I.                    Exchanged Materials.

a.     Cytoplasm.

                                                               i.      Is a homogeneous, clear jelly like material that fills cells.

b.      Organisms and their cells need water.

                                                               i.      Some hormones need access to the interior of cells to transmit messages.

                                                             ii.      Wastes must have a way to exit.

1.      Ammonium ion (NH4+) is a potentially toxic waste.

II.                 Membrane as Barrier.

a.       Membranes are composed of two thin layers.

                                                               i.      Phospholipids

1.      Form when a molecule of glycerol combines with two fatty acids and phosphate.

                                                             ii.      Proteins

1.      An organic compound composed of one or more polypeptide chains of amino acids.  [Polymer, mer = amino acid]

b.      Transport proteins.  [on/in cell membrane]

                                                               i.      Transports charged molecules such as the ions H+ or Ca+2

                                                             ii.      Also helps fairly small polar molecules such as amino acids and sugars into the cell

c.       Selectively permeable.  [cell membrane]

                                                               i.      The membrane regulates the exchange of materials in a very specific way.

d.      Glycoproteins.

                                                               i.      Proteins that are embedded in membranes and have sugar attached to them.

                                                             ii.      Sugars can also attach to the heads of membrane lipids (glycolipids) Glycoprotein’s and glycolipids act as antennae that receive chemical messages from other cells.  These are examples of complex molecules.

III.             Diffusion and Osmosis.

a.       Diffusion.

                                                               i.      Is the movement of molecules from an area of higher concentration to an area of  lower concentration.

1.      All molecules are in constant motion; they move and collide.

b.      Concentration gradient. 

                                                               i.      When there is a difference in concentration of molecules across a distance a concentration gradient exists.

c.       Osmosis.

                                                               i.      The movement of water down a concentration gradient.  [usually across a cell membrane]

1.      Osmosis is responsible for the movement of water across membranes.

d.      Turgor.

                                                               i.      The out word pressure of a cell against it’s cell wall.  [helps plants maintain rigidity (stand up)]

IV.              Passive and Active transports.

a.       Passive transport.

                                                               i.      Involves diffusion without any input of energy.

b.      Active transport.

                                                               i.      Moves substances against their concentration gradients and thus requires energy.

c.       Facilitated Diffusion.

                                                               i.      Is passive because the transported material moves down its concentration gradient.

1.      Facilitated diffusion makes transport more specific and speeds up the rate, but does not go against the gradient.  Transport proteins are often involved.

                                                             ii.      Active transport requires energy to move substances, in addition to the help of transport proteins.  This process moves molecules against the concentration gradient (from areas of lower concentration to areas of higher concentration).

1.      One source of energy is the hydrolysis of ATP (the energy transport molecule in most life).

d.      Endocytosis.

                                                               i.      Useful way for unicellular organisms, such as amoebas, or very simple multicellular organisms to get food into the internal environment.  The cell surrounds and takes in food from its environment, usually in a vacuole.

e.       Exocytosis.

                                                               i.      Helps cells remove waste materials.  (sort of "reverse endocytosis")

1.      Also moves specific molecules into the external environment, where they need to be to function.

V.                 Gas Exchange in Water.

a.       Gas exchange happens by diffusion across a membrane.

                                                               i.      A single celled organism is directly in contact with its surroundings.  Just uses diffusion.

                                                             ii.       A multicellular organism, such as plants, some cells are buried deep within the organism.  Needs some sort of gas exchange system, like gills.

                                                            iii.      Whether cells are in direct contact or in the interior of an organism the basic processes of gas exchange are essentially universal.

VI.              Adaptation to Life on Land.

a.       Organisms living on land are constantly battling the tendency to dry out.

                                                               i.      In many animals, including humans, lungs are the organs of gas exchange.

1.      Lungs are located in the chest.

                                                             ii.      The lungs minimize the effects of drying out by eliminating the one way flow of oxygen that is efficient in gills.

b.      Alveoli.

                                                               i.      The air sacs in the lung.

1.      If you lay all the alveoli in an average person’s lungs out flat, they would cover an area of about 60 m squared  (lungs are like a spinge, not a hollow sack).

c.       Cuticle.

                                                               i.      The waxy outer layer covering the surfaces of most land dwelling plants, animals, and fungi.  (part of why leaves are shiney)
 

d.      Stomates.

                                                               i.      The opening between two guard cells in the lower epidermis of a plant leaf through which gasses are exchanged with the air.

1.      Each stomate is surrounded by a specialized pair of guard cells, which function to open and close the stomate.

e.       Transpiration.

                                                               i.      The loss of water to the atmosphere by a plant through the stomates in its leaves.

f.        Homeostasis.

                                                               i.      The balanced and controlled condition in the internal environment of an organism.  [or, in an environment]

1.      A variety of waste removal mechanisms have evolved to help maintain homeostasis.

g.       Ammonia.

                                                               i.      A toxic nitrogen compound excreted by some aquatic organisms; thought to have been present in earth’s early atmosphere.

1.      Ammonia is also the chief nitrogenous waste of some vertebrates, the ocean fishes.

h.       Human Urinary systems.

                                                               i.      The human urinary system is an example of how waste removal is critical to the maintaining homeostasis.

                                                             ii.      Nephrons.

1.      The functional unit of kidney consisting of glomerules, its associated capsule, and tubule, surrounded by capillaries.  [this is where waste is removed from the blood and unine is formed]

                                                            iii.      Kidneys.

1.      The organ that regulates water and salt levels, filters water and waste from the blood, and excretes the end products.

                                                           iv.      Urinary System. 

1.      Caries the fluid formed in the kidney’s out of the body.  [ureters, bladder, urethra]

                                                             v.      Urine.

1.      Waste fluid the body creates.

                                                           vi.      Ureter.

1.      Tube that carries out the urine.

                                                          vii.      Urinary Bladder.

1.      Holding tank for urine until it’s drained or released out of the urethra.

i.       Glomerulus.  (Kidney)

                                                               i.      The ball of capillaries within the cup.

                                                             ii.      Nephrons have three functions: filtration, reabsorption, and secretion.

1.      Approximately 180 L of fluid enters the nephrons each day, yet only about 1.5 L of urine is eliminated from the bladder.

                                                            iii.      Reabsorption accounts for 85% of the salt, water, and other substances processed by the kidney.

1.      The remaining 15% is regulated by hormones or nervous system controls.                     

j.        Aldosterone.

                                                               i.      Hormone secreted by the adrenal gland.

k.      Feed back regulation.

                                                               i.      When substances inhibit their own formation.

l.         Antidiuretic hormone:  A hormone related from the posterior love of the pituitary, enhance conservation of water by the kidneys.

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By: Cody T., WHS Student, 3/2006. 

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