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51 Cards in this Set
- Front
- Back
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What are haemoglobin? |
Chemically similar proteins constructed from 4 polypeptide chains ( quaternary structure ) |
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What is a haem group and what does it carry? |
Contains iron, one O2 molecule which when binds reversibly in lungs is called oxyhaemoglobin |
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What can each Fe2+ ion combine with? |
Single oxygen molecule - 4 in humans |
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What is haemoglobin called when an oxygen molecule binds? |
Associated - high pO2 (Opposite - disassociated) |
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What is an affinity for oxygen? |
A tendancy a molecule has to bind with oxygen - depending on conditions e.g. pO2 |
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Hb + 4O2 ---> |
HbO8 |
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What is the relationship between conc. of dissolved oxygen and partial pressure? |
Greater conc. of dissolved oxygen results in higher partial pressure (pO2) |
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How is haemoglobin adapted for its function? |
Binds w/ O2 at gas exchange surfaces where there is a high pressure of O2 Readily dissociates from O2 at tissues when there is a high conc. of O2 |
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What is pCO2? |
Measure of conc. of CO2 in a cell |
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What is the Bohr effect? |
Shifts curve right, CO2 reduces affinity, reduces pH, Hb change shape, at exchange surface : CO2 conc low so affinity increases, rapidly respiring - CO2 conc high - low affinity |
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When does haemoglobin take up oxygen? |
When concentration of oxygen is high - reverse when oxygen is low |
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Why can haemoglobin bind and dissociate easily? |
It changes shape in the presence of carbon dioxide |
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What does the structure of haemoglobin depend on? |
Habitat, size and activity |
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Why is the transport of oxygen not simple? |
Temperature and CO2 concentration effect ability of haemoglobin to carry O2 |
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How can the association and disassociation of oxygen from haemoglobin be described? |
Sigmoidal graph - known as a the oxyhaemoglobin dissociation curve |
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When do organisms need haemoglobin with low affinity for oxygen? |
Small size - high metabolic rate High activity levels - fish/birds High oxygen environment - low altitude |
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What is a high affinity for oxygen? |
Takes up easily but releases less readily |
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What is low affinity for oxygen? |
Take up less easily but releases it more readily |
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How can you tell oxygen affinity using an oxygen dissociation curve? |
Further left = greater affinity Further right = lower affinity |
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How does Hb ensure there's always sufficient oxygen for respiring tissues? |
Gas exchange surface - Hb becomes saturated Hb reaches tissue with low respiratory rate - unloads 25% Hb reaches activity respiring tissue - unloads 75% |
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What is the basic function of the heart? |
Right side pumps deoxygenated blood to lungs left side pumps oxygenated blood to body |
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What type of system is the heart? |
Double circulatory |
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How many chambers are in the heart? |
4 |
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Which is the thickest chamber in the heart? |
Left ventricular wall (Thicker than right, ventricles have thicker muscular walls than atria) |
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How do the thick muscular walls benefit the heart? |
Left ventricular contracts powerfully, pumps blood around the body |
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What is the purpose of the Vena Cava? |
Major vein that returns deoxygenated blood to right side of heart |
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What is the purpose of the atrioventricular valves? |
Between atria to ventricles and stop blood flowing back to the atria when ventricles contract |
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What is the inter-ventricular septum? |
D |
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F |
D |
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D |
D |
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What are the cardiac muscles? |
Myocytes |
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What is the purpose of the myocytes? |
Contract together due to electrical impulses - heartbeat |
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How are the myocytes suited for high oxygen demand? |
2 coronary arteries feed a rich capillary bed |
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What is the purpose of the valve tendons and papilliary muscles? |
Hold valves in place - muscles contract at same time as ventricles to close valves |
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What is the purpose of the semi-lunar valves? |
In arteries - prevent backflow if blood from arteries to ventricles |
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What is the purpose of cords? |
Attach atrioventricular valves to ventricles to stop blood being forced up into atria when ventricles contract |
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What is the cardiac cycle? |
Cardiac muscles contracts, volume in chambers decrease, pressure increases, blood forced out, myogenic tissue contracts w/o nerve impulses - contractions come from within the heart - SAN |
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Cardiac output = |
Heart rate × Stroke volume |
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What is cardiac output? |
Volume of blood pumped by one ventricle of the heart in one minute, measured in dm³min-¹ |
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What occurs during diastole? |
Atria relaxed, fill with blood, ventricles relaxed, fill and recoil |
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What occurs during atrial systole? |
Atria contract, push remaining blood into ventricles which remain relaxed. Pressure now higher in ventricles than in atria so AV valves close |
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What occurs during ventricular systole? |
Atria relax, ventricles contract, pressure now greater than in arteries so semi-lunar open - pressure on ventricles below pressure in arteries so valves close |
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Where are the sino-atrial (SAN) and trio-ventricular node (AVN)? |
SAN - right atrium AVN - left atrium |
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What does this graph show? |
Behaviour of Hb changes in different O2 conc. 1st molecule of O2 binds w/ haemoglobin and distorts it - joining of first is is slow but after haemoglobin changes shape it becomes easier for rest. |
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What is the effect of CO2? |
High CO2 shifts curve to right More oxygen readily unloaded at respiring tissue
BOHR EFFECT |
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What does the amount of oxygen carried and released by haemoglobin depend on? |
Partial pressure of oxygen pH - increase in CO2 = decrease |
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What does an acidic environment causes oxygen to do? |
Dissociate from haemoglobin |
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What affinity does fetal haemoglobin require? |
Higher affinity for oxygen than adult haemoglobin to extract O2 from its mother's blood across the placenta |
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What is myoglobin? |
Pigment found in muscles which acts as oxygen store and receives it's oxygen from haemoglobin so has high affinity |
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Use figure 1 to describe how haemoglobin loads and unloads oxygen in the body |
In tissues, pO2 is low and Hb affinity for O2 is low so it unloads it's O2. In lungs, pO2 is high and Hb affinity for O2 is high so it associates with O2 |
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Describe how a heartbeat is initiated and coordinated. |
Sinoatrial node sends electrical activity wave across atria causing atrial contraction. Non-conducting tissue stops immediate contraction of ventricles. Atrioventricular node delays impulse as blood leaves atria to fill ventricles, then sends electrical activity wave down Bundle of His so ventricles contract, base up. |
