Module 3: Transport in animals Flashcards
Transport of carbon dioxide and oxygen and the cardiac cycle
Describe the structure of haemoglobin
5 points
Is haemoglobin water soluble?
-consists of 4 polypeptide chains bonded together
-there are 2 alpha sub-units and 2 beta sub-units
-each sub-unit contains a prosthetic group(haem)
-it is a globular protein found in RBCs
-it contains Fe2+ ions
yes
How many oxygen molecules can bind to 1 haemoglobin?
How does oxygen bind to haemoglobin
4
by binding to the haem groups
Oxygen binds loosly to haemoglobin , write the word equation for this reaction.
Is this reaction reversible / irreversible
Hb + 4O2 —— Hb(O2)4
haemoglobin + oxygen —– oxyhaemoglobin
this reaction is reversible
Describe how each oxygen molecule binds to haemoglobin…
1st Oxygen- the haem groups are embedded in the molecule so its less accessible to the oxygen molecule meaning the molecule takes longer to bind
2nd and 3rd-the binding of the 1st oxygen causes haemoglobin to change shape which makes the haem groups more accessible so next 2 oxygen molecules can bind easily
4th-only 1 site is left so it is harder for oxygen to bind
There are different types of haemoglobin , what is one factor that makes them different?
What does partial pressure of oxygen mean?
How does partial pressure affect the oxygen affinity of haemoglobin?
When oxygen affinity is high , does haemoglobin hold oxygen tightly/loosly?
they have different oxygen affinities
the concentration of oxygen
as partial pressure increases the affinity of haemoglobin for oxygen increases
holds on tightly
Explain how the relationship between partial pressure and oxygen affinity is useful for respiration.
4 points
-during respiration oxygen is used up rapidly
-this decreases the partial pressure of oxygen in the area
-this therefore decreases haemoglobin’s affinity for oxygen
-this results in haemoglobin readily releasing oxygen to respiring tissues so respiration can occur
How does the saturation of haemoglobin affect its oxygen affinity?
3 points
-the binding of the 1st oxygen causes a shape change
-the shape change increases the affinity for oxygen
-this makes it easier for oxygen molecules to bind
What happens to haemoglobin when the partial pressure of carbon dioxide increases?
What is the name of this effect?
haemoglobin releases oxygen more easily
The Bohr Effect
Why is the Bohr Effect important in the body?
it results in;
-haemoglobin giving up oxygen more readily to active tissues as they have a high partial pressure of CO2
-oxygen binding to haemoglobin more easily in the lungs where the partial pressure of CO2 in the air is low
Name the 3 ways CO2 is transported from the tissues to the lungs
Give percentages
5% is carried dissolved in plasma
10% combines with the amino groups of haemoglobin’s chains to form carbaminohaemoglobin
85% is transported in the form of hydrogen carbonate ions (HCO3)-
Describe the process of carbon dioxide transport , starting with its production from cell metabolism and finishing with the start of the reverse of this process
-CO2 travels from tissue cells to a red blood cell
-CO2 reacts with H2O to form carbonic acid(H2CO3)
-this reaction is catalysed by carbonic anhydrase
-carbonic acid then dissociates to form hydrogen ions and hydrogen carbonate ions
-hydrogen carbonate ions diffuse out of RBCs and into plasma down their concentration gradient
-negatively charged chloride ions move into the RBC to maintain the electrical balance of the cell
-hydrogen ions bind with haemoglobin in the RBCs to make haemoglobonic acid
What is the name given to the exchange of hydrogen carbonate ions and chloride ions?
What does haemoglobin act as when it binds with hydrogen ions , what does this ensure?
the chloride shift
acts as a buffer to prevent hydrogen ions decreasing the pH
Describe the process of carbon dioxide transport starting with the reverse of the previous steps and finishing with us breathing it out
-hydrogen carbonate ions diffuse back into RBCs and chloride ions diffuse out back into the plasma
-hydrogen carbonate ions react again with hydrogen ions to form carbonic acid
-carbonic acid is then converted back into CO2 and H2O , this reaction is catalysed by carbonic anhydrase
-the CO2 then leaves the RBC and diffuses into alveoli
-we breathe out the carbon dioxide
The heart is myogenic , what does this mean?
the cardiac muscles are able to initiate their own contractions without the need for nervous stimulation
Name the 4 chambers of the heart in order
right atrium
right ventricle
left atrium
left ventricle
Name the location of the tricuspid atrioventricular valves , the bicuspid AV valves and semi lunar valves
tricuspid-between the right atrium and right ventricle
bicuspid-between the left atrium and left ventricle
semi lunar-pulmonary artery and aorta
What is the function of valves?
to prevent the back flow of blood
What is the location and function of the septum?
it runs through the centre of the heart and prevents the mixing of de-oxygenated and oxygenated blood
What is the role of the coronary arteries?
to supply oxygenated blood to cardiac muscle to allow it to keep contracting and relaxing
What is the name of the membranes that surround the heart and what is their function?
inelastic pericardial membranes
-help to prevent the heart from over-distending with blood
Name the 3 stages of the cardiac cycle in order of occurence
atrial systole
ventricular systole
diastole
State and describe the features of atrial systole
3 points
1)the atria both contract to pump blood into the ventricles
2)this contraction forces the AV valves to open
3)the semi lunar valves are shut
State and describe the features of ventricular systole
3 points
1)both the ventricles contract to pump blood into the pulmonary artery and aorta
2)blood forces the AV valves shut
3)the semi lunar valves are forced open due to a pressure gradient between the ventricles and the vessels
State and describe the features of diastole
4 points
1)all chambers relax
2)the hearts elastic recoils which decreases the pressure inside the chambers
3) semi lunar valves close to prevent blood flowing back into the heart from vessels
4)AV valves open to allow blood from vena cava and pulmonary veins to trickle down from atria to ventricles
How do you calculate cardiac output?
heart rate x stroke volume
How is the basic rhythm of the heart maintained?
by a wave of electrical excitation
Name the 2 nodes involved in controlling heart rate
sino-atrial node
atrio-ventricular node
Describe the first stage of the heart rhythm
a wave of electrical excitation begins in the SAN causing the atria to contract
-a layer of non conductive tissue prevents the excitation passing directly to ventricles
Describe the second stage of the heart rhythm
electrical activity of the SAN is picked up by the AVN and the AVN creates a slight delay before stimulating the bundle of His which penetrates through the septum
What is the bundle of His
a bundle of conductive tissue made up of Purkyne fibres
Describe the two final stages of the hearts rhythm
-the bundle of His separates into 2 branches and conducts the wave of excitation to the apex of the heart
-at the apex the Purkyne fibres spread out through the ventricular walls , the spread of excitation triggers the contraction of the ventricles
How does the bundle of His prevent atrial systole and ventricular systole happening at the same time?
it causes a time delay in the electrical wave of excitation reaching the ventricles
What is Tachycardia?
What is Bradycardia?
when heartbeat is too rapid , it exceeds 100bpm
when heartrate slows down to below 60bpm
What does ectopic heartbeat mean?
when there are extra heart beats that are out of the normal rhythm
What is atrial fibrillation?
its an example of an arrhythmia
where rapid electrical impulses are generated in the atria
they contract very quickly but not properly and only some of the impulses travel to the ventricles
this results in the heart not pumping blood effectively
