which 2 ways can single celled organisms transport nutrients
osmosis and diffusion
why do multi cellular organisms need transport systems?
- high metabolic demands:need lots of oxygen and produce lots of waste so diffusion over long distances isnt enough to supply the amount needed
- sa:v ratio gets smaller so the diffusion distance gets bigger
- molecules such as hormones may be made in one place but needed in another
- food will be digested in one organ system but needed to be transported to every cell for respiration
whats an open circulatory system?
a circulatory system with a heart and a few vessels to contain the transport medium
whats a closed circulatory system?
a circulatory system where the blood is enclosed in blood vessels and doesnt come into contact with the cells.
what type of circulatory system do fish have?
single closed
whats a double circulatory system?
a circulatory system where the blod travels through the heart for 2 complete circulations of the body
the bigger the organism,what happens to the oxygen uptake
lower
what are the 2 types of white blood cell
phagocyte and lymphocyte
function of phagocyte
to engulf pathogen
function of a lymphocyte
to release antibodies
how are red blood cells adapted
- contain haemoglobin which absorbs oxygen from the lungs
- small:pass through narrow capillaries
- dont have nucleus:more room for haemoglobin
- biconcave: increase surface area
why is it important red blood cells are stored in a solution with a suitable water potential
if its placed in pure water water enters too quickly by osmosis causing it to burst
differences between tissue fluid and blood
tissue fluid
- between cells in tissues/blood is in arteries veins and capillaries
- doesnt contain plasma proteins or red blood cells
- doesnt contain platelets
name the type of vessel
lymphatic capillary
what can happen if the tissues of a person were insufficient
here will be an accumulation of lymphatic in the interstial tissues of the body. A build up of fluid can cause odema
explain why red blood cells may burst when placed in a solution of lower concentation
water moves into the cell too quickly by osmosis causing it to burst because of its weak cell membrane
adaptations of an artery
- thick walls:high pressure
- narrow lumen:maintain pressure
- elastic tissue:allows stretch
- collagen:provied strength
- endothelium in tunica intima:reduces friction
- elastic recoil:maintains flow
adaptations of veins
- lumen is wider:allows easier blood flow
- valves:prevent backflow
- tunica externa:thicker to prevent vessel collapsing
- fewer elastic fibres
function of circulatory sytem
carry gases around the body
in insects where does gas exchange take place
tracheal system
insect blood
haemolymph
what does blood carry in insects?
food and waste
how are arterioles adapted
less elastic filbres and smooth muscle:little pulse surge
how are capillaries adapted
- one cell thick:diffusion
- large surface area for diffusion of substances
- the total cross sectional area of the capillaries is bigger than the arteriole so rate of blood flow falls giving more time for material exchange
