Ch. 45 Gas Exchange & Circulation Flashcards
ventilation
movement of air or water through specialized gas-exchange organ (lungs or gills)
bring inside body
steps of gas exchange
1) ventilation
2) gas exchange
3) circulation
4) cellular respiration
gas exchange
takes place as CO2 & O2 diffuse between air or water and the blood at the ventilatory surface
circulation
dissolved O2 and CO2 are transported throughout body
cellular respiration
gas exchange between blood and cells occurs in tissues
- leads to low O2 levels & high CO2 levels
- O2 & CO2 diffuse between blood and cells
- ultimately produce ATP
involves transfer of electrons from compounds w/ high potential energy through an ETC & ultimately to an electron acceptor (often oxygen)
respiratory system
the collection of cells, tissues & organs responsible for gas exchange between an animal & its environment
- responsible for ventilation & gas exchange
- breathing
(ie) lungs, mouth & nose in humans
circulatory system
the system responsible for moving oxygen, carbon dioxide & other materials (hormones, nutrients, water) around the body
- need specialized liquid transport tissue
oxygen level in environment
high
oxygen level in tissues
low
carbon dioxide level in environment
low
carbon dioxide level in tissues
high
oxygen movement
diffusion from environment to tissues along respective partial-pressure gradients
carbon dioxide movement
diffusion from tissues to environment along respective partial-pressure gradients
partial pressure
pressure of a particular gas in a mixture of gases
water contains _______ (more/less) oxygen than air does
less
water is _______ (more/less) dense than air
more
water breathers have to expend ________ (more/less) energy to ventilate their respiratory surfaces than do air breathers
more
factors that determine amount of gas dissolved
1) solubility of gas in water
2) temperature of water (cold = more oxygen)
3) presence of other solutes
4) partial pressure of the gas in contact w/ the water
Habitats w/ large numbers of photosynthetic organisms tend to be relatively oxygen ________ (rich/poor)
rich
(ie) algae filled lake has lots of plants & less animals
Habitats where organisms live off existing organic material tend to be relatively oxygen ________ (rich/poor)
poor
(ie) city has more animals/humans than plants
types of gas exchange
1) direct diffusion across body surface
2) specialized organ for gas exchange on land
3) specialized organ for gas exchange in water
Animals exchange gases by direct diffusion across the body surface mostly live in _________ (wet/dry) environments.
wet
Fick’s law of diffusion
a mathematical relationship that describes the rate of diffusion of gases
conditions for largest amounts of all gas diffusion (Fick’s law)
1) the surface area for gas exchange is large
2) the respiratory surface is extremely thin for faster transportation
3) the partial pressure gradient of the gas across the surface is large
gill
outgrowth of the body surface or throat used for gas exchange in aquatic animals
- benefit: large surface area for oxygen diffusion across an extremely thin epithelium
- types: internal or external
(ie) fish
internal gill characteristics
- water must be driven over them in ventilation process
how do fish ventilate their gills?
by opening & closing their mouth and the operculum
*fast swimmers force water through gills by swimming with mouth open (ram ventilation)
operculum
a stiff gill flap of tissue that covers the gill of teloest fishes
ram ventilation
type of ventilation of water through gills by swimming with mouth open
Movement of water over gills is _________ (unidirectional/bidirectional).
unidirectional
why is water movement not bidirectional?
if water movement were bidirectional, the organism would lose oxygen
gill lamellae
a sheetlike structure made up of a bed of small blood vessels (capillaries)
capillary
small, thin-walled blood vessels that permeate all tissues & organs
- allow exchange of gases & other molecules between blood and body cells
countercurrent exchange
any anatomical arrangement that allows the maximum transfer of heat or a soluble substance from one fluid to another
- the 2 fluids must be flowing in opposite directions & have a heat concentration gradient between them
requirements for countercurrent exchange
1) fluids must be flowing in opposite directions
2) presence of a heat concentration gradient between fluids
why can’t blood flow be a concurrent flow with water flow?
over time diffusion will stop
tracheae
(in insects) a series of tube extending throughout the insect body
- connects to exterior through spiracles
spiracle
(in insects) a small opening that connects the air-filled tracheae to the external environment
- allows gas exchange to occur
how does ventilation occur in insects?
gas exchange takes place directly across the cells’ plasma membrane
- spiracles open or close to allow air to flow into tracheae, which extends throughout the body
- as a result, volume of tracheal system changes
(pressure inversely related to volume)
*does not require a circulatory system for gas to reach tissues
how do vertebrates breathe?
through the lungs, respiratory system & circulatory system
trachea
(in animals) the airway connecting the larynx to the bronchi
windpipe
bronchi
(bronchus)
one of a pair of large tubes that lead from the trachea to each lung
bronchioles
any of the small tubes in mammalian lunges that carry air from the bronchi to the alveoli
lung is made up of:
1) trachea
2) bronchi
3) bronchioles
4) alveoli
lung
any respiratory organ used for gas exchange between blood & air
- infoldings of the throat
- enclose the bronchioles & part of the bronchi
- FCN: gas exchange
alveoli
any of the tiny air-filled sacs of a mammalian lung
- provide an interface between air & blood that consists of a thin aqueous film, a layer of epithelial cells, some extracellular matrix (ECM) & a wall of a capillary
- FCN: increase surface area for gas exchange
- end of branch
- high pressure
alveoli components
an interface between air & blood that consists of:
1) a thin aqueous film
2) a layer of epithelial cells
3) some extracellular matrix (ECM)
4) a wall of a capillary
why do smokers have a harder time breathing?
tar lines their alveoli (extra lining), which prevents oxygen exchange
mode of lung ventilation among different species
1) simple lungs (snails & spiders) = air movement by diffusion
2) active ventilation by pumping air via muscular contractions (vertebrates)
positive pressure ventilation
ventilation of the lungs by using positive pressure in the mouth to “PUSH” air into the lungs
(ie) frogs do not have a secondary palette so they have to consciously swallow air
negative pressure ventilation
ventilation of the lungs by expanding the rib cage so as to “PULL” air into the lungs
- via diaphragm
- unconscious process
(ie) humans have a secondary palette so breathing is unconscious process
diaphragm
an elastic, sheetlike structure that contracts & moves downward during INHALATION, expanding the chest
- (mammals) separates chest & abdominal cavities
inhalation
(mammals) possible through diaphragm downward motion
exhalation
a passive process driven by the elastic recoil of the lungs & chest wall as the diaphragm & rib muscles relax
dead space
portions of the air passages (trachea & bronchi) that do not have a respiratory surface
- one-third of lung folume
