FLG 212 EXAM NOTES
‐ most abundant molecule in the body
‐ solvent for all living matter (ions, compounds etc.)
‐ 50-60% of total body weight
FUNCTIONS OF WATER:
‐ Solvent and transport medium
• Soluble substances: ions
• Insoluble substances: lipids (carried around through carrier proteins/other lipid
transporting molecules)
‐ Absorption
• Digestive system (absorb nutrients)
‐ Excretion
• Skin (sweat) and kidneys (urine)
‐ Medium for chemical reactions/reagent in some chemical reactions
‐ Ionisation of atoms
• Formation of K and Na ions, important for nerve signals, H ions and pH
• Determine electrical activity of cells
‐ Lubrication
• Joints, digestive system
‐ Stabilising body temperature
• Thermo-homeostasis
PROPERTIES OF WATER THAT MAKE IT SUITABLE:
(These properties make it good for maintaining body-temp)
‐ Good heat capacity
‐ Good heat conduction
‐ High latent temperature of evaporation
WATER CONTENT IN BODY VARIES ACCORDING TO:
‐ Age
‐ Sex
‐ Body fat %
, Take note that the female body fat %
increases as they hit puberty
TERMINOLOGY
‐ Intracellular fluid (ICF): water inside cell
‐ Extracellular fluid (ECF): water in all spaces outside cell
• Interstitial fluid (intercellular)
• Blood plasma
• Trans-cellular fluid (inside hollow organs)
Lymph, cerebrospinal fluid, fluid of gastrointestinal tract, intra-ocular fluids
(inside the eye) etc.
‐ Intravascular fluid: inside blood vessels
‐ Extravascular fluid: outside blood vessels
‐ Volume of water in the body is controlled by a delicate balance between
• Intake
• Excretion KIDNEYS
• Reabsorption
,WATER LOSS
‐ The body has no water reserves
• 5% water loss = thirsty
• 10% water loss = sick
• 20% water loss = death
‐ No water intake: 4-6 days will result in death
‐ Minimum intake: 0.5-1 litre/day
‐ Compulsory urine loss: 300-500 ml/day
• Anuria → no urine passed
WATER TURNOVER
‐ Whatever you put in must go out → i.e. net = 0
, DEHYDRATION
‐ Definition: A state of excessive loss of body water
‐ Causes:
• persistent vomiting
• diarrhoea
• excessive sweating
• diuresis (excessive urination
• insufficient water intake
‐ Treatment:
• water per mouth or stomach tube, saline infusion etc.
‐ Manifestation/symptoms:
• Thirst, dry mouth and throat, difficulty with speech and swallowing
• Loss of mass
• Depression of the fontanelle in infants
• Increase pulse rate, blood pressure and haematocrit
• Acidosis
‐ most abundant molecule in the body
‐ solvent for all living matter (ions, compounds etc.)
‐ 50-60% of total body weight
FUNCTIONS OF WATER:
‐ Solvent and transport medium
• Soluble substances: ions
• Insoluble substances: lipids (carried around through carrier proteins/other lipid
transporting molecules)
‐ Absorption
• Digestive system (absorb nutrients)
‐ Excretion
• Skin (sweat) and kidneys (urine)
‐ Medium for chemical reactions/reagent in some chemical reactions
‐ Ionisation of atoms
• Formation of K and Na ions, important for nerve signals, H ions and pH
• Determine electrical activity of cells
‐ Lubrication
• Joints, digestive system
‐ Stabilising body temperature
• Thermo-homeostasis
PROPERTIES OF WATER THAT MAKE IT SUITABLE:
(These properties make it good for maintaining body-temp)
‐ Good heat capacity
‐ Good heat conduction
‐ High latent temperature of evaporation
WATER CONTENT IN BODY VARIES ACCORDING TO:
‐ Age
‐ Sex
‐ Body fat %
, Take note that the female body fat %
increases as they hit puberty
TERMINOLOGY
‐ Intracellular fluid (ICF): water inside cell
‐ Extracellular fluid (ECF): water in all spaces outside cell
• Interstitial fluid (intercellular)
• Blood plasma
• Trans-cellular fluid (inside hollow organs)
Lymph, cerebrospinal fluid, fluid of gastrointestinal tract, intra-ocular fluids
(inside the eye) etc.
‐ Intravascular fluid: inside blood vessels
‐ Extravascular fluid: outside blood vessels
‐ Volume of water in the body is controlled by a delicate balance between
• Intake
• Excretion KIDNEYS
• Reabsorption
,WATER LOSS
‐ The body has no water reserves
• 5% water loss = thirsty
• 10% water loss = sick
• 20% water loss = death
‐ No water intake: 4-6 days will result in death
‐ Minimum intake: 0.5-1 litre/day
‐ Compulsory urine loss: 300-500 ml/day
• Anuria → no urine passed
WATER TURNOVER
‐ Whatever you put in must go out → i.e. net = 0
, DEHYDRATION
‐ Definition: A state of excessive loss of body water
‐ Causes:
• persistent vomiting
• diarrhoea
• excessive sweating
• diuresis (excessive urination
• insufficient water intake
‐ Treatment:
• water per mouth or stomach tube, saline infusion etc.
‐ Manifestation/symptoms:
• Thirst, dry mouth and throat, difficulty with speech and swallowing
• Loss of mass
• Depression of the fontanelle in infants
• Increase pulse rate, blood pressure and haematocrit
• Acidosis
