Term
| Where do selective changes in tubular filtrate occur? |
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Definition
| loop of henle, some in DT |
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Term
| 3 Main mechanisms that alter urine concentration |
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Definition
-hypotonic medullary interstitium
-dilution of tubular fluid in ascending LoH & distal tubule
-collecting ducts selectively permeable to water in response to ADH/vasopressin |
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Term
| What structure removes water from the medullary interstitium? |
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Definition
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Term
| What portion of the LoH is impermeable to water? |
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Definition
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Term
| If salt concentration in the tubule is decreasing, while the concentration in the blood increases, what portion of the loop of henle are we in> |
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Definition
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Term
| If salt concentration in the tubule is increasing, while the concentration in the blood decreases, what portion of the loop of henle are we in> |
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Definition
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Term
| What region of the Loop of Henle is considered the 'diluting' segment? |
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Definition
| ascending - Na is pumped out in to the interstitium leaving water in the tubule |
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Term
| Is reabsorption of salt in the ascending loop of henle active or passive? |
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Definition
| active - uses Na/K/2CL co transporters to drive salt out |
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Term
| What role does ADH play in the collecting duct? |
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Definition
| regulates aquaporin activity to produce dilate or concentrated urine (makes them more permeable to water to promote reabsorption) |
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Term
| What does aldosterone do & where does it act? |
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Definition
| enhances reabsorption of Na+ and secretion of K+ in the collecting ducts |
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Term
| How does vasopressin / ADH work? |
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Definition
1. Vasopressin binds to mmb receptor
2. cAMP messenger pathway activated
3. AQP2 water pores inserted into mmb
4. Water reasborbed by osmosis into the blood |
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Term
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Definition
| urine osmolality is equal to plasma osmolality |
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Term
|
Definition
| urine osmolality is lower than plasma osmolality |
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Term
| What is pressure natriuresis |
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Definition
| Changes in blood pressure within the kidney's vascular system when directly alters Na+ excretion |
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Term
| How does the body sense/respond to changes in water or fluid volunme? |
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Definition
Pressure natriuresis
AND
Sensors in body that detect changes in BP & osmolarity, and will lead to secretion of hormones that regulate Na+ levels |
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Term
| What hormone drives thirst? |
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Definition
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Term
| In regulating body fluid, osmoreceptors will detect changes in blood solute concentration and direct the secretion of _____ to target the urinary H2O and H2O intake (thirst) systems. |
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Definition
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Term
| How is the hypothalamus involved in regulating plasma and ECF osmolality? |
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Definition
1. Changes in osmolality trigger changes in size of chemoreceptor neurons in hypothalamus
2. Shrinking of cells increases ADH release
3. ADH increases water reabsorption in kidney, stimulates thirst |
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Term
| Where is vasopressin/ADH secreted from? |
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Definition
|
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Term
| Where are low-pressure mechanopreceptors found? |
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Definition
| cardiac atria & pulmonary vessels |
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Term
| What causes antrial natriuretic peptide to be released? What is it's general role? |
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Definition
Increase in blood pressure/blood volume in the cardiac atria & pulmonary vessels
-promotes elimination of Na+ (and subsequently water) to reduce blood volume |
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Term
| ANP directly decreases the secretion of... |
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Definition
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Term
|
Definition
-dilates afferent glomerular arteriole, constricts efferent
-decreases Na reabsorption in DCT & collecting duct
-increases blood flow through vasa recta (decreases osmolarity of medullary interstitium)
-leads to increased fluid secretion
-decreases secretion of renin & aldosterone |
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Term
| What hormone is secreted in response to an increase in blood pressure? |
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Definition
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Term
| What hormone is initially secreted in response to a decrease in blood pressure? |
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Definition
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Term
|
Definition
-decrease perfusion pressure in the justaglomerular apparatus
-increase activity of carotid pressure sensors
-decrease NaCl delivery to macula densa cells
-increases angiotensin levels = increased aldosterone secretion
-promotes more ADH secretion |
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|
Term
| Where does angiotensin II act? |
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Definition
|
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Term
| Where does aldosterone act? |
|
Definition
| distal tubules & collecting ducts |
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Term
| In the proximal tubule, ______ stimulates Na+/K+ ATPase while _____ and ______ stimulate Na+/H+ exhangers in the luminal membrane |
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Definition
norepinephrine
angiotensin II & norepinephrine |
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Term
| What region of the adrenal cortex produces aldosterone? |
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Definition
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Term
| Aldosterine is part of the _____ family |
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Definition
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|
Term
| What does aldosterone do? |
|
Definition
promotes reabsorption of Na+ and water in the distal tubules & collecting ducts to increase blood volume & pressure
Also promotes secretion of potassium |
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Term
| Where are high-pressure baroreceptors found? What do they do? |
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Definition
aortic arch & carotid sinus
-change autonomic outflow to influence blood pressure |
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Term
| What are the 3 'sensors' of blood volume or pressure? |
|
Definition
Low-pressure mechanoreceptors (volume)
High-pressure baroreceptors (pressure)
JG cells of kidney |
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|
Term
| How is potassium regulated in the body? |
|
Definition
-move back and forth between extracellular and intracellular compartment
-Potassium loading (rapid uptake by cells to prevent increase in plasma concentrations), then release slowly later on |
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Term
| What hormones shift K+ in to cells? |
|
Definition
Epinephrine
Insulin
Aldosterone |
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Term
| Acidosis causes an (increase/decrease) in plasma K+ |
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Definition
|
|
Term
|
Definition
| cell lysis resulting in a release of K+ into the extracellular compartment (tying up) |
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Term
| 70% of K+ is reabsorbed in the ____ and another 20% in the _____ |
|
Definition
proximal convoluted tubule
ascending LoH |
|
|
Term
| K+ secretion occurs primarily in.... |
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Definition
|
|
Term
| What effect does aldosterone have on K+ update? |
|
Definition
|
|
Term
| How does sodium get transported into DCT & collecting ducts? |
|
Definition
|
|
Term
| How is potassium excretion regulated? |
|
Definition
1. High K+ = increased aldosterone secretion = increased K+ secreton
2. High K+ = direct stimulation of K+ secretion by tubular cells
3. Increased tubular flow = lower K+ concentration = increased K+ secretion |
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Term
| What test is used to asses GFR, and what does it tell us? |
|
Definition
BUN/creatinine/inulin clearance
High plasma concentration indicates low GFR |
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Term
| What test is used to assess tubular function and what does it tell us? |
|
Definition
specific gravity of urine
Poor concentrating ability indicates problem with tubular function |
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Term
| What test is used to assess electrolyte regulation and what does it tell us? |
|
Definition
Abnormal Na+, K+ levels
Abnormal levels indicate a problem with GFR or tubular reabsorption |
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Term
| What test is used to assess water balance and what does it tell us? |
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Definition
dehydration
indicates inability to concentrate urine (can't reabsorb water properly) |
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Term
| What test is used to assess erythropoietin production and what does it tell us? |
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Definition
anemia
indicates inability of JG cells to produce EPI |
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Term
| What is hyperphosphatemia? |
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Definition
| increase in phosphate in the blood, indicating a decrease in GFR |
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Term
| Why is Vit D metabolism important? |
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Definition
| Vit D regulates calcium levels in the blood |
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Term
| Anemia may indicate a problem with what part of the kidney? |
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Definition
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