Human Physiology
- An Integrated Approach
Dee Unglaub Silverthorn
,Introduction to Physiology
Summary
Emergent properties: properties that cannot be predicted to exist based only on knowledge of the
system’s individual components (results from complex interactions between components)
Function → why does a system work a certain way
Mechanism → how does the system work
Homeostasis: maintenance of a relatively constant internal environment
Law of mass balance: if amount of substance in a body is constant, input must be offset by equal loss
Feedforward control: body can predict a change coming and starts response in anticipation of the
change
,Molecular Interactions
Molecules and Bonds
Lipids
- Biomolecules of mostly carbon and hydrogen
- Most have glycerol backbone with 1-3 fatty acids
- Nonpolar and not soluble in water
- Fats → solid at room temperature
- Oils → liquid at room temperature
- Saturated → no double bonds between carbon atoms
- Lipid related structures
- Eicosanoids: 2- carbon fatty acids with carbon ring and 2 carbon tails
- Prostaglandin, thromboxanes, leukotrienes
- Steroids: four linked carbon rings
- Cholesterol, cortisol
- Phospholipids: 2 fatty acids and a phosphate group
- Cell membrane
Carbohydrates
- Composed of carbon, hydrogen, and oxygen
- Monosaccharides
- Five carbon sugars → ribose, deoxyribose
- Six carbon sugars → fructose, glucose, galactose
- Disaccharides
- Sucrose, maltose, lactose
- Polysaccharides
- Glycogen, cellulose, starch
Proteins
- Polymers of amino acids
- Essential amino acids are ones we do not produce ourselves (enough)
- Primary structure: sequence of amino acids
- Secondary structure: a-helix or B-sheet
- Tertiary structure: globular, fibrous (3D shape)
- Quaternary structure: combination of subunits
Nucleotides
- Phosphate group + five carbon sugar + nitrogenous base (purine or pyrimidine)
- Form DNA, RNA, ATP, ADP, cyclic ATP
- Guanine binds with Cytosine (triple bond)
, - Adenine binds with Thymine (double bond)
Covalent bonds
- Two atoms share electrons → unpaired electrons in outer shells pair up
- Strong bond that forms molecules
- Require the most energy to make and break
- Molecules can be polar or nonpolar depending on partial charges (even distribution or not)
Ionic bonds
- Electrostatic attraction between ions
- Ex. Na+ and Cl-
Hydrogen bonds
- Bonds between hydrogen atoms and O, N, or F
- By polar regions of water atoms
Van der waals forces
- Weak and nonspecific attractions between atoms
Noncovalent Interactions
Solubility
- Hydrophilic: molecules that are soluble in water
- Hydrophobic: molecules that do not dissolve well in water (usually nonpolar molecules)
- Phospholipids have both hydrophobic and hydrophilic parts → membrane
Acids and bases
- Acids contribute H+ to solution and bases take up H+
- pH = -log(H+ concentration), more H+ → less pH → more acidic
Protein Interactions
Categories
- Enzymes: biological catalysts that speed up chemical reactions
- Membrane transporters: move substances between extracellular and intracellular
compartments
- Signal molecules: hormones / signal things
- Receptors: bind signal molecules and initiate cellular response
- Binding proteins: bind and transport molecules throughout the boy
- Immunoglobulins: antibodies protect from invaders
- Regulatory proteins: regulate cell processes (ex. transcription factors)