m11 + 12 lecture - urinary system -> fluids, electrolytes, and acid base balance Flashcards
how much of the body is made of water? (adults)
abt 60%
how much of the body is made of water? (infants)
abt 80%
how much of the body is made of water? (geriatric)
abt 55%
where is the water/fluid that makes abt 60% of the body held in?
three basic compartments:
1) intracellular fluid - 80%
2) extracellular fluid- 20%
3) interstitial fluid
what is the composition of body fluids?
moves by osmosis => generated by Na+ and proteins
- electrolytes and nonelectrolytes
- fluid movement is created by electrolytes (polar -> -/+ charge)
what are electrolytes in the bodily fluids?
- solutes which can dissolve into water and form ions
ex.) salts, acids, bases and some proteins
what are nonelectrolytes in the bodily fluids?
- solutes which are not able to dissolve in water, and carry no covalent charge
ex.) lipids, glucose, creatinine, urea
how does bodily fluids move in the body?
- driven mostly by osmotic and hydrostatic pressures in the capillaries
–> designed to bring abt equilibrium in different concentrations - most active transport in the cells is devoted to maintain concentration gradients between different ions
- allows for water to move freely from one compartment to another
sodium:
- extracellular
actions: osmotic pressure, depolarization
135-145 mEq/L
potassium
- intracellular
actions: repolarization
3.5-5.5 mEq/L
magnesium
- intracellular
actions: hydrate skeletal muscle (relaxant)
1.4-2.2 mEq/L
chloride
- extracellular
actions: chloride shift (ionic balance)
95-105 mEq/L
calcium
- intra and extracellular
actions: muscle contraction, N.T. release
HCO3-
- extracellular
actions: buffer
20-29 mEq/L
albumin
- extracellular
actions: osmosis, C.O.P.
5.5-9 g/dL
about water balance?
- to maintain proper water balance, we must take into our bodies as much as we lose
- most water intake is through our diet - 90%
- the rest is through metabolism
how much water is lost each day?
- 2500mL per day
- intake must equal this
how does water loss occur?
- urine - 60%
- insensible loss - breathing - 28%
- then in our sweat and feces
what are disorders of water balance?
dehydration
- occurs when water loss is greater than water intake over a period of time
- can result in hypovolemic shock
causes: severe burns, diabetes, vomiting, diarrhea, profuse sweating, diuretics
what is edema?
- swelling of the tissues caused by the movement of water into the interstitial spaces
- usually indicates tissue damage and if prolonged, tissue destruction (pitting edema)
why does edema occur?
- loss of osmotic pressure (intra/extra)
- loss of circulation (CV, lymph)
what is water toxicity?
- occurs when overhydrated in a short period of time
- causes symptoms resembling dehydration
- mechanism is osmosis diluting the cells and tissues to point where they cannot maintain membrane transport and essentially drown
what is acid base balance?
- bc of all the bodies proteins have H attached to them, the pH of the body has to be maintained very closely —> meaning H+ regulation is important
- the buffer systems in the body then become essential to maintain pH
what is the buffer of plasma and fluids?
- the buffer of the plasma and the fluids is the bicarbonate buffer system
what is the bicarbonate buffer system?
HCO3-, the bicarbonate ion readily accepts a free H+
- or readily donates one
- or another of its atoms to maintain pH of the environment
what is the protein buffer system?
- this occurs in the cells with intracellular proteins
- this is the most powerful buffer system in the body
what are the compensatory systems?
- respiration - changes in pH due to CO2
- renal mechanism
what does respiration due for pH?
- a very quick fix to changes in the pH of the plasma due to a change in the gases concentration
- CO2 - changes RR
- increased CO2 = decreased pH
- decreased CO2 = increased pH
what is the renal mechanism?
- this system deals with the normal physiological acids that are regularly produced in the body
- this system is the most important in handling acid base balance
ex.) phosphoric acid, uric acid, lactic acid, glutamic acid, and ketone acids
what are the kidneys in charge of regulating?
- prod. and secretion/breakdown of bicarbonate ions
- secretion and absorption of H+ –> at the nephron
what are some problems that can occur with the kidneys regulation of bicarbonate and H+?
- metabolic acidosis
- metabolic alkalosis
what is metabolic acidosis?
- occurs when the body has too much acid in its fluids
caused by: severe diarrhea, renal Dz, diabetes mellitus, starvation, alcoholism, hyperkalemia
what is metabolic alkalosis?
- a condition where the body’s pH level is elevated above normal due to an imbalance of acids and bases
caused by: vomiting, antiacid overuse, diuretics, constipation, cushing’s syndrome
when looking at a patient, what are the three things you look at to differentiate between respiratory and metabolic?
1) pH
2) CO2
3) bicarb
- if arrows are in the same direction = metabolic
- if arrows are in the opposite direction = respiratory
