Gas Exchange Flashcards
Gas Exchange
Release of CO2 end products to MG and HG
unloading oxygen is irreversible
HG has a higher affinity for CO2
Respiratory strategies
- Circulate external medium through body
- Diffusion of gases across all or most of the body surface, accompanied by transport of gases in an internal circulatory system
- Diffusion across specialized respiratory surface accompanied by circulatory surface accompanied by circulatory transport
dissassociation
water vapor
which type of water has less oxygen and why
salt/marine water because salt impedes oxygen
What affects oxygen levels
elevation/altitude
temperature decreases it if too hot or too cold
fossil fuels
Gay - Lussac’s Law
the pressure or volume of a gas is directly proportional to absolute temperature if only one of them is kept constant
Avogadros Law
one mole of gas occupies approx. 22,414 L at 0ºC and 760 mm Hg
Daltons Law
the partial pressure of each gas in a mixture of other gases present. The total pressure equals the sum of the partial pressure of all gases present at even temperature
Henry’s Law
the quantity of gas that dissolves at a given temperature is proportional to the partial pressure of that gas in the gas phase in water
Skin (Cutaneous) Respiration limitations
very thin skin minimizes diffusion distance and maximize rate
thin barrier must remain moist: enables dissolved O2 to diffuse into the cell
- confined to aquatic habitats
- limited surface area
respiratory strategies
aquatic organism = gills
terrestrial organisms = lungs
Respiratory surfaces
- very thin to be useful for diffusion
- big surface area
- blood input
- ventilation
Do O2 and CO2 diffuse at the same rate in air?
Yes, this is because they are the same size
Rate of diffusion will be greatest when
- the ability of substance to diffuse is high
- the area of the membrane is large
- the energy gradient is large
- the diffusion distance is small
what is the issue with gas exchange surfaces?
they are thin, fragile and have large surface area
Gill aspects
- originate as out-pockets (evaginations) of a body surface
- can be external or located within a respiratory cavity protected by a flap or other covering
- most common in water
- some have operculum
Lung aspects
- originate as infoldings (invaginations) of the body surface
- forming an internal body cavity that contains an external medium
- most common in air
Non directional ventilation
- medium flows past gas exchange in an unpredictable pattern (skin breathers)
- thickness affects it
tidal ventilation
- external medium moves in and out of respiratory systems in a back and forth movement
- incomplete and doesn’t empty completely (humans and other species)
Unidirectional ventilation
respiratory medium flows in at one point and exits via another
Concurrent
- PO2 of the blood equilibrate with the PO2 of the respiratory system
- all flows in the same direction
- never max saturation
Countercurrent
- PO2 of the blood leaving the gas exchange surface can approach that of the incoming medium
- opposite direction
- PP of the blood causes max saturation (no eq)
Crosscurrent
- PO2 is usually higher than what would be seen for concurrent, but lower than countercurrent
- blood flows at an angle
What kind of ventilation is in aquatic ecosystems? In air?
Aquatic - counter current
Air - tidal ventilation
What kind of pumps are the buccal cavity?
a suction and a force pump
How does the buccal pump work
- it is mostly in elasmobranches
- water rushes into the buccal cavity via mouth and spiracles
- closing mouth increases pressure in the cavity and causes it to go past the gills
- second pump makes it goes through the gills and the animal needs to be moving
Where are the gills in teleost?
in the operculum cavity.
- water goes into the mouth and it closes
- closes operculum to have water rush in and then it goes through gills
in fish the two pumps are
force pump (buccal) and operculum pump
Air respiration aspects
- higher O2 content
- not hyper or hypotonic
- air removes heat
- air causes dehydration
Amphibian lungs (frogs)
- pair of bags connected to the mouth by the glottis thin walls
Reptile Lungs
- most have 2 - tidal ventilation
- passive energy used
- some only have one lung - the right one because the body is too narrow
- no diaphragm
Bird lungs
- similar to reptiles but better because of air bags
- maintain body temp with muscles
- require lots of oxygen for muscles
- unidirectional
- posterior and anterior air sacs
- air capillaries
- parabronchi
Mammal lungs
- elastic, multichambered suspended in the pleural via a single tube = the trachea
- pleural cavity walls are the thoracic cage (ribs and diaphragm)
is there more CO2 or O2 dissolved in plasma
CO2
What does high affinity for oxygen mean? what animals have it?
Affinity indicated the readiness of HG to give up oxygen to tissue
- as blood circulates it gives O2 to other cells and pressure of O2 drops
- Llamas have a high affinity
Hemoglobin changes during developments
- larval amphibians which are aquatic have HG with higher affinities than adults
- many ectotherm adults have multiple HG
- may be an adaptation to fluctuating environments and oxygen availability
- different types of HG are expressed depending on conditions
Extreme conditions
- animals adjust gas transfer during hypoxia, hypercapnia and diving to meet tissue requirements
- adjustments require control and coordination of a cascade of systems including ventilation, gas transfer, transport in blood and diffusing of O2 and CO2
Diving
- timing depends on body and how big lung reserve is
- myoglobin is a big factor: when air is gulped, they are trying to rush the air through the body to myoglobin
- HR goes into bradycardia
Exercise
increases O2 consumption
Increases HR and blood input
increases in ventilation is limited
