Flashcards in Water Deck (37)
What portion of adult body water weight is found intracellularly?
Water is an excellent solvent for what?
ionic compounds and solutes such as glucose and AA's
Children have more water than adults in which compartment?
Water weakens what forces?
electrostatic forces and hydrogen bonding between other polar molecules
Water is involved in what type of reactions?
hydrolytic (peptide hydrolysis)
Water is produced in the body by what?
oxidative metabolism of hydrogen-containing substrates
- 300 ml/day
In what 3 ways does water act as a carrier?
1. transports nutrients and removes wastes
2. allows exchanged between cells, interstitial fluid, and capillaries
3. maintains vascular volume and blood circulation
How does water act in thermogenesis?
1. waters large heat capacity helps limit body temp fluctuations
2. water has large capacity for heat vaporization
3. sweating and evaporation allows heat loss
How does water act as a lubricator?
forms lubricating fluid for joints, saliva, gastric, intestinal, genito-urinary, and airway mucus.
How does water act as a shock absorber?
Maintains cellular shape and allows imbibition
What important function does water have for the brain and fetus?
Forms CSF for brain and spinal cord protection and suspends fetus
What is activated with increase in internal body temp?
Activation of sweat glands
How many KJ of heat is lost by evaporation of 1 gram of water?
What is sweat compared to plasma or extracellular fluid?
Intense sweating leads to greater water than electrolyte losses and results in what type of dehydration?
Hypertonic (fluid replacement is more important that salt!!)
The osmotic pressure of extracellular fluid increases when?
When water losses exceed water intake
Is ADH release or the hypothalamic thirst reflex triggered first?
ADH release (1% osmolarity increase)
What is the most important stimulus controlling thirst?
What is the cornerstone of clinical assessment of hydration status?
Urine and blood assays
High grades of urine color can also indicate what?
Gross hematuria or bilirubin excretion from jaundice
For hydration status, urine osmolarity is inferior to what?
What is the most widely used hematological index of hydration?
- greater than 300 mmol/Kg --> dehydration
What can affect bioelectrical imedance analysis?
- alcohol consumption
- menstrual cycle
How can total body water be measured?
using deuterium oxide (stable hydrogen isotope)
What are the 3 types of dehydration?
1. isotonic - net salt and water loss is equal
2. hypertonic - water loss or excess salt
3. hypotonic - loss of salt or excess water
Mild dehydration (1-2%) can impair what?
cognitive functions and physical performance
Moderate dehydration (2-5%) can result in what?
- reduced SV, CO, BP, and bloof low
How does dehydration impair cognition?
underperfusion of brain and increased stress hormones
Sever dehydration leads to what?
- dizziness, lethargy, irritable
- ortho hypotension