Ch 23 Flashcards by Kennedy Chrest

what is overview of active ventilation

use energy to actively move air or water over their gas exchange surfaces, instead of relying on passive flow (ex. wind/currents)

more reliable and controllable to match needs

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active ventilation can use what 2 things & explain

positive pressure:
- PUSHING fluid into the lungs/gills

suction:
- PULLING fluid in
ex. mammals breathing

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the rate of O2 uptake by breathing organ depends on (2)

volume of flow
oxygen removed per volume (how much they can extract from each breath)

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what is oxygen extraction efficiency

measures how an animal is at using the oxygen out of the air
- higher % = more efficient

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3 options for unidirectional ventilation

~Co-current
~Countercurrent
~Cross current

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describe Co-current gas exchange

medium flows in SAME direction as blood
- pO2 in blood leaving never goes above partial pressure of exhaled medium

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describe countercurrent gas exchange

medium and blood flow in opposite directions
- partial pressure of blood leaving is much higher than that in exhaled medium
*can be close to inhaled value

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describe cross current gas exchange

medium and blood cross eachother

-less partial pressure is picked up from L to R
*somewhat combines and so the blood PP is higher than that of exhaled medium

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rank the 3 gas exchanges

best - countercurrent
cross current
cocurrent

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CO2 partial pressure in blood/enviro; water vs air breathers

water:
- PP of CO2 in blood leaving the breathing organ is similar to the CO2 PP in the ambient water

air:
- CO2 PP in blood leaving the breathing organ is far above the CO2 PP in the atmosphere

*fish don’t care about getting rid of CO2 but we do

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which animals used skin for 100% gas exchange

lungless salamander

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birds have a ____ gas exchange membrane than mammals

thinner gas exchange membrane

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describe breathing in bony fish
- what are they called
- structure they have

teleosts
~ gill breathing (very efficient)

4 gill arches ( with 2 gill filaments per arch)
each filament has secondary lamellae (where gas exchange happens)
*thin/highly vascularized

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describe breathing in bony fish
- what type of gas exchange do they use

use countercurrent gas exchange

water -> opercular side
blood -> buccal side

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gill ventilation is _______ and mainly driven by ….

unidirectional

driven by buccal-opercular pumping
(water flows from high to low pressure)

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teleost can also use ___ ventilation

ram ventilation
- gills ventilated by forward swimming motion (doesnt use muscular pumping)
*must keep moving or suffocate
*tuna

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tuna have ______ ______ which helps….

specialized tissue to help stabilize secondary lamellae & gill filaments in high velocity water

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major (2) and weak (1) stimulus in fish

major
- decreases partial pressure in enviro or blood
- exercise

weak
- increased PP of CO2

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air breather fish have (3)

gills that do not collapse in air
accessory breathing organs instead of or in addition to gills
highly developed lungs

describe amphibian breathing (4)

ventilate via buccopharyngeal pressure pump

each lung is unicameral ( is a single, simple sac) (balloon)
are intermittent breathers
holds fresh air & must release old air first

O2 uptake vs CO2 excretion in bullfrogs

O2 uptake
- skin (tadpoles) to relying on lungs! in adults

CO2 excretion
- rely on skin! in adults

non avian reptile breathing

rely on suction pumps to ventilate lungs

lizards (intercostal muscles)
turtles ( abdominal muscles)

lungs have multiple chambers
most have 2 lungs / snakes only have 1

breathing in birds

unidirectionally ventilate their lungs
*gas exchange occurs in parabronchi

posterior air sac = receives fresh air
anterior air sac = receives old air

*cross current flow of fluid for gas exchange

do the air sacs in birds do gas exchange ?

NO they only help move the gas

2 phases of inhalation & exhalation in birds

First Inhalation Air enters through the trachea Fresh air → posterior air sacs First Exhalation Posterior air sacs contract → push fresh air into lungs Anterior air sacs contract → old air exits through trachea Second Inhalation More fresh air enters → fills posterior sacs Previous batch of air now in lungs → moves to anterior sacs Second Exhalation That air in anterior sacs → exits body New air in posterior sacs → moves into lungs

mammals ventilate their lungs ____ & contain 2 pleura

tidally 2 pleura: - parietal = membrane between pleural sac & chest wall - visceral = membrane between pleural sac and lung

2 zones of mammal respiratory system

1. conducting zone - prepare air 2. respiratory zone - gas exchange takes place

describe alveoli

site of gas exchange *epithelium 2 types: Type I - main site of gas exchange Type II - secrete surfactant - capillaries cover surface

in breathing (pulmonary ventilation) air moves ____ a pressure gradient - includes ….

down a pressure gradient includes - inhalation & exhalation

3 pressures that drive ventilation

1. intrapulmonary 2. intrapleural press 3. transpulmonary press

describe intrapulmonary pressure

- pressure inside lungs = decreases as lung volume increases (inhalation), then pressure increases (expiration)

describe intrapleural pressure

= pressure inside pleural cavity - pressure becomes more negative as chest wall expands (inhalation), and returns to initial value once chest wall recoils *always less than atmospheric

describe trans pulmonary pressure

= difference between intrapulmonary and intrapleural pressure - always positive to prevent lung collapse

what is quiet breathing

- normal, relaxed breathing at rest *active inhalation & passive exhalation

what does vital capacity contain / not contain

- inspiratory reserve volume - tidal volume - expiratory reserve volume NOT INCLUDING RESIDUAL VOLUME

3 physical factors that influence ventilation and what would you want to increase ventilation?

- lung compliance - airway resistance - alveolar surface tension increase ventilation: increase lung compliance, decrease resistance, decrease surface tension

what is lung compliance

how much effort is required to stretch lungs high compliance = lungs expand easy low compliance = difficult for lungs to expand

describe airway resistance

- encountered at bronchioles dilation = decrease resistance constriction = increases resistance

describe alveolar surface tension

attraction of water molecules to one another in liquid film lining the alveoli pulmonary surfactant = decreases surface tension (helps keep alveoli from collapsing) infant respiratory distress syndrome (IRDS) = increase in surface tension

when blood leaves the alveoli (lungs) it is _______

it is oxygenated

as body weight increases the area for gas exchange

also increases

most potent stimulus to affect ventilation in mammals

CO2 and H+

increased CO2 stimulates ____ central and peripheral chemoreceptors

both

peripheral chemoreceptors in ____ and ____ bodies sense arterial O2 levels

aortic & carotid bodies

what is required to stimulate increased ventilation

a substantial drop in O2 partial pressure *below 60 mmHg