3.4 Mass Transport in Animals Flashcards
What is the structure of haemoglobin?
A quaternary structure - 4 polypeptide chains
Bonds: peptide, hydrogen, ionic and di-sulfide bridges
Contains 4 prosthetic haem groups
Contains iron in the haem group
What is the role of haemoglobin?
To transport oxygen by binding to it in the haem group to form oxyhemoglobin
How does haemoglobin need to be efficient at transporting oxygen?
Needs to:
Readily associate with the oxygen where gas exchange takes place
And
Readily disassociate from oxygen at tissues requiring it
What is the equation to do with haemoglobin and where do they take place?
Hb + O2 ⇌ HbO8
Forwards: in the lungs (high oxygen partial pressure) from alveoli to capillaries called association ie loading of oxygen
Backwards: in the muscles - lower oxygen partial pressure (being used up for aerobic respiration) called disassociation ie unloading of oxygen
How can haemoglobin be able to associate and disassociate oxygen?
Haemoglobin has different affinities
High affinity = takes up oxygen easily but releases it less readily
Low affinity = takes up oxygen less easily but releases it more readily
Oxygen has different affinities under different conditions: Gas exchange surface?
High oxygen concentration
Low carbon dioxide concentration
High affinity of haemoglobin for oxygen
Therefore oxygen is attached
Oxygen has different affinities under different conditions: Repairing tissues?
Low oxygen concentration
High carbon dioxide concentration
Low affinity of haemoglobin for oxygen
Therefore oxygen is dettached/released
If an organism lived in a low oxygen region (eg llama) what is the ideal affinity?
High affinity
If an organism had a high metabolic rate (eg hummingbird) what is the ideal affinity?
Low affinity
Therefore unloading more oxygen as aerobic respiration takes place faster as more energy is needed
Describe the oxygen disassociation curve for haemoglobin?
S - shape
Never reaches 100% - highest saturation is 98%
What is happening at the top of the oxygen disassociation curve?
Haemoglobin has a high affinity for oxygen
It is very saturated
It loads the oxygen easily
What is happening at the bottom of the oxygen disassociation curve?
Haemoglobin has a low affinity for oxygen
It isn’t very saturated
It unloads the oxygen easily for aerobic respiration
Why would a oxygen disassociation curve by beneficial moving to the right?
Right Reduced affinity Releases oxygen for Respiration Really high metabolic rate (if applies)
Why would a oxygen disassociation curve by beneficial moving to the left?
Left Lift affinity Load O2 Locomotion to cells Low O2 environment (if applies)
If the oxygen disassociation curve moves what is this called?
The Bohr shift
If the rate of respiration is high how does this effect haemoglobin?
More CO2 being produced Lowers the pH (carbonic acid) The greater the change in haemoglobin shape (loosely knit = high affinity) The more oxygen is unloaded Therefore more available for respiration
Why is having a double circulation (goes through the heart twice) an advantage?
To pick up oxygen
Doesn’t damage the lungs as a lower pressure is used on the right side
What does pulmonary relate to?
The lungs
What does hepatic relate to?
The liver
What does renal relate to?
Kidneys
Describe the journey of blood from heart to lungs?
Deoxygenated blood enters the right atrium through the vena cava
The right atrium contracts and blood is forced into the right ventricle through atrioventricular valves
The right ventricle contracts and the blood is pumped into the pulmonary artery
The pulmonary artery transports the blood to the lungs where CO2 diffuses out into the lungs and oxygen diffuses into red blood cells and binds to haemoglobin
Describe the journey of blood through the heart from the lungs?
The blood now oxygenated at a lower pressure returns to the heart via the pulmonary vein and enters the left atrium
The left atrium contracts and the blood is forced into the left ventricle through the atrioventricular valves
The left ventricle contracts and the blood is forced under high pressure into the aorta and transported around the rest of the body
What is the Septum?
The main dividing wall between left and right
Allowing blood to go from heart to lungs then heart to body
What are the atrioventricular valves?
They are structures that respond to the pressure changes in the heart and make sure blood flows from atria to ventricles (no back flow)
What are semi-lunar valves?
L
What are coronary arteries used for?
They lie on the surface of the heart and the heart immediately needs oxygenated blood to respire for energy to contract
What do arteries do?
Carries oxygenated blood away from the heart and to the organs (except the pulmonary artery)
Name some properties of an artery?
Carries blood with high pressure - narrow lumen
Thick layer of muscular and elastic tissue to with stand high blood pressure
Flexible - can expand and contract as blood goes through
Not permeable
Doesn’t contain valves
What do veins do?
Carries deoxygenated blood from the organs back to the heart (except the pulmonary vein)
Name some properties of veins?
Carries blood with low pressure
Little muscular and elastic tissue (thinner walls)
Wide lumen
Contains valves to prevent back flow of blood
- has the aid of skeletal muscular pump to carry blood back up
What do capillaries do?
Carry blood through organs allowing exchange of substances with all living cells
Name some properties of capillaries?
Only 1 cell thick - short diffusion distance
Large network of them - large surface area
Lumen fits only one red blood cell at one time
Blood moves slowly so more efficient at diffusion
What does iole mean?
A smaller branch of the parent
Eg
Arteriole
What is the order of the cardiac cycle?
Arial systole
Ventricular systole
Diastole
Describe Arial systole?
Both atria contract
Volume of the atria decreases
Pressure of the atria increases
Forces the blood into the ventricles
Atrioventricular valves are open
Semi-lunar valves are shut
0.1 seconds
Describe ventricular systole?
Both ventricles contract
Volume of ventricles decreases
Pressure of ventricles increases
Forces the blood into the arteries
Atrioventricular valves are shut
Semi lunar valves are open
Describe diastole?
All chambers relax
Low pressure in atria so blood flows back into atria but as it fills the pressure decrease so blood drips into the ventricles (down the concentration gradient)
Atrioventricular valves are open
Semi lunar valves are shut
Why does the left ventricle have a thicker muscular wall?
The blood is pumped to the entire body requiring a greater pressure
What features are different in a foetal heart?
The ductus venosus: connecting the pulmonary artery and the aorta
A hole between atriums
How does a foetal heart change when you are born?
The ductus venosus closes upon the first breath as a result of increase in pressure and never reopens
The hole closes as a result of adrenaline causing high blood pressure when you are born
Why is it important the foetal heart changes?
Oxygenated blood and deoxygenated blood need to be separated
It could cause fatigue if not enough oxygen gets to the muscles
What is the sequence of events that controls the cardiac cycle?
Wave of excitation from SA node - both atria = contract and push blood into the ventricles
Wave reaches AV node - along purkinje fibres of bundle of His
Atria relax
Wave reaches bottom of ventricles = contract - increased pressure causes AV valves close
Forces blood in pulmonary artery + aorta through SL valves
Ventricles relax, pressure below aorta, SLV shut - then the cycle repeats
Describe the wave of excitation through the AV node?
It is slower so there’s time for the atria to contract and for all the blood to flow into the ventricles
What analogy of bundle of His and purkinje fibres do we use?
The bundle of His is like the whole cable
The purkinje fibres are like the little wires running through the cable
Why does the wave of excitation not flow through the ventricles?
The wave reaches the bottom and force the ventricles to contract from the bottom up
Otherwise the blood would be forced downwards
What is lub dub?
Lub - atrioventricular valves shutting
Dub - semilunar valves shutting
What is the equation for cardiac output?
Cardiac output = stroke volume x heart rate
What is cardiac output?
The volume of blood pumped by one ventricle in one minute
dm^3 min^-1
What is stroke volume?
Volume of blood pumped out of the ventricle in one beat
dm^3
What is heart rate?
Number of contractions of the ventricle in one minute
min
What are some cardiovascular diseases? What are they?
Atheroma - fat deposits in arteries
Thrombus - blood clot caused by a fatty deposit
Aneurysm - bulge in the wall of the artery
Angina - chest pain from slight blockage in coronary arteries
Myocardial infarction - blockage in coronary arteries and the heart cannot get enough oxygen
