Gas Exchange Flashcards
Ventilation
A mechanical process that moves gas into and out of the body
Passive and active
Respiration
Biological process occurring in all cells in the body where food and oxygen are taken in to release energy for the cell
Water as a respiratory medium
Kroghs diffusion coefficient
air = 11 seawater = 0.000034
As a resp. medium water paws greater phys. challenges than air
Oxygen solubility reduces as salinity increases
Water density
800x denser than air
Viscosity 35x higher at 40 degrees and 100x at 0 degrees
Importance of light and oxygen
Earliest life were heterotrophs required autotrophs
linked by photosynthesis and respiration
Gas exchange - 2 mechanisms
Diffusion - across membrane
Convection - brings inspired gas to peripheral regions and removes waste
Gas exchange - structures
Internal = usually actively ventilated
External = relies on water movement
Ventilation processes
Unidirectional- different entrance and exit
Tidal (in-out)
Non directional (unpredictable)
Bimodal breather
Can breath air or water
Gas exchange - diffusion
O2 and CO2 move across epithelium - transport into tissue
From high partial pressure to low partial pressure
Echinoderms - gas exchange
Sea stars perform gas exchange across epithelium of branchial papulae and tube feet
Complex respiratory trees in holothurians
Polychaete - gas exchange
Distributed gills along body wall
Forced over gills by ciliary beating
Tentacles function as gills
Molluscs - gas exchange
Diverse respiratory system
Mantle overhangs which contains internal gills
Ciliary action generates current around gills
These gills also serve secondary function as feeding organs
Crustaceans
-Branchial chambers ventilated by specialised appendage that drives water through an opening
-Negative pressure is created within branchial chamber drawing water in
Merostomata
Pairs of hinge plate book gills
Fish
Gills - counter current flow
Sharks
Well developed spiracles that allow water to be drawn into the buccal cavity over gills (active ventilation)
bi modal respiration
-Obtain oxygen from two different sources: water (via gills) and air (via specialized respiratory structures such as lungs or other air-breathing organs)
-Cope with hypoxic conditions – particularly where warm water temperatures significantly reduce the amount of dissolved O2
Gas exchange: Speeding up diffusion
*Pump blood through the gills
*Pump water across the gills (ventilation)
*Increase gill surface area – have thin gill epithelium (gill cover)
*Optimizing convection – concurrent (same direction of bloodflow) vs countercurrent gas exchange
Respiration versus Metabolism
-Respiration includes the transport of oxygen into the body/cells and transport of carbon dioxide out of the body
-Metabolism includes the cellular processes by which energy is obtained such as through the breakdown of glucose (includes cellular respiration).
Aerobic metabolism
requires oxygen
-efficient = 38 atp from 1 glucose
- carried out by eukaryotes in the mitochondria via kreb cycle
Anaerobic respiration
doesnt require oxygen
inefficient but faster = only 2 atp
performed by eukaryotes and pro.
completed in the cytoplasm by glycolysis
Steady state locomotion
- “Cruising”/”Routine” behavior: Fueled aerobically, primarily using red muscle fibers
- Can be sustained for long periods of time
Unsteady state locomotion
- Sudden, intense exertion (“burst”): Fueled anaerobically, primarily utilizing white muscle fibers
- Causes lactate accumulation
- Can lead to fatigue
Energy savings during locomotion: Flying birds
- Social behavior also provides energy savings to locomotion.
- E.g., birds are flying in a v-formation.
Energy savings during locomotion: Schooling fish
- Fish can use the same principles to save energy when swimming schools, with following fish taking advantage of the eddies produced by leading this.
- Fish take advantage of eddies produced by leading fish
- In the striped surfperch, we see this effect both in terms of pectoral fin beat frequency and in terms of oxygen consumption, with both traits lower in following or trailing fish.
metabolism
-a useful characteristic to measure as it can tell us a lot of information about an animal´s ambient state, in particular helping us to understand what factors increase or decrease the energetic demand of an individual, influencing how much food it needs.
-the rate at which an animal consumes energy and is measured in units of calories per unit time or watts
what is metabolic rate referred to as
metabolic rate is sometimes referred to aa the rate of heat production
standard metabolic rate
an ectotherm´s minimal maintenance costs and is an integrated measure of an animal´s physiological energy expenditures
basal metabolic rate
An endothermic animal that thermoregulates, like birds or humans
the amount of energy (calories) that an organism needs to maintain basic bodily functions while at rest.
routine metabolic rate
includes both minimum maintenance costs and the energetic needs to maintain routine activity.
Maximum metabolic rate
represents an animal´s maximum aerobic metabolic limits
Aerobic scope
Difference between an organism’s resting metabolic rate (RMR) or basal metabolic rate (BMR) and its maximum aerobic metabolic rate (MAMR)
Factors that influence metabolic rate
intensity of physical activity and the temperature of the environment
gender, food, age, circadian rhythms, body size, reproduction, hormones, and more
Specific Dynamic Action
Increase in metabolic rate caused by food ingestion
Body size
- Larger animals in general have high absolute metabolic rate than smaller animals
- However, this increase in metabolic rate is slower than linear (1:1)
Hypoxia
- Episodes of low dissolved oxygen following natural (e.g., rock pool) or anthropogenic (e.g., eutrophication follow runoff of pollutants from land) factors
- Oxygen solubility declines at warmer temperatures, so hypoxic events exaserbated by climate change
3 strategies to cope with hypoxia
-Enhance oxygen uptake, transport, and delivery
-Rely more heavily on anaerobic metabolism
-Depress their metabolic needs for lower reliance on aerobic metabolism
Methods to measure metabolic rate
Indirect calorimetry - Most accurate but technically and logistically difficult
Direct Calorimetry - by burning the materials under pure oxygen conditions, and measuring the heat released
– Respirometry - Measures an animal´s rate of respiratory gas exchange, particularly oxygen consumption, as a proxy for aerobic metabolism
Field metabolic rate
Metabolic rate measured in a free-roaming animal and holistic measurement of metabolic rate in a particular ecological context
- biologgers and otoliths microchemistry
