Respiration Flashcards
How did oxygen build up in the atmosphere
Cyanobacteria in oceans started producing oxygen via photosynthesis
what was Earth’s first mass extinction
oxygen build up killed anaerobic bacteria
What does oxygen serve as
an electron acceptor in the oxidation of carbon-based fuels
what are the four reasons oxygen is consumed
- Stable and abundant in the atmosphere
- Reduction of O2 = large free energy release/e- transfer
- aerobic metabolism = 4x more energy/mol glucose oxidized than anaerobic
- can diffuse across membrane and bind to heme moieties in proteins = O2 delivery to organs and electron transfer functions
How does gas exchange take place
via diffusion, gas diffuses down pressure gradients created by differences in partial pressures, requires a large surface area
Respiration in worms
they do not have a RS, open CS = capillaries near surface, diffusion over whole body occurs
What are the two sources animals can extract O2 from?
air and water
What is the differences of O2 in air vs. water
less O2 available in water (water = denser and more viscous = harder to move), obtaining O2 from water requires more effort
What two factors affect O2 solubility?
temperature and solute concentration (proportional)
How do aquatic animals extract O2 from water
Gills
What are gills
Internal or external outfoldings of the body that create a large surface area for gas exchange
How do fish gills work?
Fish gills use a countercurrent exchange system —> blood flows in the opposite direction to water passing over the gills
Blood PO2 is always < Water PO2 (blood = less saturated) so oxygen diffuses down the pressure gradient
how efficient are fish gills
more than 80-90% of the O2 in the water is removed
What RS do insects use
tracheal system = network of tubes throughout the body that supplies O2 to every cell
CS and RS = separate
what are some components of the tracheal system and what is their function?
Spiracles = openings connected to trachea, gated to minimize water loss
Sacs = air storage
what must large insects do to meet O2 demands?
they must actively ventilate their TS
How do amphibians breathe
Through positive pressure breathing which ventilated their lungs by forcing air down the trachea (air forced in/out)
How do birds breath?
Have 8/9 sacs that keep air flowing through the lungs, with air passing through in one direction. Air is passed through the entire system in two cycles of inhalation and exhalation. Highly efficient
Pathway of air through a bird
1st inhalation —> posterior air sacs —> 1st exhalation —> lungs —> 2nd inhalation —> anterior air sacs —> 2nd exhalation
what is inhalation/exhalation in birds
inhalation = air sacs fill
exhalation = air sacs empty and lungs fill
What is the pathway of air through the RS in mammals?
Nostrils —> pharynx —> larynx —> trachea —> bronchi —> bronchioles
what do nostrils do
filter, warm, humidify and sample air for odors
what does the pharynx do
directs air to lungs and food to stomach
how is food prevented from entering the trachea
swallowing moves larynx upward and the epiglottis covers the glottis in the pharynx
why does air not go to the stomach?
there is no negative pressure
How is the respiratory system kept clean?
mucus escalator = cilia and mucus line the epithelium of the air ducts and move particles up to the pharynx, allows particles to be swallowed into the esophagus
What is the impact of the CFTR gene
Cl-/HCO3- imbalances
What is the role of Cl- in mucous production?
Cl- allows for the flow of water, low Cl- levels = no hydrated mucous = thick and sticky
What are alveoli function and structure
site of gas exchange, air sacs at tips of bronchioles with a moist film of epithelium
why are alveoli susceptible to contamination
lack cilia
what do alveoli secrete and why?
surfacants (detergent) which break surface tension
How do mammals ventilate their breathing
negative pressure breathing = pulls air into lungs
what is tidal volume
the volume of air inhaled with each breath
what is the vital capacity
maximum tidal volume
What occurs during inhalation
diaphragm contracts (moves down) increasing lung volume, rib cage expands
what occurs during exhalation
diaphragm relaxes (moves up) and ribs cage gets smaller
what remains after exhalation and why
residual volume of air to prevent collapse of lungs
What are the partial pressure s of O2 and Co2 in the blood arriving in the lungs relative to alveoli
low O2, high CO2
where does each gas diffuse in the alveoli
O2 diffuses into blood, Co2 diffuses into air
what occurs in tissue capillaries for diffusion
pressure gradients favour diffusion of O2 into the IF and CO2 into the blood
Where does O2 diffuse to
- alveolar spaces —> lung capillaries
- Systemic capillaries —> tissues
Where does Co2 diffuse to
- tissues —> systemic capillaries
- lung capillaries —> alveolar spaces
What is the pathway of oxygenated air following inhalation
Alveolar spaces, AV/lung capillaries , pulmonary veins, heart, systemic arteries, systemic capillaries, tissue
What is the pathway of Co2 in deoxygenated blood following diffusion out of the body tissue
tissue, systemic capillaries, systemic veins, heart, pulmonary arteries, lung capillaries, AV spaces, exhalation
What are respiratory pigments
proteins that transport oxygen and increase the amount of oxygen the blood can carry
what respiratory pigments is used by arthropods and molluscs and what is its binding component
hemocyanin, copper
what respiratory pigment do most vertebrates and some invertebrates use
hemoglobin,
what are hemoglobins structure
made of dimers (alpha and beta subunits —> 2 each) which contain 4 iron-containing heme groups
how many oxygen molecules can each hemoglobin molecule carry
up to four
What is binding affinity defined by
kd (dissociation constant)
How does affinity affect Hb ability to bind
high affinity = low saturation of O2 needed to bind
low affinity = high saturation needed to bing
What does oxygen bind to in hb
Iron (protoporphyrin)
What are the qualities of the tense state
low affinity, deoxygenated, compact structure (hard for O2 to bind), low cooperativity
what are the characteristics of the relaxed state of Hb
high affinity, oxygenated, open structure (easy for O2 to bind), high cooperativity
what does the dissociation curve for hemoglobin and oxygen essentially mean
in areas of high oxygen availability, oxygen is not needed to be unloaded so saturation is high (lungs), in tissues at rest, oxygen availability is lower due to respiration of the tissues, meaning some oxygen needs to be unloaded from the hemoglobin leading to lower saturation, in tissues during exercise lots of oxygen is being consumed so there is little oxygen availability meaning lots of oxygen needs to be unloaded leading to low saturation
What factors cause a shift right and why
increased PCO2, Lower pH, increased temperature, and increased BPG
Lowers the oxygen affinity of Hb —> oxygen is unloaded easier assisting O2 delivery
What is BPG and how does it affect Hb?
Product of glycolysis, fits into the whole in the Hb of the T state preventing O2 from binding
favours T state, not R state
What are the characteristics of myoglobin and what is its function
emergency store of oxygen (for the heart), monomeric = 1 subunit = no cooperativity = no R/T state
found in muscles
Where is Co2 transported
7% = blood plasma
23% = binds to amino group of Hb
70% = transported as bicarbonate
What is carbon monoxide poisoning caused by
Co binds to heme group in Hb more strongly than O2, creating HbCO
How is breathing controlled
sensors in aorta and carotid arteries monitor Co2 and O2 concentrations in blood and signal breathing control centers
What are the breathing control centers
main = medulla oblongata, additional = pons
What are some adaptations in marine animals (6)
large blood to body volume ratio
stockpile O2
Store O2 in myoglobin of muscles
change buoyancy for passive gliding
anaerobic respiration
decrease blood supply to muscles
