W1 Biochem

winniesmith's version from 2016-11-13 20:34

Section 1

Question Answer
What does water do Bathes our cells, dissolves and transports compounds in blood, provides a medium for molecular movement into and throughout cellular compartments, separates charged molecules, dissipates heat, participates in chemical reactions.
what percentage of our body mass is water (adults)?60%
what percentage of a childs body is water?75%
2 types of fluid in the bodyIntracellular (ICF)(60%) and extracellular (ECF)(40%)
What is extra cellular fluid made up offInterstitial(66%) and Blood (plasma) (33%) and Transcellular water
What is transcellular fluid?Very small volume of extracellular fluid- urine,sweat, gastrointestinal secretions, capillary leakage (eg inflammation)

Section 2

Question Answer
Bonds in waterCovalent bond between the oxygen (becomes more -ve) and hydrogen (becomes more +ve). Water becomes dipolar. Hydrogen bonds between water molecules (weak non-covalent bonds, 4 close neighbouring water molecules.)
Why is water a good solventOrganic molecules and inorganic salts can readily dissolve in water because it readily forms hydrogen bonds and electrostatic interactions. H bonds are strong enough to dissolve polar molecules and separate charges, however are weak enough to allow movement of water and solutes.
Strength of bonds in waterCovalent bond (O2-H) is twenty times as strong as the hydrogen bond (continuously break and reform, every 10 pico seconds)
Why is water good at thermal regulationStructure allows it too resist temperature change.High heat of fusion (large temp drop to change into solid ice). High thermal conductivity(heat is dispersed quickly- such as heat in brain to dissipate into blood/body water pool). High heat of vaporisation (when sweat evaporates from skin, there is a cooling effect).
How does water respond to an input of heatby decreasing hydrogen bonding
How does water respond to coolingincreased hydrogen bonding.

Section 3

Question Answer
What are electrolytesGeneral term for inorganic anions and cations and bicarbonates.
What electrolytes are in ECFNa+ and Cl-.
What electrolytes are in ICFK+ and phosphates.
What is the movement of water called?osmosis
How does water move?Through ion channels in semi permeable membranes.
Why does water move?Moves from an area of low osmolarity to an area of high osmolarity, to achieve equal osmolarity across membranes.
What is osmotic pressure?The force needed to maintain equal volumes of water on each side of a membrane.

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