer 20

carbon monoxide

Question 21

how does carbon monoxide bind

Answer 21

blocks bindings sites and forms carboxyhaemoglobin which prevent oxygen form being released and binded which results in oxygen depletion
this is because the binding of CO is irreversible
so less oxygen gets to brain

Question 22

how can small organism exchange materials with their environment

Answer 22

they have a high SA:V ratio

Question 23

what do large animals have in order to exchange

Answer 23

have specialist transport systems as they have a small SA:V

Question 24

what does the complexity of the transport system depend on

Answer 24

-how large the organism is and its SA:V - lower SA:V more complx need
-how active the organism is - more active greater need for exchange

Question 25

what transport materials are needed for exchange

Answer 25

-transport medium- dissolved materials can be carried from one area to another
-closed system of vessels to contain transport medium
-mass flow system to care for pressure

Question 26

what is an example of a mass flow system

Answer 26

mammalian circulatory system

Question 27

what does the human circulatory system consist of

Answer 27

a muscular pump to provide pressure - the heart
a series of vessels to transport blood eg arteries veins and capillaries
transport medium - blood

Question 28

how is blood pumped round the body

Answer 28

by pressure generated by the heart

Question 29

what is the mammalian circulatory system known as

Answer 29

a double circulatory system

Question 30

what is the double circulatory system

Answer 30

-systemic system - takes blood from left side of the heart to the body and returns it to right side of heart
-pulmonary system - blood from right side of heart to lungs and return to left side

Question 31

How does the double circulatory system prevent the mixing of blood

Answer 31

the right side of heart generates enough pressure to send blood through the lungs without damaging them
and left side can generate more pressure to send around the body

Question 32

what is the heart made of

Answer 32

cardiac muscle

Question 33

why is the heart myogenic

Answer 33

generates own electric charge and can contract on its own

Question 34

what is the heart divided into

Answer 34

two by the septum

Question 35

what does the right side of the heart do

Answer 35

receives deoxygenated blood from body via vena cava
and pumps blood to lungs via pulmonary artery

Question 36

what does the left side do

Answer 36

receives oxygenated blood from lungs via pulmonary vein
then pumps blood to body via aorta

Question 37

why does the left side of the heart have thicker muscle

Answer 37

generate higher pressure to pump blood around body
and right only goes to lungs

Question 38

what are the upper chamber called

Answer 38

atria one atrium and receive blood from veins

Question 39

what are the lower chambers called

Answer 39

ventricles receive blood from artery’s

Question 40

why are there atrioventricular valve between the atria and ventricles

Answer 40

to prevent backflow of blood

Question 41

what are the valves held in place by

Answer 41

tendons

Question 42

how is the heart muscles provided with oxygen and nutrients

Answer 42

by the coronary arteries

Question 43

what is the heartbeat cycle called

Answer 43

the cardiac cycle

Question 44

what is the definition of the cardiac cycle

Answer 44

the series of events that take place in one heart beat, including muscle contraction and relaxation

Question 45

what is the series of processes that happen in the cardiac cycle

Answer 45

Atrial and Ventricular diastole
Atrial systole
Ventricular systole

Question 46

how does the volume and pressure effect the cycle

Answer 46

Contraction of the heart muscle causes a decrease in volume in the corresponding chamber of the heart, which then increases again when the muscle relaxes
Volume changes lead to corresponding pressure changes
When volume decreases, pressure increases
When volume increases, pressure decreases

Question 47

what is the importance of valves

Answer 47

Throughout the cardiac cycle, heart valves open and close as a result of pressure changes in different regions of the heart
Valves open when the pressure of blood above them is greater than the pressure in front of them
They close when the pressure of blood below is greater than the pressure behind them
Valves are an important mechanism to stop blood flowing backwards

Question 48

what is atrial systole

Answer 48

The walls of the atria contract
Atrial volume decreases
Atrial pressure increases
The pressure in the atria rises above that in the ventricles, forcing the atrioventricular (AV) valves open
Blood is forced into the ventricles
There is a slight increase in ventricular pressure and chamber volume as the ventricles receive the blood from the atria
The ventricles are relaxed at this point; ventricular diastole coincides with atrial systole

Question 49

what is ventricular systole

Answer 49

The walls of the ventricles contract
Ventricular volume decreases
Ventricular pressure increases
The pressure in the ventricles rises above that in the atria
This forces the AV valves to close, preventing back flow of blood
The pressure in the ventricles rises above that in the aorta and pulmonary artery
This forces the semilunar (SL) valves open so blood is forced into the arteries and out of the heart
During this period, the atria are relaxing; atrial diastole coincides with ventricular systole
The blood flow to the heart continues, so the relaxed atria begin to fill with blood again

Question 50

what is diastole - both atria and ventricles

Answer 50

The ventricles and atria are both relaxed
The pressure in the ventricles drops below that in the aorta and pulmonary artery, forcing the SL valves to close
The atria continue to fill with blood
Blood returns to the heart via the vena cava and pulmonary vein
Pressure in the atria rises above that in the ventricles, forcing the AV valves open
Blood flows passively into the ventricles without need of atrial systole
The cycle then begins again with atrial systole

Question 51

how does the cardiac cycle happen in terms of timing

Answer 51

it is a continuous process and both sides of heart contract and relax simultaneously

Question 52

describe the cardiac cycle graph

Answer 52

Analysing the cardiac cycle
The lines on the graph represent the pressure of the left atrium, aorta, and the left ventricle
The points at which the lines cross each other are important because they indicate when valves open and close
Point A - the end of diastole

The atrium has filled with blood during the preceding diastole
Pressure is higher in the atrium than in the ventricle, so the AV valve is open
Between points A and B - atrial systole

Left atrium contracts, causing an increase in atrial pressure and forcing blood into the left ventricle
Ventricular pressure increases slightly as it fills with blood
Pressure is higher in the atrium than in the ventricle, so the AV valve is open
Point B - beginning of ventricular systole

Left ventricle contracts causing the ventricular pressure to increase
Pressure in the left atrium drops as the muscle relaxes
Pressure in the ventricle exceeds pressure in the atrium, so the AV valve shuts
Point C - ventricular systole

The ventricle continues to contract
Pressure in the left ventricle exceeds that in the aorta
Aortic valve opens and blood is forced into the aorta
Point D - beginning of diastole

Left ventricle has been emptied of blood
Muscles in the walls of the left ventricle relax and pressure falls below that in the newly filled aorta
Aortic valve closes
Between points D and E - early diastole

The ventricle remains relaxed and ventricular pressure continues to decrease
In the meantime, blood is flowing into the relaxed atrium from the pulmonary vein, causing an increase in pressure
Point E - diastole

The relaxed left atrium fills with blood, causing the pressure in the atrium to exceed that in the newly emptied ventricle
AV valve opens
After point E - late diastole

There is a short period of time during which the left ventricle expands due to relaxing muscles
This increases the internal volume of the left ventricle and decreases the ventricular pressure
At the same time, blood is flowing slowly through the newly opened AV valve into the left ventricle, causing a brief decrease in pressure in the left atrium
The pressure in both the atrium and ventricle then increases slowly as they continue to fill with blood

Question 53

example cardiac cycle calculation

Answer 53

Step 1: Work out the length of one heart beat

It takes 0.7 seconds for completion of one cardiac cycle, which is one heart beat

So there is 1 cycle in 0.7 seconds

Step 2: Calculate how many heart beats occur per second

Divide by 0.7 to find out how many cycles in 1 second

1 divided by 0.7 = 1.43 beats in 1 second

Step 3: Calculate how many heart beats occur per minute

Multiply by 60 to find out how many cycles in 60 seconds

1.43 cross times 60 = 85.71 beats in 60 seconds

So the heart rate is 85.71 beats / min

Question 54

what are the blood vessels of an animal

Answer 54

Arteries: transport blood away from the heart (usually at high pressure)
Veins: transport blood to the heart (usually at low pressure)
Arterioles: arteries branch into narrower blood vessels called arterioles which transport blood into capillaries

Question 55

what is the structure of an artery

Answer 55

Arteries carry oxygenated blood away from the heart. This filters into arterioles, which lead to the rest of the body.
Artery walls have thick muscular layers. Thick, muscular walls are needed to withstand the high pressure that arteries are put under
Thick elastic layers too. Elastic tissue allows the walls to stretch and recoil, to keep in line with the pulsating flow at which the blood travels through.-maintain blood pressure and squeeze arteries
Smooth muscle helps blood flow. Smooth muscle lined with smooth endothelium reduces friction and creates less restriction for the blood to move through.- contract and relax to allow dilation and constriction
Overall, the artery wall is very thick. This ensures that the vessel does not burst under pressure.
There are no valves in arteries. This is because the blood is always under high pressure, so it doesn’t flow backwards. Except in the case of the arteries leaving the heart, which have valves.

Question 56

what is the structure of the arterioles

Answer 56

Arterioles carry blood from arteries to capillaries.
Arterioles are very similar to arteries. They are different in that they are smaller in diameter and have a thinner muscle layer and lumen.- the total cross-sectional area is bigger- combined vol is bigger so blood pressure and speed drops
The muscle layer is thicker and elastic layer is thinner than in arteries. The muscle layer is thicker so that the movement of blood into the capillaries can be controlled, and the elastic layer is thinner because blood pressure is lower in the arterioles.
Lots of smooth muscle - contract + relax to allow vasoconstriction and vasodilation

Question 57

what is the structure of the capilleries

Answer 57

Capillaries exchange substances between the blood and body tissues. They are the smallest of the blood vessels.
Site of metabolic exchange.- very slow exchange can happen quicker
Capillary walls are just one cell thick. They are made up of a single layer of endothelial cells which allows for rapid diffusion of substances.- short diffusion path
There are many capillaries throughout the body and they are highly branched. This means that there is a large surface area for the exchange of substances and that all cells are very close to a capillary.
Capillaries are extremely narrow. Red blood cells are flattened against the side of the capillary because they are so narrow. This decreases the diffusion distance between the red blood cells and the cells that need oxygen, increasing the rate of diffusion.
Small spaces are left between the endothelial cells that make up the capillary wall. These spaces allow white blood cells to leave the capillaries and destroy infections in tissues.
-fenestrations enable blood plasma to leave

Question 58

what is the structure of veins

Answer 58

Veins transport deoxygenated blood from the body back to the heart.
The muscle and elastic layers are relatively thin. The muscle layer is thin because constriction isn’t needed to control the flow of blood to the tissues as veins take blood back to the heart.-diastole of ventricles means lower chest pressure so creates lower pressure than veins creating a conc gradient The elastic layer is thinner because the blood is transported slowly and under low pressure, so the veins won’t burst.
Overall, the wall is not very thick. A thick wall isn’t needed because the pressure within the veins is too low for them to be at risk of bursting.
Veins have valves. As blood pressure in the veins is so low, the valves ensure that blood doesn’t flow backwards.
They have a wide lumen. This maximises the volume of blood that is carried to the heart.
Weak pulse of blood. This indicates that there is very little elastic tissue or smooth muscle as the veins don’t need to stretch or recoil.
often near large muscle groups

Question 59

what is the process of blood plasma turning to tissue fluid

Answer 59

When blood is at the arteriole end of a capillary, the hydrostatic pressure is great enough to push molecules out of the capillary
Proteins remain in the blood; the increased protein content creates a water potential (osmotic potential is very low) between the capillary and the tissue fluid
However, overall movement of water is out from the capillaries into the tissue fluid
At the venule end of the capillary, less fluid is pushed out of the capillary as pressure within the capillary is reduced
The osmotic potential is higher and hydrostatic pressure is lower , so water begins to be reabsorbed back into the capillary from the tissue fluid- 90%
Overall, more fluid leaves the capillary than returns, leaving tissue fluid behind to bathe cells
If blood pressure is high (hypertension) then the pressure at the arteriole end is even greater
This pushes more fluid out of the capillary and fluid begins to accumulate around the tissues. This is called oedema

Question 60

what is the process of the lymph

Answer 60

Some tissue fluid reenters the capillaries while some enters the lymph capillaries
The lymph capillaries are separate from the circulatory system
They have closed ends and large pores that allow large molecules to pass through
Larger molecules that are not able to pass through the capillary wall enter the lymphatic system as lymph
Small valves in the vessel walls are the entry point to the lymphatic system
The liquid moves along the larger vessels of this system by compression caused by body movement. Any backflow is prevented by valves
The lymph eventually reenters the bloodstream through veins located close to the heart
Any plasma proteins that have escaped from the blood are returned to the blood via the lymph capillaries
10% of the tissue fluid is absorbed by the lymph