Respiration: Strategies & Ventilation Characteristics Flashcards
what respiratory strategies do animals larger than a few mm use (3)
- circulate the external medium through the body
- diffuse the gases across the body surface, accompanied by circulatory transport
- diffuse gases across a specialized respiratory surface, accompanies by circulatory transport
which organisms circulate external medium through their body for respiration? (3)
- sponges
- cnidarians
- insects
which organisms diffuse gases across their body surface, accompanied by circulatory transport (3)
- most aquatic invertebrates
- some amphibians
- bird eggs
what is the name of the respiration strategy that involves diffusion of gases across their body surface, accompanied by circulatory transport
- cutaneous respiration
what is required for cutaneous respiration (2)
- skin must be thin
- skin must be moist
which organisms diffuse gases across a specialized respiratory surface accompanied by circulatory transport
- vertebrates
what kinds of specialized respiratory surfaces are used for respiration (2)
- gills: evaginations
- lungs: invaginations
what is the requirement for specialized respiratory surfaces (2)
- thin
- moist
which organisms rely on diffusion through water/air (2)
- unicellular animals
- small, thin animals
which organisms rely on bulk flow of water (no circulatory system)
- sponges
- cnidarians
which organisms rely on bulk flow of air (no circulatory system)
- insects
which organisms rely on diffusion, accompanies by circulatory system for gas transport (2)
- leech
- earthworm
which organisms rely on ventilation and a circulatory system for gas transport
- vertebrates
how does ventilation of respiratory surfaces affect static boundary layers
- reduces the formation of static boundary layers
types of ventilation (3)
- nondirectional
- tidal
- unidirectional
ventilation types: nondirectional
- medium flows past respiratory surface in an unpredictable pattern
ventilation types: tidal
- medium moves in and out of the chamber
ventilation types: unidirectional
- medium enters the chamber at one point and exits at a another point
where do gases enter the blood
- at the respiratory surfaces
what is the efficiency of gas exchange affected by (3)
- contact time between medium/blood and the respiratory surface
- thickness of the respiratory membrane
- direction of flow
how can contact time impact the efficiency of gas exchange (2)
- contact time is too long: not enough new O2 will be delivered
- contact time is too short: not enough time to diffuse O2
how can thickness of respiratory membranes affect gas exchange (2)
- physical instability if too thin
- gases cannot diffuse if too thick
what accounts for the inability for blood to reach equilibrium with the medium in PO2 after it exits the respiratory surface (2)
- effect of thickness of the respiratory epithelium and mucus
- boundary layer effects
what will the PO2 be closer or further from the medium PO2 in a animal with efficient respiration
- it will be closer to reaching the medium PO2 (higher than a less efficient respiration system)
ventilation graph: non-directional ventilation and efficient gas exchange (2)
- medium PO2 remains constant at a high level
- blood PO2 approaches medium PO2, coming near to its value as it leaves the respiratory surface
ventilation graph: non-directional ventilation and non-efficient gas exchange (2)
- medium PO2 remains constant at a high level
- blood PO2 approaches medium PO2, but does not come near to its value as it leaves the respiratory surface
ventilation graph: tidal ventilation and efficient gas exchange (2)
- medium PO2 changes: inhalant PO2 is slightly higher than exhalant PO2
- blood PO2 approaches exhalant medium PO2, coming near its value as it leaves respiratory surface
why does the inhalant PO2 differ from the exhalant PO2 in the medium of animals with tidal ventilation
- the medium stored in the respiratory surface will lose O2 to the blood, causing its PO2 to drop
unidirectional flow: types (3)
- concurrent flow
- countercurrent flow
- crosscurrent flow
ventilation graph: concurrent flow (2)
- medium PO2 changes: medium PO2 entering the respiratory surface is much higher than the medium PO2 leaving
- blood PO2 approaches the PO2 of the medium leaving the respiratory surface
ventilation graph: countercurrent flow (2)
- medium PO2 changes: medium PO2 entering the respiratory surface is much higher than the medium PO2 leaving
- blood PO2 approaches the PO2 of the medium entering the respiratory surface
ventilation graph: crosscurrent flow (2)
- medium PO2 changes: medium PO2 entering the respiratory surface is higher than medium PO2 leaving
- blood meets medium at varying points, creating an exiting PO2 that is greater than the exiting medium PO2
specialized respiratory surfaces: characteristics (6)
- allows rest of body to be thick/protected
- protected in body cavity (sometimes), allowing surface to remain moist
- higher effective surface area as it is unconstrained by skin properties
- highly vascularized (lower diffusion distance)
- highly ventilated
- synchronized with circulatory system
what are important respiratory differences between water and air (2)
- O2 solubility in air is 30 times greater than water
- CO2 solubility in air is similar to water
what are the implications of low O2 solubility for water breathers
- to remove the same amount of O2, 30 times more water must be ventilated than air to remove the same amount of oxygen
if a water breather has sufficient flow for O2 uptake, what are the implications for CO2 excretion (2)
- water breathers are better at extracting CO2 from the body due to high flow rate
- blood CO2 levels are low
water is more dense than viscous air, what are the implications for cost of ventilation
- water breathers require a lot of energy to move H2O through their system
ventilation strategies: unidirectional flow (2)
- used by most water breathers
- allows for countercurrent exchange
ventilation strategies: tidal flow (3)
- air-breathers
- used because air flows easily; tidal ventilation would be too much work for water breathers
what affects the work required to breathe (3)
- lung elastance
- compliance
- airway resistance
lung compliance (2)
- how easy it is to stretch a structure
- high compliance = easy to stretch
lung elastance
- how readily a structure returns to its orginal shape
what diseases can alter lung elastance and compliance (2)
- fibrotic lung disease
- emphysema
fibrotic lung disease (2)
- caused by inhalation of small, damaging material like asbestos
- scarring thickens walls of the lungs
fibrotic lung disease: affect on lung work (2)
- scarring reduces lung compliance
- makes inhalation more difficult, which requires more work
aqueous fluid and surface tension
- aqueous fluids have substantial surface tension due to hydrogen bonding between water molecules
surface tension and lungs (2)
- aqueous fluid surface tension would cause alveoli walls to stick together
- this would increase energy needed to inflate lungs
how do surfactants affect lung work (2)
- surfactants produced by type II alveolar cells reduce surface tension
- increases lung compliance and reduces work required to breathe
how does emphysema affect lung work (3)
- walls of the alveoli break down
- increases lung compliance, but reduces lung elastance
- easy to inhale, but difficult to exhale
airway resistance and airway radius (2)
- airway resistance is inversely proportional to airway radius to the 4th power
- small change in radius has a large change to resistance and flow
bronchoconstriction (3)
- reduction in airway radius
- results from stimulation of parasympathetic nervous system
- can be caused by histamine or irritants
bronchodilation (3)
- increase in airway radius
- results from stimulation of sympathetic nervous system
- can be caused by adrenaline or high alveolar PCO2
asthma (2)
- excessive bronchoconstriction
- variety of causes including allergens, exercise, weather, etc
tidal volume (2)
- volume of air moved in one ventilatory cycle
- Vt
dead space (3)
- air that does not participate in gas exchange
- anatomical dead space or alveolar dead space
- Vd
anatomical dead space
- volume of trachea and bronchi
alveolar dead space
- volume of alveoli that are not perfused
what are the effects of increased dead space
- lower surface area for gas exchange
which animals have a lot of dead space, what are the implications (2)
- animals with long necks (trachea length)
- must have thinner trachea, but this may increase resistance
ventilation-perfusion matching (2)
- matching of ventilation and blood flow
- helps to make gas exchange more efficient at the respiratory surface
ventilation perfusion ratio
- Va/Q
ventilation perfusion ratio: Va
- alveolar ventilation
ventilation perfusion ratio: Q
- cardiac output
Va/Q = 1
- match of O2 delivery at gas exchanger with ability to transport O2 away from the gas exchange site
how is blood rate controlled to match alveoli ventilation
- arterioles dilate or constrict to distribute blood
how would the arterioles change in low PO2 alveolus
- arterioles would constrict
why is ventilation-perfusion matching beneficial
- diversion of blood flow to functional alveoli
