respiration 4

Question 1

What are the main differences seen in the respiratory systems of amphibians and reptiles?

Answer 1

• repitiles have complex multicameral lungs, use aspiration via muscles rather than buccal force pump
• amphibians use cutaneous breathing, some have gills

Question 2

What are the strengths and limitations of the respiratory system used by insects?

Answer 2

-size limited due to tracheal path embracing environment

Question 3

Demonstrate how the mechanisms that allow animals to breathe air have developed from those seen in water breathers.

Answer 3

some fish breathe air in hypoxic environments, have special structures for breathing air

Question 4

main animal lineages that live terrestrially

Answer 4

vertebrates and arthopods, also molluscs

Question 5

mollusc air breathing

Answer 5

-aka pulmonates, lack gills and instead have a highly vascularized mantle cavity that acts as lungs

Question 6

air breathing crustaceans

Answer 6

-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

Question 7

chelicerates; spiders and scorpions

Answer 7

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

Question 8

insect ventilation

Answer 8

• 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

Question 9

insect vent mechanisms

Answer 9

1. diffusion
2. 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
3. ram ventilaion/draft vent in some flying insects-expansion and contraction of tracheae

Question 10

discontinuous gas exchange in insects phase 1

Answer 10

closed phase: spiracles closed, no exchange with environ, O2 and CO2 converted to HCO3-, decreasing total pressure in tracheae

Question 11

discontinuous gas exchagne in insects phase 2

Answer 11

flutter phase: spiracles open and close in rapid succession

-air movs into tracheae and body due to low pressure

Question 12

phase 3

Answer 12

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

Question 13

unusual air breathers

Answer 13

many aquatic insects breathe air via snorkel or air bubbles

Question 14

air breathing in fish

Answer 14

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

Question 15

types of respiratory structures in air breathing fish

Answer 15

• 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

Question 16

two circuit circulatory system

Answer 16

-separate pumonary circuit allows separation of oxygenated blood coming from pulmonary system and deoxygenated blood coming from the tissues

Question 17

amphibians breathing

Answer 17

• cutaneous resp, external gills, simple bilobed lungs, though more complex in terrestrial frogs
• ventilation is TIDAL using buccal force pump

Question 18

amphibians structures

Answer 18

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

Question 19

intermitten breathers

Answer 19

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

Question 20

reptile breathing

Answer 20

• 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)

Question 21

bird ventilation

Answer 21

• 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

Question 22

mammal resp system

Answer 22

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

Question 23

pleural sac

Answer 23

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

Question 24

mammalian ventilation: inspiration

Answer 24

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

Question 25

mammalian exhalation

Answer 25

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