Cardiovascular System 1.1 3 Flashcards
Explain the transportation of oxygen
When fully saturated haemoglobin will carry 4 oxygen molecules
This happens when partial pressure of oxygen in the blood is high
At the tissues, oxygen is released from the oxyhaemoglobin due to lower pressure of oxygen in the tissues – this is known as oxygen dissociation
In the muscles oxygen is stored by myoglobin – this loves oxygen and will store it for the mitochondria until it is used by the muscles
Mitochondria are the centres in the muscle where aerobic respiration takes place.
What is the vascular shunt mechanism?
The redistribution of cardiac output
(during exercise the skeletal muscles require more oxygen so more blood needs to be redirected in order to meet this increase in oxygen demand)
What is vasoconstriction and vasolidation?
Vasolidation- The widening of the blood vessels to increase the flow into the capillaries
Vasoconstriction - The narrowing of the blood vessels to reduce blood flow into the capillaries
How is blood flow controlled?
Both blood pressure and blood flow are controlled by the vasomotor centre which is found in the medulla oblongata of the brain.
Chemoreceptors detect chemical changes e.g. increased carbon dioxide and lactic acids.
They send a signal to the vasomotor centre which redistributes blood flow through
* Vasodilation
* Vasoconstriction
How does redirection of blood flow occur?
- It occurs through stimulation of the sympathetic nerves located in the walls of the blood vessel
Redistribution of blood is important to…?
Increase the supply of oxygen to the working muscles
Remove waste products from the muscles, such as carbon dioxide and lactic acid
Ensure more blood goes to the skin during exercise
Direct more blood to the heart during exercise
What is aterio- venous oxygen difference? (A-VO2 diff)
- The difference between the oxygen content of the arterial blood arriving at the muscles & the venous blood leaving the muscles.
What is the A-VO2 diff like at rest & at exercise?
At rest:
- The arterio-venous difference is low as not much oxygen is required by the muscles
During exercise:
- Much more oxygen is needed from the blood for the muscles so the arterio-venous difference is high
- This increase will affect gaseous exchange at the alveoli so more oxygen is taken in & more carbon dioxide is removed
- Training also increases the arterio-venous difference as trained performers can extract a greater amount of oxygen from the blood
What is ventilation?
- Getting air into and out of the lungs
What is external respiration?
Gaseous exchange between the lungs & blood
Transport of gases
What is internal respiration?
Exchange of gases between the blood in the capillaries and the body cells
What is cellular respiration?
- The metabolic reactions and processes that take place in a cell to obtain energy from fuels such as glucose
What suggestions are there as to why the cardio vascular drift happens?
- When we sweat, a portion of this lost fluid comes from the plasma volume (this makes the blood more viscous/thicker)
- This decrease in plasma volume will reduce venous return & stroke volume
What is the Bohr shift?
- When an increase in blood carbon dioxide & a decrease in pH results in a reduction of the affinity of haemoglobin for oxygen
What does the oxyhaemoglobin dissociation curve show?
- Helps us to understand how haemoglobin in our blood transports & releases oxygen
- The curve represents the relationship between oxygen & haemoglobin
During exercise why does the S-shaped oxygen dissociation curve shift to the right?
- S-shaped curve shifts to the right because when muscles require more oxygen, the dissociation of oxygen from haemoglobin in the blood capillaries to the muscle tissue occurs more readily
- This shift to the right is known as the Bohr Shift
- On tissues there is a low partial pressure of oxygen & a high partial pressure of CO2, so haemoglobin unloads at this point- Meaning that even more oxygen is avaliable to the tissues
What 3 factors are responsible for this increase in the dissociation of oxygen from haemoglobin?
- Increase in blood temperature- When blood & muscle temperature increases during exercise, oxygen will dissociate from haemoglobin more readily
- Partial Pressure of carbon dioxide increases- As the level of blood carbon dioxide rises during exercise, oxygen will dissociate faster from haemoglobin
- pH- More CO2 will lower the pH in the blood, a drop in blood pH will cause oxygen to dissociate from haemoglobin more quickly (Bohr Shift)
