chapter 7 -exchanged surfaces and breathing

Question 1

why is diffusion alone enough for single - celled organisms

Answer 1

they have low metabolic activity so oxygen demands and co2 production of cell are relatively low. they have a large SAV ration

Question 2

what are features of an effective exchange surface

Answer 2

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)

Question 3

what are some feature of the nasal cavity

Answer 3

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

Question 4

what is trachea made of

Answer 4

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

Question 5

why does trachea have incomplete rings of flesible cartialge instead of complete

Answer 5

so food can move easily down the oesophagus behind trachea

Question 6

what is structure of bronchus

Answer 6

have smaller incomplete rings of flexible cartilage than trachea

Question 7

what is structure of bronchioles

Answer 7

no cartilage
walls contain smooth muscle to contract and constrict
lined with flattened epithelium for gaseous exchange

Question 8

what is structure of alveoli

Answer 8

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)

Question 9

what are adaptations of alveoli

Answer 9

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

Question 10

what is the inner surface of alveoli covered in

Answer 10

water, salts and lung surfactant so alveoli remains inflated

Question 11

what does lung surfactant do

Answer 11

allows alveoli to remain inflated

Question 12

what happens during inspiration

Answer 12

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

Question 13

what happens during expiration

Answer 13

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

Question 14

what happens during asthma attack

Answer 14

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

Question 15

what are 2 ways to treat asthma

Answer 15

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

Question 16

how do lung surfactants help babies first breath

Answer 16

contain phospholipids and hydrophobic and hydrophilic proteins stopping alveoli collapsing and sticking together as baby exhales

Question 17

why do insects have a different gaseous exchange systems to animals

Answer 17

they. have a tough exoskeleton so no gaseous exchange can take plasce
they do not have blood pigments to carry oxygen

Question 18

how does gas exchange take place in insects

Answer 18

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

Question 19

why does little gas exchange take place at trachea

Answer 19

chitin is relatively impermeable to gases

Question 20

what are alternative methods of gas exchange in insects

Answer 20

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.

Question 21

why does trachea have incomplete rings of cartialge

Answer 21

so food can move easily down oesophagus behind trachea

Question 22

what is an effect of smoking

Answer 22

stops cilia beating mucus up throat

Question 23

what is structure of trachea in insects

Answer 23

Trachea are lined with chitin to keep them open if they are pressed

Question 24

what is structure of tracheoles in insects

Answer 24

have no chitin and are single elongated cell

Question 25

what type of transport occurs in trachea and tracheoles

Answer 25

mainly diffusion

Question 26

where is tracheal fluid

Answer 26

end of tracheoles

Question 27

what does tracheal fluid do

Answer 27

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

Question 28

how are gills adapted for gas exchange

Answer 28

large SA
good blood supply
think layers for gaseous exchange

Question 29

which organ is responsible for gas exchange in fish

Answer 29

gills

Question 30

what are gills covered by

Answer 30

gill cavity and operculum which maintains a flow of water

Question 31

what does gill lamellae do

Answer 31

rich blood supply and large SA for main site of gaseous exchange

Question 32

what does gill filaments do

Answer 32

need a flow of water to keep them apart exposing large SA needed for gaseous exchange

Question 33

how does effective gaseous exchange occur in fish

Answer 33

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