Physiology 4 Flashcards
Oxygen picked up by blood at the ___ must be transported to the ___ for use in ___.
lungs , tissue , cells
Carbon dioxide produced in ___ must be transported to the ___ for removal from the body.
tissues , lungs
Name two factors which account for the difference in partial pressure of oxygen between the alveoli are arterioles?
- Unbalance in ventilation/perfusion ratio
2. Shunting of blood
Describe Henry’s Law.
The amount of gas which will dissolve in a liquid (e.g blood) is directly proportional to the partial pressure of that gas
How is most oxygen transported in the blood?
Bound to haemoglobin
What is the normal oxygen concentration in arterial blood (in ml/L)?
200ml/L
What percentage of oxygen is transported in the blood bound to haemoglobin?
98.5%
What percentage of oxygen is transported in the blood in its dissolved form?
1.5%
Haemoglobin binds _____ to oxygen.
reversibly
How many haem groups does an adult haemoglobin molecule have?
4
How many oxygen molecules does a haem group carry?
1
Haemoglobin is fully saturated when __ of its haem groups have an oxygen bound.
4
What term is used for a haemoglobin molecule with all four of its subunits bound to oxygen?
Fully saturated
What is the primary factor which determines the percentage saturation of haemoglobin?
Partial pressure of oxygen (PO2)
What shape is the oxygen-haemoglobin dissociation curve?
Sigmoidal
Is saturation related to haemoglobin concentration?
No
Write a word equation for Oxygen Delivery Index (DO2I).
Oxygen delivery index = Oxygen content of arterial blood x Cardiac index
What is cardiac index?
Relates the cardiac output to the body’s surface area (i.e size of the individual)
What are the units of cardiac index?
L/min/metre^2
What are the units of Oxygen content of arterial blood?
ml/L
What are the units are Oxygen Delivery Index?
ml/min/metre^2
What is the normal range for cardiac index?
2.4 - 4.2 L/min/metre^2
What is the equation used to obtain oxygen content of arterial blood (CaO2)?
CaO2 = 1.34 x [Hb] x SaO2 (percentage haemoglobin saturation)
What determines the percentage haemoglobin saturation?
Partial pressure of oxygen
Name two factors which impair oxygen delivery to tissues.
Decreased partial pressure of inspired oxygen
Respiratory disease
Anaemia
Heart failure
What does partial pressure of inspired oxygen depend on?
Atmospheric pressure (Boyle's Law) Proportion of oxygen in the gas mixture
What is the normal proportion of oxygen in atmospheric air?
21%
Atmospheric pressure varies with ____.
altitude
How can some respiratory disease decrease the oxygen content of blood?
Decreases partial pressure of oxygen in the arteries –> decreases Hb saturation
How does anaemia reduce the oxygen content of blood?
Reduces the available Hb concentration
Binding of one oxygen molecule to Hb increases the affinity of other subunits to oxygen. What is this called?
Cooperativity
How does heart failure impair oxygen delivery to tissues?
Reduces cardiac output
____ gives the oxygen-haemoglobin dissociation curve a sigmoid shape.
Cooperativity
The Bohr Effect causes the oxygen-haemoglobin dissociation curve to shift to the ____.
right
Name 3 conditions which cause the Bohr Effect in oxygen-haemoglobin dissociation curves.
- Increased partial pressure of carbon dioxide
- Increased [H+]
- Increased temperature
- Increased [2,3-Biphosphoglycerate]
The Bohr Effect causes haemoglobin to give up oxygen in ____.
tissues
Tissue conditions promote the ____ of oxygen to tissues by haemoglobin.
offload
How does the structure of foetal haemoglobin (HbF) vary from adult haemoglobin?
Foetal haemoglobin has 2 alpha subunits and 2 gamma subunits
Foetal haemoglobin interacts less with ,-_____ in red blood cells.
2,3-Biphosphoglycerate
2,3-Biphosphoglycerate interacts LESS with what type of haemoglobin?
Foetal haemoglobin
What type of haemoglobin has a greater affinity for oxygen than HbA?
Adult haemoglobin
Foetal haemoglobin has a greater affinity for ___ than adult haemoglobin.
oxygen
Compared to the oxygen-haemoglobin dissociation curve of adult haemoglobin, that of foetal haemoglobin is shifted to the __.
left
Wha is an advantage of foetal haemoglobin’s increased affinity for oxygen in development?
Allows oxygen transfer from mother to foetus even when the partial pressure of oxygen is low
Where is myoglobin found?
Skeletal muscle and cardiac muscle
How many haem groups does a myoglobin molecule have?
1
Does myoglobin possess cooperativity?
No
What shape is an oxygen-myoglobin dissociation curve?
Hyperbolic
Why is an oxygen-myoglobin dissociation curve hyperbolic?
No cooperativity
Myoglobin releases oxygen at (high / low) partial pressures.
low
Myoglobin provides (long-term / short-term) storage of oxygen in anaerobic conditions.
short-term
Myoglobin offers short-term storage of oxygen in what type of conditions?
Anaerobic
What does the presence of myoglobin the blood indicate?
Muscle damage
If a person has muscle damage, what may be present in their blood?
Myoglobin
