UNIT 1.2 BAIC CHEMISTRY Flashcards
DESCRIBE basic chemistry as it relates to the human body
DEFINE various chemical structures as they relate to the human body
DEFINE pH
- to maintain homeostasis, body fluids must maintain a specific balance of acids and bases.
- more hydrogen ions (H+) dissolved in a solution = more acidic
- more hydroxide ions (OH-) = more basic (alkaline)
Chemical reactions in the body are sensitive to small changes in acidity or alkalinity
-pH scale= 0 to 14
-pH scale is based on the number of H+ in solution.
DESCRIBE how the body maintains pH within the limits of homeostasis
Maintaining pH: Buffer Systems
While the pH of fluids from different parts of the body varies, the normal limits of each fluid are quite narrow
Blood pH is maintained between 7.35 and 7.45 by homeostatic mechanisms
Even though strong acids and bases may be taken into the body or be formed by body cells, the pH of fluids inside and outside cells remains almost constant (homeostasis).
Mass
amount of matter
Chemistry
science of the structure and interactions of matter. anything that takes up space and has mass
chemical elements total? In human body? Major ones?
- All forms of matter are made up of a limited number of building blocks
- 118 elements total
- 26 elements present in human body
- 4 major ones (O, C, H, and N) make up 96%
- 8 others contribute 3.6%; See Table 2.1
- 14 more in tiny amounts account for the remaining 0.2% of the body’s mass
- Examples: C= carbon, Na = sodium, Cl = chlorine
iodine (I) is essential for
thyroid function
Atoms
- smallest unit of an element that retains characteristics of an element
- consist of a nucleus (made of protons and neutrons)
- Overall charge of an atom is neutral
- can gain, lose or share electrons
Electrons (e-)
tiny, negatively charged particles
-Electron shells
- surrounds the nucleus
- maximum electron capacity (2 or 8)
Atomic number
- number of protons in the nucleus= atomic number
- Every element has a different number
- Ex: hydrogen = 1 proton, sodium = 11 protons, chlorine = 17 protons, etc.
Mass Number
- total number of protons plus neutrons
- Ex. sodium (11 protons and 12 neutrons) Mass number = 23
Atoms that gain electrons have what tyoe of charge
- gain = negative charge
Atoms that lose electrons
- lose = positive charge
Ions
- are electrically charged atoms
- represented by writing chemical symbol followed by the number of positive (+) or negative (-) charges
- example, Ca2+ , H+, O2-
cations
- positively charged ions
anions
negatively charged ions
Molecules
- formed when atoms share electrons
- consist of 2 or more atoms of the same (O2) or different (H20) elements
Molecular formula
- indicates the number and type of atoms that make up a molecule
- subscript indicates the number of atoms for the symbol to the left of the subscript
- ex: H20, subscript ‘2’ indicates two hydrogen atoms
- water molecule, H20, 1 atom of oxygen shares electrons w/2 atoms of hydrogen
Compounds
- substances containing 2 or more different elements
- oxygen (O2) is not a compound. only one element
Free radicals
- unstable ions or molecules that can be destructive to other nearby molecules because of unpaired electrons in their outer shells
- break important body molecules by giving up or taking an electron
- ex: superoxide (O2-); an oxygen molecule with an additional electron
Chemical bonds
- forces that bind the atoms of molecules and compounds together.
- Type of bond that will form based on the # of electrons in element’s outer shell
main types of bonds
- ionic
- covalent
- hydrogen bonds
valence shell
of electrons in element’s outer shell
octet rule
atoms combine to form molecules and share electrons to form arrangements with eight electrons in the outer shell
Ionic Bonds
- Electron is donated or accepted
- opposite attract
- teeth, bones
cation
Positive ion
anion
negative ion
Electrolytes
- formed when ionic compounds break apart into anions and cations in solutions
- conduct electricity
- critical in H2O movement, acid-base balance, producing nerve impulses
Covalent bonds
- form when two atoms share pairs of electrons
- greater the number of shared pairs of electrons, the stronger the covalent bond
- Most common type of bond in the body
- Most do not break apart when the molecule is dissolved in water
- Single covalent bond shares 1 pair of electrons
- ex: Hydrogen molecule (H2) is formed when 2 hydrogen atoms each share their single electrons to complete their valence shell
Nonpolar covalent bonds
- share electrons equally
- Polar bonds between identical atoms are always nonpolar
- ex: methane molecule (CH4) is nonpolar since there is no part of the molecule with a stronger charge than any other part
Polar covalent bonds
- unequal sharing of electrons
- Water is a very important example in living systems; the side of the water molecule with the hydrogen atoms is slightly positive, while the side with the oxygen atom is slightly negative
Hydrogen bonds
- result from the attraction of oppositely charged parts of molecules rather than sharing of electrons.
- Hydrogen atom with a partial positive (δ+) charge attracts the partial negative (δ-) charge of another atom
- ex: force of attraction is from charged parts of molecules, not from sharing electrons
- Weak compared to ionic and covalent bonds
- Contributes to the strength and stability within large complex molecules (water, DNA, proteins)
Chemical reactions
- old bonds break and/or new bonds form between atoms
- Build body structures and carry our bodily functions. both involve transfers of energy
- Most reactions involve both breaking and forming bonds, so the overall reaction may release or require energy
Energy
- capacity to do work
Potential energy
- stored energy (by position of chemical bonds)
- Chemical energy is a form of potential energy stored in the bonds of molecules
Kinetic energy
- energy of matter in motion
- chemical energy from food is turned into kinetic energy to walk and heat energy to maintain body temperature
Breaking old bonds
releases energy
forming new bonds
requires energy
Synthesis reactions
- When two or more atoms, ions, or molecules combine to form new larger molecules
- ex: A + B > AB
- Example: 2H2 + O2 > 2 H2O
anabolism
-Synthesis in the body
Decomposition reactions
- Splitting molecules apart into smaller molecules, ions, or atoms
- ex: AB > A + B
- Example: CH4 > C + 2H2
- Breakdown of starches into glucose molecules during digestion
- Energy is released in the body as nutrients are broken down by decomposition
- Energy may be stored as ATP (adenosine triphosphate)
ATP is used to power energy requiring synthesis reactions to build body structures
catabolism
Decomposition in the body
ATP (adenosine triphosphate)
- used to power energy requiring synthesis reactions to build body structures
Exchange reactions
- Involve both synthesis and decomposition
- AB + CD > AD + CB
- HCl + NaHCO3 > H2CO3 + NaCl
- H+ from HCl combines w/ bicarbonate ion (HCO3-) from NaHCO3, while the sodium ion (Na+) from NaHCO3 has combined with the chloride ion (Cl-) from HCl
Reversible reactions
- can go in either direction under different conditions (two half arrows)
1. A + B ↔ AB
2. AB ↔ A + B
3. AB + CD ↔ AD + CB - Some reactions are reversible only under specific conditions (written above or below direction arrows)
Metabolism
sum of all the chemical reactions in the body
2 types Chemical compounds
- organic
- inorganic
Inorganic compounds
- Structure: Lack carbon; ionic or covalent bonds
- Examples: Water, carbon dioxide, bicarbonate, acids, bases, and salts
- Inorganic acids, bases and salts dissociate into ions in the water
acid + base salt + H20
HCl + NaOH NaCl + H2O
Acids and bases react to form
- salts
- acid + base > salt + H20
- HCl + NaOH > NaCl + H2O
Salts dissociate into
a cation and an anion (not H+ or OH-)
Acids dissociates into
H+ ions (and one or more anions)
Bases dissociate into
OH- ions (hydroxide and one or more cations)
Organic compounds
- Always contain carbon, usually contain hydrogen, and always contain covalent bonds
- Ex: Carbohydrates, Lipids, Proteins, Nucleic acids, Adenosine triphosphate (ATP)
Carbohydrates
- sugars, glycogen, and starches
- most common energy source for life
types of Lipids
- triglycerides (fats or oils)
- phospholipids
- steroids
- fatty acids
- fat soluble vitamins (A,D,E, and K)
Proteins
- body structures
- regulate enzyme processes
- provide protection
- aid muscle contraction
Nucleic acids
DNA and RNA
Adenosine triphosphate (ATP)
- principal energy storing molecule of the body
Water
- most important and abundant chemical in human body (55-60% by mass)
- Vital compound for life
- Good solvent
- absorbs and releases heat slowly, lubricates
- Involved in digestion, circulation, elimination of wastes, regulating body temperature
pH scale
- based on the number of H+ in solution
- extends from 0 to 14
- pH 7 is neutral (pure water)
acidic
- A solution with more H+ than OH-
- pH below 7
basic (alkaline)
- solution with more OH- than H+
- pH above 7
logarithmic scale
- change of one whole number represents a 10-fold change in the number of H+
- A pH of 6 is 10 time more acidic that a pH 7; pH of 9 is 100 times more alkaline than a pH of 7
Buffer Systems
One example of a buffer system is the carbonic acid–bicarbonate buffer system
If there is an excess of H+, HCO3- can remove the excess H+ as follows:
Conversely, if there is shortage of H+, the H2CO3 can function as a weak acid and provide H+ as follows:
