L12 - Cardiorespiratory System Flashcards
Respiratory surfaces must be kept moist for diffusion to take place, what 2 ways is this maintained by animals?
1) living somewhere moist/damp
2) Have covered or full internalised structures for gas exchange
Why do insects ventilate in bursts rather than continuously like humans?
To conserve water
Describe the Buccopharyngeal pump in amphibians
1) Amphibians expand their buccal cavity, lowering the pressure in it which drags air in
2) They shut their mouth and nose, which forces the air into the lungs
3) Exhale by opening the nose, and is caused by the elastic recoil of the lungs
What is the problem with the Buccopharyngeal pump system of Amphibians?
demands mouth to be shut, therefore they can’t eat and breath at the same time
Reptiles work with a negative pressure breathing system, what does this mean?
Expanding their lungs lowering the pressure in the cavity, therefore dragging air in.
They can expand their lungs with the mouth open, and can therefore eat and breath at the same time
If turtles lungs are fused to their carapace how do they use a negative pressure breathing system?
They have a series of abdominal muscles which link the carapace with the underside, which contract and expand the whole of their cavity to drag air in.
What is meant by saying Crocodiles use a ‘rudimentary diaphragm’ as part of their negative pressure breathing system?
Crocodiles have muscles and a series of membranes attached to the gastro-intestinal organs.
These form a plunger so when the muscles contract it pulls the organs down, increasing the size of the thoracic cavity decreasing the pressure.
(Their ribs also move outwards like others)
How can elephants use their trunks as a snorkel?
Elephants lungs have a very dense layer of connective tissue surrounding the inter-pleural space of the lungs, which gives them the capability to expands their lungs under high pressure.
What are the lungs of birds like?
They are small and ridged with no alveoli. Instead they have vascularised tubes called parabronchi which are connected to air sacs.
Birds have lungs they rely mostly on air sacs for ventilation. While bird lungs are smaller in comparison to mammals, the air sacs account for 15% of the total body volume, compared to 7% lung volume in mammals.
If birds lungs are rigid, how does air flow through
They act like a series of bellows to move air unidirectionally through the respiratory system. Birds lack a diaphragm, so the air sacs allow the tract to maintain a fixed volume with oxygenated air constantly flowing in a single direction through them. Exhalation is the thing requiring muscular contraction.
What are parabronchi?
Avian lungs do not have alveoli as mammalian lungs do, but instead contain millions of tiny passages known as parabronchi, connected at both ends by the dorsobronchi and ventrobronchi.
Why are birds lungs more efficient than mammal lungs?
Air passes through the lungs during both exhalation and inspiration, causing little to no mixing of new oxygen-rich air and stale carbon dioxide rich air as in mammalian lungs.
Thus, the partial pressure of oxygen in a bird’s respiratory tract is the same as the environment, and so birds have more efficient gas exchange than mammals do.
What are the advantages of the birds respiratory system developing like this?
Air sacs aid flight by:
- reducing the bird’s weight
- helping the bird to change its centre of gravity as it changes posture from the fairly upright when not flying to the generally horizontal when flying
- increasing the capacity of the respiratory system for the large volume of air required to provide the oxygen necessary for the energy required for flight
