Chapter 27 Flashcards
Body fluid
Consists of water and dissolved solute constitutes between 55 and 60% of total body mass
What are the parts of extra cellular fluid?
80% is interstitial fluid and 20% is blood plasma
What are the two general barriers that separate intracellular fluid, interstitial fluid and blood plasma?
Plasma membrane and blood vessel walls
Thirst center
Found in the hypothalamus governs the urge to drink
What’s the main factor that determines body fluid volume?
Urinary salt (NaCl) loss
What’s the main factor that determines body fluid osmolarity?
The extent of urinary water loss
What is antidiuretic hormone also known as?
Vasopressin
What are the two most important hormones that regulate the extent of renal sodium reabsorption and thus how much is lost in the urine?
Aldosterone and atrial natriuretic peptide
Aldosterone
Increases sodium reabsorption in the late distal tubules and collecting ducts of the kidneys which relieves the sodium deficiency in the plasma
Occurs after a decrease in blood pressure
Atrial natriuretic peptide
Occurs with an increase in blood volume
Stretching of the atria of the heart promotes the release
Promotes natriuesis; elevated excretion of sodium into the urine
What can increase the osmolarity of extra cellular fluid?
A salty meal
A decrease in the osmolarity of extra cellular fluid can occur from what?
Drinking a large volume of water
Water intoxication
A state in which excessive body water causes cells to swell dangerously
What are the four general functions in the body when electrolytes dissolve and dissociate?
- Because they are largely confined to particular fluid compartments then non-electrolytes certain ions help control the osmosis of water between fluid compartments
- Ions help maintain the acid base balance required for normal cellular activities
- Ions carry electrical current which allows production of action potentials and graded potential’s
- Several ions serve as co-factors needed for optimal activity of enzymes
Sodium
Most abundant ion in extracellular fluid
Accounts for half of the osmolarity an extra cellular fluid
Necessary for generation and conduction of action potentials in neurons and muscle fibres
Kidneys excrete and conserve sodium as necessary
Sodium is controlled in the blood by aldosterone, antidiuretic hormone, and atrial natriuretic peptide