Respiration Flashcards
Cell respiration
In the cell, O2 + Sugar -> Energy + CO2 + H2O
External Resp
Gas exchange with environment, in and out of cells and in and out of the body
Two basic steps in gas exchange (External Respiration)
Passage of O2/CO2 through a respiratory membrane
Transport of O2/CO2 between respiratory membrane and the cells of the body via some method of dispersal
How do respiratory gases transport across the plasma membrane?
Respiratory gases (O2 and CO2) diffuse easily through the lipid bilayer (simple diffusion) since they are so small
Cutaneous Respiration
Where?
What Conditions?
Skin serves as respiratory membrane
Found in some aquatic and terrestrial animals
3 conditions needed:
Very small body size (less than 1 mm in diameter)
High SA: Volume ratio (mass)
Very low metabolic rate
Explain how body size matters relative to cutaneous respiration
As body size increases, volume of cells increases much more rapidly than surface area (where diffusion occurs), thus making it inefficient to oxygenate cells solely with this process
Volume = L ^3
SA = L^2
SA : Volume ratio
Smaller things have higher surface area to volume ratios
Animals that rely solely on cutaneous respiration
Sponges (aquatic) ,
Hydras (aquatic),
Flatworms (aquatic or terrestrial),
Earthworms (aquatic or terrestrial),
Plethodontid salamanders (primarily terrestrial) (can get large but have low metabolic demand)
Hellbender Amphibian unique because…
Example of how many amphibians have respiratory organs, but still rely extensively on cutaneous respiration
30-74 cm
FEATURES THAT INCREASE SA FOR CUTANEOUS RESPIRATION
body and head are dorsoventrally flattened
skin is loose and wrinkled
however, they also have lungs
Respiratory organs have…
Respiratory membranes that are localized
An increased surface area to maximize their gas exchange potential
(Gills and Lungs are examples of respiratory organs)
Air vs. Water properties in terms of gases
79% Nitrogen, 21% oxygen (.04% CO2)
Fast diffusion
Water: generally 1% oxygen or less, diffusion slow
Comparatively, air has 20x more oxygen than water
Comparatively, gas molecules diffuse 10,000x more faster in air than in water
2 types of gills… in…
External Gills - in larval salamanders, many invertebrates
Internal gills - in fishes, molluscs, arthropods
Tadpoles and bony fish have…
Internal gills
Respiratory membranes in fish are composed of…
Long sections called gill fillaments
On the gill filaments exists lamella(e) that are perpendicular to the direction of gill filaments
Bony fish Gills use…
Countercurrent exchange-
Water flows across the lamellae in opposite directions relative to blood within the respiratory membrane
This process works because concentration of O2 is paralleled by the blood flow through the lamellae, allowing oxygen to go down its concentration gradient
Countercurrent exchange
Systems do not reach equilibrium and exchange takes place over the entire length
More O2 is exchanged (relative to concurrent)
Concurrent exchange
Systems reach equilibrium and no further oxygen takes place at the theoretical half-way point because oxygen will no longer be able to go down its concentration gradient past 50%
Ventilation
Movement of respiratory medium (air or water) over the respiratory membrane (alveoli, lamellae, etc)
Lungs and tracheal systems must also be ventilated
Water is moved across the gills through a variety of mechanisms… (4)
Ambient water currents
Locomotion of the animal (pushing water against the surface relative to the movement)
Cilia action
An active pumping mechanism
Active pumping mechanism
Generation of negative/positive pressure, or some combo
Gill ventilation by bony fishes using pumping mechanism (4)
Opercular vs Buccal
buccal and opercular cavities expand, creating negative pressure
Mouth opens and water rushes in
Mouth closes and buccal cavity contracts, generating positive pressure
Operculum opens and water is pushed out
Ram ventilation
Used by?
Keep mouths open while swimming
This forces water into the mouth, through the buccal and opercular cavities, and over the gills
No active pumping involved
Tuna, Mackerel, Herring, Many sharks
Why aren’t gills seen on many terrestrial animals?
Which have gills and what makes them viable?
Gills would dry out and collapse
A few terrestrial animals do have gills - pillbugs, land crabs, and they are supported by living in moist environments and have an exoskeleton to support gills
Gas exchange on land: 3 methods
Cutaneous respiration, Lungs, Tracheal Systems
Do some animals live part of their life in water and another part on land?
Yes, tadpoles and larval coastal giant salamanders have external gills, whereas metamorphosed adult frogs and LCGS have lungs (LCGS use cutaneous gas exchange)
Vertebrate lungs are called….
How is air moved in and out?
Vertebrate lungs
Air is moved in and out by the pumping action of adjacent body parts
Frog lung breathing
at what point is positive versus negative pressure
Glottis is closed, a lowering of floor of mouth draws air into a pocket in ventral part of mouth cavity (- pressure)
Glottis opens, and elastic recoil of lungs drives stale air out and over fresh air being held in ventral part of mouth cavity
Raising of floor of mouth pumps fresh air into lungs
Pumping action continues until lungs are filled. Glottis then closes
Alternative amphibian external respiration
what is the disadvantage of this over lung ventilation?
Amphibians may ventilate mouth cavity alone - moist lining acts as respiratory membrane -
-less ability to gather oxygen than in a high SA lung
Amphibians can also rely extensively on cutaneous respiration
Human Breathing system
Where does diffusion happen?
External nares -> nasopharynx -> pharynx -> glottis -> larynx -> trachea -> bronchi -> bronchioles -> alveolar sacs -> alveoli
Gases diffuse directly between alveoli and capillaries
Inspiration
pressure - or +?
Generation of negative pressure
Caused by external intercostal muscles and diaphragm contracting.
- elevates the ribs and pushes the sternum forward
Expiration (relaxed)
pressure - or +?
Positive pressure
Diaphragm relaxes, external intercostal muscles relax, elastic recoil pushes air out of lungs
Elastic recoil
Elastic recoil means the rebound of the lungs after having been stretched by inhalation
Expiration (active)
Decrease in volume of chest cavity
Still positive pressure
Contraction of abdominal muscles - pushes diaphragm towards anterior of body
Contraction of internal intercostal muscles causes the ribs to go down
Tracheal systems
found on what?
Extensive network of hollow thin-walled tubes (tracheae) that branch into every part of the body
Insects, centipedes, millipedes, and some spiders
Tracheae system ->
relative to cells?
oxygen delivery?
Tracheae –> tracheoles –> cells
Tracheoles branch into a fine network over the cells, where nearly every cell in the body is near a tracheole
Tracheal system delivers oxygen directly to the tissues
What respiratory system is most efficient in animals
Tracheal system
Smaller insect tracheal system
Simple diffusion
Larger or more active insects
EG grasshoppers
Forcibly ventilate their tracheae
This is done by contraction of abdominal muscles that compresses the internal organs and forces air out of the tracheae
As the muscles relax, the abdomen springs back to its normal volume and air is drawn in
Large air sacs attached to portions of the main tracheal tubes increase the effectiveness of this bellows-like action
Why are respiratory organs needed in larger, active animals, but not smaller, inactive ones?
In smaller, inactive animals, the demand for oxygen is lower and the smaller the animal is, the greater its surface area to volume (and mass) ratio is. With a great surface area to volume ratio, cutaneous respiration effectively gets diffused oxygen from the cutaneous membrane to the cells of the animal much more effectively than a bigger animal.
Cell respiration Vs External respiration
Cell respiration is when a cell uses oxygen and sugar to create energy, CO2, and H2O whereas
External respiration is the process of getting oxygen through a respiratory membrane and to the cells of the animal’s body
Air vs Water
Air is 20x more oxygen rich than water and, oxygen diffuses 10,000 times more rapidly in air than in water
In water, oxygen is far less common than it is in the air. This challenge has to be overcome by water-dwelling animals. In water, oxygen diffuses far less rapidly, so water-dwelling animals must be able to be far more efficient with their oxygen usage in the body relative to land-dwelling animals.
Advantages and Disadvantages of cutaneous respiration
What animal?
Pros: Passive gas exchange happening with no body space needed to be allocated to respiratory organs. Hard to damage
Cons: Limited ability to do gas exchange and therefore evolution into larger size cannot happen without flattening out as a result, limited development pattern
Advantages and Disadvantages of gill respiration
What animal?
Pros: Gills are able to extract oxygen from the environment effectively using the property of countercurrent flow through their lamellae relative to the waterflow across it. Since they are localized, the body cavity can be utilized more efficiently.
Cons: Since it is localized, damage to it can be fatal
Advantages and Disadvantages of tracheal respiration
What animal?
Pros: Highly efficient way of getting oxygen to tissues
Cons: Takes up a lot of volume of the body cavity
Advantages and Disadvantages of lung respiration
What animal?
Pros: Since oxygenation is localized, body cavity can utilize space more effectively.
Cons: Since it is localized, damage to it can be fatal
Compare and contrast the mechanics of lung ventilation in a frog vs a lizard vs a human
Lizards, Frogs, and Humans have lungs. Therefore, they all have alveoli and the alveoli-capillary interface is how they get oxygen to their system.
Frogs utilize positive and negative pressure by lowering the floor of their mouth to create negative pressure and posit a pocket of air, then the glottis opens and air is rushed out through the nares and mouth by elastic recoil. The mouth and nares close, then the floor of the mouth is brought back up, causing the trapped air to flow into the lungs with the glottis open. The glottis closes again, and the cycle continues.
Lizards have intercostal muscles but no lungs. Lizards are able to flex their chest muscles to increase the negative pressure of the lungs and draw air in, then elastic recoil causes the air to escape. The process is cyclical.
Humans use
