mass transport Flashcards
(26 cards)
mass transport is
a system for moving large amounts of materials in an organism
a system that will provide an efficient supply of materials over large distances
features of a mass transport system
medium to transport materials
closed system of tubes which branch to carry substances to all parts of the organism
mechanism for creating a pressure difference
mechanism to keep movement in one direction
a way to control flow to suit changing needs
closed system
blood is fully enclosed within blood vessels at all times
diastole
restimg phase of the hearts cardiac cycle when the chambers of the heart are refilling with blood
the atria and ventricles are relaxed
blood will enter the atria via the vena cava and pulmonary vein
the blood flowing into the atria increases the pressure within the atria
atrial systole
the phase of the cardiac cycle where the atria contracts while ventricles relax
as the atria muscle walls contract, increasing the pressure this causes the atrioventricular valves to open and blood flow into the ventricles
the ventricular muscular walls are relaxed
ventricular systole
the period of contraction of the ventricles
ventricles contract
blood is ejected from the heart into the aorta and pulmonary trunk
ventricular pressure rises until it reaches a peak
pressure in the heart
as a chamber fills with blood the pressure is going to rise
when a chamber contracts the pressure is going to rise
changes in pressure affect whether a valve is open or closed
fluids always move from areas of high pressure to areas of low pressure
flow diagram of heart
atria contract and ventricles relax ventricles start to fill with blood so pressure inside them increases pressure in atria is at its highest pressure fall gradually in aorta atrioventricular valves open and semi lunar shut
atria relax
atria relaxed ventricles contract atrioventricular valve closes semi lunar valves open and then shut. ventricular pressure rises steeply until it is above pressure in the aorta pressure in the aorta rises then ventricular pressure falls
atria and ventricles relaxed semi lunar valves shut atrioventricular valves open. pressure in ventricles starts to rise slowly pressure in atria starts to rise slowly, pressure in aorta falls slightly and slowly
veins
carry blood from all parts of the body back to the heart. they carry blood at low pressure. their walls are thinner than artery walls and have valves
artery
carry blood away from the heart to all parts of the body. the walls are thick, elastic and expandable. they carry blood at high pressure and have no valves
capillaries
carry blood through body tissues, delivering oxygen and glucose to cells for respiration. they have very thin walls that are only one cell thick and link arteries to veins
maintaining high blood pressure
during systole blood is pumped through the aorta and other arteries at high pressure. the elastic fibres of arteries enable them to expand and allow blood through
during diastole the blood pressure in the arteries drop. the elastic recoil of the artery walls help force the blood on
4 components of blood
plasma
white blood cells
platelets
red blood cells
plasma
largest component of blood-55%
transport nutrients hormones and proteins to the parts of the body that need it. cells also deposit theor waste products into the plasma, and the plasma in turn helps remove this waste from the body
tissue fluid
liquid that surrounds the cells in your body
formed from blood plasma movinf out of the capillaries so diffusion can occur
how tissue fluid is formed
capillaries have small gaps in the walls so that liquid and small molecules can be forced out
as blood enters the capillaries from arterioles the smaller diameter results in a high hydrostatic pressure so water glucose amino acids ions and oxygen are forced out
this is known as ultrafiltration
how tissurw fluid is reabsorbed
large molecules remain in the capillaries and therefore create a lowered water potential
toward the venule end of the capillaries the hydrostatic pressure is lowered due to the loss of liquid but the water potential is very low
water reenters the capillaries by osmosis
exchange at capillaries- reabsorbtion
lower hydrostatic pressure in blood than tissue fluid die tk ultrfiltration and blood entering wider tube
ultrafiltration slows down
proteins left in blood create more negative water potential in blood them tissue fluid
water moves from tissue fluid into blood by osmosis
small molecules into blood through diffusion
exchange at capillaries- ultrafiltration
higher hydrostatic pressure in blood than tissue fluid due to heart pumping, elastic recoil and blood entering narrower tube
forces small molecules through capillary walls and into tissue fluid
large molecules and blood cells too large to leave stay in plasma
exchange at capillaries- formation of lymph
tissue fluid that doesnt enter the blood enters the lymph capillary
this makes the fluid lymph
lymph capillaries join to make lymph vessels lymph vessels retirn lymph to blood via ducts near the heart
erythrocytes adaptations
red blood cell
biconcave shape maximises surface area for gas exchange
small and flexible to pass through narrow capillaries
no nucleus more room to carry respiratory gases
packed with haemoglobin
haemoglobin
made up of 4 globular proteins
and 4 iron ions
haemoglobin is the molecule that allows erythrocytes to carry respiratory gases
has an affinity for oxygen
when haemoglobin becomes oxygenated it is known as oxyhaemoglobin
role of haemoglobin
to transport oxygen
readily associate with oxygen at gas exchange surfaces
readily dissociate with oxygen at tissues
gets round this by changing its affinity under different conditions
affinity of haemoglobin
affinity is the degree to which one substance combines with another
haemoglobin has different affinities for oxygen molecules under different conditions
the hogher the oxygen concentration the higher the affinity for oxygen
