lecture 4- electrolyte balance

intracellular fluid

fluid contained within a cell, it represents 2/3 of body fluid

extracellular fluid

includes the fluid portion of blood (plasma) and lymph which accounts for 7% of body fluid and the fluid between cells (interstitial) which makes up 30% of body fluid

sodium and chloride are found in

extracellular fluid

potassium and phosphate are principal electrolytes in

intracellular fluid

osmosis

the passage of water through a membrane from an area of low to high electrolyte concentration. where ions move, water follows passively, absorb water from colon

isotonic

having equal concentration of solutes, normal conditions

hypertonic

having high concentration of solutes, cell shrinks, water leaves

hypotonic

having low concentration of solutes, cells swell, water flows inside

cells that line the colon

actively absorb sodium, water follows sodium which facilitates the efficient absorption of water from the large intestine into the blood stream

during illness

when large volumes of fluid are lost, osmosis can lead to a life-threatening condition (hypertonic), where cells shrink and loose their ability to pump blood leading to cardiac failure

electrochemical gradient

a difference in both the concentration of solutes and the electrical charge across the cell membrane, maintained by an energy dependent pump that can transfer sodium from inside to outside the cell

when sodium is pumped outside the cell

potassium enters the cell in attempt to balance the loss of the positively charged sodium ions

result of sodium-potassium pump

the inside of the cell has a slight negative charge relative to the outside (polarization)

nerve impulse starts in response to

stimulation, causing positively charged sodium ions to rush into the cell, which makes the inside of the cell less negatively charged (depolarization)

depolarization will stimulate

influx of sodium into an adjacent area of the membrane, the electrical signal (action potential) is transmitted along the nerve cell from one cell to the next

immediately after the change in electrolyte balance

potassium leaks out of the cell and sodium is actively pumped out of the cell to re-establish the normal electrolyte balance (re-polarization)

action potential

change in the electrical charge of the nerve cell membrane, resulting in an electrical signal that can be transmitted from one nerve cell to the next

electrolytes

provide another critical function by maintaining fluid pH in a very narrow range

deviation from normal pH

negatively affect the rate at which chemical reaction take place within the body and the ability of hemoglobin to bind oxygen

acids are continuously produced when

carbs, lipids, and proteins are used by the body to provide energy to the cells, and need to be neutralized

acidosis

pH of 7.0-7.3, feel disoriented and fatigued; ex. uncontrolled diabetes, starvation, diarrhea, and emphysema

alkalosis

pH 7.5 or higher, when body loses too much acid through diuretics, vomiting, or pneumonia, feel agitated and dizzy

the lungs help to regulate pH

exhaling air is the main way to get rid of carbon dioxide, an acidic byproduct of the chemical reaction of energy metabolism

kidneys help regulate pH

excreting acids or bases into the urine

buffer

compound that can accept or donate H+ ions, depending on the pH of the solution; phosphate is an important buffering agents

one teaspoon of salt contains

2400mg of sodium

functions of sodium

absorbed by digestive tract, attract water, nerve impulse conduction, muscle contraction, and absorption of some nutrients

fluid balance is maintained by

moving or actively pumping sodium ions where more water is needed

if blood sodium is low

sodium is secreted back into the blood as it flows through the kidney, resulting in a decreased urine output

if blood sodium levels are high

the sodium is filtered out by the kidneys and excreted into the urine, when the excess sodium is removed, water follows, resulting in greater urine output

sodium deficiency

can lead to muscle cramps, nausea, vomiting, dizziness, and later shock and coma, very unlikely

the majority of sodium in the typical diet comes from

salt added during food processing or preparation at restaurants

AI for sodium

1500mg 14 years and older

1200mg 1-13 years old

2300mg for CDRR

sodium sensitive

sodium has a direct effect on their blood pressure, as their sodium intake increases so does their blood pressure

functions of potassium

water balance, nerve impulse transmission, and muscle contraction; all membranes contain an energy dependent pump that can transfer sodium from inside to outside the cell

intracellular fluids contain

95% of the potassium in the body, higher potassium intake is associated with lower blood pressure values

low blood potassium (hypokalemia)

a life threatening problem, lack of appetite, muscle cramps, confusion, and constipation, heart beats irregularly decreasing its capacity to pump blood; typically due to chronic diarrhea or vomiting that increases excretion of potassium

vulnerable populations for potassium deficiency

people with eating disorders or alcohol use disorders, low calorie diet, endurance athletes, people who take potassium wasting diuretics (water pills) for high blood pressure

foods high in potassium

fruits, vegetables, coffee, milk, whole grains, peas, lentils, and meats

potassium is absorbed

from the small and large intestines, 90% of what we absorb gets consumed

AI for potassium

2600mg for females; 3400mg for men; most adults do not meet their intake

avoiding too much potassium

when kidneys function poorly, potassium increases in the blood, inhibiting heart function and leading to a slowed heart beat, if left untreated leads to cardiac arrest

functions of chloride

a negatively charged ion found in extracellular fluid, regulates fluid balance, overall maintenance of acid-base balance in the body, immune response, nervous system functions

chloride deficiency

disturb aid-base balance, due to extended vomiting and poor diet, or some laxatives

chloride food sources

seaweed, celery, tomatoes, and olives

AI for chloride

DV = 2300mg, UL is 3600mg

avoiding too much chloride

since found in salt, most Americans consume too much, increased salt leads to increased blood pressure, select low salt foods