Lecture 9: Respiratory System Flashcards
what are the 3 functions of the rs?
- gas exchange: diffusion of O2 and CO2
- ventilation: movement of air and water
- production of sound: vocals
how are gills developed in fish?
- pharyngeal pouches align with branchial grooves
- closing plate separates each pouch and groove
- plates rupture to form gill slits
how are lungs developed?
endodermal evagination from gut tube posterior to pharynx
how does embryonic respiration occur in fish and lissamphibians?
gases diffuse through egg and skin of embryo
how does embryonic respiration occur in monotremes and reptiles?
eggshell via pores
how does embryonic respiration occur in therian mammals?
gases circulate via placenta
what are the 3 features of a good gas exchanger?
- minimal thickness - faster diffusion
- moistness - facilitates diffusion
- maximal surface area
what facilitates cutaneous respiration?
integument
what are the benefits of gills?
adapted for extracting oxygen from the water
what kind of gills do cyclostomata have?
pouched
what kind of gills do elasmobranchs have?
septal
what kind of gills do osteichthyes and holocephali have?
reduced
what is a spiracle?
reduced first gill slit in elasmobranchs
what is a pseudobranch?
smell hemibranch with a spiracle
gas exchange: describe concurrent exchange
- oxygenated water and deoxygenated blood enter the same end and flow in the same direction
- quickly reaches equilibrium - O2 equal at 50
gas exchange: describe countercurrent exchange
- oxygenated water and deoxygenated blood enter through opposite ends
- equilibrium never reached
where are external gills present?
- larval lissamphibians and fish
- adults of some salamanders
bird lungs: describe crosscurrent blood flow
- air flows unidirectionally through bronchial system and fills air capillaries
- blood capillaries run perpendicularly across several air capillaries
mammal lungs: what is the flow of the “respiratory tree”
- trachea, bronchi, bronchioles
- bronchioles lead to alveoli = gas exchange
- bidirectional flow
- constant ventilation with low metabolic costs
swim bladder: define physostomous
primitive; connected to digestive tract by pneumatic duct
swim bladder: define physoclistous
derived; not connected to digestive tract, instead gas enters bladder through gas gland
define ventilation
moving air or water across respiratory surfaces
what’s the process of unidirectional gill ventilation?
flows through gill chambers, across a series of gills, and out to the exterior
what parts of the fish allow them to “breathe”
digestive tract, lining of the mouth, oropharynx
what’s the process of tidal (bidirectional) ventilation?
air passes through trachea, branches into lungs (inhalation), back out through the tracheal branches, then trachea (exhalation)
what kind of airflow do birds and non-avian reptiles have?
unidirectional
what’s the process of tidal ventilation in adult lampreys?
when mouth is unavailable for ventilation, water enters and exists gill pores
what kind of muscles aid gill-based ventilation?
cranial
what kind of muscles aid lung-based ventilation?
cranial or axial
what is ram ventilation?
keeping mouth open while moving forward allows water into the pharynx
- aid by locomotor muscles
what phases does dual pump have?
- suction phase: oral and opercular cavities open to allow water to enter
- force phase: oral and opercular closed so water flows out
what are the phases of two-stroke oral pump?
- used by lissamphibians
1. oral expansion: gases from lungs enter mouth
2. oral compression: gases forced out and go to lungs and exterior
what is the four-stroke oral pump?
exhalation and inhalation phases have 2 strokes each
- separation reduces mixing of fresh and stale air
what are the phases of the four-stroke oral pump EXHALATION
- first oral expansion: mouth closed; stale air moves from lungs into mouth
- first oral compression: mouth open; air is forced out of mouth
what are the phases of the four-stroke oral pump INHALATION
- second oral expansion: mouth open; fresh air moves from exterior to mouth
- second oral compression: mouth closed; air is forced in to the lungs
what are the hydrostatic effects of the four-stroke pump?
- water pressure increases with depth
- exhalation near the surface and 2nd compression with head turned down helps air go into the lungs
can lungfish drown?
yes; they are air-breathers and they have reduced gills
how does an aspiration pump work?
- air is sucked in by pressure within the thorax, which fills the lungs
- mouth has no role
what are the phases of an aspiration pump?
inhalation: rib cage expands, diaphragm back
exhalation: rib cage contracts, diaphragm forward
how does an aspiration pump work in crocodilians?
- liver acts as a piston to help ventilate lungs
- inhalation: diaphragmatic muscles help expand thoracic cavity
how does an aspiration pump work in turtles?
- limb movements help expand and compress cavity
- specialized muscles in shells help with ventilation by moving viscera and shoulder girdle
how does an aspiration pump work in mammals?
- muscular dome-shaped diaphragm helps with ventilation
- contraction flattens diaphragm which increases the volume of the thorax (inhalation)
- relaxation restores shape, reducing volume volume of the thorax (exhalation)
how does an aspiration pump work in birds?
- have membranous air sacs
- lungs contain parabronchi (small passages)
- one way flow through parabronchi
what are the phases of biphasic breathing in birds?
- inhalation 1: air enters through trachea and goes through parabronchi and posterior air sacs
- exhalation 1: parabronchial air exists through trachea and air in posterior air sacs moves into parabronchi
- inhalation 2: parabronchial air moves into anterior air sacs
- exhalation 2: air from anterior air sacs and parabronchial air exists through trachea
how does the furcula aid in breathing?
it’s able to bend during downstroke and recoil during upstroke; able to inflate and deflate interclavicular air sac
what are the functions of larynx?
- prevents air from leaking out the lungs
- prevents foreign substances from entering the lungs
- expels foreign substances that threaten the trachea
what are vocal cords and how do they produce sound
- membranous folds flanking glottis
- produce sounds when they vibrate under tension
what is syrinx?
- present where trachea bifurcates into primary bronchi
- contains membranes that produce sound when they vibrate under tension
- tension is produced by syringeal muscles
