Chapter 7 - Water and Electrolytes Flashcards
How much water is stored in the body on average for males and females?
42kg for males (70kg male) 30kg for females (50kg females)
What are the two general compartments for water distribution in the body?
EFC (Extracellular fluid)
As: Plasma (in blood)
Interstitial (between cells)
EFC makes up about 33% of body’s water
26% interstitial
7% plasma
IFC (Intracellular fluid)
66% of the water is inside cells
Osmotic vs hydrostatic pressure?
Osmotic - water moves from low solute concentration TO high solute concentration
Hydrostatic - water moves from high pressure region to low pressure region
What does it mean if a cell is HYPOTONIC?
Solute concentration is higher outside the cell - net water movement is out of the cell
What does it mean if a cell is HYPERTONIC?
Solute concentration is lower inside the cell - net water movement is inside of the cell
Def: Electrolyte
A substance that, when dissolved in water, splits or dissociates “lysis” into ions that can conduct electricity in a solution
Cation vs Anion?
Cation - positively charged ions
Anions - negatively charged ions
What are the cations involved in fluid balance?
Sodium (Na+)
Potassium (K+)
Calcium (Ca2+)
Magnesium (Mg2+)
What are the anions involved in fluid balance?
Chloride (CL-)
Bicarbonate (HCO3-)
Phosphate (PO4^3-)
Proteins
What are the main CATIONS and ANIONS in PLASMA?
Cation: Na+ (sodium)
Anion: Cl- (Chloride) and HCO3- (bicarbonate) along with minor amounts of proteins
What are the main CATIONS and ANIONS in INTERSTITIAL FLUID?
Cation: Lots of Na+ (sodium), tiny amount of K+ (potassium)
Anion: Cl- (Chloride) and HCO^3- (bicarbonate).
Almost same constitution as plasma except no proteins in ISF
What are the main CATIONS and ANIONS in INTRACELLULAR FLUID?
Cations: Lots of K+ (Potassium) and small amt of Na+ (sodium) - flipped from ISF and plasma
Anions: Lots of PO4^3- (phosphate) due to so many cellular processes using phosphate, and some protein anions
Sensible vs Insensible water loss
Sensible - obvious, easy to measure - e.g. urine (~1.5L/d), feces (~100 mL/d), sweat (~100mL/d)
Insensible - difficult to observe - e.g. breath/skin moisture (~1L /d)
Overall ~2.5L/d water loss at rest
Generally want to consume 3L/d total between liquid and solid intake and excrete excess
What is a diuretic?
Any substance that increases urine output
What are some examples of diuretics?
Alcohol is a mild diuretic - inhibits antidiuretic hormone (ADH) - the ‘brakes’ of urine production
Caffeine - increases blood flow to kidneys and Na/Cl excretion
Not considered a problem for athletes at reasonable doses
What is a concern with hyper hydration?
If intake of sodium is not high enough, can experience hyponatremia - ‘hypo’ = low, ‘na’ = sodium, ‘emia’ = in blood
Extremely low solute concentration of blood means the blood is extremely hypotonic compared to, in this case, CNS neurone - causes rapid shift of water into neutrons and therefore brain swelling
- Called CEREBRAL EDEMA
What levels of hypo hydration can impact athletic performance?
Even moderate hypo hydration can cause huge swings in athletic performance and training
Severe hypo hydration can contribute to hyperthermia
What is the primary consequence of exercise on fluid homeostasis within the body?
Primary consequence is impaired thermoregulation - ability of body to control its temperature.
Aggravated in hot and humid environments
How much water can an athlete lose in a session?
1-2L/h in high temp with protective clothing
>2.5L/h in prolonged exercise in the heat
What is the rate of fluid absorption during exercise
Around 1-1.5L/h - so in intense prolonged exercise in high temp, can sweat out faster than can reabsorb
What is the loss of blood volume from sweating called?
Hypovolemia
What two main components do hypovolemia impede?
O2 delivery to exercising muscle
Heat transfer out of body surface - less sweat means less body temp regulation
In EXTREME circumstances, resulting hyperthermia can be fatal
What are the corresponding body temperatures for normal body temperature, hyperthermia and hyperpyrexia?
Normal - 36.5-37.5
Hyperthermia - >38.5 degrees
Hyperpyrexia - >40 degrees
