Physiology Unit 1 CHEMISTRY REVIEW

Transcription

1 Physiology Unit 1 CHEMISTRY REVIEW

2 Defini7ons Types of energy Kine7c vs. poten7al Forms of energy Chemical Ex: ATP Ma0er and Energy Electrical Ex: Ac7on poten7al of an neuron Mechanical Ex: Ac7on of muscles in moving body Radiant (Electrochemical) Ex: Light energy

3 Atoms Smallest unit of ma0er Composed of subatomic par7cles Protons carry a posi7ve charge Neutrons are electrically neutral Electrons carry a nega7ve charge Nucleus is composed of protons and neutrons Electrons orbit the nucleus Shells Fixed distance from the nucleus 2, 8, 18, 32 Orbitals The direc7on the electrons move around the nucleus can hold 2 electrons

4 Elements = every specific type of atom Atomic number: # protons Atomic mass: #protons + # neutrons

5 Chemical Composi7on of the Body 117 elements (as of 2006) 92 naturally occurring 24/112 are essen7al 7 essen7al minerals Ca, P, K, S, Na, Cl, Mg 13 essen7al trace elements Fe, I, Cu, Zn, Mn, Co, Cr, Se, Mo, F, Sn, Si, V 99% of the body s atoms Carbon - Oxygen Hydrogen - Nitrogen

6 Ions Atom that has gained or lost one or more valence electrons electrolytes anions vs. ca7ons Minerals Mg 2+, Ca 2+, Fe 2+, SO 4-2 Trace elements Na + (atomic number 11) Cl - (atomic number 17) H + (atomic number 1)

7 Isotopes Elements with a different number of neutrons Radioisotopes Instability and disintegra7on of atomic nucleus Occurs in heavier isotopes Half- life = amount of 7me required for ½ of radioac7vity to be lost as isotope disintegrates Applica7ons Radioac7ve tracers Radia7on therapy for cancer

8 Thyroid Scan Measures health of thyroid by detec7ng radioisotope iodine- 131 taken up by thyroid gland normal thyroid enlarged cancerous

9 Valence Electrons Shells surround electrons First shell can contain only 2 electrons. If more than 2 electrons, must occupy shells more distant Second shell can contain 8 electrons Valence electrons Electrons in the outer most orbital that par7cipate in chemical reac7ons (if orbit incomplete) Form chemical bonds

10 Free Radicals Atoms containing a single unpaired valance electron Highly reac7ve Formed by specific enzymes, UV radia7on, smoking, pollu7on The Good Begins process of pathogen destruc7on by white blood cells The Bad Can damage self DNA or cell membranes To prevent free radical damage the body has a defense system of an#oxidants Vitamins E, C, A (derived from beta carotene)

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12 Chemical Bonds Chemical bonds: Interac7on of valence electrons between 2 or more atoms. Number of bonds determined by number of electrons needed to complete outermost shell.

13 Chemical bonds link atoms together to produce molecules Covalent Polar covalent Ionic Hydrogen van der Waals forces strongest weakest

14 Covalent bonds Atoms share electrons Most prevalent in organic compounds Non- polar = no charge

15 Polar covalent bonds Unequal sharing of electrons Result = posi7ve and nega7ve poles H 2 O Makes hydrogen bonds possible Oxygen, nitrogen, phosphorous have tendency to pull electrons towards themselves.

16 Ionic bonds Complete transfer of one or more electrons from one atom to another form ions when dissociate Na Cl Na + Cl -

17 Hydrogen Bonds Electrical a0rac7on between hydrogen in one polarized bond and oxygen or nitrogen on another or in the same molecule Surface tension, cohesion

18 Van der Waals Forces Very weak a0rac7ons between nonpolar regions of molecules Important in protein structure and structure of other large molecules Caused by hydrophobic interac7ons polar groups turn outward toward aqueous solu7on Non- polar groups turn inward towards each other

19 Solu7ons Solutes and solvents Solubility Hydrophilic Hydrophobic Amphipathic

20 Solubility Glucose, amino acids, are H 2 0 soluble. Hydra7on spheres form around atoms of oxygen, nitrogen, phosphorous Charged complex ions and their ca7ons form hydra7on spheres Hydrophilic molecules Molecules composed of non- polar covalent bonds are not H 2 0 soluble Lipid soluble Cannot form hydra7on spheres Hydrophobic molecules

21 Hydra7on Spheres

22 Solu7ons Concentra7on Amount of solute present per unit volume of solu7on (g/l) Moles = amount of a compound in grams equal to its molecular weight Ex) 180g of glucose in 1 L of solu7on = 1 Molar solu7on of glucose (1 mol/l) Small volumes in human body mmol/l = mol/l µmol/l = mol/l nmol/l = mol/l

23 Acids, Bases, and ph Acids = proton donors Bases = proton acceptors ph = - log [ H + ] ph scale 0 (most acidic) to 14 (most basic) more free H + in solu7on = lower ph = more acidic!!!

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25 Buffers System of molecules and ions that act to prevent changes in [H + ]. Stabilizes ph of a solu7on. In blood: H C0 2 < > H 2 C0 3 < > H + + HC0 3 - Reac7on can proceed in either direc7on (depending upon the concentra7on of molecules and ions).

26 Types of Chemical Reac7ons Anabolic reac7ons endergonic Catabolic reac7ons exergonic Coupled reac7ons (A +B - - > C+D - - > E+F) Exchange reac7ons (AB + CD - - >AD + BC) Oxida7on- reduc7on reac7ons Oxida7on = giving up electrons Reduc7on = accep7ng electrons