BIOL 261 FINAL CHP 16 Flashcards
What 3 pressures contribute to a +10 mmHg filtration pressure in the renal corpuscle:
- glomerular hydrostatic pressure (55 mm Hg)
- colloid osmotic pressure (30 mm Hg)
- capsular hydrostatic pressure (15 mm Hg)
Why do we need to regulate GFR?
- if its too high, needed substances cannot be reabsorbed quickly enough and are lost in the urine
- if too low, everything is reabsorbed, including wastes that are normally disposed of
If we change MAP how does that affect GFR?
- GFR stays constant
- JG apparatus releases renin **
How is GFR regulated under myogenic response?
- as BP increases-> GFR increases-> afferent arteriole constricts->GFR decreases
- as BP decrease->GFR decreases->afferent arteriole dilates->increase in GFR
How is GFR regulated under tubuloglomerular regulation?
- if Na is high in DCT->GFR increases->afferent arteriole constricts
- if Na is low in DCT->GFR decreases->afferent arterioles vasodilate
How is GFR regulated under ANS?
- sympathetic NS (Epi + NE)-> vasoconstricts
- angiotensin 2->vasoconstrictor afferent arteriole
When BP changes, _______ stays the same regardless.
Filtration rate
Renin released from JG apparatus when: (2)
- aff. art. MAP drops
- macula densa cells sense low plasma osmolarity or LOW Na
- increased urine output
What is reabsorbed in the PCT?
- amino acids
- Na
- glucose
- bicarbonate
What is secreted in the PCT?
- antibioitics
- creatinine
- uric acid
What is reabsorbed at the DCT and what hormone is responsible for that?
sodium-aldosterone; calcium-PTH
How is glucose handled in the PCT?
Reabsorbed
Ascending loop of henle is permeable to:
Na, impermeable to water
What is secreted in the DCT?
Urea and protons
Positive homeostatic feedback loop for blood osmolarity:
Stimulus: Decrease in Blood Osmolarity (overly hydrated)
Sensor: Osmoreceptors in hypothalamus
Integrator: Hypothalamus/ posterior pituitary gland
-Inhibits Antidiuretic Hormone-
Effector: Collecting ducts of nephron
Response: Decrease in aquaporin, decrease in H2O reabsorption, increase in urine output.
Result: Increase in blood osmolality
Water is reabsorbed into the collecting duct due to AHD. How does that effect blood osmolarity and urine output?
Decreases blood osmolarity and urine output
Normal acid-base balance of blood in nephron is:
7.35-7.45
How does the nephron regulate pH of blood?
- pH < 7.35 = acidosis
* pH > 7.45 = alkalosis
Negative homeostatic feedback loop for blood osmolarity:
Stimulus: Increase in Blood Osmolarity (dehydrated)
Sensor: Osmoreceptors in hypothalamus
Integrator: Hypothalamus/ posterior pituitary gland
-Releases Antidiuretic Hormone-
Effector: Collecting ducts in nephron
Response: Increase in aquaporin, increase in H2O reabsorption, decrease in urine output.
Result: Decrease in blood osmolality
Acid-base balance affect on pH of urine:
Adds more H+-> more acidic
Osmolarity of blood is:
300 mOsm/liter
PCT:
70% of water and ions reabsorbed
How does diabetes mellitus act as a diuretic and how does that effect urine output?
Due to the glucose pulling water back into the urine
Increased urine output
How does diabetes mellitus cause glucosurea?
Increased blood glucose due to not enough insulin to balance sugar levels
When does DM cause glucosurea?
When renal threshold is past 175 mg/dl of plasma-> hits threshold->saturates filtrate with glucose
How does going deeper into the renal medulla cause an increase in osmolarity?
As you go deeper into the medulla, it becomes saltier and you have more urea so your osmolarity increases and most of the water gets reabsorbed due to high osmolarity
In the ascending loop, what is not possible?
Osmosis
What causes you to pull in Ca from your urine?
Parathyroid hormone
H+ and HCO3 filtered from the glomerulus combine to make:
Carbonic acid
Carbonic acids splits into:
Bicarbonate and protons
What are you doing in the PCT?
Reabsorbing bicarbonate and kicking out H+
How does the kidney change urine filtrate osmolarity through the PCT->DCT
300 mOsm/liter in PCT-> 100mOsm/liter in DCT
Water gets pulled in at:
Descending limb
