Chapter 14- water and sodium

intracellular fluid compartment

2/3 of body water, contains potassium, magnesium, and phosphate

extracellular fluid

1/3 of body water, has 2 compartments interstitial fluid which is fluid between cells and intravascular fluid which is fluid in the blood and lymph, sodium and chloride

electrolytes

the most abundant solute that forms when salts dissociate in solution and forms ions

physiological functions that depend on water

maintain blood volume that permits the transport of nutrients and oxygen, forms specialized fluids throughout the body, lubricates, acts as a solvent, moistens exposed tissues, regulates body temp, and removes waste products via urine

in response to increased osmotic pressure

the pituitary gland releases ADH which signals the kidneys to retain water, reducing urine output, while simultaneously falling blood pressure initiates pressure receptors in the kidneys trigger the release of renin

renin activates

angiotensinogen, forming angiotensin I, in the lungs angiotensin I is converted to angiotensin II which constricts blood vessels and releases aldosterone by the adrenal glands

aldosterone signals

the kidneys to retain more sodium and chloride, therefore more water, so low blood pressure causes the kidneys to increase water conservation

dehydration can occur via

diarrhea, vomiting, fever, inability to consume sufficient fluid, poorly controlled diabetes, burns, heavy exercise, hot weather, dry environments, or high altitudes

signs of mild to moderate dehydration

dry mouth and skin, fatigue, muscle weakness, decreased urine output, deep yellow urine, headache, and dizziness, solute concentrations in the blood ride, BP decreases HR increases due to low blood volume

sodium, potassium, and calcium aid in

the transmission of nerve impulses throughout the body

iron and magnesium function

as cofoactors and enable enzymes to carry out chemical reactions

sodium- food sources

75-80% is added during food processing and at restaurants, naturally present in foods and provides about 10% of sodium we consume, salt added in cooking provides 10-15%

sodium- absorption and transport

almost all absorbed in the intestinal tract, absorbed by active transport in both small and large intestine

sodium- functions

helps in the absorption of glucose and some amino acids in the small intestine, required for normal muscle and nerve function, and aids in water balance

muscle contraction and nerve impulse conduction

rely on the electrical charge created by the shift of both sodium and potassium ions across the cell membrane

sodium- deficiency

rare, excessive perspiration, only when weight loss from perspiration exceeds about 2% of total body weight is there concern