4.2 Flashcards
gas exchange
why do very small organisms not need a gas exchange or transport system
diffusion distance from the outside to the inner most areas in very small
large sa:vol
metabolic demands are low
what are the 3 main factors that affect rate of diffusion
surface area
concentration gradient
diffusion distance
give 5 ways lungs are adapted for gas exchange
large surface area
thin walls (small diffusion distance)
rich blood supply (maintain conc gradient)
most surfaces (gases dissolve)
permeable surfaces
why are the airways covered in hairs and have a lining that secrete mucus
filter out dust, small particles and pathogens that you breathe in
how does your body raise the temperature if the air that you breathe in
rich blood supply
why are moist surfaces needed in gas passages
increase level of water vapor in the air
what is the epiglottis
flap of tissue that prevents food entering gas exchange system
what is the name for the voice box
larynx
what are the incomplete rings of cartilage needed for
prevent trachea and bronchi from collapsing
describe bronchioles
small tubes that spread through lungs & end in alveoli
(no cartilage so can collapse)
where are the intercostal muscles found
between the ribs and are important in breathing
what are the pleural membranes and cavity
pleural membranes:
surround lungs & line chest
cavity:
space between pleural membranes, allows easy breathing
what is the diaphragm
broad sheet of tissue that form the floor of the chest cavity
what is the electrostatic recoil of the lungs
elastic connective tissue forces air out of lungs as they stretch when you breathe in
what is the use of the lung surfactant
coast alveoli
stops collapsing alveoli
makes breathing easier
how are alveoli adapted for gas exchange
single layer of flattened epithelial cells
capillaries one cell thick so short diffusion distance
folded surface increases surface area
constant blood supply maintains concentration gradient
moist so gasses dissolve
define breathing/ventilation
physical movements of the chest change the pressure so that air is moved in or out
what is the mass transport system
an arrangement of structures by which substances are transported in the flow of a fluid with a mechanism moving it around the body
where are the intercostal muscles
between the ribs
Is inhalation an active or passive process
active
explain inhalation
muscles around the diaphragm contract so it is lowered and flattened
the intercostal muscles contract raising the rib cage upwards and outwards
this increases the volume chest cavity so the pressure is lower and air moves in
explain exhalation
muscles surrounding the diaphragm relax so it moves into the resting domed shape
intercostal muscles relax so ribs move down and in
volume of chest cavity decreases causing an increase in pressure so air moves out of the lungs
how can exhalation be forced
contraction of abdominal muscles forcing the diaphragm upwards increasing pressure in the chest cavity causing exhalation
how does the airways prevent infection
produce a lot of mucus lining the airways which traps tiny particles and organisms which is moved upwards to the back of your throat by cilia and digested by the acid in your stomach
describe insects gas exchange system
spiracles on the exoskeleton lead to the trachea which becomes tracheoles that lead to muscle fibers
what are spiracles
openings along the side of the thorax and abdomen for the entry and exit of respiratory gases which are opened and closed by sphincters
why do spiracles need to be controlled by sphincters
to control water loss
what is the trachea in insects
large tubes supported by chitin in the insect respiratory system carrying air directly into the body for gas exchange running alongside and and into the insect dividing into tracheoles
what are tracheoles
minute tubes of elongated cells with no chitin lining so are fully permeable for gas exchange spread throughout the tissue and penetrating into some individual cells
how does the insect respiratory system work
air enters through spiracles moves along trachea to tracheoles where the large surface area allows gas exchange to take place
how do insects increase rate of gas exchange when they are active
tracheoles contain water which reduces gas exchange however when the insect is very active lactic acid builds up which affects the osmotic concentration of cells and causes water to move out of the tracheoles to the cells exposing additional surface area for gas exchange
how is the opening and closing of spiracles coordinated
controlled by sphincters stimulated by respiratory centers in the nervous center which respond to levels of CO2 & O2 as well as lactic acid build up
how do very active insects supply extra oxygen
mechanical ventilation - air is actively pumped into the tracheal system through muscular pumping movements of the thorax and abdomen which changes the pressure causing air to be drawn in or out
collapsible trachea - air sacs act as air reservoirs and increase the volume of air moved through the respiratory system via ventilating movements of the thorax and abdomen inflating and deflating them
what is the outer structure of the gills
gills are contained in a gill cavity which is covered by a protective bony flap called the operculum
why is the operculum important
it maintains the flow of water over the gills even when the fish is stationary
explain gas exchange in fish
water flows in through the mouth over the gills and the lamellae where gas exchange occurs then out through the operculum `
how is a fish gas exchange well adapted for gas exchange
gill filaments have a large surface area
the lamella has a rich blood supply to maintain a concentration gradient
they do counter current exchange to maximize gas exchange along the entire length of the lamella
thin walls for short diffusion distance
overlapping of gill filaments slows down the flow of water therefor allowing more time for gas exchange
what is the countercurrent exchange system
water moving over the gills moves in the opposite direction to the blood in the blood vessels maintaining a concentration gradient as it ensures equilibrium of oxygen is not met allowing diffusion to occur across the entire length of the lamella
describe the structure of a leaf
waxy cuticle on the surface of the leaf
then the upper layer of epidermis
then the palisade mesophyll
then the spongy mesophyll which also contains xylem vessels, phloem tissue and air spaces
then the lower epidermis which has guard cells and stomata
how is the spongy mesophyll adapted for gas exchange
irregularly shaped to increase surface area
arranged with large air spaces between them and are moist so gasses can dissolve and gas exchange can occur more freely between cells
why is the waxy cuticle needed
it is impermeable therefor acts as a barrier to diffusion through the surface of the leaf
what are stomata
specialized pores found mainly in the epidermis on the underside of the leaf through which gases diffuse into and out of the cell
describe the structure of a guard cell
border a stomata
specialized epidermal cell
sausage-shaped
contain chloroplasts
cellulose in their cell walls is unevenly distributed
how are stomata closed
when conditions are not in favor of photosynthesis turgor pressure is low as the potassium ions are excreted therefor due to the unsymmetrical thickness of cellulose in the cell wall the guard cells become flaccid and close the stomata
how are stomata opened
when conditions are favorable for photosynthesis solutes are moved into the guard cells by active transport therefor water moves into the guard cells by osmosis causing them to swell and increase turgor pressure
this opens the stomata due to the uneven bending as the spiral thickenings of cellulose means that only the outer walls stretch creating semicircular pore openings
what solutes are most commonly moved into the stomata
potassium ions
describe the structure of guard cells
contains nucleus, vacuole and chloroplasts
thickened inner wall
thin outer wall
what are lenticels and why are they needed
loosely arranged cells with many air spaces link the inner tissue of the trunk and the air so gas exchange can take place
