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Terms in this set (40)
why do animals need transport systems?
1) SA:V ratio gets _______ as organisms get _______, so _______ and amount of _______ becomes relatively smalll.
2) metabollic demands get high so _________ isn't enough to supply everything.
3) _________ / ___________ may be made/digested in one place but needed in another place/every cell
4) waste products of ________ need to be _______ from cells and _________ to excretory organs.
surface area available
2) diffusion over long distances
3) Molecules (eg hormones, proteins)
why animals need transport systems (memory words)
- surface area to volume ratio decreases
so diffusion distance gets bigger
and surface area (to absorb/remove) gets smaller
- metabollic demands are too high for diffusion to supply the amounts needed
- molecules/ food/ waste need to be transported
features that most circulatory systems have in common
a pumping mechanism
a transport medium
vessels to carry the transport medium
adaptations of capillaries
1) large surface area
2) walls are a single endothelial cell thick
3) total cross sectional area of capillaries is greater than the arteriole supplying them
veins don't have a ______ because the _______ from the heart pumping are lost as blood _________ through ________ __________.
why do veins not have a pulse
surges from the heart pumping are lost as blood passes through narrow capillaries
what are found along thorax and abdomen of insects
spiracles (through which gas exchange and water loss takes place)
how are spiracles adapted to minimise water loss?
there are spiracles _________ that can open/close the ________ . they are kept ________ to minimise water loss.
as closeD as possible
more of the spiracles open when ________ or ______
O2 demands rise
CO2 levels build up
why can ONLY little gas exchange take place in the trachea of insects?
Trachea are _______ by _________ ____ ________ (to keep them open in case they are bent or pressed). chitin makes up the _________ and its relatively impermeable to _____.
spirals of chitin
why can gases diffuse through tracheoles but not trachea?
________ are lined by chitin which is relatively _________ ___ ________ so little gas exchange takes place but tracheoles have ____ _______ ________ so are freely permeable to gases.
impermeable to gases
have no chitin lining
the elastic fibres in artery walls 1_______ pumped out of the heart and 2____ to take the larger blood volume.
the elastic fibres 3________ in between contractions of the heart in order to help give a 4______.
(1) enable them to withstand the force of blood
(3) recoil and return to their original length
(4) continuous flow
why does blood easily flow over the arteries?
lining of the arteries, the endothelium is smooth
function of elastic fibres in artery walls?
- withstand force of blood pumped out of the heart and stretch to take the larger blood volume
- even out surges of blood (pumped from the heart) to give a continuous flow
what vessel is between the arteries and capillaries
how are arteriole walls different to arteries
(arteriole walls have)
- more smooth muscle
- less elastin
function of smooth muscle in arterioles
(gives them the ability to)
constrict and dilate to control the flow of blood into individual organs
when smooth muscle in the ARTERIOLE contracts........
it constricts THE VESSEL and PREVENTS blood flowing into a capillary bed
what happens for vasodilation in arterioles to take place?
smooth muscle in arteriole WALL relaxes
what vessels do the capillaries link
arterioles with venules
GAPS between 1________ that make up the capillary 2_____ in most areas of the body are relatively LARGE
- so, substances can 3______ the capillaries into the tissue fluid that 4_______.
(1) endothelial cells
(3) pass out of
(4) surrounds the cells
cross-sectional area of the capillaries.......
is always greater than the arteriole supplying them
cross-sectional area of the capillaries is always greater than the arteriole 1_______, this means that
- rate that blood flows through capillaries 2_____
- and hence there is 3______ to exchange materials 4______ between the blood and the cells
(1) supplying them
(3) more time
(4) by diffusion
adaptations of capillaries (memory words)
- Surface area is large
- Thin diffusion distance (single endothelial cell thick)
- cross sectional (area of capillaries)
veins have 1____ walls with 2____
(2) a little smooth muscle
describe the vein walls
- lots of collagen
- relatively little elastic fibre
- thin and smooth lining, the endothelium
- little smooth muscle
how easily does blood flow over veins
easily because there is the endothelium (a smooth lining)
Deoxygenated blood in veins has to be pumped to the heart, however it is difficult because the blood is 1______ and 2______.
(1) under low pressure
(2) needs to move against gravity
veins are adapted so deoxygenated blood can return back to the heart (rough outline)
1) majority of veins have 1_______ that can open and close
2) location - many of the bigger veins 2_____
3) breathing movements of the 3_______
(1) one way valves at intervals
(2) run between the big active muscles in the body
(3) chest act as a pump
vein adaptation : one-way valve at intervals
when blood flows 1______ the valves open so the blood 2______.
however the valves close 3_______ in order to 4_______ backflow of blood
(1) in the direction of the HEART
(2) can pass through
(3) IF blood STARTS to flow backwards
vein adaptation : many big veins run between big active muscles of the body
- this means that when those muscles contract 1_______
- and this forces 2______.
(1) they SQUEEZE the veins
(2) blood towards the heart
2 extra adaptations of the GILLS (to ensure MORE EFFICIENT gas exchange in the water) include:
1) tips of ________ overlap
2) the WATER that moves 2_______ and the 3______ in the gill filaments
- flow in 4_______ directions
- and so, a counter-current exchange system 5______.
(1) adjacent gill filaments
(2) over the gills
(5) is set up
tips of adjacent gill filaments overlap,
- this increases the 1______ water over the gill SURFACE
- and therefore slows down the 2_______
- meaning 3.......
(1) resistance to the flow of
(2) movement of water
(3) there is more time for gas exchange to take place
a counter-current exchange system is set up in the gills
- this ensures that 1________ are maintained THAN if blood and water flowed in the same direction
- this is needed for 2________ to take place
- meaning 3_______ gas exchange can take place
(1) steepER concentration gradients
(2) fast, efficient diffusion
function of (tips of adjacent gill filaments overlapping) - summarised
MORE TIME for gas exchange to take place
function of (counter-current exchange system in gills) - summarised
MORE gas exchange can take place
hydrostatic pressure 1______ the further away you get from the heart because
(2) fluid loss from capillaries
(3) increased cross sectional area of vessels
plasma proteins remain in the blood because they are simply too large to 1_____ the gaps between the 2_____ cells
(1) fit through
tissue fluid flows from 1______
- the around the tissues
1) back to capillaries
2) or into 2______
(2) a lymph vessel
tissue fluid re-enters the capillaries due to......
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