Human Physiology Fundamentals Overview

1. Biol 155Human Physiology Instructor: Dr. Robert Harris Office: 1354 Biological Sciences Phone: 822-5709 Email: harris@zoology.ubc.ca

2. Course requirements: • Texts: Fundamentals of Anatomy and Physiology 6th ed. Frederic H. Martini Anatomy & Physiology Coloring Workbook, 7th ed. Elaine Marieb • Read course synopsis!!! Failure to read it, or failure to listen to what I say does not constitute an excuse • Lecture Notes and synopsis are posted at: http://www.science.ubc.ca/~biomania/biol153/lecture/main01.htm

3. Mark Breakdown • Biol 153: Lecture: 60% Lab: 40% Course Total: 100% • The lecture mark is based on: • One mid-term exam in each term: 20% (10% each) Winter exam: 20% Final exam: 20% Total: 60%

4. Mark Breakdown cont. • Biol 155: • marks will be based solely on the lecture exams, which will be weighted as follows: • One mid-term exam in each term: 30% (15% each) • Winter exam: 35% • Final exam: 35% • Total: 100%

5. Atomic structure and elements • An element is a substance that retains its chemical and physical characteristics even when it is broken down into its smallest units. • The smallest practical unit, for our purposes is the atom.

6. The chemical characteristics are determined by the number of protons • These are the three forms of hydrogen • All three have one electron • All three have one proton

7. Electron orbits • Number of electrons generally equals number of protons. • There are specific orbits (or shells), that contain a specific maximum number of electrons

8. Charged atoms • Atoms are most stable when there are 8 electrons in the outermost shell. • In order for the outermost shell to be filled, atoms will either take in or give off electrons. When this happens there is a change in net charge. • Charged atoms (ions) can be electrically attracted (opposite charges attract) • This is known as ionic bonding • Ionic bonds are fairly weak

9. Covalent bonds • Another way atoms can fill their outer shell is to share electrons with another atom • The electrons orbit around BOTH nuclei • This is known as a covalent bond • Covalent bonds are much stronger than ionic bonds

10. Molecular dipoles • When covalent bonds are formed, the electrons may not be shared equally between the atoms • This unequal sharing can result in an uneven distribution of electrical charges on the molecule • This is known as a partial charge, or a dipole

11. Hydrogen bonding • Water molecules interact with each other electrically • The partial negative charge around the oxygen is attracted to the partial positive charge around the hydrogen • These very weak electrical attractions are called hydrogen bonds

12. Ions in aqueous solution • Water molecules can form hydrogen bonds with ions • Ions in solution have a layer of tightly bound water molecules around them • This layer of water molecules is known as the hydration sphere • Water can form hydrogen bonds with uncharged molecules as well (providing there is a partial charge)

13. pH is the negative log (the small p) of the hydrogen concentration (the large H) In pure water, some of the H2O molecules will dissociate into H+ and OH- The H+ concentration in pure water is 0.1 mM, or 1x10-7 moles/L (hence pH 7)

14. Molecular Representations • There are several ways or representing molecular structures • Here are three representations of glucose • Linear model • Structural model • Space-filling model

15. Synthetic and Lytic Reactions • Smaller organic molecules can be linked together • Often this involves the production of H2O • Larger organic molecules can be broken down into subunits • This often consumes H2O, hence the term “Hydrolysis”

16. Energetics of chemical reactions • In order for chemicals to react, they must first overcome an energy barrier • This is known as the activation energy • Some bonds are easily reorganized, resulting in a lower activation energy

17. Enzyme catalyzed reactions • Enzyme has binding sites for the reactants • The active region will attack the bonds in the precursors • Once bonds have been reorganized, product is released

18. Polymers in organic systems • A polymer is a chain made up of repeating subunits • Useful compounds are often stored in the form of a polymer • For example, glycogen is a branched polymer of glucose • Glycogen molecules can have different numbers of glucose subunits • Proteins are also polymers

19. Fatty acids and lipids

20. Phospholipids in aqueous solutions • Phospholipids and glycolipids are amphipathic • Meaning they have a hydrophillic region and a hydrophobic region • When they are in solution, they form micelles

21. Structure of Amino Acids • All amino acids have the same basic structure • A carboxylic acid side • An amino group side • A side group on the central carbon • The side group is referred to as the R-group

22. Primary protein structure

23. Secondary protein structure • The chain of amino acids can form folds and coils in different regions, depending on the amino acid sequence

24. Tertiary protein structure • The tertiary structure of a protein is the 3D shape of a single subunit. • This is a combination of all the folds, coils and sheets. • This is usually dictated by hydrophobic and hydrophilic interactions with water

25. Tertiary and Quaternary protein structure • The quaternary structure of a protein is the interactions between the different subunits • If a protein is only composed of a single subunit, there is no quaternary structure

26. DNA and RNA structure

27. Adenosine triphosphate (ATP) • Adenosine backbone • Three phosphate groups attached in a chain • Last two have high energy bonds

28. Characteristics of a lipid bilayer: • At normal temperatures, a lipid bilayer is liquid. • This means that the phospho- and glycolipids which make it up can move freely, within the bilayer. • Because of the hydrophobic layer in the centre, a bilayer is impermeable to water. • Because of the hydrophilic and hydrophobic interactions, a bilayer is structurally quite strong.

29. Membrane fluidity

31. Membrane proteins:

41. Diffusion

44. Effect of osmotic concentration on cells • Cell membranes are semipermeable, and thus subject to osmotic forces. • Animal cell membranes are flexible, and allow for inflation and deflation depending on the movement of water

45. Transport of solutes through cell membranes • Cell membranes are made up of phospholipids arranged in a bilayer. • The centre of the bilayer is hydrophobic, which means that hydrophilic molecules cant penetrate. • Hydrophobic and lipid-soluble molecules can penetrate cell membranes. • In order for hydrophilic molecules to be taken up, a transport mechanism is needed. • These transport mechanisms are integral membrane proteins.

46. Ion channels • Ions are fairly small molecules. • Specialized proteins in the membrane form aqueous pores, which allow ions through. • The driving force is the chemical gradient • These pores can be quite selective. • Most of these pores are regulated • Example: CFTR

47. Facilitated diffusion • Molecules that are slightly larger need more help in getting into or out of cells. • Rather than a pore, molecules are actually bound to carrier protein, which translocates molecule. • Driving force is still the chemical gradient

48. Active transport • In order to move ions against a concentration gradient, energy must be used. • Energy is supplied by the hydrolysis of the terminal high-energy bond of ATP. • Example: Na-K-ATPase

49. Active secondary transport • ATPases only pump ions, nothing bigger. • Larger molecules are transported by coupling them to movement of an ion down its concentration gradient. • Ions can also be transported in this way. • Example: Na-coupled glucose uptake.

50. Membrane transport and cycling • Molecules can bind to cell surface receptors and then be internalized. • This same mechanism can be used to recycle membrane.