Body Fluids

Body fluids are liquids originating from inside the bodies of living humans. They include fluids that are excreted or secreted from the body.

Body Fluids Bodily fluid includes the following: Bile Blood serum Gastric juice Mucus (including nasal drainage) Saliva Sweat Urine

And Tears.

Body Fluids Total amount of fluid in the human body is approximately 70% of body weight Body fluid has been divided into two compartments – Intracellular fluid (ICF) Inside the cells 55% of total body water Extracellular fluid Outside the cells 45% of total body water

Body Fluid Compartments

Water: Life as we know it evolved in water and is still absolutely dependent on it. The properties of water are therefore of fundamental importance to all living things.

Water is composed of H2 and O2. Its chemical formula is H2O. the H–O–H bond has an angled Shape. At temperatures on the earth’s surface, water is liquid.

Properties of water: 1.Polarity: O–H bonds are polarized due to the high electronegativity of oxygen One side of the molecule carries a partial negative charge (δ). Whereas the other is correspondingly positively charged.

Separation of the positive and negative charges gives the molecule the properties of an electrical dipole. Water molecules are therefore attracted to one another like tiny magnets, and are also connected by hydrogen bonding.

Hydrogen Bonding. A hydrogen bond is the attractive force between the hydrogen of one molecule and an electronegative atom of a Another molecule.  Usually the electronegative atom is oxygen, nitrogen, or fluorine, which has a partial negative charge.

When liquid water vaporizes, a large amount of energy has to be expended to disrupt these interactions.

2. Hydration In contrast to most other liquids, water is an excellent solvent for ions. The dipolar water molecules arrange themselves in a regular fashion corresponding to the charge of the ion. They form hydration shells and shield the central ion from oppositely charged ions.

Water has a high dielectric constant of 78—i. e Water has a high dielectric constant of 78—i. e., the electrostatic attraction force between ions is reduced to 1/78 by the solvent.

Di electric constant The dielectric constant means that substances whose molecules contain ionic bonds will tend to dissociate in water producing ions. The large dielectric constant of water means that the force between the ions in a salt is very much reduced permitting the ions to separate

These separated ions become surrounded by the oppositely charged ends of the water dipoles and become hydrated.  Coulomb's Law F = (k . q1 . q2) / D . r2 where: F is the force between the two electric charges q1 and q2 at a distance r apart D is the dielectric constant of the solvent.

Electrically charged groups in organic molecules (e. g Electrically charged groups in organic molecules (e.g. ,carboxylate, phosphate, and ammonium groups) are also well hydrated and contribute to water solubility. Hydroxy groups compounds, such as glycerol (on the left) or sugars, are also easily soluble, because they can form H bonds with water molecules.

Hydrophilic interactions Water is an excellent solvent for ions and for substances that contain polarized bonds. Substances of this type are referred to as polar or hydrophilic (“water-loving”). In

Hydrophobic interactions Substances that consist mainly of hydrocarbon structures dissolve only poorly in water. Such substances are said to be a polar or hydrophobic. Propane CH3-CH2-CH3

Amphipathic substances Molecules that contain both polar and apolar groups are called amphipathic or amphiphilic.

This group includes soaps, phospholipids and bile. Amphipathic compounds form micelles—i. e., spherical aggregates with their head groups facing toward the outside, or extended bi layered double membranes.

Acids and bases Acids are defined as substances that can donate hydrogen ions (protons), Bases are compounds that accept protons.

THEORIES OF ACIDS AND BASES Arrhenius, Bronsted-Lowry, and Lewis Propose Theories of acids and bases, and explains the relationships between them.

The Arrhenius Theory of acids and bases Acids are substances which produce hydrogen ions in solution. Bases are substances which produce hydroxide ions in solution.

The Bronsted-Lowry Theory An acid is a proton (hydrogen ion) donor. A base is a proton (hydrogen ion) acceptor.

The Lewis Theory An acid is an electron pair acceptor. A base is an electron pair donor. Comparision:

Acid–base reactions always involve pairs of acids and the associated conjugated bases. The stronger the acid or base, the weaker the conjugate base or acid, respectively. For example, the very strongly acidic hydrogen chloride belongs to the very weakly basic chloride ion.

Weak acids and bases Weak acids and bases are only partially ionized in their solutions, whereas strong acids and bases are completely ionized when dissolve in water.

Common Weak Acids Acid Formula Formic HCOOH Acetic CH3COOH Trichloroacetic CCl3COOH Hydrofluoric HF Hydrocyanic HCN Hydrogen sulfide H2S Water H2O Conjugate acids of weak bases NH4+

Ionization of Week Acids Acetic acid, CH3COOH, is a typical weak acid, and it is the ingradient of vinegar. It is partially ionized in its solution. CH3COOH = CH3COO- + H+

Weak base  a weak base is a chemical base that does not ionize fully in an aqueous solution. As Brønsted–Lowry bases are proton acceptors, a weak base may also be defined as a chemical base in which protonation is incomplete.

Ammonia is a typical weak base Ammonia is a typical weak base. Ammonia itself obviously doesn't contain hydroxide ions, but it reacts with water to produce ammonium ions and hydroxide ions.

However, the reaction is reversible, and at any one time about 99% of the ammonia is still present as ammonia molecules. Only about 1% has actually produced hydroxide ions. A weak base is one which doesn't convert fully into hydroxide ions in solution.

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