Renal Physiology Flashcards
What is Wilm’s tumor?
A tumor of the kidney found in childhoood that is associated with aniridia and related ocular complications
How many Wilm’s tumor cases occur in the US annually?
500
How do the kidneys regulate osmotic pressure?
Excreting dilute or concentrated urine
The kidneys regulate what molecules?
Na, K, Ca, Mg, Cl, HCO3, PO4, and SO4
What do the kidneys eliminate from the system?
waste products - urea, uric acid, creatinine
Drugs and toxins
The kidneys produce ______ and vitamin _
Erythropoietin and Vitamin D3
The kidneys degrade ____ and ___
insulin and PTH
The kidneys help regulate the acid/base balance by synthesizing _______
ammonia
How do the kidneys regulate extracellular fluid?
By controlling Na and water excretion
The kidneys adjust blood pressure by regulating __ excretion and producing ____
regulating Na excretion
producing renin
The kidneys synthesize ____ and _____ which affect renal blood flow and Na excretion
Prostaglandins and kallikreins
Total body water makes up __% of body weight
60%
In regards to body fluid, the intracellular compartment makes up __% of body weight while the extracellular compartment make up __%
intracellular - 40%
extracellular - 20%
What are the major electrolyte cations?
Na, K, Ca, Mg
What are the major electrolye anions?
Cl, HCO3, PO4, SO4
What does the macula densa of distal convoluted tubule do?
monitors composition of fluid in the tubular lumen
What do the extraglomerular mesangial cells do?
Transmit information from macula densa to granular cells
What is another name for the extraglomerular mesangial clles?
Lacis cells
What do the granular cells do?
Synthesize renin
What are granular cells made of? Where are they located?
Modified smooth muscle cells with epithelioid appearance located in afferent arteriole close to glomerulus
The JG (granular) cells secrete renin in response to what?
- Beta-1 adrenergic stimulation
- Reduced renal perfusion pressure
- Decreased NaCl reabsorption by the macula densa
Reduced renal perfusion pressure is detected directly by _____
JG cells
NaCl reabsorption by the macula densa is due to _____
reduction in glomerular filtration rate (GFR)
Excreted = ____ - ____ + ____
Excreted = filtered - reabsorbed + secreted
The clearance of substrate is equal to what?
[(Urine concentration of substance) x (urine flow rate)] / (plasma concentration of substance)
What is the glomerular filtration rate (GFR)?
Rate at which plasma is filtered by the glomeruli
Inulin clearance is the same thing as what?
the Glomerular filtration rate
What are the normal values of the Glomerular filtration rate?
110 - 125 mL/min
What fructose polymer is used to measure GFR?
inulin
Why is inulin ideal to measure GFR?
- Freely filterable by glomeruli
- Not reabsorbed or secreted by tubules
- Not synthesized, destroyed, or stored in kidneys
- Nontoxic
- Concentration in plasma and urine determined by simple analysis
A clearance ratio of >1 indicates what?
Secretion
A clearance ration of <1 indicates what?
Reabsorption
Creatinine is a derivative of what substance?
creatine phosphate
Why is the relationship between GFR and plasma creatinine inversely related?
the kidneys continuously clear creatinine from the plasma
Creatinine adds __% to urinary values
20%
What is the glucose threshold in urine?
200 mg%
What two mechanisms do the kidneys use to autoregulate renal blood flow?
Myogenic mechanism
Tubuloglomerular feedback mechanism
Is there more renal blood flow in the cortex or the medulla?
cortex
How many liters per minute flow through the renal system?
1.2L / min
What are the five major vasoconstrictors related to renal blood flow?
Adenosine Angiotensin II Endothelin Thromboxane Vasopressin
What are the six major vasodilators related to renal blood flow?
Atrial natriuretic factor Dopamine Histamine Kinins NO Prostaglandins
How does the Myogenic mechanism help autoregulate blood flow?
Increased pressure stretches vessels and opens cationic channels resulting in depolarization and calcium influx
How does the tubuloglomerular feedback mechanism help autoregulate blood flow?
Increased pressure increases GFR -> increases NaCl reabsorption and ATP release from macula densa.
What do the negative ions in the barrier of the Glomerulus do?
Restrict the filtration of negatively charged compounds such as albumin
What is the driving force for reabsorption of solutes and water in the proximal convoluted tubule?
Na reabsorption by Na / K ATPase
