BIOL373 - UNIT 4C: INTEGRATED CONTROL OF WATER AND
ELECTROLYTE HOMEOSTASIS I EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS GRADED A++
What electrolytes is the kidney involved in in terms of homeostasis?
1. ECF volume through Na+ and K+
2. K+ for excitability of muscle and nerves
3. acid base balance by H+
4. Ca2+ ECF ion important for neural function
5. HPO4 and HCO3
How are kidneys involved in behavioral mechanisms?
By driving thirst and salt appetite
What is the homeostatic defense of decreased blood volume/pressure?
low pressure volume :
1. cardiovascular response by baroreceptors causing vasoconstriction (fast)
2. kidneys retain more H2O to try and increase volume (slow)
3. behavioral: increase water intake by thirst to increase ECF and ICF to fix BP
What is water balance?
water consumed (majorily food & drink but also metabolism) = water lost (urine > skin
sweat > lungs breathing > feces)
When is skin and lungs increased in terms of water loss?
, In an extremely dry environment
When is feces increased in terms of water loss?
diarrhea
Why can't kidneys restore lost water but can conserve water?
*** figure out this image
What are the general strategies for regulating urine osmolarity?
1. vasopressin on distal nephron
2. regulation of vasopressin release
3. formation of salt gradient in medulla
True or false: every single nephron has a collecting duct that passes through the
renal medulla
true
How does osmolarity change in the filtrate?
1. proximal tubule = 75% water & solute are reabsorbed
2. descending loop = H2O is brought back in vasculature but not solute
3. ascending loop = solute is brought back in vasculature but not H2O.
4. causes low solute in filtrate = hypoosmotic filtrate
5. distal nephron (distal tubule + collecting duct) = tweak final outcome according to
body needs; regulate H2O by hormones
6. depending on needs of body (distal nephron), we can vary osmolarity of urine
excreted between 5-1200 mOsM/L
True or false: osmolarity increases deeper in the medulla
ELECTROLYTE HOMEOSTASIS I EXAM QUESTIONS AND
ANSWERS WITH COMPLETE SOLUTIONS GRADED A++
What electrolytes is the kidney involved in in terms of homeostasis?
1. ECF volume through Na+ and K+
2. K+ for excitability of muscle and nerves
3. acid base balance by H+
4. Ca2+ ECF ion important for neural function
5. HPO4 and HCO3
How are kidneys involved in behavioral mechanisms?
By driving thirst and salt appetite
What is the homeostatic defense of decreased blood volume/pressure?
low pressure volume :
1. cardiovascular response by baroreceptors causing vasoconstriction (fast)
2. kidneys retain more H2O to try and increase volume (slow)
3. behavioral: increase water intake by thirst to increase ECF and ICF to fix BP
What is water balance?
water consumed (majorily food & drink but also metabolism) = water lost (urine > skin
sweat > lungs breathing > feces)
When is skin and lungs increased in terms of water loss?
, In an extremely dry environment
When is feces increased in terms of water loss?
diarrhea
Why can't kidneys restore lost water but can conserve water?
*** figure out this image
What are the general strategies for regulating urine osmolarity?
1. vasopressin on distal nephron
2. regulation of vasopressin release
3. formation of salt gradient in medulla
True or false: every single nephron has a collecting duct that passes through the
renal medulla
true
How does osmolarity change in the filtrate?
1. proximal tubule = 75% water & solute are reabsorbed
2. descending loop = H2O is brought back in vasculature but not solute
3. ascending loop = solute is brought back in vasculature but not H2O.
4. causes low solute in filtrate = hypoosmotic filtrate
5. distal nephron (distal tubule + collecting duct) = tweak final outcome according to
body needs; regulate H2O by hormones
6. depending on needs of body (distal nephron), we can vary osmolarity of urine
excreted between 5-1200 mOsM/L
True or false: osmolarity increases deeper in the medulla
