Circulatory System Flashcards
Explain why a double circulatory system is important for humans.
.Blood passes through the heart twice per circuit.
.Higher pressure.
.Allows blood to be pumped around our whole body- large distance since we are multi-cellular.
Which structure does deoxygenated blood enter the heart from the body?
Vena cava
Which structure does deoxygenated blood leave the heart to go to the lungs?
Pulmonary artery
Which structure does oxygenated blood enter the heart from the lungs?
Pulmonary vein
Which structure does oxygenated blood leave the heart to go to the body?
Aorta
What is a special feature of the left side of the heart?
It has much more thick muscle tissue to provide pressure for the blood to be pumped to the body.
Explain what happens during atria systole.
The atria contract, causing a higher pressure in the atria compared to the ventricles, so remaining blood is forced into the ventricles through the AV valves.
Explain what happens during ventricular systole.
Ventricles contract, causing higher pressure in the ventricles than the atria, so the AV valves are forced shut and blood is forced through the semi lunar valves into the aorta and pulmonary artery.
Explain what happens during diastole.
All 4 chambers of the heart relax simultaneously. Pressure in ventricles is lower than pressure in aorta and pulmonologist artery, so semi lunar valves are forced shut.
Describe the structure of haemoglobin.
It is a large protein with a quaternary structure. 4 polypeptide chains, each with a haem group which contains an iron ion.
How many oxygen molecules can bind to one haemoglobin?
4
What is loading/association?
When oxygen joins to haemoglobin to form oxyhaemoglobin near the lungs.
What is unloading/dissociation?
When oxygen is removed from oxyhaemoglobin near active body tissue.
Define affinity for oxygen.
The tendency a molecule has to bind with oxygen. This is not fixed and changes due to certain conditions.
Define partial pressure of oxygen.
A measure of oxygen concentration. The greater the concentration of dissolved oxygen in cells, the higher the partial pressure.
Describe what happens at the alveoli in the lungs.
The alveoli have a high pO2, haemoglobin has a low pO2, so its affinity for oxygen is high. Oxygen loads.
Describe what happens at active body tissue.
Respiring tissue has a low pO2, haemoglobin has a high pO2, so affinity for oxygen is low. So, oxygen unloads.
What does the lower, flat part of an oxygen dissociation curve show?
Body tissues, oxygen is dissociating since partial pressure of oxygen is low in respiring tissue.
What does the steep, middle section of an oxygen dissociation curve show?
Oxygen beginning to bind to haemoglobin, positive cooperativity means there is a high attraction, so oxygen associates easily.
What does the plateau at the top of an oxygen dissociation curve show?
The alveoli, where haemoglobin is completely saturated with oxygen since there is a very high partial pressure of oxygen due to the lungs.
Describe the structure of an artery.
.Thick muscle layer for pressure,
.Small lumen, folded endothelium for pressure,
.Elastic layer,
.Tough outer layer to prevent bursting due to high pressure.
Describe the structure of an arteriole.
.Small lumen,
.Thick circular muscles to maintain pressure.
Describe the structure of a vein.
.Wide lumen,
.Little elastic and muscle tissue, no need for high pressure,
.Valves to stop back flow of deoxygenated blood.
Describe the structure of a capillary.
.One cell thick for efficient diffusion,
.Wide lumen.
