B3.1-Gas exchange Flashcards
gas exchange definition
The process by which these gases are exchanged between living organisms and their environment
why large animals require a specialized gas exchange system
-larger organisms have a smaller SA:V ratio so outer surface of organism cant carry out rapid gas exchange
-specialized larger gas exchange is required
-example: alveoli in lungs, spongy mesophyll
properties of gas exchange surfaces
-permeable membrane: allows gases to diffuse across freely
-large surface area: increases quantity of gas exchanged
-thin tissue layer: shorter distance of diffusion, one cell thick
-moist: surface is covered in moisture to allow gases dissolve and diffuse
adaptations for maintaining conc gradient
-dense network of capillaries surrounding tissues involved in gas exchange
-continuous blood flow through capillaries surrounding tissues involved ingas exchange
-animals with lungs= ventilate lungs with air, bringing high conc of 02 to alveoli and removing co2
-animals with gills=water is moved through gills, high conc of 02
adaptation of gills
features of inspiration
-diaphragm contracts, flattens
-external intercostal muscles contract
-ribcages moves up and out
-increasing volume in thorax
-air flows in
lung structure
-trachea (made of cartilage rings)
-bronchus
-bronchioles (ending in alveoli)
-diaphragm
-intercoastal muscles
-ribs
features of exhalation
-diaphram returns to dome shape
-abdomen muscles contract
-intercostal muscles contact
-ribcage moves down and in
-decreasing volume in thorax
-pressure rises
-air flows out
ventilation definition
movement of air in/out of the alveoli in the lungs facilitating gas exchange
-how lungs are adapted for gas exchange
1)alveoli secretes surfactant: prevents alveoli walls for adhering, reduced surface tension and provides a moist surface area for gas exchange
2) alveoli provides large surface area
3)short distance for diffusion: alveoli one cell thick
4) alveoli surrounded by extensive capillary beds to create a conc gradient
Features of inhalation
-air drawn in
-volume of thorax increases
-diaphragm contracts/flattens
-rib cage moves out
-external intercostal muscles contract
-pressure inside thorax decreases
-abdomen muscles contract
Features of exhalation
- air forced out
-volume of thorax decreases
-pressure inside thorax increases
-rib cage moves in
-external intercostal muscles relax
-diaphragm relaxes- turns back to dome shape
-abdomen muscles contract
spirometer
measures lung volume
tidal volume
volume of air breathed in/out in typical cycle when at rest
inspiratory reserve volume
the maximum volume of air that can be breathed in (measured from max point of tidal volume)
expiratory reserve volume
max volume of air a person can breathe out (measured from min point of tidal volume)
vital capacity
The sum of inspiratory volume plus tidal volume plus expiratory volume
adaptations for gas exchange in leaves
- waxy cuticle; wax lipid layer covers epidermis cells, reduced evaporation of water from leaf
- guard cells; open and close to allow Co2 and O2 to pass through
3.palisade mesophyll cells; packed upper region of cylindrical cells containing chloroplast, located to receive max sunlight - spongy mesophyll; loosely packed cells, air spaces for gas exchange
- Veins located in central leaf provide access to all cell layers
6.stomata; open and close guard cells
factors affecting transpiration
- increased light increases transpiration. Light stimulates guard cells to open -stomata- permits diffusion
- increased temp increases transpiration. Water particles gain kinetic energy, so particles diffuse through stomata at quicker rate
- increased winds speeds increases transpiration. Moves water vapor away from leaf when air flows part, reducing conc of water outside leaf.
- humidity decreases transpiration. Conc of water outside leaf increases, decreases conc gradient.
Partial pressure
Pressure exerted by a single gas when found in a mixture of gases
Hemoglobin structure in relation to oxygen binding
iron atom in haem group binds with O2.
4 iron atoms means it has the capacity to transport 4, O2.
4 02= fully saturated
Affinity
Attraction for more oxygen
Cooperative binding
The binding of 1 O2 molecule to haemoglobin increasing its affinity for remaining oxygen.
relationship with oxygen binding and affinity
when there is no oxygen bound=low affinity
1 oxygen binds- haemoglobin changes shape making the next oxygen binding easier
allosetric binding of CO2 to haemoglobin
-haemoglobin can bind to CO2 whic changes its affinity for O2. This is called allosetery.
-binding of Co2 results in increase of release of 02 molecules (bohr shift)
structure of foetal haemoglobin
- has a different structure; 2 alpha, 2 gamma chains
- has higher affinity for 02
mother to feotus transfer
-in placenta capilaries of mother and foetus come close.
-foetal side of placenta is lower in 02 and higher in C02
-conc gradient between blood is aided by foetal haemoglobin greater affinty for 02
Oxygen dissociation curve
shows the affect of the cooperative binding of 02 molecules (partial pressure against percentage haemoglobin saturation)
Explanation;
-low partial pressures of 02, haemoglobin has low affinity for 02, shown by slow initial increase
-1 02 binds to haemoglobin causing a change which increases the affinity
-rapid increase in 02 saturation as partial pressures of o2 increases, allowing additional 02 molecules to bind
-high partial pressures- curve flattens and most haemoglobin is saturated
oxygen association curve in relation to body
in lungs- high partial pressure of 02 in capillaries
-haemoglobin becomes saturated with 02 as it has a high affinity due to high partial pressure
-respiring tissues use 02, low partial pressure for 02 around tissues
structure of 02 association graph in foetal and adult haemoglobin
foetal haemoglobin graph shifted to left as it has a stronger affinity meaning percentage saturation is higher at every partial pressure
oxygen dissociation curve showing adult hemoglobin and CO2
- Co2 shifted to right
