Respiration Flashcards
Composition of air- nitrogen
78%
Composition of air- oxygen
21%
Composition of air- carbon dioxide
0.04%
Partial pressure of O2 at sea level
21.2 kPa
101KPa x 0.21
Pressure equation
p = ma/A
p= 101KPa
Diffusion definition
A physical process by which ions of molecules move from a region of greater concentration to a region of lesser concentration
Fick’s law
R = D x A (p/d)
R - rate of diffusion
D- diffusion constant
A - area
p- difference in partial pressures between interior of organism and external environment
d - diffusion distance
Factors that increase diffusion
Large surface area
Small diffusion distance
High concentration gradient
What is required for gas exchange
A moist surface- O2 and CO2 must be dissolved in water to diffuse across a membrane
Value of PCO2 at sea level and high elevation
Close to 0
The respiratory medium - air
About 21% O2
Thinner at higher altitudes
Easy to ventilate
Respiratory medium - water
O2 amount much less than air (0.0015%)
O2 lower in warmer water
Harder to ventilate
What is the better respiratory medium
Air>water
8000 times better
What does the structure of the gas exchange surface depend on
Size of organism
Where it lives- water or land
Metabolic demands of the organism
Characteristics of gas exchange surfaces
Large surface area
Small diffusion distance
Moist
Favourable concentration gradient
Respiration in mollusca- snails
Snails have open circulatory system
Transport fluid is hemolymph
Hemocyanin is present in the hemolymph as the respiratory pigment that transports O2
What is the respiratory pigment in mollusca- snails
Hemocyanin
What is the transport fluid in mollusca-snails
Hemolymph
What is the respiratory protein family Planorbidae (snails and slugs)
Hemoglobin
Gas exchange in Annelida - earthworms
Takes place through the skin
May occur through gill filaments in some aquatic forms
O2 directly transported in the blood by either hemoglobin or chlorocruorin
Respiratory pigment in Annelida- earthworms
Hemoglobin or chlorocruorin
Gas exchange system of arthopoda- arachnids
Open circulatory system
O2 and CO2 carried in spider hemolymph by Hemocyanin
Respiratory organs- trachea and book lungs
Respiratory organs of Arthropoda - arachnids
Trachea
Book lungs
Respiratory pigment in arthopoda- arachnids
Hemocyanin
Gas exchange system in arthopoda- crustaceans
Gills protected by exoskeleton- feather like and attached to basal segments of the legs
Open circulatory system
Respiratory system is Hemocyanin
Respiratory medium in crustaceans
Hemocyanin
Gas exchange in insects eg locust and cockroaches
Simple tracheae with valved spiracles
Gas exchange system in insects eg mosquito larvae
Metapneustic system with only terminal spiracles
Gas exchange system in insects eg most endoparasitic larvae
Entirely closed tracheal system with cutaneous gas exchange
Gas exchange in insects eg larvae of carrion and some parasitic flies
A tracheal system with only terminal spiracles
Biological gills
Tracheated cuticular lamellar extensions from the body
Gas exchange in insects eg mayfly nymphs
Closed tracheal system with abdominal tracheal gills
Effect of temperature on oxygen solubility in water
O2 becomes less soluble as temperature increases
Ectotherms (aquatic animal) need more O2 when temperature rises as their metabolic rate rises
Gas exchange in insects eg dragonfly nymphs
Closed tracheal system with rectal tracheal gills
Physical gills
An adaptation common among some types of aquatic insects, which holds atmospheric oxygen in a respiratory area which does not have gills but have spiracles
Why is p= 101KPa
= 10300kg x 9.81 m/s^2 / 1 m^2
= 101000 Kg m/s^2
1N = 1 Kg m/s^2
= 101000 N
1Pa = 1N
=101000Pa
=101KPa
Siphon in metapneustic system
Contains hydrophobic hairs to prevent water entering
Tracheal system in insects
Tracheoles are highly branched so reach every cell in the insect
What is a siphon
tubular organ of the respiratory system of some insects that spend a significant amount of their time underwater, that serves as a breathing tube
siphon uses the water’s natural surface tension to attach for a breath
Still water vs turbulent water
Still water- high O2 at the surface but rapidly declines as the distance increases from the air
Turbulence increases rate of solution and breaks down diffusion gradients
Freshwater vs salt water
Freshwater can dissolve 25% more O2 than seawater
Oxygen binding capacity of haemoglobin
Can bind 4 oxygen molecules (8 oxygen atoms)
1.34 mL O2 per gram of haemoglobin
Blood plasma vs haemoglobin
Increases the total blood oxygen capacity x70 compared to dissolved oxygen in blood plasma
Haemoglobin
Iron-containing oxygen-transport metalloprotein
Oxygen transport in ice fish
Crocodile icefish of Antarctic waters lack any haemoglobin or red blood cells
Oxygen is dissolved in plasma
How can icefish live without haemoglobin
Low metabolic rates
High solubility of oxygen in water (cold)
Icefish blood can only carry around 10% of close relatives.
Fish gills
Gill arches support the primary lamellae (gill filaments)
Forms curtain through which water flow from the buccal cavity to the opercular cavity
How do fish gills work
Valves exist within the mouth and the operculum cavity that mean water only moves in one direction
Suction pump phase
Pressure pump phase
Ram ventilation
Suction pump phase
Opens mouth
Expands buccal cavity and closes opercular valve
Water is pulled into the mouth
All vertebrates have haemoglobin apart from…
Crocodile Icefish
Pressure pump phase
Closes mouth
Contracts buccal cavity and opens opercular valve
Water is pushed through gills to opercular cavity and out
Ram ventilation
Mouth kept slightly open and fish swims forward
Water is pushed through gills to the opercular cavity
Most efficient in fast moving species
Gills surface area
Gill arches support the primary lamellae (Gill filaments)
Secondary lamellae run perpendicular to the primary lamellae surface
Elasmobranchs- sharks and rays
Gills support is different- septa create structural difference compared with teleost fish
allow for blood to be circulated between the supporting septum and the distal edge of the primary lamellae
Counter-current flow
Water and blood flow in opposite directions to maintain a concentration gradient
Typical mammalian lung structure
Blind-ended sac ending in alveoli
Trachea- 2 bronchi- — bronchioles—- terminal bronchioles— alveolar sacs
How are mammalian lungs ventilated
Passively
Expansion of thoracic cavity is by contraction of intercostal muscles and flattening the diaphragm
Negative pressure
Dead space
Some air not exchanged during breathing
Lung systems in amphibians
Simple balloon-like structures
Actively ventilated
Use positive pressure
Amphibian lungs are inefficient why is this ok
Low metabolic demands
Additional mechanisms to supplement their oxygen supply
Amphibian respiration
Air is taken into the buccal cavity and associated air sacs, which expand (buccal ventilation). The lungs are full of air during this phase because they are separated off from the buccal cavity.
In the next phase the lungs are allowed to empty by passive contraction of the walls and air is forced out of the nasal cavity and upper part of the buccal cavity.
The mouth is then closed and the buccal cavity and air sacs are actively compressed forcing the air into the lungs (lung ventilation).
Now that the buccal cavity is empty the frog can take a breather to fill the buccal cavity and the cycle starts again.
Tissues used for gas exchange in amphibians
Buccopharyngeal
Cutaneous
Pulmonary
Buccopharyngeal tissue in amphibians
Use the mucosal surface lining the buccal cavity and pharynx as respiratory surfaces
Amphibians and environmental hypoxia
Maximise cutaneous gas exchange
Increase surface area by folded skin
Larval amphibians
Rely on gills during aquatic phase
Size and complexity depends on oxygen levels in water - greater area required in habitat as with lower dissolved oxygen
Ventilation in reptiles
Lungs typically ventilated by combination of expansion and contraction of ribs via axial muscles and buccal pumping.
Lung has a single bronchus running down the centre, from which numerous branches reach out to individual pockets throughout the lungs.
Pockets are similar to, but much larger and fewer in number, than in mammalian lungs
In tuataras, snakes, and some lizards, the lungs are simpler in structure, similar to that of typical amphibians.
Snakes and limbless lizards typically possess only the right lung as a major respiratory organ.
snakes and limbless lizards
Only have the right lung as a functional structure due to restricted body volume
Ventilation in turtles
Unable to move ribs
Use their forearms and pectoral girdle forces air in and out of the lungs
Ventilation in turtles
Unable to move ribs
Use their forearms and pectoral girdle forces air in and out of the lungs
Lung ventilation in crocodile
Sac-like lungs that use a hepatic piston method to ventilate the lungs
Liver is pulled back by a muscle anchored to the pubic bone , which in turn pulls the bottom of the lungs backwards, expanding them- negative pressure
Lung ventilation in alligators
Recent research has shown that internal organisation of the parabronchi within the lungs allows for uni-directional flow of air through the lungs
Inspired air enters parabronchi rather than lungs
Will improve efficiency of gas exchange
Avian respiratory system
Series of air sacs
The lungs are tubular and air flows through them in one direction: front to back.
Tubular parabronchi
Birds- respiratory cycle
Contrary to mammalian lung systems birds require two inspiration/expiration events to complete a respiratory cycle
Air is stored in the air sacs at different parts of the cycle
Efficiency of gas exchange is increased
During the first inspiration air moves via the bronchi to the posterior air sacs that expand to accommodate it.
During expiration the air moves from the posterior air sacs to flow forwards through the lungs. An aerodynamic valve prevents it moving back into the bronchi. It is during this phase that gas exchange takes place.
During the second inspiration the air moves into the anterior air sacs that expand to accommodate it.
During the second expiration the air is forced out of the anterior air sacs into the bronchi and out via the trachea.
Bird pulmonary circulation
takes blood from the anterior of the lung to the back so the deoxygenated blood first encounters air that is relatively depleted of oxygen but this means that there is still a diffusion gradient from the air to the blood and oxygen can be harvested. As the blood moves backwards it encounters air that is higher in oxygen so even though the blood has gained oxygen there is still a gradient between the air and blood. This counter-current flow system maximises gain of oxygen and loss of carbon dioxide.
Respiration in bird eggs
Bird eggs have a rigid shell that excludes the embryo from the external air. This restricts the loss of water vapour from inside the egg but it can also potentially restrict the amount of oxygen entering the egg and carbon dioxide leaving the egg.
shell contains pores that allow exchange of gases. The eggshell is built of crystals of calcium carbonate organised into blocks. The blocks mainly abut against each other but where they don’t a pore forms.
Most pores are simple tubes but as eggs get bigger the pore becomes more complex. The ostrich pore is branched towards the outside of the shell. Emu eggshells have a reticulated layer towards the outer surface that is topped by another layer.
Gas exchange by eggs
Oxygen consumption = oxygen conductance x difference in oxygen concentration across the eggshell.
MO2 = GO2 x (PeO2 - PnO2).
Where: MO2 = daily oxygen consumption by an egg (mlO2/day); GO2 = water vapour conductance (mlO2/day/Torr); PeO2 = oxygen concentration inside the egg (Torr); and PnO2 = oxygen concentration outside the egg (Torr).
Gas diffusion through the egg shell pore
Pore numbers are fixed and the amount of oxygen inside the eggshell is generally the same. The amount of oxygen in the nest is higher than inside the egg and so oxygen diffuses across into the egg
Chick development at 5 days of incubation
Vascular yolk sac membrane serves as the primary respiratory membrane for the first week of development
The extra-embryonic membranes in eggs- older eggs
CHORION – continuation of the amnion and forms the outermost layer of embryonic tissue.
In combination with allantois forms CHORIO-ALLANTOIS, which lines the inside of the eggshell and is the main respiratory membrane from around day 10 of development in the chick
Why is the bird ventilation system so efficient
No dead space
Air is constantly moved through the system
Temperature is inversely related to oxygen solubility. Salinity is also inversely related to oxygen solubility. Which one of the following options will have the lowest concentration of dissolved oxygen?
Fresh water coming from your tap
Fresh water in the Arctic Tundra
Fresh water in West Africa
Sea water in the Atlantic ocean off West Africa
Sea water in the Arctic Ocean
Sea water in the Atlantic ocean off West Africa
