8. Fluid and Electrolyte Balance Flashcards
What are the functions of water in the body?
- medium for chemical reactions
- participates in chemical reactions
- distributes nutrients to cells
- removes waste products from cells
- lubricant for joints
- moistens organs, GI tract, eyes, skin
- maintains body temperature
- maintains blood volume
Describe the control mechanisms that regulate water intake and output.
Water intake:
- kidneys regulate water levels in the body; they conserve water if you are dehydrates and they can make urine more dilute to expel excess water if necessary
Water output:
- urine excretion greatest output; average water loss per day: 1950 mL (8.5 cups)
- small amount lost in feces
- through skin as perspiration (insensible)
- from lungs (insensible)
What are the recommended intakes and sources of water?
AI for total water (fluid and food):
- women: 2.7L/day (11 cups)
- men: 3.7 L/day (15 cups)
Fluid alone:
- women: 2.2 L (9 cups)
- men: 3L (13 cups)
What are some health consequences of dehydration?
Body water loss:
- 1 to 2% loss: feeling of thirst
- 4% loss: tired, dizzy, headache
- 10% loss: decreased heat tolerance and weakness
Leads to:
- kidney failure
- coma
- death
What are the 4 minerals that function as electrolytes?
- Calcium
- Sodium
- Potassium
- Magnesium
How do electrolytes control fluid balance, acid-base balance, and nerve impulse transmission?
Acid-base balance:
- pH is determined by concentrations of H+ ions; acids produced as by-products of nutrient metabolism; acids must be neutralized to maintain pH; normal extracellular pH: 7.4
Nerve impulse transmission:
- all membranes can pump sodium (Na+) from inside to outside the cell; when Na+ is pumped out of the cell, K+ enters to balance loss of positively charged Na+
What are some dietary sources and daily requirements of the electrolyte minerals?
Sodium:
- packaged foods
- fast food
- frozen meals
Potassium:
- milk
- fried beans
- orange juice
Calcium:
- milk
- cheese
- bread
Magnesium:
- whole grains
- dark, leafy vegetables
- dried beans and legumes
Describe factors that can contribute to the development of hypertension.
What are the water percentages in the body?
Muscle: 73%
Adipose tissue: 10 to 20%
Bone: approx. 20%
Human body: 50 to 70%
As body fat content increases, % of lean tissue decreases and total body water decreases; extremely lean athletes: 70%
What is the antidiuretic hormone (ADH)?
Secreted by the pituitary gland when blood concentration of solutes is high.
Tells kidneys to reduce water excretion which increases in blood volume.
What is aldosterone?
Produced by adrenal glands when blood volume is low.
Tells kidneys to conserve sodium and water which increases blood volume.
What is angiotensin?
Hormone that signals adrenal glands to produce aldosterone and thus conserve sodium and water, increases blood volume.
What are the functions of sodium?
- digestive tract absorbs almost all consumed
- adds flavour to and preserved foods
- attracts water to maintain fluid balance
- helps nerve impulse conduction
- helps absorption of some nutrients such as glucose
What are the functions of potassium?
- maintaining water balance
- nerve impulse transmission
- principle positively charged intracellular ion
- increasing potassium intake can lower blood pressure
What are the functions of chloride?
Primary negatively charged ion in extracellular fluid
Functions:
- acid-base balance: component of stomach acid (HCI)
- immune response: used as white blood cells attach to foreign cells
- nerve function
