transport systems in animals 3.1.2 Flashcards
why do multicellular organisms require specialised transport systems (SIZE) ?
- size = the diffusion distance is larger, outer layers of cells use up the supplies before it reaches the center this all decreases the rate of diffusion
why do multicellular organisms require specialised transport systems (SA:V) ?
- SA;V = larger animals have a small SA:V which means for each gram of tissue in their body has a small area of exchange surface
why do multicellular organisms require specialised transport systems (LEVEL OF METABOLIC ACTIVITY) ?
- level of metabolic activity = larger organisms have more cells meaning a higher level of metabolic activity meaning there is a greater demand for oxygen and nutrients
why do multicellular organisms require specialised transport systems (TRANSPORT) ?
- transporting materials = hormones and enzymes are often produced in a gland but required further away in an organ, digested food must be transported to all cells ,waste products must be removed by excretory organs
what is a circulatory system comprised of ?
a heart
a fluid in which substances are transported
vessels through which the fluid can flow
what are the types of circulatory systems
open
closed single
closed double
what is an open circulatory system ?
a heart that pumps a fluid called haemolymph through short vessels and into the open cavity called the hemocoel
the haemolymph directly bathes the tissues to enable diffusion of substances
when the heart relaxes the haemolymph is sucked back in via pores called ostia
the haemolymph circulated due to movement of the organism but a steep concentration gradient cannot be maintained
eg. insects
what is an closed circulatory system ?
the blood is fully enclosed within blood vessels at all times , so it doesn’t come into direct contact with cells
the heart pumps blood into vessels and capillaries so substances diffuse into and out of cells
this allows for vasodilation and vasoconstriction
eg. all vertebrates
what is a single circulatory system ?
the blood flows through the heart once for each circuit of the body
it passes through both sets of gills and the body tissue before returning to the heart - this is inefficient but fish overcome this with countercurrent flow
(always closed)
eg. fish
what is a double circulatory system ?
the blood flows through the heart twice for every circuit of the body
2 separate circuits the pulmonary and the systemic circulation
eg. mammals
what are the advantages and disadvantages of single circulation ?
ad - less complex
- doesn’t require complex organs
dis - low blood pressure
- slow movement pf blood
- activity of animal is low
what are the components of blood vessels ?
elastic fibres - protein elastin, provide flexibility allowing for stretch and recoil, evens out the surges of blood from heart into a continuous flow
smooth muscle - provides strength, contacts and relaxes to change size of lumen and alter blood flow to different tissues
collagen - provides structure and support
endothelium - interlining of all blood vessels, single layer of cells which are smooth to reduce friction against blood flow
how does the pressure of the blood change along the vessels ?
- as heart contracts and relaxes it pumps blood into aorta and arteries at a high pressure, the elastic fibres expand to allow for maximum flow
- as blood moves towards capillaries there is more friction against the endothelium vessels get smaller = lower pressure and less velocity
- enters capillaries at a low pressure to prevent damage and travels slower to give more time for gas exchange
- in veins pressure drops and the elastic recoils of walls helps to force blood on
what are arteries and arterioles (function ,structure) ?
function - take blood away from heart at high pressure
lumen - narrow to maintain high pressure
elastic fibres - lots to withstand the force of blood, they stretch and recoil with heart contractions , even out surges of blood from heart
smooth muscle - lots of it for vasodilation and vasocontraction according to the bodies needs
collagen - structural support and prevents overstretching
aorta has the most and smaller arterioles have less
what are capillaries (function and structure) ?
function - allow exchange of substances between blood and other nearby cells
lumen - only a bit larger than the red blood cells so they travel in a single file line - less diffusion distance
endothelium - one cell thick - reduced diffusion distance, walls are leaky to allow plasma and other substances to leave the blood
size - very small ,large surface area = cross sectional area is larger than the arteriole, this reduces the rate of blood flow to prevent damage
no elastic fibres, no smooth muscle, no collagen
what are veins and venules (function and structure) ?
function - carry blood towards heart at low pressure
capacity - very large, 60 % of blood in veins
lumen - larger to reduce friction
elastic fibres - thin layer as they don’t need to stretch and recoil
smooth muscle - little
collagen - lots to provide structural support
have valves to prevent backflow of blood
what are the roles of blood ?
a type of connective tissue
transport roles : hormones, oxygen, urea, platelets, food molecules, co2, white blood cells
defence
maintaining pH of bodily fluids
thermoregulation
what is the composition of blood ?
erythrocytes ( red blood cells ) 45%
leucocytes (white blood cells ) and thromboplastins ( platelets ) 1%
plasma 55%
what is the adaptations of erythrocytes ?
- biconcave shape : large SA:V
- haemoglobin ; bind to oxygen
- no nucleus ; more space to carry oxygen
- small diameter ; short diffusion distance
how are capillaries adapted ?
8 micrometres wide to only allow one red blood cell at a time ; slow flow to prevent damage and give time for exchange
what is plasma made of ?
-water
-ions (Na+ ,K+)
-proteins (hormones)
-nutrients (glucose, amino acids)
-wastes (urea)
-gases (o2,co2)
large plasma proteins
what are the large plasma proteins in the plasma ?
fibrinogen - blood clotting
globulins - immune system
albumin : important in maintaining the osmotic potential of the blood
it is dissolved in the water of plasma, increasing its solute potential and decreasing its water potential
this draws water into the blood by oncotic pressure
what is the lymphatic system ?
-contains lots of lymphocytes
-lots of lipids (absorbed in lacteal villi)
made of
- lymphatic capillaries
- lymph nodes
- lymphatic tissue
what passes from the plasma to the tissue fluid?
a few white blood cells , water and dissolved solutes
everything else is too large to fit
