Renal Structure and Function Flashcards
Which metabolic waste products are excreted by the kidneys?
- Urea
- Uric acid
- Creatinine
- Bilirubin
How is urea produced?
Proteins -> Amino acids-> NH2 removed-> forms ammonia-> liver convert ammonia to urea
Uric acid is produced from _________ catabolism.
Nucleic acid
Creatinine is produced from _______ catabolism.
Creatine phosphate
Azotemia
Nitrogenous wastes in blood
Uremia
Toxic effects as wastes accumulate
There are two types of bilirubin. What are they and where are they located?
-
Unconjugated (indirect) bilirubin
- Created from rbc breakdown
- Travels in the blood to the liver
-
Conjugated (direct) bilirubin
- Bilirubin once it reaches the liver
- Undergoes a chemical change
- Moves to the intestines before being removed through your stool
Normal total bilirubin
- Under 18: 1 mg/dl
- Over 18: 1.2 mg/dl
- In urine: <1 mg/dl
NOTE: Normal results for conjugated bilirubin should be less thab 0.3 mg/dl
Normal serum creatinine concentrate
0.6 to 1.2 mg/dL
Normal BUN concentration
8 to 25 mg/dL
BUN to creatinine ratio is elevated in ____________.
Preranal acute kidney injury
NOTE: An elevated level would be a ratio greater than 20:1
Pre-Renal vs. Post-renal acute kidney injury
-
Pre-Renal
-
Inadequate Perfusion
- Not enough blood at sufficient pressure to allow filtering
-
Inadequate Perfusion
-
Renal
-
Cellular Damage/Intristic
- Damage to the cells that make filtering mechanism possible
-
Cellular Damage/Intristic
-
Post- Renal
-
Obstruction
- Urine unable to drain adequately-system “backed up”
-
Obstruction
Which chemicals are excreted from the kidneys?
- Pesticides
- Food additives
- Toxins
- Drugs
What hormones are produced in the kidney?
- Renal erythropoetic factor
- 1,25 dihydroxycholecalciferol (Vitamin D)
- Renin
What hormones are metabolized and excreted by the kidney?
- Most peptide hormones
Examples: Insulin, angiotensin II, etc.
How do the kidneys regulate erythrocyte production?
- Decreased O2 delivery to kidney
- Increased erythropoetin
- Increased erythrocyte production in kindeys
The kidneys produce the ___ (active/inactive) form of vitamin D.
Active
*1,25 dihydroxy vittamin D3
Vitam D3 is important in ___ and _____ metabolism.
Phospahate; calcium
How do kidneys regulate acid- base balance?
- Excrete acids
- Regulate body fluid buffers
NOTE: KIdneys are the only means of excreting non-volatile acids
Kidneys role in gluconeogenesis
Kidneys synthesize glucose from precursors during prolonged fasting
How do kidneys regulate arterial pressure?
Endocrine organ
- Renin-angiotensin system
- Prostoglandins
- Kallikrein-kinin system
Control of extracellular fluid volume
Nephron Tubular Segments

Function of proximal convoluted tubule
Reabsorption of water, ions, and all organic nutrients
Function of distal convoluted tubule
Secretion of ions, acids, drugs, toxins
NOTE: Distal convoluted tubules also have reabsorption ability of water, sodium ions, and calcium ions, under hormonal control
Function of collecting duct
Variable reabsorption of water and reabsorption or secretion of sodium, potassium, hydrogen, and bicarbonate ions
Function of renal corpuscle
Production of filtrate
Function of Loop of Henle
- Further reabsorption of water (descending limb) and both sodium and chloride (ascending limb)
Function of papillary duct
Delivery of urine to minor calyx
What are the basic mechanisms of urine formation?
- Filtration
- Reabsorption
- Secretion
- Excretion

Distinguish between the variability and selectivity of filtration, reabsorption, and secretion.
Filtration
- Somewhat variable
- Not selective
Reabsorption
- Highly variable
- Selective
Secretion
- Highly variable
Renal Handling of Different Substances

Renal Handling of Water and Solutes
NOTE: Glomerular filtration rate decreases with age, which can lead to varies stages of kidney disease
What affect can NSAIDs have on glomerular filtration rate?
Decrease
- NSAIDs block the protective prostaglandin effect. GFR is not maintained. Acute kidney injury can ensue
NOTE: In the absence of NSAIDs, in the setting of decreased effective circulating volume, the afferent arterioles vasodilate via prostaglandin whileefferent arterioles vasoconstrict. GFR is maintained
__________ are the primary regulators of the extracellular fluid volume.
Kidneys
How do the kidneys control blood pressure?
By increasing the ECF
NOTE: Kidneys maintain blood plessure by keeping fluid balance and metabolite balance
Createnine is used to measure__________.
Glomerular filtration rate
What factors to can lead to a decrease in perfusion?
- Decrease in blood pressure
- Increase in resistance for efferent arteriole
What are the major stimuli for the renin-angiotensin system?
- Low blood pressure
- Decrease in salt
- Hyperkalemia
Mechanism by which low salt leads to an increased production of aldosterone
- Low salt stimulates renin
- Renin produces angiotensin I
- That is converted to angiotensin II
- Angiotensin II stimulates the adrenal cortex to release aldosterone
- Aldosterone acts of Na-K- ATPase that is on the basal lateral membrane to promote sodium reabsorption and potassium secretion
The cortex contains ______ of the blood supply in the kidney.
80%
Outside of the colelcting duct is the _______, which serves as a reservoir for the filtration to travel into the pelvis and then into the ureters.
Minor calyx
What the two capillary beds of the kidneys and what takes place in each?
-
Glomeruli capillary
- Where filtration takes place
-
Peritubular capillary
- Where reabsorption and secretion occurs
NOTE: The afferent arteriole brings blood into glomeruli capillary where it is filtered. The remaining blood from the glomerular capillary and goes back to efferent arteriole and back to circulation
Tubular glomerular feedback mechanism
States that the filtrate that travels in the proximal tubule, and loop of henle goes across the macula densa cells. These cells sense sodium concentration and flow rate.
Is the proximal tubule considered hypo-osmotic, hyper-osmotic, or iso-osmotic?
Iso-osmotic
*This means that reabsorbing water and electrolytes in similar concentration and the reabsorption of filtrate has the same osmolarity as the plasma