Exchange and Transport Flashcards
why do single celled organisms not need a transport system
substances can diffuse directly into or out of the cell across the cell surface membrane
why is diffusion across the outer membrane slow in multicellular organisms
long diffusion pathway, low surface area to volume ratio
high metabolic rate
how do you calculate surface area to volume ratio
surface area/ volume
give examples of special features of exchange surfaces and real life examples of where they can be found
large surface area- root hair cells
thin- alveoli
good blood supply- gills
draw and label a pair of lungs
what is the function of goblet cells and where are they found
line the trachea bronchi and larger bronchioles , secrete mucus which traps microorganisms to prevent them reaching alveoli
what is the function of cilia and where are they found
hair-like structures lining the airways
beat mucus secreted by goblet cells no move trapped particles upwards towards the throat where it is swallowed to prevent lung infections
what is the function of elastic fibres and where are they found
walls of trachea, bronchi, bronchioles and alveoli
expand when inhaling and recoil to help push air out when exhaling
what is the function of smooth muscle in the gas exchange system and where is it found
walls of trachea, bronchi and bronchioles, allows diameter to be controlled (relaxes when exercising to allow more air)
where is cartilage found in the gas exchange system and what is its function
rings of cartilage in the walls of the trachea and bronchi provide support, strong but flexible, stops trachea and bronchi collapsing when inhaling and pressure drops
describe what happens during inspiration
external intercostal muscles and diaphragm contract
ribcage moves upwards and outwards, diaphragm flattens and volume of thorax increases
lung pressure decreases
air flows into lungs
active process
describe what happens during expiration
external intercostal muscles relax and diaphragm relaxes
ribcage moves downwards and inwards
thorax volume decreases, pressure increases
air is forced out of the lungs
passive process unless forced (internal intercostal muscles contract)
what is tidal volume
the volume of air in each breath
what is vital capacity
max amount of air that can rebreathed in or out
what is breathing rate
number of breaths per minute
describe the structure of gill filaments
made up of thin plates called gill filaments/primary lamellae
gill filaments are covered in gill plates or secondary lamellae which increase surface area
each gill is supported by a gill arch
gill plates have lots of blood capillaries
describe the counter-current system in gills and its benefits
blood flows through gills in one direction and water flows over gills in opposite direction
creates and maintains a steep conc. gradient so as much oxygen as possible diffuses from water into blood
Describe the ventilation system in fish
the fish opens its mouth
this lowers the floor of the buccal cavity
volume of buccal cavity increases, decreasing pressure
water is then sucked into cavity
when fish closes its mouth buccal cavity is raised again
volume decreases, pressure increases and water is forced out along gill filaments
each gill is covered by an operculum, increase in pressure force this to open so water can leave gills
describe gas exchange in insects
air moves into tracheae through pores called spiracles, oxygen trails down conc. gradient towards cells
CO2 from cells move down conc. gradient towards spiracles to be released
tracheae branch off into smaller tracheoles which have thin permeable walls and contain fluid which oxygen dissolves in and diffuses into the cells
use rhythmic abdominal movements to change volume of their bodies to move air in and out of specials
