Respiratory System 1 Flashcards
Tetrapods
Animals with 4 limbs
Amphibians were first tetrapods followed by reptiles
Respiration
Internal vs External respiration
Sequence of events that results in exchange of O2 and CO2 between external enviro and mitochondria
Internal: Mitochondria consume O2 to produce ATP, producing CO2
External: Organisms obtain O2 from enviro and get rid of CO2
Bulk flow or diffusion?
Unicellular organisms
Small
Large
Diffusion
Diffusion
Bulk flow and diffusion
4 steps of animal respiration:
Ventilation
External respiration
Gas transport
Internal respiration
Bulk flow/Gas exchange across respiratory surface
Diffusion/Gas exchange across respiratory surface
Bulk flow in circulatory system
Diffusion/Gas exchange at tissues
- Cellular respiration/Mitochondrial respiration
- O2 consumed to make ATP, producing CO2
Fick equation (Rate of diffusion)
dQ/dt = DA(dC/dx)
When will rate of diffusion be greatest?
Diffusion coefficient (D), area of membrane (A) and energy gradients (dC/dx) are LARGE
Diffusion distance is SMALL (why gas exchange surfaces are thin)
The ideal gas law (Gases exert pressure)
PV = nRT
Total pressure exerted by a gas is related to the ___ of the gas and the ___ .
Dalton’s law of partial pressures
Number of moles
Volume of the chamber
In a gas mixture, each gas exerts its own partial pressure
- Sum of partial pressures in a gas mixture yields total pressure of gas mixture
Henry’s law (Gases dissolve in liquids)
[G] = Pgas x Sgas
What is Henry’s law?
Why is this important?
Is CO2 or O2 more soluble in water?
The amount of gas that will dissolve in a liquid is determined by the partial pressure of the gas and the solubility of the gas in the liquid
Gas molecules in the air have to first dissolve in liquid to diffuse into a cell
CO2 -> More CO2 will be dissolved at the same partial pressure
Graham’s law (Gases diffuse at different rates)
Does O2 or CO2 diffuse faster?
In aqueous solutions?
When gases are dissolved in liquids, the relative rate of diffusion of a gas is proportional to its solubility in the liquid and inversely proportional to the square root of its molecular weight
O2 (it’s also lighter)
CO2 (because more soluble)
Diffusion rates at constant temperature (Fick w/ Henry and Graham’s law)
At constant temp, the rate of diffusion is proportional to and inversely proportional to?
At constant tenp, rate of diffusion is proportional to:
- Diffusion coefficient of the gas
- Partial pressure gradient
- Cross-sectional area
- Solubility of the gas in the fluid
Inversely proportional to:
- Diffusion distance
- Molecular weight of the gas
Boyle’s law: P1V1 = P2V2
Bulk flow
Since gases don’t have a fixed volume or shape, how do they respond to pressure changes?
Fluids and gases flow from areas of high to low pressure
Mass movement of liquids or air as the result of oressure gradients
Changing their volume (gases are compressible, but not liquids and solids)
Frictional resistance (Resistance opposes bulk flow of fluids)
Q = deltaP/R
How does resistance increase and decrease in tubes?
Resistance increases in proportion to length of tube and viscosity of the fluid
Resistance decreases in inverse proportion to radius of the fourth power
As organisms (decrease/increase) in size, their ratio of surface area to volume (decreases/increases)
This limits the area available for diffusion and (decreases/increases) diffusion distance
Increase
Decreases
Increases
Animals more than a few millimeters thick use 1 of 3 respiratory strategies
1) Circulating the external medium thru the body
- Sponges, cnidarians, insects
2) Diffusion of gases across the body surface + circulatory transport (Cutaneous respiration)
- Most aquatic invertebrates, some amphibians, eggs of birds
3) Diffusion of gases across a specialized respiratory surface + circulatory transport (Gills/evaginations or lungs/invaginations)
- Vertebrates
Ventilation of respiratory surfaces (increases/reduces) the formation of static boundary layers (makes it gas exchange more efficient)
- Boundary layer?
Reduces
Region of solution that’s in direct contact w/ the animal’s body surface
Types of ventilation
- Nondirectional
- Tidal
- Unidirectional
Medium flows past the respiratory surface in unpredictable pattern
- PO2 in blood leaving gas exchanger approaches PO2 in the medium
- If ventilation is inefficient, oxygen depleted boundary layer (thick) will form at respiratory surface
External medium moves in and out of respiratory movement
- PO2 of blood equilibrates w/ the PO2 of respiratory cavity
- Respiratory cavities never fully empty (fresh air mixes w/ oxygen-depleted residual air)
Respiratory medium enters chamber at one point and exits at another
- Concurrent flow (same): PO2 or respiratory medium will equilibriate
- Countercurrent flow (opposite): PO2 of blood approaches that of the incoming medium (Most efficient)
- Crosscurrent flow (at an angle): PO2 of blood is usually higher than what would be seen for concurrent, but lower than countercurrent
What ventilation method do these use?
Most water-breathers
Air-breathers
Insects
Unidirectional
Tidal
Air filled tubes
Cold water holds (more/less) gas than warm water
Seawater with (high/low salinity) holds more gas than (high/low salinity) water
Deep water, which has a (high/low) pressure, holds (more/less) gas than shallow water
More
Low, high
High, more
Mollusks gill and mantle cavity ventilation strategies (2)
1) Beating of cilia on gills move water unidirectionally
- Countercurrent blow flow
- Snails and clams
2) Muscular contractions if mantle propel water unidirectionally thru mantle cavity past gills
- Countercurrent blood flow
- Cephalopods (squid)
Crustacean ventilation strategies:
- Barnacles and small species (cocepods)
- Shrimp, craps, lobsters -> Gill bailer
Lack gills and rely on diffusion
Gill bailer propels water out of branchial chamber, sucking water across gills from negative pressure
- Unidirectional; Countercurrent blood flow
Jawless fish (hagfish and lamprey) ventilation strategies
- Velum
- Multiple pairs of gill sacs
- Velum (muscular pump) propels water through the respiratory cavity
- Unidirectional; Countercurrent blood flow
For lamprey:
- When mouth attached to prey, ventilation tidal thru gill openings
Elasmobranch (cartilaginous fish) ventilation
- Sharks, skates, rays
- Buccal pump
- Constantly move to keep water flowing thru gills
- Buccal cavity acts as suction and force pump
- Countercurrent blood flow
1) Expand buccal cavity
2) Increased volume sucks fluid into buccal cavity via mouth and spiracles
3) Mouth and spiracles close
4) Muscle contraction forces water past gills and out via external slits
Teleost (bony) fish ventilation
- Buccal-Opercular pump
The development of positive pressure within the buccal cavity of vertebrates
- Forces air into lungs or water across gills
- Unidirectional flow
Ram ventilation
Obligate ram ventilators
Fish swim forward w/ mouth open (allows water to flow across gills without active pumping)
Lost ability to actively pump water over their gills
Fish gills have how many gill arches in each opercular cavity and rows of gill filaments projecting from each gill arch?
Arranged for what kind of flow?
4 gill arches
- Each containing afferent (deoxy to secondary lamellae) and efferent (oxy to the gill arch) blood vessels
2 rows of gill filaments
Countercurrent
- Blood flow thru capillaries in secondary lamellae is opposite the flow of water thru the gills
Pulmonate molluscs ventilation method
Lack gills so mantle cavity highly vascularized and acts as lung instead
Pumping of mantle cavity moves air in and out of lungs
Insect ventilation
1) Contraction of abdominal muscles
- Tidal or unidirectional
2) Ram/draft ventilation
3) Discontinuous gas exchange
- Closed phase: No gas exchange; O3 used and CO2 converted to HCO3; lowered total pressures
- Flutter phase: Air pulled in
- Third phase: Total pressure increases as CO2 can no longer be stores as HCO3; spiracles open and CO2 released
How do aquatic insects breathe air?
Mosquito have siphons (snorkels)
- Hydrofuge hairs repel water from entering siphon
Water beetles have air bubbles
Amphibian ventilation
- 3 types of respiratory structures
- Flow
- Pros and cons
- Movement of glottis and air
Cutaneous respiration (breathe thru skin), external gills, bilobed lungs
Tidal flow using buccal force pump
Pros: High SA, exposed to medium
Cons: Easily damaged, not suitable in air
1) Air enters pocket cavity in mouth
2) Glottis opens and air pushed out
3) Mouth closes and glottis opens, pushing air into lungs
4) Glottis closes and gas exchange occurs
Reptile ventilation:
- Flow
- Number of lungs + suction pumps
- Rely on inspiration and expiration
- Snakes/lizards, turtles/tortoises, crocodilians
Tidal
2 lungs, rely on suction pumps
Snakes/Lizards: Contract intercostal muscles, ribs move outward, increasing volume
Turtles/Tortoises: Abdominal muscles expand and compress lungs
- Disadvantage: When trying to breathe, muscles may be in constant contraction from motions, so some use buccal pumping to support
Crocodilians: Diaphragmaticus muscles contract, lowering volume in abdominal cavity, increasing columenin lungs
Bird ventilation
- Flow; Air-blood flow
- Lungs stiff and doesn’t change volume much
- Flexible air sacs
- Parabronchi
Unidirectional flow; Crosscurrent
Gas exchange occurs at parabronchi
2 cycles of inhalation and exhalation:
1) Inhalation into posterior air sacs
2) Exhalation of fresh air from posterior air sacs to lungs
3) Inhalation of stale air from lungs to anterior air sacs
4) Exhalation of stale air from anterior air sacs to trachea
