3.2 Transport in Animals Flashcards
Describe atrial systole.
As the blood flows into the atria (pulmonary vein to the left atria and vena cava to the right atria), the atria contracts. This increases the pressure and forces blood into the ventricles.
Describe ventricular systole.
The atria relaxes and the ventricles contract so the blood pressure in the ventricles increases. This pressure shuts the atrioventricular (AV) valve so that the blood doesn’t flow back into the atria. This increase in ventricular pressure forces the blood out of the ventricles and towards the arteries. The oxygenated blood on the left side goes through the aorta and the deoxygenated blood on the right side goes through the pulmonary artery.
Describe diastole.
The blood pressure in the arteries (aorta and pulmonary) are higher than that of the ventricles so the semi-lunar valve shuts. As both the ventricles and atria are relaxed, the AV valve opens and blood flows into the atria from the veins as the process repeats.
What does myogenic mean?
A muscle that is self stimulating.
What is the sinoatrial node (SAN)?
The SAN transmits waves of electrical signal along the walls of the atria at regular intervals. It is the pacemaker of the heart and is located on the wall of the right atrium.
Describe the atrioventricular node (AVN).
The waves of excitation can’t pass from the atria to ventricles directly as there is no conducting tissue in between. This creates a slight delay in between atrial systole and ventricular systole to make sure the atria fully empty. The wave of excitation then passes through the AVN to the bundle of his which is conducting. The wave is then transmitted to the apex (bottom) of the heart via the purkyne fibres.
What is the function of the aorta?
It pumps oxygenated blood from the left ventricle to the rest of the body.
What is the function of the pulmonary artery?
It pumps deoxygenated blood from the right ventricle to the lungs.
What is the function of the vena cava?
It pumps deoxygenated blood from the rest of the body to the right atrium.
What is the function of the pulmonary vein?
It pumps oxygenated blood from the lungs to the left atrium.
What is the function of the coronary artery?
It pumps oxygenated blood to the cardiac muscle (to use itself).
What is the septum?
A wall of muscle separating the two ventricles and making sure oxygenated and deoxygenated blood don’t mix.
What is partial pressure?
The concentration of oxygen in surrounding cells. When partial pressure is high, haemoglobin has high association with oxygen but when partial pressure is low, haemoglobin has high dissociation with oxygen.
What type of protein is haemoglobin?
A globular protein.
Describe the structure of haemoglobin.
Each polypeptide in haemoglobin has a haem prosthetic group. This prosthetic group has an iron ion which is what makes the haemoglobin red. Haemoglobin has a quaternary structure with 4 polypeptide chains which is what allows one haemoglobin molecule to potentially associate with 4 oxygen molecules.
What is formed when oxygen binds to haemoglobin?
Oxyhaemoglobin.
What is the Bohr Shift?
When there are high levels of carbon dioxide, haemoglobin’s affinity for oxygen decreases. This allows haemoglobin to drop of oxygen to areas with high levels of carbon dioxide (high levels of respiration).
At what point is tissue fluid formed?
At the arterial end of the capillaries there is a great hydrostatic pressure (and a low oncotic pressure) this forces the fluid out of the capillaries to bath the cells.
What does the tissue fluid consist of?
Plasma with dissolved nutrients and oxygen.
What is the function of arteries?
To carry blood away from the heart to the rest of the body.
How are arteries adapted to perform their function?
- thick walls to manage high pressure
- contains elastic tissue which allows the arteries to stretch with the flow of blood
- walls contains smooth muscle tissue to control blood flow
- thin lumen to maintain high blood pressure
What is the function of veins?
To carry blood from the rest of the body to the heart.
How are veins adapted to perform their function?
- wide lumen to maximize the volume of blood carried (keeps pressure low)
- contains valves to prevent the backflow of blood
- has thin walls as the blood pressure is low
- doesn’t contain much elastic or smooth muscle tissue as blood pressure is low
What are the functions of capillaries?
Where substances can exchange substances between the blood and tissues (e.g oxygen)
