3.4 Mass Transport in Animals Flashcards by Kirsty Welshman

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

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What is the role of haemoglobin?

To transport oxygen by binding to it in the haem group to form oxyhemoglobin

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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

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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

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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

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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

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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

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If an organism lived in a low oxygen region (eg llama) what is the ideal affinity?

High affinity

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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

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Describe the oxygen disassociation curve for haemoglobin?

S - shape

Never reaches 100% - highest saturation is 98%

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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

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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

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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)

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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)

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If the oxygen disassociation curve moves what is this called?

The Bohr shift

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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

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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

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What does pulmonary relate to?

The lungs

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What does hepatic relate to?

The liver

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What does renal relate to?

Kidneys

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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?

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