WEEK 1 Flashcards
What are the statistics of total body water in men and women?
60% of body weight in men and 50% in women
Intracellular fluid makes up how much of total body water?
2/3
What is the statistic of interstitial fluid in the body?
Interstitial fluid volume is 3/4 of the extracellular fluid volume
What are the statistics regarding interstitial fluid and extracellular fluid volume?
Interstitial fluid volume is 3/4 of the extracellular fluid volume (ECFV) and plasma is about 1/4 of the ECFV
What happens with TBW regarding ageing?
TBW percentage decline with ageing
What is the correlation between body fat and TBW?
as % of fat increases, TBW decreases
What is the relationship between water and K+, Glucose, ATP and Proteins?
Water acts as a solvent for K+, Glucose, ATP and Proteins
Describe the mechanism of why water is a dipolar molecule
Oxygen is more electronegative than hydrogen therefore the electrons shared in the covalent bond are attracted towards the Oxygen atom giving oxygen a partial -ve charge and hydrogen a partial +ve charge, making the molecule dipolar
Knowing that H2O is a dipolar molecule, what does it readily dissolve?
Charged and polar biomolecules (e.g carboxylic acids, protonated amines, phosphate esters or anhydrides)
Are biologically important gases such as CO2, O2 and N2 polar or non-polar?
non-polar
Define ‘Hydrophilic’ molecules
Compounds that dissolve easily in water
What does CO2 form in aqueous solution?
H2CO3 and is transported as the bicarbonate ion
Explain the formation of H2O molecules
Tetrahedral arrangement of orbitals around the O2 atom allows each H2O molecule to form hydrogen bonds with as many as 4 neighbouring H2O molecules
Explain the reasoning behind the change of state in H2O molecules
When there is more heat more disorganised molecules are in continuous motion, less bonds are formed, regular lattice structure is prevented which leads to a change in state
MORE HYDROGEN BONDS = MORE SOLID MATERIAL
What is an electrolyte?
Ions capable of carrying an electrical charge
What are the major cations (+) in the body?
Na, K, Ca and Mg
What are the major anions (-) in the body?
Cl, HCO3, HPO4, SO4
Knowing that electrolytes are unevenly distributed, where are Na+, Cl-, K+ and phosphates found in the body?
Na+ and Cl- are major in the extracellular fluid (ECF) and K+ and phosphates are major in cells
What is serum osmolality affected by and what is its range?
Serum osmolality is affected by the concentration of blood chemicals and ranges from 275 to 295 most/kg
What does “BUN” stand for?
Blood urea nitrogen
What is the equation to calculate Serum osmolality?
2(Na) + Glucose/18 + BUN/1.8
What is the difference between Isotonic solutions, Hypertonic solutions and Hypotonic solutions?
Isotonic solutions = Cells retain their normal size and shape since concentration of water is in equilibrium
Hypertonic solutions = Cells lose water and shrink since concentration of solutes is greater outside than inside the cell
Hypotonic solutions = Cells take on water by osmosis until they become bloated and burst since concentration of solutes is greater inside the cell than outside
What is the difference between an acid and a base?
Acids are compounds that donate a hydrogen ion and bases are compounds that accept hydrogen ions
What is the equation to calculate pH?
pH = log 1/[H+] or -log[H+]
What are the causes of change in pH?
- Altered enzyme activity
- Membrane permeability
- CNS Activity
- Electrolyte distribution
- Increased myocardial irritability
- Decreased cellular viability
- Organ dysfunction
What can happen in the body if the body pH increases or decreases?
pH decrease can lead to a loss of consciousness (depressed CNS) and pH increase (acidosis) can cause over excitability, tingling sensation and muscle twitches
Define what a “Buffer” is
A substance or group of substances that tend to control the H+ ion concentration in solution by reacting with hydrogen ions of an acid added to the system and releasing hydrogen ions to a base added to the system. A buffer consists of a weak acid and its conjugate base.
What are the fastest to slowest buffers in the human body?
Chemical buffer (a fraction of a second), Respiratory system (1-3 mins), Renal system (a few hours to a day)
What are the two types of acids in the human body?
Volatile acids (CO2) and Non-volatile acids (Amino acids, fatty acids, nuclear acids)
What are the different buffer systems in the body?
- Bicarbonate buffer
- Phosphate buffer
- Plasma proteins buffer
- Haemoglobin
What is the role of the phosphate buffer?
Used in producing urine and is found in small concentrations in blood
What is the role of buffers in plasma?
To carry H+ and CO2 out through the lungs
What is the mechanism behind Diabetic Ketoacidosis?
Free fatty acids leave adipocytes (fat cells) that are converted by the liver to acetoacetic acid and B-hydroxybutyric acid that dissociate to produce H+ ions and anions. The H+ lowers her blood pH and a metabolic acidosis known as diabetic ketoacidosis (DKA) develops.
Define ‘Osmolality’ and what it means to have high osmolality and low osmolality
Osmolality = The concentration of dissolved particles of chemicals and minerals
High osmolality means there are more particles in your serum and lower osmolality means the particles are more diluted. (Osmosis is from Low osmolality to High osmolality)
