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Physiology-Osmoregulation
Exam 3
22
Physiology
Undergraduate 3
12/01/2013

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Term
osmolarity
Definition
number of osmoles/liter of solution
Term
osmole
Definition
number of moles of a chemical compound that contributes to its osmotic pressure
Term
ionic gradient
Definition
ions move along a concentration gradient (high to low concentrations)
contributes to osmotic pressure
Term
hypotonic
Definition
low extracellular solute concentration, water flows in
Term
isotonic
Definition
same solute concentration in and out of cell, no net flow of water
Term
hypertonic
Definition
high extracellular solute concentration, water flows out, plasmolysis
Term
osmoconformers
Definition
maths the internal osmotic pressure to external osmotic pressure
larger tolerance range

positive linear relationship tolerance range
Term
osmoregulators
Definition
maintain internal osmotic pressure, even when external osmotic pressure changes

horizontal tolerance range -----________-----
Term
tolerance range
Definition
range of conditions in which you wont die
Term
fluids of cell
Definition
intercellular fluid: within cells
interstitial fluid: outside of cells
lymph/plasma: coming from heart
Term
types of osmotic exchange
Definition
1. obligatory osmotic exchange
-routes of water loss: respiratory, urinary, fecal
-dessication

2. regulatory
-ATPase pumps: active transport across membrane, expensive (Na/K, H proton pump)
-Symporters/cotransporters: transport proteins when things are moving in same direction (Na/glucose, NaKClCl)
-Antiporters: transport proteins when things are moving in opposite directions (Na/H)
-Protein Channels
Term
Effect of food and water on osmoregulation
Definition
-catabolism
-salt content of food
-salt content of drinking water
-protein content of food (protein catabolism creates nitrogenous waste)
Term
Kinds of Waste
Definition
-ammonia: cheap, toxic (aquatic animals)

-urea: more expensive, soluble in water, less toxic (mammals)

-uric acid: expensive, low water solubility (insects, reptiles, birds, humans during purine metabolism--kidney stones or gout)
Term
types of osmoregulatory systems
Definition
1. Secretory System
2. Filtration-Reabsorption System
Term
Secretory System
Definition
-can generate export mechanisms to move out specific things

-in marine fish, freshwater fish, insects
Term
Filtration-Reabsorption System
Definition
-dumps everything through a filter to catch larger things
-lose good and bad, must bring good things back in (requires energy)
-more expensive in long run

-in vertebrate kidneys
Term
Kidney Anatomy
Definition
Nephron: secretes plasma, where absorption of H2O and salt happens; helps create proper concentration of urine
-glomerulus
-Bowman's capsule: wraps around glomerulus
-proximal convoluted tubule
-afferent arteriole (in)
-efferent arteriole (out)
Term
Renal circulation
Definition
-completely arteriole capillaries
-designed to maintain pressure
-paratubular capillaries wrap around nephrons
Term
process of urine production
Definition
1. Glomerular filtration
-creation of filtrate, happens at junction, lose 20% of plasma not proteins

2. Tubular reabsorption
-reacquire tools/things you don't want to lose

3. Tubular secretion
-salt balance
-acid-base balance in body

Humans produce 180 liters of filtrate a day, but only 1 liter of urine; filtered water is reabsorbed
Term
Nephron anatomy
Definition
Loop of Henle: creates concentration gradient for urine components
-Descending: low Na permeability (not moving), low urea permeability (not moving), high Water permeability (moving out of tubule)
-Ascending: high Na permeability (moving out of tubule), low Water permeability (not moving)

Distal tubule
-moving K, H, NH3 into tubule for excretion (lumen)
-uptake NaCl into plasma (based on hormonal control)
-HCO3 moves into interstitial space

Collecting duct
-permeable to Water, variable
-NaCl moves out (takes energy)
-Urea moves out

Concentration
-Fluid is iso-osmotic relative to local interstitial fluid
-Gradients in interstitial fluid create hypo-osmotic, iso-osmotic, or hyper-osmotic urine
Term
Loop of Henle
Definition
1. NaCl actively transported out of tubule
2. Osmotic water loss via salt impermeable membrane
3. Urea leaks out of permeable collecting duct membrane
4. Water follows osmotic pressure, making higher solute concentrations at bottom of the loop

As you move from outside of interstitial space into center of kidney, concentration of Na, Cl, and Urea skyrocket
Term
Control of Urine Concentration
Definition
-Renin: interacts with inactive Angiotensinogen, becomes Angiotensin I, converted by an enzyme to be activated Angiotensin II

-Angiotensin II stimulates adrenal cortex to release Aldosterone

-Aldosterone increases Na reabsorption into blood, which increases blood pressure

-Angiotensin II also causes vasoconstriction which increases blood pressure by:
increasing arterial pressure via volume reduction
increasing arterial pressure via increased stroke volume due to venous return because of venous vasoconstriction

-vasopresin: increases arterial pressure and water permeability
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