Fluid Balance Flashcards
What 3 major factors does blood composition depend on? (3)
- Diet
- Cellular metabolism
- Urine output
What are the 4 major roles that kidneys have in keeping the blood constant? (4)
- Excretion of nitrogenous wastes
- Ensuring proper blood pH
- Maintaining the water balance of the blood
- Maintaining the electrolyte balance of the blood
In a young, healthy adult, how much does water account for in women and in men? (2)
- Women - 50% water
2. Men - 60% water
How many main locations does water occupy and what are the locations called all together? (2)
- Three main locations
2. Fluid components
How much of the body fluid is intracellular fluid?
2/3 of the body fluid
What does it mean when fluid is “intracellular”?
The fluid is contained within living cells
What does it mean when fluid is “extracellular”?
The fluid is contained outside of living cells
How much of the body fluid is extracellular?
1/3 of the body fluid
What is included in extracellular fluid? (4)
- Blood plasma
- Interstitial fluid
- Cerebrospinal fluids
- Serous fluids
What does plasma serve as while it circulates through the body delivering substances?
A highway that links the internal and external environments
What links the internal and external environments?
Plasma
Where does most of our body fluid come from?
Fluids and foods we ingest in our diet
How much water is produced during cellular metabolism?
About 10% of the water in our body
What is the driving force for water intake?
Thirst mechanism
Describe the thirst mechanism. (2)
- Highly sensitive cells in the hypothalamus (osmoceptors) are excited by an increase in plasma solute content
- Osmoreceptors activate the hypothalamic thirst center
How much of an increase in plasma solute is required to excite the osmoreceptors?
An increase in plasma solute content of just 2-3% is enough
Why does the mouth become dry when the thirst mechanism is active?
The salivary glands are obtaining the water that they rewire from the blood
List the 3 routes by which water leaves the body. (3)
- Vapourize out of the lungs
- Lost in perspiration
- Leaves the body by stool
What is reabsorption of water and electrolytes by the kidneys primarily regulated by?
Hormones
What happens when blood volume drops? (2)
- Arterial blood pressure drops
2. → decreases the amount of filtrate formed by the kidneys
What does antidiuretic hormone (ADH) do?
Prevent excessive water loss in the urine
How does ADH prevent excessive water loss in the urine?
ADH travels to the kidneys’ collecting ducts and causes the duct cells to reabsorb more water
Define: electrolytes
Charged particles (ions) that conduct an electrical current in an aqueous solution
What are 2 effects of electrolyte movement? (2)
- Alters blood volume and blood pressure
2. May severely impair the activity of irritable cells like nerve and muscle cells
Define: aldosterone
Hormone that helps to regulate blood composition and blood volume by acting on the kidney
