Respiration Flashcards
What are the steps of respiration?
VEntilation
gas exchange
gas transfer
gas exchange
Cellular respitation
What happens during gaseous exchange?
O2 transferred via diffusion from alvaeoli into the pulmonary vein.
CO2 transferred from the pulmonary artery into the alveoli.
O2 transported towards tissues, diffuses from blood into the cells.
CO2 diffuses from cells into circulatory system towards lungs.
What is partial pressure?
The percentage of a specific gas in a mixture. The % of gas timesed by the atmospheric pressure.
What is the PO2 at sea level?
160mmHg
What is the PCO2 at sea level?
0.2mmHg
What does the atmosphere weight support at sea level?
Column of mercury (Hg) = 760mmHg
What does dalton’s gas law state?
a specific gas in a mixture will exert pressure as if there are no other gases present.
What does boyle’s law state?
increasing the volume of a qunantity of gas, decreases the pressure of the gas.
What does Henry’s law state?
a quantiy of gas that dissolves at a certain temperature is proportional to the partial pressure of that gas in gaseous state.
What is fick’s law of diffusion?
allows us to calculate the rate of diffusion.
What affects diffusion rates?
BOdy size:
The larger the animal the smaller the surface-to-volume ratio and the larger the diffusion distance. Therefore larger animals had to evolve structures and organ specialised for respiration.
NAme the different types of respiratory organs.
Gills
Trachea
Lungs
How do fish with gils breahte?
Gils have a large surface area for highly efficient gaseous exchange. Undergoes counter current exchange = blood flows through the gills and passes by water flowing in the opposite direction over the gils. O2 is transferred from the water into the blood continuously as equilibrium is never reached.
How do insects with trachea breathe?
The trachea consists of a network of air-filled passages that transfer O2 directly to the body tissues and cells, which allows O2 and CO2 to be diffused faster. There is no circulatory systems.
How do amphibians breathe?
Breathe with lungs and positive pressure breathing.
Air is forced into the lungs, nostrils open air flows in and buccal cavity expands. Nostrils close, glottis opens, buccal cavity contracts and air flows into expanded lungs.
Buccal cavity expands and the lungs contract = air flows from lungs into buccal cavity. Nostrils open and glottis closesand buccal cavity contracts = air flows out of buccal cavity into environment.
How do mammals breathe?
Mammals have lungs and breathe via negative pressure breathing.
Lungs have negative pressure so that air can flow into the low pressured area. Respiration rhythm is determined by nerve impulses that fire for 2sec and rest for 3sec. During firing, respiratory muscles contract, when neuron stops respiratory muscles relax.
Lungs have a branched system of passages that end in alveoli where gas exchange occurs. Gases can only diffuse dissolved in aqueous solution due to moist respiratory surfaces.
Lungs are filled and controlled by pulmonary stretch receptors which prevents over inflation.
Hering-Breur refllux - control of breath-by-breath breathing.
Gas in blood ins controlled by chemoreceptors to regulate blood acidity and pH.
What are the advantages and disadvantages of mammals lungs?
Advantages:
Reduces water loss
High SA:V
blood vessels around the alveoli decreases the diffusion distance.
Disadvantages:
Tidal ventialation
Residual volume
Concurrent
O2 cannot diffuse over bronchi
O2 concentration in lungs is lower that environmental O2 concentration due to water vapor and residual volume.
What are the adption of mammalian lungs?
Thin layer of lung lining fluid
Aveoli produce surfactants
Other cells produce mucous that captures dirt
Cilia moves the mucous.
Quiet breathing
Resting respitation
Vigorous breathing
forced in and exhalation
Strenuous excersise
How do birds breathe?
Unidirectional and continuous = allows birds to maximise the environmental O2 on external side of exchange surfaces.
I breath takes 2 cycles to be exhaled
2 volumes are inhaled to make breathing continuous
Air moves into posterior sac into lungs and into anterior sac.
Lungs are small with maximised gaseous exchange and cross current flow between blood and air.
PO2 of lung surface = PO2 atm
NOt sensitive to blood CO2
How is O2 transported in the body?
Bound to respiratory pigments -heamoglobin (98.5%) or present as gas (1.5%).
O2 is poorly soluble in blood.
Heamoglobin can bind to 4 O2 molecules - binding to the first makes the second easier but the 3rd and 4th a high PO2 is needed.
What determines the Hb-O2 affinity?
PO2 of environment
A high Po2 increases the affinity - will bond to O2, at lungs
A low PO2 decreases the affinity - will release O2, at body cells
O2-Hb dissociation curve
S-shaped curve shows the O2 saturation of Hb and the corresponding PO2.
Curve plateau = Hb is highly saturated and favours O2 loading at lungs
Curve Steep slope = drop in PO2 leads to a decrease in O2 saturation, favours release of O2 in body cells
