T/F: Movements of nutrients, respiratory gases, & wastes are typically unidirectional.
T/F: Osmolarities of all body fluids are equal.
Increasing extracellular fluid (ECF) content can be expected to cause
a shift in water out of the cells
Intracellular fluid volume is determined by the
Extracellular fluid (ECF) solute concentration
T/F: For the body to remain properly hydrated, water intake must be equal to water output.
Most water enters the body through..
ingested liquids & solid foods.
Body water produced by cellular metabolism is called
metabolic water (or water of oxidation)
Water that vaporizes out of the lungs in expired air or diffuses directly through the skin is called
insensible water loss
A rise in plasma osmolarity triggers:
1) thirst (which prompts us to drink water) 2) release of antidiuretic hormone (ADH), which causes kidneys to conserve water & excrete concentrated urine
A decline in plasma osmolarity...
inhibits thirst & ADH release
The driving force for water intake.
The thirst mechanism
Output of certain amounts of water is unavoidable. These outputs are known as
obligatory water losses
______________ help explain why we cannot survive for long without drinking.
Obligatory water losses
Obligatory water loss includes:
insensible water losses & sensible water losses
The body's water volume is closely tied to a powerful water magnet known as
ionic sodium (Na+)
Factors that trigger ADH release by reducing blood volume include:
-prolonged fever -excessive sweating -vomiting or diarrhea -severe blood loss -traumatic burns (under these conditions ADH also acts to constrict arterioles which directly increases blood pressure; hense ADH's other name, vasopressin)
Principle abnormalities or disorders of water balance are
-Dehydration -Hypotonic hydration -Edema
When water output exceeds intake over a period of time & the body is in negative fluid balance, the result is
______________ is in which plasma proteins pass through "leaky" renal filtration membranes and are lost in urine.
What happens when lymphatic vessels are blocked?
-The small amount of plasma proteins that seep out of the blood stream are not returned to the blood as usual -As leaked proteins accumulate in the IF, they exert an increasing colloid osmotic pressure, which draws fluid from the blood & holds it in the interstitial space
Edema can impair tissue function because
excess fluid in the interstitial space increases the distance nutrients and oxygen must diffuse between the blood & the cells
The most serious problems resulting from edema affect what system?
The salt balance of the body is known as
What are the functions of salt in the body?
-important in controlling fluid movements -provide minerals essential for excitability, secretory activity, and membrane permeability
Salts are lost from the body in..
perspiration feces urine
disorder entailing deficient mineralcorticoid hormone production by the adrenal cortex
The appetite for abnormal substancs such as chalk, clay, starch, or burnt match tips is known as
____________ holds a central position in fluid and electrolyte balance and overall body homeostasis
In normal plasma, _______ is the single most abundant cation in the ECF and the only one exerting significant osmotic pressure.
T/F: While sodium content of the body may change, its ECF concentration normally remains stable.
True (because of immediate movement of water into or out of the ICF and longer-term adjustments due to the ADH & thirst mechanisms)
T/F: Salt follows water.
False; water follows salt!!
Regulation of the Na+-water balance involves a variety of ________ & _________ controls.
neural & hormonal controls
What hormone "has the most to say" about renal regulation of sodium ion concentration in the ECF?
Aldosterone's central role
maintaining blood volume & blood pressure
T/F: Water always follows Na+
T/F: Aldosterone increases ECF volume
The most important trigger for aldosterone release from the adrenal cortex is...
the renin-angiotensin mechanism mediated by the juxtaglomerular apparatus of the renal tubules
What 3 situations make the juxtaglomerular apparatus respond by making its granular cells to release renin?