Mass transport in animals Flashcards
Definition of haemoglobin
A complex protein with a quaternary structure composed of 4 polypeptides, each containing a haem group. Has an affinity to oxygen.
Equation for Hb and what it forms
Hb + 4O2–> Oxyhaemoglobin
Percentage saturation equation
maximum saturation x100
Partial pressure definition
The proportion of oxygen in a mixture of gases or a solution
pp in lungs vs respiring tissue
lungs: High PP, more O2 loaded, higher saturation, hb has a higher affinity for o2
Respiring tissue: lower pp, more o2 unloaded, lower saturation, hb lower affinity for O2
Lower pO2 means less Hb is saturated
Loading/dissociation definition
When oxygen is taken up by Hb
Unloading definition
When O2 is released by Hb
Affinity definition
A natural attraction for O2- Hb has a high affinity to oxygen.
Partial pressure in the lungs
pp of O2 is high in the capillaries, Hb has a high affinity for O2 at a high pp. haemoglobin becmes almost fully saturated as the blood cells pass through pulmonary capillaries
pp in respiring tissues
pp is lower, Hb has a lower affinity for O2 at a lower pp and so oxyhemoglobin starts to break down and unloads oxygen. Oxygen released then available to the tissue to be used in aerobic respiration
Binding cooperativity
The first O2 molecule alters the tertiary structure of the Hb molecule. This exposes the 2nd and 3rd O2 binding site- making it easier for the O2 molecules to bind and load.
Effect of Co2
High Co2- Hb affinity for O2 is even lower. If pCO2 increases the saturation of Hb decreases, causing oxygen dissociation curve to shift to the right
effect of increasing respiration rate
tissue cells respire aerobically, quickly reducing the dissolved O2 in the surrounding of the tissue fluid. this reduces the pO2 to a lower level than normal.
Oxygenated blood arriving with fully saturated hb begins to unoad more oxygen and more oxygen will be released from the haemoglobin to the tissue cell- because the surrounding pO2 is lower andso haemoglobin will have an even lower affinity
CO2 effects
makes blood more acidic- lowers pH. This alters the tertiary structure, proteins change shape- lower affinity for O2 at high levels of CO2. The more the cells respire, the more the graph will shift to the right.
Heat from respiration helps mammals to maintain a constant body temperature
Smaller mammal has greater surface area to volume ratio
so more heat lost
so greater rate of respiration
Oxygen required for aerobic respiration- hb releases more oxygen
Adaptation to Environment
Genetic differnces between species and populations leads to differnt haemoglobin affinities. Mutations cause variation affnity
3 types of Hb
- type A adult humans and species that live on land at sea level
- type B- live in an environment where pO2 is lower. They form Hb where dissociation curve is shifted to the left. Hb has a higher affinity for O2. Becomes fully saturated at a lower pO2 and rapidly unloads. Foetus similar to thus
- type C- shift to the right, for those with a higher metabolic rate. Hb has a lower affinity for O2 so dissociates from the Hb more readily. O2 is more readily available to respiring cells.
The oxygen dissociation curve of a foetus is to the left of that for its mother. Explain why
- Higher affinity, loads more oxygen
- At low high partial pressure
- oxygen moves from mother to foetus
Lugworms and their dissociation
Hb has high affinity for oxygen which enables the lugworm to saturate haemoglobin at low pO2 as between tides the O2 concentration in the burrow will be very low.
Blood flow through the heart
Function of heart is to pump blood around the body. there is a double circulatory system. Blood passes through the heart and is pumped to the lungs, returning back to the heart (pulmonary circulation). Blood no passes through the heart a second time (re-pressurised) and pumped round the body organs before returning to the heart (systemic circulation)
Blood moves around the body due to the pressure differnce between the pressure in the heart and the blood vessels- mass flow