SAMENVATTING: MENSELIJKE EN BIOLOGISCHE ZIEKTELEER
HOOFDSTUK 1: The Chemistry of Living Things
1.1 all Matter consists of elements
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1.2 Atoms combine to form molecules
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1.3 Life depends on water
o no molecule is more essential to life than water = 60% of our bodyweight
o properties of water:
1. Excellent solvent
2. Liquid at body temperature
3. Can absorb and hold heat energy
4. Evaporation (verdamping) of water uses op heat energy zweten
5. Water participates in essential chemical reactions
1.3.1 Water is the biological solvent:
o solvent= a liquid witch other substances dissolve
water is the ideal solvent in living organisms because it is a polar liquid at body
temperature.
Bv sodium chloride (NACL) water keeps the ions dissolved
o solute= any dissolved substance
o Hydrophilic= polar molecules that are attracted to water and interacts easily
o hydrophobic= nonpolar, neutral molecules do not interact easily with water and will not dissolve in it.
1.3.2 Water is liquid at body temperature:
o Between 0 and 100 degrees= this temperature range because there is just enough heat energy in
water to break weak hydrogen bonds between water molecules.
below 0 there no longer enough heat energy to break the hydrogen bonds, they orient themselves
into a stable, unchanging, rigid lattice structure.
above the 100 all hydrogens bonds are completely broken and escape into the atmosphere as gas
o Excellent for transporting solutes
transport is the primary function of blood
o Water is the main constituent of all liquids
1. It fills our cells
2. It occupies the spaces between cells
3. Fills the fluid-filled not occupies by living cells
1.3.3 Water helps regulate the body temperature
o Water can absorb and hold a large amount of heat energy.
it prevents rapid changes in body temperature when changes occur in metabolism or in the
environment
o Our bodies generate heat during metabolism
so being able to lose heat is important for a constant body temperature
sweat from the surface of our bodies
1.3.4 water participates in chemical reactions
o Involved in many of the chemical reactions
, 1.4 The importance of hydrogens ions
Hydrogen= most important ions in our body
1.4.1 Acids donate hydrogen ions, bases accept them
o Bond between hydrogen and oxygen are strong
it can break the electron from one hydrogen atom is transferred to the oxygen atom water
molecule breaks into two ions
o Acid molecule= is any molecule that can donate an acidic solution and H+ ion.
added to pure water= an acidic solution (higher H+ concentration than pure water)
o Base molecule= is any molecule that can accept an H+ ion.
added to pure water= an alkaline solution (lower H+ concentration than pure water)
Opposite effects on the H+ concentration of solution neutralize each other
1.4.2 The Ph scale express hydrogen ion concentration
o Scientists use the Ph scale to indicate the acidity or alkalinity of a solution
o Ph scale = measure of the hydrogen ion concentration of a solution
scale ranges from 0 tot 14
1. Pure water= 7 neutral point (ion concentration of 10-7 moles/liter)
2. Acidic solution= pH less than 7 (bv Ph of 5= H+ concentration of 10 -5 moles/liter)
3. Basic solution= pH greater than 7 (bv pH of 9= H+ concentration of 10 -9 moles/liter)
o pH of blood= 7,4 more alkaline than neutral water
o changes in the pH of body fluids can affect how molecules are transported across the cell membrane
and how rapidly certain chemical reactions occur.
a change in hydrogen ion concentration can be dangerous because it threatens homeostasis!!
1.4.3 Buffer minimizes changes in Ph
o Buffer= is any substance that tends to minimize the changes in pH that might otherwise occur when an
acid or base is added to a solution.
essential for homeostasis of pH in body fluids
o When an acid is added and the number of H+ ions increase, the base form of the buffer pair accepts
some of the H+ ions
minimizing the fall in pH that might otherwise occur
o When a base is added that might take up too many H+ ions, the acid form of the buffer pair releases
additional H+ ions
minimizing the rise in pH that might otherwise occur
o Bicarbonate and carbonic acids = one of the most important buffer pairs in body fluids
when blood becomes too acidic bicarbonate accepts H+
o The more buffers that are present in a body fluid, the more stable the pH
1.5 The organic molecules of living organisms
Organic molecules= molecules that contain carbon and other elements held together by covalent bonds
1.5.1 Carbon is the common building block of organic molecules
o Carbon is relatively rare in the natural world. (Less 0,03%)
organisms actively accumulate it 18% of body weight in humans
o Carbons= building block of all organic molecules
many ways it can form strong covalent bonds with other atoms
o In addition to their complexity, there is almost no limit to the size of organic molecules derived from
carbon.
macromolecules: thousands or even millions of smaller molecules
1.5.2 Macromolecules are synthesized and broken down within the cell
o dehydration synthesis or condensation reaction= Macromolecules are built within the cell itself.
subunits are joined by covalent bonds
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