Gas Exchange Flashcards
(26 cards)
How many steps are there in gas transport? What types are they?
Four steps of transport - two connective and two diffusive
Long distance transport by convection, short range across barriers by diffusion
Where do the steps of gas transport take place in humans?
Breathing in the lung
Diffusion across gas exchanger in lung from air to blood
Second convective step in blood circulation
Diffusion from capillary to mitochondria in the tissue
How does the partial pressure of O2 change through the exchange process?
The partial pressure gradually decreases as the O2 moves from air to lungs and through the circulation
What is the relationship between lung area and metabolism?
Respiratory surface area is proportional to metabolic rate
What is the equilibrium reaction with CO2 and bicarbonate?
CO2 + H2O H+ + HCO3-
What are the two ways acid-base balance is regulated?
Ventilatory regulation of PCO2
Ion exchange with HCO3- (or H+) in gills or kidneys
What is the equation for the gas law?
PV=nRT
What is the percentage of O2 and CO2 in dry air?
How do you calculate PO2 if water vapor is present?
21% of air is O2
CO2 is negligible
PO2 = 0.21 x (barometric pressure - water vapor pressure)
In what direction do gasses diffuse?
Gasses diffuse down partial pressure gradients not concentration
What is the equation for concentration of oxygen?
cO2 = PO2 x a (or B)
a = solubility B = capacitance
What is the general equation for convective transport in a gas exchange organ? What do the variables stand for?
M = V x (Ci - Co)
M = rate of O2 uptake or CO2 excretion V = Ventilation (breathing rate) Ci = concentration of inhaled gas
How many lobes are in each side of the lungs?
Right lung has three lobes, left lung has two lobes
What are tidal volume and vital capacity?
What is risidual volume?
Tidal volume is the normal inspiration and expiration
Vital capacity is the maximum inspiration and expiration
Volume that cannot be expired in order to keep the lungs from collapsing
How to the ribs function in ventilation?
Intercostals rotate ribs
External rotate ribs up and out
Internal rotate ribs down and in
How do birds ventilate differently from mammals?
How do frogs ventilate differently?
They have two air sacs - caudal and cranial. The air travels into caudal, across the bronchi and into the cranial. On exhalation the air moves from the cranial, out.
Frogs have no diaphragm, so they take a mouthful of air and push it into the lung
How do trachea work in aquatic insects?
There are many different styles of breathing:
Some exchange gas with the outside air by breaking the surface
Some create a bubble of air to travel in
Some actually have gills
What type of exchanger are fish gills? How many layers of folding are there and what are they?
They are countercurrent exchangers
3 layers of folding
- arches
- filaments
- lamellae
How does the ventilation of fish gills work?
The buccal and opercular cavities are both filled at the same time when the mouth is open, but the operculum is closed.
The mouth closes, and the operculum opens to allow water from opercular cavity to leave and from buccal cavity to move across the gills
What is the ventilated pool model? What is the pressure of oxygen like?
Each inhalation is mixed with a pool of gas remaining in the lung, with the PO2 in the lung remaining almost constant
Pexpired = Palveolar = Parterial
How do water breathers compensate for the needed volume of water to get enough air?
They are able to extract 80% of oxygen from the water, compared to 33% in humans, so they don’t need to move as much water through. They also have a much lower metabolic rate
What is ram ventilation? What animals do they take place in?
What are the one exception to flow-through rules?
High speed fish and sharks
When they swim quickly, they use that speed and locomotion muscles for ventilation
Lampreys use tidal ventilation
What are the three features of hemoglobin binding? Briefly explain them
Reversible binding - tertiary structure causes pockets for O2
Sigmoid curve - Hemoglobin can only bind so much oxygen, when it carries four molecules it is saturated. The more O2 bound, the higher the affinity is to bind more
Affinity - High affinity means that O2 binds to Hb at low PO2 (P50). Loading is favoured by high affinity
Explain Bohr shift and Haldane shift
Bohr shift is the effect of protons on O2 binding to Hb - favours dissociation of O2
Haldane shift is effect of O2 binding on protons - favours dissociation of protons to make Hb more acidic
What are the three factors of pigment concentration?
Metabolic rate - high metabolic rate means high concentration
Type of circulation - open (lower concentration) or closed
Diving - Hb used for O2 storage and transport in divers, have very high concentration
