insects transport + ventilation + exchange surfaces Flashcards
open circulatory system definition
a transport system with a heart but few vessels to contain the transport medium
haemolymph definition
the blood like fluid contained in insects body cavity
haemocoel definition
an open cavity within insects
dorsal definition
front/under side of an insect
ventral definition
back/top side of an insect
how are open and closed circulatory systems different
- in open systems blood is not enclosed in vessels
- in open systems the fluid fills body cavities and makes direct contact with organs + tissues
- open systems are less efficient
what is an advantage of open circulatory systems
less vulnerable to pressure
what is a disadvantage of open circulatory systems
requires a low metabolic rate so not possible for larger animals
lack of a transport system means it is only effective across small distances e.g. up to 1cm
what kind of organisms have open circulatory systems
hard bodied insects
what does haemolymph contain
water, salts, organic compounds e.g. lipids, carbohydrates, proteins
not oxygen or circulating oxygen carrying proteins as their gas exchange systems are sufficient to supply them with O2
what colour is haemolymph
green or yellow
not red as no red blood cells as it does not carry O2
outline the movement of haemolymph in a hard bodied insect
- haemolymph is pumped through the dorsal vessel along front side of insect
- it travels to the haemocoel
- it is then reabsorbed by the dorsal vessel
what type of circulatory system do soft bodied insects have
closed circulatory systems
what is the difference between blood/haemolymph in soft bodied insects and hard bodied insects
blood in soft bodied insects contains an O2 carrying pigment
example of a closed circulatory system in a soft bodied insect
e.g. earthworms
- have a main heart and 5 other pumps that pump blood around
- their blood vessels distribute blood to all structures within each segment of the body
how do insects obtain O2
they don’t breathe
insects survive by dissolving gas in and out
outline what happens in inspiration in insects
nothing - passive diffusion
outline what happens in expiration in insects
- muscles contract to flatten body
- this decreases volume of tracheal system
- pressure inside > pressure outside
- air is forced out
what is the structure + function of the cuticle
an impermeable structure that forms a layer covering the insects body
it prevents water loss as well as too much O2 + CO2 dissolving in and out
what is the structure and function of spiracles
these are small holes in the cuticle that allow gases to enter + leave the system
they can be closed using valves, which prevents water loss and stops excess O2 during rest periods
what is the structure + function of tracheae
tracheae connect the insects internal organs + tissues to the spiracles
they are reinforced by chitin rings
they branch off into tracheoles
what is the structure + function of tracheoles
they are smaller branches of tracheae
the tip of the tracheoles is the site of most gas exchange in insects - they make direct contact with cells with high metabolic activity to ensure they have adequate O2 supply for respiration
why does O2 move into insect and CO2 move out
when cells are respiring actively O2 is used up, this decrease in [O2] creates a conc gradient causing O2 to diffuse towards cells
at the same time, CO2 production from respiration also creates a diffusion gradient, so CO2 diffuses out of insect
how is gas exchange made more efficient
when insects have low activity levels, the tracheole ends contain fluid
as activity increases this fluid is removed as muscle cell walls produce lactic acid
this causes water potential of cell to decrease
this ensures gas exchange occurs faster and closer to cells
what fluid is contained in the tracheoles of an insect + what is its purpose
tracheal fluid
this improves the efficiency of gas exchange
outline the movement of oxygen in an insect
air - cuticle - spiracle - trachea - tracheole where it diffuses down to the ends and across to cells
