transport in animals snap revise Flashcards
why is there a need for transport systems in animals
all living cells need a constant supply of oxygen and nutrients- respiration occurs to produce ATP
-nutrients need to be moved around
what’s an exchange surface in humans
the lungs
factors requiring an organism to have a transport system
- size- big= large diffusion distance
- surface area to vol ratio- big= small sa:vol
- level of metabolic activity
features of a good transport system and what they might have
- a fluid medium running through them
- a pump to create the pressure for circulation
-exchange surfaces for substances to enter and exit
might have:
-vessels or tubes
-two circuits
what are open circulatory systems
ones in which blood is not always held in vessels
what has open circulatory systems
insects
two disadvantages of open circulatory systems
- blood pressure remains low= slow flow of blood
- circulation is affected by body movements
what are closed circulatory systems
are ones which the blood is held in vessels
what separate fluid does organisms with closed circulatory systems have
tissue fluid
two key advantages of closed circulatory systems
+ blood pressure in vessels can be high and circulation is rapid
+ circulation is not affected by any body movements.
what are single circulatory systems
ones which the blood flows through the heart once for each circuit of the body
compare the pressure of single circulatory systems and double circulatory systems
double has a higher pressure
why do fish have single circulatory systems
- counter current flow maintains a large diffusion gradient for exchange in the gills
- most fish are exothermic and the water is thermally insulating
whats a double circulatory systems
ones which the blood flows twice for every circuit of the body
talk about the pressure in double circulatory systems
- pressure to the lungs is low (pulmonary circuit)
- pressure to the body is high (systemic)
whats tissue fluid
extracellular fluid which bathes the cells of most tissues
state the circulatory system that a fish has
closed single
explain why larger organisms need transport systems rather than relying on diffusion
- large organisms ahve a small surface area to vol ratio. This means some tissues are too far for molecules to be exchanged fast enough. Transport systems ensure that even tissues far away from the organisms surface can exchange molecules rapidly
describe features of the mammalian circulatory system that makes it well suited for transport
- blood plasma acts as a fluid transport medium which moves molecules easily throughout the body
- blood vessels ensure that blood is transported where its required
- the heart pumps the blood ensuring that it circulates the body; this means tissues can undergo exchange continuously. Mammals have systemic and pulmonary circuits. This maximises gas exchange at the alveoli in the lungs which have surfaces specialised for exchange
suggest why some animals require complex transport systems with reference to activity
more metabolically active animals require faster exchange of gasses at the tissue as well as a faster supply of glucose for respiration. complex transport systems allow for faster and more efficient transport of molecules like oxygen and glucose for respiring tissues
what does transporting blood in vessels allow for
allows for it to be pumped at high pressure delivering nutrients and removing waste efficiently
what are the 5 vessels in the circulatory system
- arteries
- arterioles
- capillaries
- venules
- veins
what do all blood vessels have
a smooth thin inner layer of cells called endothelium
what do the arteries do
carry blood away from the heart at high pressure
state the arrangement of arteries
- to cope with high pressure, artery walls are very thick
- artery walls have thick layers of elastic tissue and smooth muscle encased in a thick outer layer of collagen
state the general things abt arterioles
- simmilar structure to arteries but are smaller and have relatively thinner muscle and elastic layers
- contraction of the smooth muscle constricts the arteriole and is used to control the flow of blood through the body
state the general things abt capillaries
- capillaries have very thin walls consisting of just a single celled layer of endothelium
- the lumen of the capillaries is very narrow and can squeeze red blood cells against the endothelium to improve transfer of oxygen
what do veins do
carry low pressure blood back to the heart
state the arrangement of veins
- vein walls are not thick and the lumen is very wide to maximise blood flow
- veins have valves to ensure the low pressure blood only flows in the right direction
state the general things abt venules
- smaller than veins and lack valves
- they deliver blood from the capillary beds to the veins
functions of the blood
- carries substances in the circulatory system
- forms part of the immune system
- the blood carries hormones around the body as part of cellular communication
- distributes heat around the body
what is the fluid component of the blood called
blood plasma
why is the blood plasma important
the blood plasma holds dissolved gasses and organic molecules and provides a fluid medium for the blood cells
whats the most common type of cell found in blood
erythrocytes- red blood cells
what are other cells found in blood apart from RBCs
- leucocytes- white blood cells
- blood platelets- tiny fragments of other blood cells that are involved in clotting process
in what type of circulatory system is body tissue bathed in blood
open circulatory systems
in what type of circulatory system is body tissue bathed in tissue fluid
closed circulatory systems
what is tissue fluid used to exchange
exchange nutrients and gasses between cells of the body in the circulatory system
how is tissue fluid slightly different to blood
tissue fluid contains the same nutrients that blood contains but without most blood cells and proteins
where is tissue fluid formed
at the arterial end of a capillary bed
how is tissue fluid formed
high hydrostatic pressure in the blood forces blood plasma through the capillary endothelium into the existing tissue fluid
(high hydrostatic pressure at arterial end and low at venous end)
-this force is resisted by oncotic pressure in the tissue fluid but this force is weaker (doesn’t want things out the blood)
The hydrostatic pressure will always have a greater influence than the oncotic so fluid always ends up leaking out from the blood to the tissue fluid from capillaries
how is tissue fluid returned to the blood
- oncotic pressure in the tissue fluid remains constant throughout the capillary bed
- at the venous end of the capillary bed, the hydrostatic pressure is much lower
- tissue fluid containing waste products of metabolism travels back into the blood forming blood plasma
what forms at the arteriole end of the capillary
tissue fluid ( here hydrostatic pressure outweighs the oncotic pressure)
what forms at the venous end of the capillary
low hydrostatic pressure so fluid moves from the tissue into the blood so the blood can take away co2 and waste( here hydrostatic pressure doesn’t outweigh the oncotic pressure)
whats the lymphatic system
a network of vessels and organs that help maintain the internal fluid environment of the body as well as transporting some proteins and fats
what does too much tissue fluid go to
some drains into lymph capillaries that are part of the lymphatic system
what does the lymphatic system transport lymph to
transports lympth aroun the body
