transport in animals Flashcards
what is a single circulatory system
blood flows through the heart once for each circuit of body
what’s a double circulatory system
blood flows through heart twice for each circuit of body
what are features of a good transport system
-A fluid or medium to carry nutrients
-A pump to create pressure to push fluid
-Exchange surfaces
-Tubes or vessels to carry blood
-Two circuits
what are properties of arteries
-carry blood away from the heart
-blood at high pressure so thick elastic walls to withstand pressure
-small lumen to maintain high pressure
-has layers: tunica intima, tunica media and tunica adventitia
-blood flows into artérioles
what are the 3 layers in arteries
-tunica intima
-tunica media
-tunica adventitia
what are properties of veins
-carry blood back to heart
-blood at low pressure
-thin walls
-large lumen
-collagen and smooth muscle in walls
-contain valves to stop back flow of blood
what are in the walls of veins
collagen and smooth muscle
what are properties of capillaries
-walls one cell thick for gas exchange
-walls leaky (fenestrations)
-narrow lumen-increases resistance and reduces rate of flow
-blood flows into venules
what are fenestrations in capillaries
tiny openings or pores
where does the blood flow from capillaries
venules
where does the blood flow from arteries
into arterioles
process of exchange at capillaries
-blood enters capillary at artériole end with a high hydrostatic pressure
-high pressure forces plasma out of holes in capillary wall which forms tissue fluid
-tissue fluid contains oxygen, glucose or anything small enough to fit through holes
-red blood cells, large proteins and some white blood cells remain in capillary
-exchange occurs between tissue fluid and cells
-tissue fluid rich in CO2 and waste moves back into the venule end of the capillary due to low hydrostatic pressure in the capillary
how does size effect transport systems
-cells inside large organisms are further from surface so diffusion pathway increases
-reduces diffusion
-the outer cells would use up the supplies and inner cells would be deprived
how does surface area to volume ratio effect transport systems
-small animals have a large surface area to vol ratio
-this means that each tissue in their body has a sufficient area for exchange to occur
-larger animals have a smaller surface area to volume ratio
-this means that each tissue has a smaller area of body for exchange to happen
how does level of metabolic activity effect transport systems
-more active animals need good supplies of nutrients and oxygen to supply energy for movement
-same applies for animals that want to keep warm
what are advantages of a double circulation in mammals
example of a single circulatory system animal
fish
example of double circulatory system in animals
mammals
what is hydrostatic pressure
pressure in a vessel
what is oncotic pressure
pressure created by the presence of solutes
what is tissue fluid
formed by plasma leaking from the capillariesw
what does tissue fluid do
surrounds the cells in the tissue and supplies them with the oxygen and nutrients they need
how does substances dissolve into the tissue fluid
as blood plasma leaks from the capillary it carries dissolved substances into the tissue fluid
what is the movement of substances leaking from capillary to tissue fluid
mass flow
what are the molecules that are too large to be forced out of the tiny gaps in capillaries
-red blood cells
-platelets
-large proteins
what is the effect of large molecules remaining in the capillaries
create a lowered water potential
what is teh pressure like towards the venule end of capillaries
the hydrostatic pressure is lowered
why is the hydrostatic pressure towards the venule end lowered
due to the loss of liquid, but the water potential is very low
how does water re enter the capillaries
by osmosis
what happens to the liquid tissue fluid that doesnt get reabsorbed
the rest of the tissue fluid absorbed into the lymphatic system and eventually drains back into the bloodstream near the heart
what does blood do when theres negative oncotic pressure
move into blood
what does blood do when theres positive oncotic pressure
move out of the blood
relate the structure of arteriolar and venules to their function
-branch off arteries and veins in order to feed blood into capillaries
-smaller then arteries and veins so that the change in pressure is more gradual as blood passes through increasingly small vessels
how does tissue fluid form
as blood is pumped through small vessels, hydrostatic pressure is greater than oncotic pressure so fluid moves out of the capillaries. it then exchanged substances with the cells
