respiration 4 Flashcards
What are the main differences seen in the respiratory systems of amphibians and reptiles?
- repitiles have complex multicameral lungs, use aspiration via muscles rather than buccal force pump
- amphibians use cutaneous breathing, some have gills
What are the strengths and limitations of the respiratory system used by insects?
-size limited due to tracheal path embracing environment
Demonstrate how the mechanisms that allow animals to breathe air have developed from those seen in water breathers.
some fish breathe air in hypoxic environments, have special structures for breathing air
main animal lineages that live terrestrially
vertebrates and arthopods, also molluscs
mollusc air breathing
-aka pulmonates, lack gills and instead have a highly vascularized mantle cavity that acts as lungs
air breathing crustaceans
-similar to marine crust, but gills are stiff
-vent via beating of scaphognathite
-branchial vacity is highly vascularized and acts as the primary site of gas exchange
Isopods gills are supported by chitin, gills contain air-filled tubues (pseudotrachea) to bring gas by diffusion into interstitial fluid
chelicerates; spiders and scorpions
have four book lungs; lamellae projecting into air-filled cavity/atrium that opens to outside via spiracle where gases diffuse in and out
- some spiders also have a tracheal system
- technically evanginations, so they are a type of gill
insect ventilation
- extensive tracheal system: air filled tubes that lead deep into body cavity, connected to outside by spiracles and branch inside into tracheoles, which are filled with hemolymph to dissolve O2 into tissues
- hemolymph have highe surface area and wet surface, ideal for diffusion
insect vent mechanisms
- diffusion
- bulk flow of air via contraction of abdominal muscles and movement of thorax; flow can be tidal or unidirectional (in and out of spiracles or in one out another
- ram ventilaion/draft vent in some flying insects-expansion and contraction of tracheae
discontinuous gas exchange in insects phase 1
closed phase: spiracles closed, no exchange with environ, O2 and CO2 converted to HCO3-, decreasing total pressure in tracheae
discontinuous gas exchagne in insects phase 2
flutter phase: spiracles open and close in rapid succession
-air movs into tracheae and body due to low pressure
phase 3
excess CO2 cannot be stored as HCO3-, total pressure in tracheae increases and spiracles open to releases CO2
-this system protects from too much oxygen and minimizes water loss
unusual air breathers
many aquatic insects breathe air via snorkel or air bubbles
air breathing in fish
many aquatic environ are hypoxic, so air breathing can be beneficial
- they swim to the surface and ventilate gills with well axygenetated water just at the surface
- some also gulp air into buccal cavity, which can also be highly vascularized for gas exchange
- this has evolved multiple times in fish
types of respiratory structures in air breathing fish
- reinforced gills that do not collapse
- highly vascularized mouth and pharyngeal cavity, and stomach, lungs
- venting is tidal, using the same buccal force for water breathing
two circuit circulatory system
-separate pumonary circuit allows separation of oxygenated blood coming from pulmonary system and deoxygenated blood coming from the tissues
amphibians breathing
- cutaneous resp, external gills, simple bilobed lungs, though more complex in terrestrial frogs
- ventilation is TIDAL using buccal force pump
amphibians structures
external gills adv: high surface area, exposed directly to medium
dis: easily damaged, not suitable in air
- two pumps: lungs and buccal cavity
- two control vavles: nares and glottis
intermitten breathers
amphibians let air in buccal cavity, then release air from lungs out nares before buccal air enters lungs, this prevents mixing of oxy and deoxy air
reptile breathing
- most have two lungs
- can be simple honeycombed (unicameral) or highly divivded chambers in more active species (multicameral), each served by a bronchus
- some are not vascularized and only assist in air movement, not gas exchange
- breathe tidal, rely on aspiration suction pumps
- preform inhalation and exhalation via intercostal muscles on ribs (lizards), abdomina muscles (turtles), or diaphragm (crocodiles)
bird ventilation
- unidirectional and continuous
- lungs are stiff and their volume does not change; they rest between series of air sacs that act as bellows to lighten the bird
- gas exchange occurs as air flows through parabronchi in lungs, blood is CROSSCURRENT
- ventilation requires TWO cycles of inhalation and exhalation
- air flows posterior then move back forward into lungs, second inhalation moves stale air into anterior air sac, and compression of second exhalation pushes stale air out
mammal resp system
upper tract: mouth, nasal, pharynx, trachea
lower: bronchi and gas exchange surfaces/alveoli-alveoli are site of gas exchange, outer surface of which are covered in capillaries
pleural sac
each lung is surrounded by pleural sac, two layers of cells with a small pleural cavity between them
- cavity contains pleural fluid and keeps the lungs expanded via negative pressure cancelling out chest wall recoil and lung recoil
mammalian ventilation: inspiration
somatic motor neurons stim inspiratory muscles
-contraction of external intercostals and diaphragm move ribs out and diaphragm down, volume of thorax increaess, lungs expand and air is pulled in
mammalian exhalation
nerve stim of inspiratory muscles stops, muscles relax, ribs and diaphragm return to original positions and air is passively pushed out of lungs
-forced exhalation can occur during heavy breathing
