respiratory gas exchange Flashcards
2 types of respiration and what do they entail
external respiration - gas exchange from external environment to cells
cellular respiration - energy production via aerobic metabolism
3 functions of external respiration
O2 uptake,
CO2 removal
pH regulation
2 types of gas movement
diffusion,
bulk transport
what is the name of the equation for measuring diffusion rate
Fick’s law
what happens if diffusion constant (D) increases
rate of diffusion increases
what happens if area (A) increases
rate of diffusion slows
what happens if there is a higher pressure (p) difference between the two sides
rate of diffusion increases
what happens if the distance over which diffusion occurs (d) increases
rate of diffusion decreases
4 qualities of gas exchange surfaces
permeable to gas,
moist,
thin,
maximise surface area
3 types of breathing method
cutaneous breathers (through skin),
water-breathers (gills),
air-breathers (lungs or tracheae)
how do flatworms carry out gas exchange
only a few cells thick so easy diffusion across membrane
how do earthworms carry out gas exchange
excrete mucus to stay moist, if dry the earthworm suffocates
skin is thin to minimise diffusion distance
gas diffuses across thin membrane to very dense net of capillaries
how do salamanders respire
soley skin breathers
explain respiration throughout a tadpole and frog lifecycle and the changes that occur
tadpoles get more oxygen via skin breathing as they are exclusively aquatic - use both gills and skin for oxygen uptake - cutaneous
frogs have no gills, instead using the lungs which are responsible for most of the oxygen uptake, however carbon dioxide excretion still happens through ski
give 2 examples of a water-breather and how they are adapted
axolotls have a crown of feathery gills to maximise surface area
fish have highly evaginated gills protected by a bony flap
what do air-breathers require
structural support
what are the benefits of being an air breather
occurs internally so easier to keep surface moist
what animals are capable fo both water and cutaneous breathing
amphibious fish e.g. mangrove killy fish
what animals use convection of external medium only to achieve gas exchange and how
Cnidarians (jellyfish and corals) use tentacles or flagella to move water and maintain concentration gradient
what animals use convection of internal medium only to achieve gas exchange
earthworms
3 challenges of water breathing
susceptible to toxic molecules in water,
high viscosity and dense,
low oxygen solubility,
low diffusion rate
what is the flow of water in fish gills and what is the benefit of this
unidirectional to maintain concentration gradient across gills allowing constant diffusion
what are 2 methods of ventilation in fish and which uses energy
active buccal pump - uses energy
ram ventilation
explain how the active buccal pump works
fish opens mouth increasing volume of buccal chamber, drawing water in
closes mouth, contracts buccal cavity, forcing water out over gills
explain how ram ventilation occurs
occurs in fast-moving fish - open their mouths and water moves in naturally due to fast speed
how many gill arches are there
4
what do gill arches have attached to them and what are these made up of
gill filaments with many lamellae
what is the role of lamellae
creates dense network of capillaries
where does counter-current exchange occur in fish gills
between the blood flow in the lamellae and the flow of water over the gills - opposite directions
what is the oxygen extraction efficiency of fish
70%
what is the oxygen extraction efficiency of humans
25%
is carbon dioxide easier to excrete as an air-breather or water-breather
easier as a water-breather
what was the possible driver of the evolution on to land
in the tropics the water is warm and oxygen solubility is low, fish that live there must be able to breathe out of water as water source can dry up
what is the colloquial name for a well-known amphibious fish species
lungfish
3 challenges of breathing air
water loss,
heat loss,
structural support
how do insects air breathe
have spiracles which are open to the air and connect to the tracheae
what structure do mammals have to maximise surface area
alveoli
what is another benefit of alveloli
minimise diffusion distance with thin alveoli cell walls and are surrounded by capillary network
what are the 2 types of capillaries found in birds and what do they do
air capillaries to minimise diffusion distance
blood capillaries to maximise blood flow
what other structure do birds have present
air sacs
what is the unit of gas exchange in birds
air capillaries
what is the direction of air flow in birds and how is it beneficial
unidirectional using a 2 cycle breathing system = no mixing of inhaled and exhaled breathe improving concentration gradient
what type of gas exchange to birds use
cross-current
how effective is cross-current exchange
more efficient than concurrent but less so than counter-current
