transport in humans Flashcards
(21 cards)
transport of materials in unicellular organisms
-single cell, do not need a transport system for exchange or distribution of materials
-exchange of materials occurs easily by diffusion
-larger exposed surface area
transport in multicellular organisms
-needs a transport system, cells are located deeper in the body further away from external environments.
- cannot rely on diffusion
why is diffusion important to living cells
important in exchanging substances like oxygen, carbon dioxide, nutrients ( e.g. glucose, amino acids, mineral salts) and waste
functions of a transport system
1) transport nutrients and oxygen
2) to remove waste products
3) helps the body to fight diseases
what is the blood made up of
plasma(55% of blood), white blood cells and platelets and red blood cells
white blood cells and platelets and red blood cells make up of 45% of blood
what is a blood plasma
-pale yellow liquid
-composed mainly water (90%)
- constituents of plasma:
-> hormones e.g. insulin
-> soluble proteins e.g. fibrinogen, albumin, globulin, prothrombin, antibodies
-> food substances e.g. glucose, amino acids, fats and vitamins
-> excretory products e.g. urea, uric acid, creatinine, bicarbonate ions( dissolved co2)
-> dissolved mineral salts e.g. chlorides, sulphates, phosphates of calcium, potassium, sodium and hydrogencarbonates
what is a red blood cell
- constitutes 99% cells in the blood
- produced in the bone marrow
- destroyed at the spleen
- limited lifespan of 120 days ( no nucleus-> no control of cell activities-> short lifespan)
- contains a red pigment, haemoglobin(Hb)
what is haemoglobin
- a special kind of protein containing iron
- one haemoglobin holds 4 oxygen molecules and transports oxygen to different parts of the body
what is white blood cells
- larger than red blood cells
- fewer in number compared to red blood cells
- produced in the bone marrow
- destroyed at the spleen
- limited lifespan of a few days although they have a nucleus
- colorless as they do not contain haemoglobin
- irregular in shape and contain a nucleus each
- mobile-> they are able to move, change their shape ad squeeze through walls of thinnest blood capillaries
what are the 2 types of white blood cell
1) -large rounded nucleus
- small amount of non-granular cytoplasm
- produce antibodies against microorganisms
2) -lobed nucleus
- granular cytoplasm
- able to engulf and destroy foreign particles
what are blood platelets or thrombocytes
- not true cells
- fragments of cytoplasm which are membrane bound
- importance for the clotting of blood
transport function of blood
plasma-> transports digested food substances( e.g. glucose, amino acids), excretory products( e.g. urea and carbon dioxide), hormones, heat( all the chemical reactions in the cell produces heat)
red blood cell-> transports oxygen
how is the red blood cell adapted for its function
- filled with red pigment haemoglobin-> essential for binding oxygen
- absence of nucleus-> allows more haemoglobin to be packed into the cell so that it can carry more oxygen
- biconcave shape-> increases surface area to volume ratio for efficient uptake of oxygen
- elastic-> enables cells the squeeze through tiny blood capillaries
transport of oxygen to body cells
1) blood passes through the lungs, oxygen diffuses from the air sacs in the lungs into the blood.
2) haemoglobin combines with oxygen to form oxyhaemoglobin
3) blood transport oxygen to all the tissues of the body
4) at the tissue cells, oxyhaemoglobin releases the oxygen
why do people living at high altitudes have an increased number of red blood cells
high altitude-> lower oxygen concentration in atmosphere( surrounding air)
people at higher altitudes-> increase red blood cell-> more haemoglobin in person-> more oxygen transported to cells of a person per unit time( increased oxygen capacity)-> person receives more oxygen
protective function of blood
- blood clotting
- phagocytes
- production of antibodies
the clotting process
- blood clots when exposed to air, this seals the wound, preventing the entry of bacteria and further lose of blood
1) damaged tissue and platelets release an enzyme known as thrombokinase
2) thrombokinase converts prothrombin(inactive) to thrombin(active)
3) thrombin converts soluble fibrinogen to insoluble fibrin threads which entangle blood cells and form a blood clot
what are phagocytosis
-phagocytosis is the process of engulfing and destroying foreign particles (bacteria)
- some phagocytes may be destroyed in the process
- dead cells combined with dead bacteria to form pus
production of antibodies
- antibodies are produced by lymphocytes
- antibodies bind to bacteria and cause their surface membranes to rupture( break down)
- toxins produced by bacteria are neutralised
- bacteria cells clump together in the presence of antibodies
- phagocytes carry out phagocytosis to engulf and destroy clumped bacteria cells
organ transplant and tissue rejection
- tissue or organ transplant involves replacing damaged or diseased tissue or organ with healthy tissue or organ form the same person or a donor
- transplanted organs may be treated as foreign by the body
- thus, lymphocytes would produce antibodies to attack the transplanted organ-> tissue rejection
- ways to reduce the risk of tissue rejection includes a tissue match( donor and recipient must be genetically as close as possible) and use of immunosuppressive drugs
the circulatory system in man
heart: a muscular pump which pumps bloo
