chapter 7 -exchanged surfaces and breathing Flashcards
why is diffusion alone enough for single - celled organisms
they have low metabolic activity so oxygen demands and co2 production of cell are relatively low. they have a large SAV ration
what are features of an effective exchange surface
increases SA- more exchange and overcomed limitation of low SA;V ( root hair cells,villi)
thin layers - short diffusion distances ( alveoli,villi)
good blood supply - the steeper the concentration gradient, the faster the diffusion. Good blood supply maintains this( alveoli,gill of fish,villi)
ventilation - maintains concnetration gradient ( alveoli, gills of fish)
what are some feature of the nasal cavity
large SA
good blood supply which warms air to body temperature
hairy lining which secreyes mucus to trap pathogens
moist surfaces - increases humidity of incoming air reducing evaportation from exchange surfaces
what is trachea made of
wide tube supported by incomplete rings of strong flexible cartilage providing structural support to prevent collapse
lined with ciliated epithelium and goblet cells to trap microorganisms
why does trachea have incomplete rings of flesible cartialge instead of complete
so food can move easily down the oesophagus behind trachea
what is structure of bronchus
have smaller incomplete rings of flexible cartilage than trachea
what is structure of bronchioles
no cartilage
walls contain smooth muscle to contract and constrict
lined with flattened epithelium for gaseous exchange
what is structure of alveoli
consists of thin, flattned epithelial cells with collagen and elastin
elastic tissues allow alveoli to stretch as air is drawn and help squeeze out ( elastic recoil)
what are adaptations of alveoli
large SA for gaseous exchange3
thin layers which single epithelial cell thick so diffusion distance between air in alveolus and blood in capillaries are short
good blood supply - maintain steep concentration
good ventilation - maintain stepp concentration gradient
what is the inner surface of alveoli covered in
water, salts and lung surfactant so alveoli remains inflated
what does lung surfactant do
allows alveoli to remain inflated
what happens during inspiration
diaphgragm contracts,flattening and loweing
external intercostal muscles contract moving ribs upwards and outwards
volume of thorax increases so pressure is reduce
air is therefore drawn in through nasal to equalize pressures in and out of chest
what happens during expiration
diaghpragm relaxes so moves up into resting dome shape
external intercostal muscles relax so move inwards and downwards
volume of thorax reduces and pressure increases
therefore air is drawn out through nasal until pressure in and out is equal again
what happens during asthma attack
cells lining bronchioles release histamines making epithelial cells inflamed and swollen stimulating goblet cells to produce muscus and smooth muscle to contract making airways narrow and difficult to breath
what are 2 ways to treat asthma
relievers- immediate relief by attaching to active sites on surface membrane of smooth muscle in bronchioles making them relax and dilating airways
preventers- reduce sensitivity of lining of airwats
how do lung surfactants help babies first breath
contain phospholipids and hydrophobic and hydrophilic proteins stopping alveoli collapsing and sticking together as baby exhales
why do insects have a different gaseous exchange systems to animals
they. have a tough exoskeleton so no gaseous exchange can take plasce
they do not have blood pigments to carry oxygen
how does gas exchange take place in insects
air enters through spiracles but water is also lost so spiracles are closed when insect is inactive. Spiracles lead to trachea carrying air into body of insect. Trachea branch to narrower tubes to tracheoles which spread throughout tissue and gaseous exchange take place between air and respiring cells
why does little gas exchange take place at trachea
chitin is relatively impermeable to gases
what are alternative methods of gas exchange in insects
mechanical ventilation of tracheal system - air is actively pumped into system by muscular pumping of thorax. These movement change volume of body changing pressure in tracheae so air is drawn into trachea
collapsible enlarged air sacs- increase amount of air moved throughout gas exchange system.
why does trachea have incomplete rings of cartialge
so food can move easily down oesophagus behind trachea
what is an effect of smoking
stops cilia beating mucus up throat
what is structure of trachea in insects
Trachea are lined with chitin to keep them open if they are pressed
what is structure of tracheoles in insects
have no chitin and are single elongated cell
what type of transport occurs in trachea and tracheoles
mainly diffusion
where is tracheal fluid
end of tracheoles
what does tracheal fluid do
limits penetration of air for diffusion but when oxygen demands build up , a build up of lactic acid results in water moving out of tracheoles by osmosis exposing more SA for gaseous exchange
how are gills adapted for gas exchange
large SA
good blood supply
think layers for gaseous exchange
which organ is responsible for gas exchange in fish
gills
what are gills covered by
gill cavity and operculum which maintains a flow of water
what does gill lamellae do
rich blood supply and large SA for main site of gaseous exchange
what does gill filaments do
need a flow of water to keep them apart exposing large SA needed for gaseous exchange
how does effective gaseous exchange occur in fish
tips of adjacent gill filaments overlap increasing resistance to flow of water over gill surfaces slowing down movement of water so more time for gaseous exchange to take place
- water moving over gills and blood in gill flow in a counter current system
