Mass transport in animals Flashcards
What are haemoglobin?
Proteins with a quaternary structures, different forms are found in different organisms
What is the role of heamoglobin
- They unload oxygen under a set of conditions and they load oxygen under a set of conditions
- Bind to oxygen in order to transport it across the body
Describe the primary structure of heamoglobin molecules
Sequences of amino acids in 4 polypeptide chains
Describe the secondary structure of haemoglobin molecules
Each of the 4 polypeptide chains twist to form an alpha helix structure
Describe the tertiary structure of haemoglobin molecules
Each polypeptide chain is folded into a specific shape, important for the role of carrying oxygen
Describe the quaternary structure of haemoglobin molecules
4 polypeptide chains are linked to form a spherical molecule
Each polypeptide is associated with a haem group, which has an FE2+ ion
Each FE2+ ion can combine with a single O2 molecule, meaning there is a total of 4 O2 molecules that can be carried by a single heamoglobin molecule in humans
A and B link to form a spherical molecule
What is meant by loading/ assosciation of oxygen molecules
This is the process of haemoglobin binding to oxygen molecules, this happens in the lungs
What is meant by unloading/ disassociation of oxygen molecules
This is the process of haemoglobin releasing its oxygen molecules, this happens in the tissues
What is haemoglobins role which makes it efficient at transporting oxygen
Readily associates with oxygen at the surface where gas exchange takes place
Readily dissociates with oxygen at tissues requiring
Describe the affinity of haemoglobin
Haemoglobin can change its affinity for oxygen under certain conditions
This is because the haemoglobins shape changes in certain substances such as carbon dioxide
CO2 causes the shape of the haemoglobin to change so it binds more loosley to oxygen, causing it to release its oxygen
Explain how affinity of haemoglobin changes around the body
At a gas exchange surface, oxygen concentration is high, and CO2 concentration is low, causing haemoglobin to have a higher affinity meaning oxygen associated
At a respiring tissue, oxygen concentration is low and CO2 concentration is high, causing haemoglobin to have a lower affinity so oxygen is dissociated
Explain how DNA leads to different heamoglobin molecules having different affinities for oxygen
Different base sequences in DNA/ amino acid sequences/ teritary structure/ different quatenary shape and structure means there are different affinities for oxygen
Why might someone breathing in CO cause unconsiousness
-CO begins to occupy all sites on haemoglobin instead of oxygen,
- This means no oxygen will be carried to respiring tissues, respiration reduces, less function of tissues
Describe what an oxygen dissociation curve shows
- Graph of the relationship between the saturation of the haemoglobin with oxygen and the partial pressure of oxygen
Explain the shape of the oxygen dissociation curve
- The shape of the haemoglobin makes it hard for the first oxygen molecule to bind to one of the sites on one of its 4 polypeptide subunits as they are close together, this means at low oxygen conc, there is a little oxygen binding to the haemoglobin molecule
- The binding of this first oxygen molecule causes the quatenary structure and therefore the shape of it to change, making it easier for the other sub-units to bind to the oxygen molecule,
-This means there is a smaller increase of partial pressure needed to bind the second oxygen than the first ( positive cooperativity) this means gradient of the graph steepens
This changes after the binding of the 3rd oxygen, in practise it is harder to bind the 4th oxygen molecule due to probability as most binding sites are occupied, harder to find a free binding site for 4th oxygen molecule
Gradient of the graph reduces and graph flattens off
Describe 2 features of the oxygen dissociation curve that structure the curve
-Further to the left of the curve, greater affinity of haemoglobin for oxygen, loads easier but unloads less easily
- Further to the right of the curve haemoglobin has a lower affinity for oxygen, unloads easier but loads less easy
Define partial pressure
The amount of a gas that is present in a mixture is measured by its contribution of pressure to the overall pressure
Measured in kPa
Describe how haemoglobin may behave at a gas exchange surface and how this influences an oxygen dissociation curve
Gas exchange surfaces have low concentrations of CO2 because it diffuses across exchange surface in order to be excreted , this means haemoglobin has a higher affinity for oxygen, coupled with the high concentration of oxygen in the lungs, means that oxygen is readily loaded by haemoglobin
This means a graph plotted using figures from blood at a gas exchange surface will shift the graph left due to low CO2 conc
Describe how haemoglobin may behave differently at a highly respiring tissue and how does this influence an oxygen dissociation curve
Respiring tissues have high concentrations of CO2 , meaning affinity of haemoglobin in this area is reduced, coupled with the low concentration of oxygen in the muscles, means that oxygen is readily unloaded from haemoglobin into muscle cells
This means a graph plotted using figures from blood at respiring tissues will shift right, due to high conc of CO2
Describe the loading, transport and unloading
Loading- at a gas exchange surface carbon dioxide is always being removed, meaning there is a low conc of CO2 here, causing PH to slightly increase, changing the shape of haemoglobin enabling it to load oxygen readily
Transport- New shape of haemoglobin due to increased PH means that affinity is increased so oxygen is not released during transportation
Unloading- Carbon dioxide is released by respiring tissues, and CO2 is acidic in solution meaning shape of haemoglobin is changed to have a lower affinity of oxygen causing haemoglobin to unload its oxygen
How do the adaptions of haemoglobin ensure sufficient oxygen is being transported to active tissues?
Higher rate of respiration in tissues means there is more CO2 produced, lowering the PH, meaning the greater the shape of the haemoglobin changes meaning the more readily the oxygen is unloaded so it is more avainable for respiration
Describe common features of exchange systems
- A suitable medium in which to carry substances e.g blood usually liquid based as water can dissolve substances and move easily but this can also be gases
-Form of mass transport, bulk over large distances
-Closed system of tubular vessels containing transport medium and forms branching network to distrubute to all areas of the body
-Mechanism for moving transport medium, needs a pressure gradient
Describe the circulatory system of mammals
Double closed circulatory system
where blood is confined to vessels and passes through the heart twice for each complete circuit
This is because when blood passes through the lungs pressure decreases, if this passed immediately to the body low pressure would make circulation very slow
Blood is then returned to the heart to increase the pressure before being circulated to the rest of the tissues
High temp and metabolism in body is therefore needed as substances are delivered around the body quickly
Arteries veins and cappilaries are used, diffusion at the end large SA, short pathway, steep siffusion gradient
Describe function of renal vein
Carries deoxy blood away from the kidney
State main advantage of double circulatory system in humans
Increases blood pressure, therefore increases the rate at which oxygen is delivered to respiring tissues
State 2 factors making it more likely that an organism will have a circulatory system such as an heart
- A high metabolic rate( highly active)
- A low SA- Vol ratio
Describe the function of the pulnomary vein
Carried oxy blood from lungs to heart
Attached at the left atrium
Describe the function of the pulnomary artery
Carries deoxy blood from heart to the lungs, so oxygen can be replenished and waste products removed
Attached to the right ventricle of the heart
Describe the function of the vena cava
Takes deoxy blood into the heart back from the tissues
Describe the main difference between the 2 pumps of the heart
The left side deals with oxy blood from the lungs, the right side deals with deoxy blood from the rest of the body
Right ventricle pumps blood only to the lungs, meaning it has thinner walls, left ventricle pumps blood to rest of the body, meaning it has thicker walls to exert this force needed to transport blood over long distances under high pressure
Name the valves in the heart and each of their functions
The left atrioventricular valve ( bicuspid)
The right atrioventricular valve ( tricuspid)
They both prevent the backflow of blood into the atria when the ventricles contract
Describe the function of the aorta
Connects to the left ventricle and carries oxy blood to all tissues in the body apart from the lungs
Give order of blood vessles used in cardiac cycle
Pulnomary vein - left atrium- left ventricle- aorta
Vena cava- right atrium- right ventricle- pulnomary artery
Describe effects of a coronary artery getting blocked
E.g a blood clot will lead to myocardial infaction or a heart attack, as this area of heart muscle is deprived of blood and therefore oxygen
They will begin to respire anaerobically so die
Describe stage 1 of the cardiac cycle ( diastole relaxation)
Atria and ventricles are both relaxed
- Blood returns to the atria of the heart through the P vein and the vena cava
- Atria start to fill and the pressure in them increases
- When this pressure exceeds that of the pressure inside the ventricle, atrioventricular valves open allowing passage of blood into the ventricles
- The ventricle walls are relaxed causing them to re-coil and reduces the pressure inside the ventricles
- This causes pressure to be higher in the aorta and the p artery
- This means semi lunar valves close in the aorta and the p artery
Describe stage 2 of the cardiac cycle ( atria systole)
- Atria now contracts to push remaining blood into the ventricles
- Ventricles remain relaxed
- ## Left and right atrioventricular valves open to allow thi passage of blood
Describe stage 3 of the cardiac cycle ( ventricular systole)
- After the ventricles are filled with blood, the ventricular walls contract, increasing blood pressure in them
- This forces shut the atrioventricular valves in order to prevent backflow of blood into the atria
- The shutting of these valaves further increases the blood pressure, and this begins to exceed the pressure of the aorta and PA
- This means semi lunar valves now open
- Now blood is pushed into the aorta and pa from each side using thick muscular ventricular walls
How are valves in the cardiovascular system specialised
Designed so that they open whenever the difference in blood pressure either side of them favours the movement in the required movement
When pressure differences are reversed, and blood would usually go in the other direction than what’s required, these valves should close
Describe the location and function of the atrioventricular vaves
- Found between the right/ left atrium and the ventricles
- Prevent back-flow of blood during ventricular systole, when the pressure inside the ventricle exceeds that of the atria
- These valves have to close so blood can be forced into the PA and the aorta rather than back into the atria
Describe the location and function of the semi- lunar valves
- Found in the aorta and the pulnomary artery
- Prevents back-flow of blood into the ventricles when the pressure in the aorta and the PA exceeds that of the ventricles
- This happens when the aorta and the PA recoil increasing the pressure inside of them, and when the ventricles relax, decreasing the pressure in them
Describe the location and function of pocket valves
- Found in veins that occur throughout the venous system
-Ensure that when veins are squeezed, blood flows back towards the heart instead of away
Describe the structure of these valves
-Number of flaps of fibourus flexible tissue
-When pressure is greater on the convex side of the valve, they open to allow blood to pass through
- When pressure is greater on the concave side, blood collects within the bowl of these cups, pushing them together to stop blood passing through
What is cardiac output
Volume of blood pumped by one ventricle in one minute, depends on
- Heart rate
-Stroke volume
How to calculate cardiac output
Heart rate X stroke volume
Describe pressure changes in the left ventricle of the heart during the cardiac cycle
-Low pressure at first
- Pressure then rises when blood is pushed in from the left atrium when it contracts
-Atrioventricular valve then closes and pressure rises dramatically as thick walls of ventricle contract
- Then when ventricular pressure exceeds that of the aortic pressure, blood is forced out past semi lunar valves causing a pressure decrease
- Ventricles empty and walls relax
Describe pressure changes in the left atrium during the cardiac cycle
-Atrial pressure is always low because the walls are thinner and cannot create as much of a force
- P is highest when it is contracting
- This drops when an atrioventricular valve closes and atria walls begin to relax
-Atria then begins to fill with blood then pressure slightly inc
This decreases again when an atrioventricular valve opens causing some blood to move into the ventricle
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Describe the pressure changes in the aorta during the cardiac cycle
-Rises when ventricles contract forcing blood into the aorta
- It then gradually falls but always stays relativley high
-Recoil in the elastic tissue of the aorta causes a slight rise in pressure at the start of diastole
Describe volume changes that occur in the left ventricle during the cardiac cycle
Rises when the atria contract and ventricles fill with blood
This then suddenly drops when blood is forced out into the aorta when semilunar valve opens
Volume then increases when ventricles fill with blood again
Describe the function of arteries
Carrys blood away from the heart into arterioles
Describe the function of arterioles
Smaller arteries that control blood flow from arteries to cappilaries
Describe the function of capilaries
Tiny vessles which link arterioles to veins
Describe the function of veins
Carry blood from cappilaries back to heart
Describe the basic layered structure of arteries arterioles and veins
- Tough fiborous outer layer which resists pressure changes from both within and outside
-Muscle layer that contracts and controls flow of blood - Elastic layer that recoils in order to control the blood pressure by bouncing and recoiling
-Smooth endothelium to reduce friction and thin to allow diffusion - Lumen which is the central cavity for which blood flows through
Describe how arteries are suited to their function
- Muscle layer is thicker than veins, meaning smaller arteries can be constricted and dialated in order to control volume of blood passing through them
-Elastic layer is thick compared to veins, as they need a higher bp to travel further distances in body, elastic wall streches during systole and recoils during diastole, maintains smooth pressure surges with a high pressure
-Thickness of the wall is great to avoid bursting of walls - No valves due to constant high bp in the arteries
How are arterioles structure suited to their function
-Muscle layer is relatively thick compared to arteries, this contraction by this muscle reduces the size of the lumen
This means blood flowing into the cappilaries can be controlled which supply tissues with blood
- Elastic layer is thinner due to blood pressure being lower
How are the structure of veins related to their function
-Muscle layer is relatively thin as veins carry blood away from the tissues towards the heart, so constriction and dialation does not control blood flow
-Elastic layer is thin cpmapred to arteries as the low pressure inside will not cause the veins to burst, pressure is too low to cause recoil action
- Thickness is small due to low pressure, wont burst the veins, and can make them flattened easy so blood flow is aided
- Valves to prevent backflow of blood, make sure pressure only directs blood in the direction of the heart
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Describe the function of blood cappilaries
Exchange metabolic substances between the blood and the rest of the body e.g glucose carbon dioxide, oxygen and water
How is the function of blood capillaries suited to their function
- Their walls are mainly lining layers, making them very thin allowing for a short diffusion distance of materials, allows for rapid diffusion of materials
-Numerous and largely branched providing a large SA for exchange
-Narrow diameter, permeate tissues, no cell is far from a capillary, short diffusion pathway, rapid diffusion
-Lumen is so narrow that RBC are pushed against walls, reducing diffusion distance, rapid diffusion - Spaces between endothelium cells allowing WBC to escape and fight tissue infections
What is a tissue fluid
-Solution containing glucose and amino acids, fatty acids, ions and oxygen and water
- This supplies the substances in it to respire cells in the tissues
- In return it receives CO2 and other waste material from the tissues
- Formed by blood plasma and is the means of how substances are exchanged with cells
How is tissue fluid formed from blood plasma
-Blood pumped from heart is carried by arteries, then arterioles, then capillaries, getting narrower each time
- This creates a hydro-static pressure at the arterial end of the capillaries as the blood is pumped by the heart
-This hydro-static pressure causes blood plasma to move out of the capillaries creating a tissue fluid containing substances found in the blood plasma
- This pressure forces small molecules out, leaving all cells and proteins in the blood as they are too large to cross membrane ( ultrafiltration)
Describe other forces which resist the ultrafiltration of tissue fluid out of the blood plasma
- Hydrostatic pressure of tissue fluid outside capillaries which resists outward movement of fluid
- The lower water potential of the blood due to plasma protiens which cause water to move back into the blood in capillaries
How is tissue fluid returned back to the capillaries
-Loss of tissue fluid from the capillaries reduces hydrostatic pressure inside of them
- This means by the time blood has reached the venous end of the capillary hydrostatic pressure is lower than that of the tissue fluid around it
- This means tissue fluid is forced back down the new pressure gradient into the capillaries
- Due to large protiens being left in the capillary alongside water loss already , the water potential of the blood plasma at the venous end has a lower water potential than that of the water potential of tissue fluid
- This means water leaves the tissue and moves back into capillary down water potential gradient during osmosis
Describe the role of lymphatic system in tissue fluid
-The remainder of tissue fluid that doesnt return back to capillaries is carried back via this system
- The system resembles capillaries and merges to form large vessels forming a network in the body which drain their contents back into veins by 2 ducts that joins veins close to the heart
