1 Renal Function Flashcards
System of the body whose primary goal is to excrete unwanted substances
Urinary system
Main function of urinary system
Excretion of unwanted substances
4 Main Components of Urinary System
Kidney
Ureter
Bladder
Urethra
Main component: filter
Kidney
Connects kidney and bladder
Ureter
Storage of urine
Bladder
functional unit of the kidney
Nephron
How many nephrons are present in EACH kidney
1-1.5 million
Types of Nephron
Cortical
Juxtamedullary
Types of nephron is based on
Location
Percentage of cortical nephron
85%
85% of nephron is known as
Cortical nephron
Type of nephron that removes waste and reabsorbs nutrients
Cortical nephron
Location of cortical nephron
Cortex
15% of nephrons are
Juxtamedullary
Juxtamedullary takes up ___% of nephrons
15%
Type of nephron where concentration of urine occurs
Juxtamedullary
Urinary filtrate flow (10)
- Bowman capsule
- Proximal convoluted tubule
- Descending loop of Henle
- Ascending loop of Henle
- Distal convoluted tubule
- Collecting duct
- Renal calyces
- Ureter
- Bladder
- Urethra
Renal blood flow
- Renal artery
- Afferent arteriole
- Glomerulus
- Efferent arteriole
- Peritubular capillaries
- Vasa recta
- Renal vein
Sites for water and salt exchange
Loop of henle
RENAL FUNCTIONS (4)
- Renal Blood Flow
- Glomerular Filtration
- Tubular Reabsorption
- Tubular Secretion
Human Kidney receives __% of the blood
25%
Human Kidney receives 25% of the blood from ____
Renal artery
Blood enters the nephron via
Afferent arterioles
average body surface
1.73 m^2
Total Renal Blood Flow
1200 mL/min
Total Renal Plasma Flow
600-700 mL/min
Coil of 8 capillary lobes
Glomerulus
Nonselective filter of plasma substances
Glomerulus
Factors influencing filtration process
Cellular Structure of the Glomerulus
Hydrostatic pressure
Oncotic Pressure
Feedback mechanism of RAAS
RAAS
Renin-angiotensin-aldosterone system
Based on cellular structure, Plasma filtrate must pass….
- Capillary wall membrane
- Basement membrane (basal lamina)
- Visceral epithelium of the Bowman’s Capsule
____ increase capillary permeability but do not allow passage of large molecules and blood cells
Pores
thin membranes covering the filtration slits
Podocytes
Foot processes
Podocytes
Principle: repels molecules with negative charge
Shield of negativity
Results from the smaller size of the efferent arterioles and the glomerular capillaries
Glomerular pressure
Regulates the blood flow to and within the glomerulus
Renin-Angiotensin-Aldosterone System (RAAS)
RAAS Respond to changes in
blood pressure and plasma sodium content
Respond to changes in the blood pressure and plasma sodium content
Renin-Angiotensin-Aldosterone System (RAAS)
Angiotensinogen are found where and it produces what
Plasma, produces angiotensin I
Angiotensin converting enzymes are found where
Lungs
Function of aldosterone
Sodium retaining
Sodium retaining hormone
Aldosterone
causes the kidneys to release less water (water reabsorption), decreasing the amount of urine produced.
Anti diuretic hormone
Substances are removed from the glomerular filtrate and returned to the blood
Tubular reabsorption
Two types of transport mechanism for tubular reabsorption
Active and passive transport
It is when the plasma concentration exceeds the renal threshold
Maximal reabsorptive capacity
Plasma concentration where the active transport stops
Renal threshold
Renal threshold for glucose
160-180 mg/dL
Active or passive? Location of reabsorption?
Glucose
Active, PCT
Active or passive? Location of reabsorption?
Chloride
Active, ALH
Substances for active transport
Glucose
Amino acid
Salt
Chloride
Sodium
Substances of passive transport
Water
Urea
Sodium
Where Renal concentration begins
Descending and Ascending Loop of Henle
Water is removed by osmosis in the
Descending Loop of Henle
Na and Cl are reabsorbed in the
Ascending Loop of Henle
Selective reabsorption process
Countercurrent Mechanism
Serves to maintain the osmotic gradient of the medulla
Countercurrent Mechanism
Involves the passage of substances from the blood in the peritubular capillaries to the tubular filtrate
Tubular secretion
One of its function is for Elimination of waste products not filtered by the Glomerulus
Tubular secretion
Tubular secree regulates acid base balance through secretion of ___
Hydrogen ions
Types of renal function test
Glomerular filtration test
Tubular reabsorption test
Tubular secretion and renal blood flow test
Test under glomerular filtration test
Clearance test
- creatinine
- cystatin C
- Beta 2-microglobulin
All Clearance Tests are examples of Glomerular Filtration Test except
Free water clearance
Measures the rate in milliliters per minute at which the kidneys are able to remove a filterable substance from the blood
Glomerular filtration test
Give some Characteristics of Substance to be tested for Glomerular Filtration Test
A. Should not be reabsorbed or secreted by the tubules
B. Substance must be stable for 24 hours
C. Plasma level should be constant
D. Substance should be available in the body
E. Availability of the tests to analyze the substance
Clearance Test in the Past
Urea CT
Inulin CT
polymer of fructose
Inulin
UREA CLEARANCE TEST require ___ hour sample
2
Earliest clearance test
Urea CT
Problem of urea clearance test
reabsorbed by the tubule (40%)
Disadvantage of Inulin clearance test
Exogenous, infused at constant rate
First step After confirming if the specimen is from the correct px
Measure volume
Test which Requires 24-hour sample
Creatinine clear test
Creatinine Clearance Test requires ___ hour sample
24
Endogenous procedure for evaluating glomerular filtration
Creatinine CT
Creatinine Clearance Formula
Urine creatinine conc ( mg/dL) x urine volume in ml/minute / plasma creatinine conc
Corrected Creatinine Clearance Formula
UV/P x 1.73/A
Reference range for Corrected Creatinine Clearance Formula
Male 107 – 139 mL/min
Female 87 – 107 mL/min
Used for routinely screening patients as part of a metabolic profile and to monitor patients already diagnosed with renal disease or at risk for renal disease
Estimated Glomerular Filtration Rates
Produced by all nucleated cell at constant rate
Cystatin C
Cystatin C are produced by
Nucleated cell
Filtered readily by the glomerulus and reabsorbed and broken down by the renal tubular cells
Cystatin C
Cystatin C is Filtered readily by the glomerulus and reabsorbed and broken down by the
renal tubular cells
Recommended: Pediatric patients, Elders, People with Diabetes, Critically-ill
Cystatin C clearance test
Dissociates from human leukocyte antigen at constant rate
Beta 2 micro globulin
Beta 2 micro globulin Dissociates from ____ at constant rate
human leukocyte antigen
Most sensitive indicator of a decrease in GFR
Beta 2 micro globulin
Used to determine the ability of the tubules to reabsorb essential salts and water that have been non-selectively filtered by the glomerulus
Concentration test
Principle: salts and water are reabsorbed in the tubules
Tubular Reabsorption Test
largely determined by the body’s state of hydration
Urine concentration
Sample of Tubular Reabsorption Test
Obsolete test
Osmolality
Freezing-Point Osmometers
Vapor Pressure Osmometers Specific Gravity Determination
Free Water Clearance
Test which uses reagent strip
Specific Gravity Determination
Test under obsolete test
Mosenthal Test
Fishberg Test
Measures only the number of particles in a solution
Osmolality
Free Water Clearance Formula
Urine Osmolality x volume / plasma Osmolality
Free water clearance
Positive result – _____
Negative result – _____
Zero result –______
Positive result – hydration Negative result – dehydration Zero result – no effect
Historical test for Tubular Secretion and Renal Blood Flow Test
Phenolsulfonpthalein Excretion Test (PSP)
Most commonly associated with the tubular secretion and renal blood flow
P-aminohippuric acid (PAH)
Indigo Carmine Test is for
Px with unilateral kidney disease
Reference range: Titratable Acidity and Urinary Ammonia
70 mEq/day
Oral acid load
Ammonium chloride
