gas exchange Flashcards
what is the name of insects specialised gas exchange system
the tracheal system
what are spiracles
- valve openings made of rings of chitin
- helps limit water loss by evaporation
what are the tracheoles
thin open ended tubes
function of tracheoles
- filled with fluid to help gas dissolving
- penetrate into tissue of insects and speed up gas exchange with tissue
describe ventilation in insects
- mechanical process in insects
- insect abdomen moves up and down to change pressure and ventilate the tracheal network
- maintaining a concentration gradient for diffusion
what do the network of larger trachea and smaller tracheoles give
a large surface area
VENTILATION GRAPH (FLASHCARD)
what occurs when insect abdomen moves down
- abdomen moves down
- increase volume, decreases pressure
- spiracles open, air (oxygen) moves into trachea
- carbon dioxide moves out
what occurs when insect abdomen moves up
- abdomen moves up
- decrease in volume, increase in pressure
- spiracles close, air(oxygen) moves out of trachea
- O2 conc increases, CO2 conc decreases
describe the structure of gas exchange system in fish
- contains gill plate called operculum (acts as a valve)
- contain multiple projections named gill filaments
- filaments contain lamella on them which participate in gas exchange
- blood capillaries flow counter-current to water
how do lamalle aid in gas exchange
- allow for a large SA:VOL
- very thin so provide a short diffusion path
why are the blood capillaries counter current to water in fish
- maintains a concentration gradient along the entire length of the lamella
- blood leaving gills are almost fully saturated with oxygen
why is gas exchange in fish not tidal
lots of energy would be required to push the dense water back out of the mouth
ventilation in fish (describe inspiration)
- mouth opens
- operculum closes the opening at the end of the pharynx
- floor of the buccal cavity is lowered
- volume inside the mouth cavity increases, decreasing pressure
- water can flow into the mouth
ventilation in fish (describe expiration)
- mouth closes
- floor of buccal cavity is raised
- volume inside the mouth cavity decreases, increasing pressure
- water forces back over the gills
- operculum closes + water flows out
how are the leaves of dicotyledonous plants adapted for gas exchange (2)
- contain small pores called stomata, provide a short diffusion distance to cells
- interconnected air-spaces throughout mesophyll tissue provide a large surface area for gas exchange
what adaptions do cacti have to limit water loss (5)
- thick cuticle
- small leaf SA:VOL ratio
- stomata sunken in leaves
- deep roots
- widespread shallow roots
how does a thick cuticle limit water loss
stops uncontrolled evaporation from leaf cells
how does a small leaf SA:VOL ratio limit water loss
reduces SA for evaporation
how does stomata sunken in pits limit water loss
maintain humid air around the stomata for a shallower concentration gradient
how does deep roots limit water loss
allows access to deep water sources
how does widespread shallow roots limit water loss
allows for rapid access to water
what adaptions do marram grass have to limit water loss (4)
- thick cuticle
- small leaf SA:VOL ratio
- leaf hairs
- rolled leaves
how do leaf hairs and rolled leaves limit water loss
maintain humid air around stomata for a shallower concentration gradient
describe components in gross structure of the human gas exchange system
- lungs
- trachea
- bronchi
- bronchioles
- alveoli
what are the lungs
highly branched network of tubules ending in many air sacs called alveoli. provide a large SA:VOL ratio for gas exchange
what is the trachea
flexible airway supported by rings of cartilage to prevent collapse
what are the bronchi
two tube divisions leading to the left and right lung. lined with ciliated epithelium and mucus secreting goblet cells to remove dirt particles
what are the bronchioles
smaller branches with smooth muscle walls, lined with ciliated epithelium
what are alveoli
microscopic, elasticated, very thin air-sacs. closely associated with the pulmonary arteries. is the site of gas exchange
name the six features of the alveolar epithelium as a surface over which gas exchange takes place
- ventilated from bronchioles (maintains conc gradient for gas exchange)
- thin, flat, one-cell thick alveolar walls (provides short diffusion distance so diffusion is rapid)
- alveolar epithelium walls folded to increase surface area
- moist to help gasses (CO2 + O2) dissolve
- associated with many capillaries (provide large SA:VOL ratio for gas exchange with blood)
- capillary cells thin
describe inspiration in humans (5)
- external intercostal muscles contract
- diaphragm contracts
- volume in thorax increases
- air pressure decreases
- air pressure greater outside than inside so air flows in, inflating the lungs
describe expiration in humans (6)
- internal intercostal muscles contract
- diaphragm relaxes
- elasticated alveoli recoil
- volume in thorax decreases
- air pressure increases
- air pressure in lungs greater than outside so air flows out, deflating the lungs
