ANATOMY AND PHYSIOLOGY – HUB1019F
Cellular physiology
CHEMICAL COMPOSITION OF THE BODY:
States of matter:
o Solid – compact and have a definite shape
o Liquid – definite volume and take the shape of their container
o Gas – no shape nor volume
ELEMENT: a substance which cannot be split into a simpler substance by using chemical
procedures
There are 26 elements in the human body
Major elements:
1. Oxygen There are 8 lesser elements & 14 trace
2. Carbon elements
3. Hydrogen
4. Nitrogen
ATOM: the smallest chemical unit of a molecule
The nucleus of an atom contains protons and neutrons, the electrons move around the
nucleus in an electron shell (orbit)
o Protons (+) are positively charged
o Neutrons are neutral
o Electrons (-) are negatively charged
The ATOMIC NUMBER is the number of protons in the nucleus
The atomic number identifies the element – gives element number
The MASS NUMBER is the number of protons + neutrons
The atomic mass is the average mass of all its naturally occurring isotopes
Isotopes – when an atom exists as one or more species having the same atomic number
BUT only differ in their number of neutrons and therefore their atomic mass differ
,The number of electrons in the orbit equals the number of protons within the nucleus of
the atom
Atoms have a net charge of ZERO (protons = electrons)
The number of protons in an element: atomic mass – atomic number
Electrons can occupy any position in a certain volume of space – orbital
Orbital is a barrier (energy shell) preventing electron from passing beyond
1st orbital – 2 electrons Electrons fill from closest orbital to the nucleus to the
2nd orbital – 8 electrons one furthest away
3rd orbital – 8 electrons
4th orbital – 18 electrons
When atoms gain or lose electrons, they form an ION
Ionisation is the process of losing or gaining electrons – ions can be positive or negative
MOLECULE: formed when two or more atoms SHARE electrons
COMPOUND: substance that contains atoms of two or more different elements
Chemical bonds are forces that hold together the atoms of a molecule or compound –
bond is dependent on valence electrons
Valence electrons in the outermost circle participate in chemical reactions
IONIC BONDS:
Results when valence electrons from one atom are completely transferred to a second
atom and ions are formed
• Cations: positively charged and move towards the negative pole (cathode)
• Anions: negatively charged and move towards the positive pole (anode)
Easily dissociate and the ions attract POLAR water molecules and hydration spheres are
formed around each ion – formation of hydration spheres makes molecule become
soluble
ELECTROLYTE: an ionic compound (cation + anion) which breaks apart in solution.
COVALENT BONDS:
Occurs when atoms share valence electrons
, Covalent bonds between identical atoms are the strongest because electrons are equally
shared – has to do with electronegativity.
The larger the number of electron pairs shared, the stronger the bond
It is the MOST COMMON chemical bond in the body
Non-polar molecules and bonds form when electrons are equally distributed between
atoms
There can be single, double or triple bonds
Non-polar covalent bonds:
o Methane – CH4
o Ammonia – NH3
Polar covalent bonds occur when covalent bonds are formed between two different
atoms and electrons may be pulled towards one of the atoms – not equally distributed
The end towards which the electrons is pulled makes the molecule negatively
charged
Polar covalent bonds are weaker and can ionise
Oxygen, nitrogen and phosphorous pull electrons towards themselves – higher
electronegativity difference
Water is POLAR and serves as a solvent
HYDROGEN BONDS:
Usually form between slightly positive hydrogen with a second electronegative atom
(oxygen or nitrogen)
They are weaker than covalent bonds
Formed between oppositely charged atoms
Functions: folding/bending of long organic molecules (proteins)
Bonds 2 DNA strands
Surface tension
Capillary action
Cellular physiology
CHEMICAL COMPOSITION OF THE BODY:
States of matter:
o Solid – compact and have a definite shape
o Liquid – definite volume and take the shape of their container
o Gas – no shape nor volume
ELEMENT: a substance which cannot be split into a simpler substance by using chemical
procedures
There are 26 elements in the human body
Major elements:
1. Oxygen There are 8 lesser elements & 14 trace
2. Carbon elements
3. Hydrogen
4. Nitrogen
ATOM: the smallest chemical unit of a molecule
The nucleus of an atom contains protons and neutrons, the electrons move around the
nucleus in an electron shell (orbit)
o Protons (+) are positively charged
o Neutrons are neutral
o Electrons (-) are negatively charged
The ATOMIC NUMBER is the number of protons in the nucleus
The atomic number identifies the element – gives element number
The MASS NUMBER is the number of protons + neutrons
The atomic mass is the average mass of all its naturally occurring isotopes
Isotopes – when an atom exists as one or more species having the same atomic number
BUT only differ in their number of neutrons and therefore their atomic mass differ
,The number of electrons in the orbit equals the number of protons within the nucleus of
the atom
Atoms have a net charge of ZERO (protons = electrons)
The number of protons in an element: atomic mass – atomic number
Electrons can occupy any position in a certain volume of space – orbital
Orbital is a barrier (energy shell) preventing electron from passing beyond
1st orbital – 2 electrons Electrons fill from closest orbital to the nucleus to the
2nd orbital – 8 electrons one furthest away
3rd orbital – 8 electrons
4th orbital – 18 electrons
When atoms gain or lose electrons, they form an ION
Ionisation is the process of losing or gaining electrons – ions can be positive or negative
MOLECULE: formed when two or more atoms SHARE electrons
COMPOUND: substance that contains atoms of two or more different elements
Chemical bonds are forces that hold together the atoms of a molecule or compound –
bond is dependent on valence electrons
Valence electrons in the outermost circle participate in chemical reactions
IONIC BONDS:
Results when valence electrons from one atom are completely transferred to a second
atom and ions are formed
• Cations: positively charged and move towards the negative pole (cathode)
• Anions: negatively charged and move towards the positive pole (anode)
Easily dissociate and the ions attract POLAR water molecules and hydration spheres are
formed around each ion – formation of hydration spheres makes molecule become
soluble
ELECTROLYTE: an ionic compound (cation + anion) which breaks apart in solution.
COVALENT BONDS:
Occurs when atoms share valence electrons
, Covalent bonds between identical atoms are the strongest because electrons are equally
shared – has to do with electronegativity.
The larger the number of electron pairs shared, the stronger the bond
It is the MOST COMMON chemical bond in the body
Non-polar molecules and bonds form when electrons are equally distributed between
atoms
There can be single, double or triple bonds
Non-polar covalent bonds:
o Methane – CH4
o Ammonia – NH3
Polar covalent bonds occur when covalent bonds are formed between two different
atoms and electrons may be pulled towards one of the atoms – not equally distributed
The end towards which the electrons is pulled makes the molecule negatively
charged
Polar covalent bonds are weaker and can ionise
Oxygen, nitrogen and phosphorous pull electrons towards themselves – higher
electronegativity difference
Water is POLAR and serves as a solvent
HYDROGEN BONDS:
Usually form between slightly positive hydrogen with a second electronegative atom
(oxygen or nitrogen)
They are weaker than covalent bonds
Formed between oppositely charged atoms
Functions: folding/bending of long organic molecules (proteins)
Bonds 2 DNA strands
Surface tension
Capillary action
