Bart - Metamorphosis - Respiration and Neurons Flashcards
What are the main steps involved in buccal breathing in elasmobranchs like sharks?
The ventilatory process in sharks involves two main steps:
* Step 1: The shark expands the volume of the buccal cavity, creating suction. Water enters through the mouth and spiracles.
* Step 2: The shark closes its mouth and spiracles, contracting the buccal cavity. Water is forced over the gills and out through the external gill slits.
How does the opercular valve contribute to buccal breathing in teleost fish?
The opercular valve helps maintain unidirectional water flow over the gills in teleost fish by:
* Opening during the compression of the opercular cavity, allowing water to exit.
* Closing to prevent backflow when the mouth opens for the next cycle.
What role do pressure changes in the buccal and opercular cavities play in teleost ventilation?
Pressure changes in the buccal and opercular cavities are essential for teleost ventilation:
* Negative pressure in the buccal cavity draws water in through the mouth.
* Positive pressure pushes water from the buccal cavity over the gills into the opercular cavity.
* Negative pressure in the opercular cavity sucks water from the buccal cavity across the gills, while positive pressure expels water through the opercular valve.
Describe the ventilatory cycle in lungfish during air breathing.
The ventilatory cycle in lungfish during air-breathing involves:
* Step 1: The mouth opens, and the buccal cavity expands, drawing air in.
* Step 2: The mouth closes, and the buccal cavity compresses, forcing air into the anterior chamber of the air-breathing organ.
* Step 3: The posterior chamber contracts, exhaling spent air via the operculum.
* Step 4: The anterior chamber opens and contracts, forcing air into the posterior chamber for gas exchange.
How do amphibians like bullfrogs partition gas exchange between gills, lungs and skin at different life stages?
Amphibians partition gas exchange among gills, lungs, and skin as follows:
* Tadpoles rely equally on gills and skin for O2 and CO2 exchange.
* As metamorphosis proceeds, the lungs gradually take over O2 uptake, while the skin becomes the primary site for CO2 elimination.
* In adult frogs, lungs are responsible for most O2 uptake, but the skin plays a major role in CO2 excretion.
What hormonal mechanism drives the transition from gills to lungs in anurans during metamorphosis?
The transition from gills to lungs during metamorphosis in anurans is driven by:
* The pituitary gland releases thyroid-stimulating hormone (TSH), triggering the thyroid to release thyroxine.
* Thyroxine induces the growth of lungs and apoptosis of gill cells, facilitating the transition to lung-based respiration.
How do dragonfly larvae and adult dragon flies differ in respiratory mechanisms?
Dragonfly larvae and adults differ in their respiratory mechanisms:
* Larvae use rectal gills to extract oxygen from water.
* Adult dragonflies use a tracheal system to breathe air, facilitating oxygen diffusion into body tissues for flight.
How do damselfly and dragonfly gills differ in their structure and function?
Damselfly and dragonfly gills differ in:
* Damselflies have three external gills that actively move through water for gas exchange.
* Dragonflies have internal tracheal gills located within the branchial chamber, ventilated by water movement.
Why do dragonfly nymphs adjust the frequency of their pumping movements rather than the amplitude?
Dragonfly nymphs adjust respiratory frequency rather than amplitude because:
* They already pump water at maximum amplitude to ensure complete renewal of water in their rectal gills.
* Frequency is the only variable that can be adjusted to increase or decrease gas exchange efficiency.
How do central pattern generators (CPGs) control the transition from undulatory to limb based swimming in Xenopus laevis?
Central pattern generators (CPGs) control the transition from undulatory to limb-based swimming by:
* Generating rhythmic alternating muscle contractions for undulatory swimming in tadpoles.
* As limbs develop, a separate limb-based CPG emerges, and by adulthood, locomotion relies on synchronized limb movements controlled by this CPG.
