Renal Function Flashcards
The kidneys are bean shaped and are located on the posterior abdominal wall in the area known as the __________.
Retroperitoneum
What is the mass of an adult human kidney?
150 grams
A human adult kidney measures roughly _______ in length, _______ in width, and _______ in
depth.
12.5 cm (length)
6 cm (width)
2.5 cm (depth)
Each kidney contains approximately _______________ functional units called _________.
1 to 1.5 million; nephrons
What at the two types of nephrons in human kidney?
Cortical nephrons and Juxtamedullary nephrons
This type of nephron makes up approximately 85% of the total nephron and are found mainly in the cortex of the kidney.
Cortical Nephron
This type of nephron have longer loops of Henle that extend deep into the medulla of the kidney.
Juxtamedullary Nephron
This type of nephron is responsible primarily for removal of waste products.
Cortical Nephrons
This type of nephron is responsible primarily for the concentration of urine.
Juxtamedullary Nephrons
This type of nephron is responsible primarily for reabsorption of nutrients.
Cortical Nephrons
What are the general functions of the kidney?
- EXCRETORY FUNCTION
A. Glomerular filtration
B. Tubular reabsorption
C. Tubular secretion - Regulation of water balance in the body.
- Regulation of acid-base balance
- Regulation of electrolytes
- Regulation of Blood pressure through secretion of Renin
- Stimulates Erythropoiesis through secretion of EPO
The ________ supplies blood to the kidney.
Renal Artery
The human kidney receives approximately______ of the blood pump.
25%
Total renal blood flow: _____________________
1200 mL/min
Renal plasma flow: ______________________
600 to 700 mL/min
Order of blood flow in the Nephron
Renal artery → Afferent arteriole → Glomerulus (Filtration) → Efferent arteriole → Peritubular capillaries→ Vasa recta→ Renal vein
The pressure that is created by the varying sizes of the arterioles, which is important for glomerular filtration and to maintain consistency of glomerular capillary pressure and renal blood flow within the glomerulus.
Hydrostatic Pressure
Order of Urine formation from the nephron
Glomerulus → Bowman’s capsule → PCT → DLH → ALH → DCT → Collecting Ducts
The glomerulus consists of a coil of approximately____ capillary lobes referred to collectively as the _______ .
eight (8) ; capillary tuft
The walls of glomerulus are referred to as the__________ .
glomerular filtration barrier
The glomerulus is located within the ________ , which forms the beginning of the renal tubule.
Bowman’s capsule
A non-selective filter for plasma substances with molecular weights of less than _____________.
70,000 daltons
What is the normal SG of the fluid leaving the glomerulus?
1.010
Plasma filtrate must pass through three cellular layers:
- Capillary wall membrane
- Basement membrane (Basal lamina)
- Visceral epithelium of Bowman’s capsule
The endothelial cells of the capillary wall differ from those in other capillaries by containing pores and are referred to as ___________.
fenestrated
TRUE or FALSE
The pores DECREASE capillary permeability but do not allow the passage of large molecules and blood cells.
FALSE; increase
What do you call the intertwining foot processes of the inner layer of Bowman’s capsule?
podocytes
Filtration slits, aka _____ , only allows 7-9 nm of molecules to pass through.
Nephrin
This repels molecules with a negative charge even though they are small enough to pass through the three layers of the barrier.
Shield of negativity
Maintains the glomerular blood pressure
Juxtaglomerular apparatus
______________________ - found in the afferent arteriole, secretes the Renin enzyme
juxtaglomerular cells
______________________ - found in the DCT, sensor of change in blood pressure
macula densa
Determine the state of blood pressure:
Dilation of afferent arteriole, Constriction of efferent arteriole
Decrease Blood pressure
Determine the state of blood pressure:
Constriction of afferent arteriole, Dilation of efferent arteriole
Increase Blood pressure
System that regulates the flow of blood to and within the glomerulus
RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM (RAAS)
RAAS responds to changes in _______ and ____________ that are monitored by the juxtaglomerular apparatus.
blood pressure and plasma sodium content
Juxtaglomerular apparatus is consists of the ____________ in the afferent arteriole and the __________ of the distal convoluted tubule
juxtaglomerular cells (Afferent) ; macula densa (DCT)
What is the effect of low plasma sodium content of the body?
decreases water retention within the circulatory system, resulting in a decreased overall blood volume and subsequent decrease in blood pressure
Primary electrolyte affected when RAAS is activated
Sodium
Stimulus of RAAS
Decrease Blood Pressure/Low Plasma sodium
Flow of RAAS
- Low Blood Pressure/Low Plasma sodium
- Renin Secretion
+ Angiotensinogen - Angiotensin I
+ ACE (Lungs) - Angiotensin II
- Vasodilation (Afferent) and Vasoconstriction (Efferent) / Sodium reabsorption at PCT / Aldosterone for Sodium retention / ADH for water reabsorption
TRUE OR FALSE:
As systemic blood pressure and plasma sodium content in- crease, the secretion of renin decreases.
True
The constant actions of _________ produce a constant pressure within the nephron.
angiotensin II
What is the only difference between the compositions of the filtrate and the plasma?
Absence of plasma protein, any protein-bound substances, and cells.
The body must not lose ______ of water-containing essential substances every minute.
120mL
What is the composition of urine?
95 % water
5 % solutes
- Total solute in 24’hours = 60 grams (35 grams organic substances, 25 grams inorganic substances)
What are the cellular mechanisms involved in tubular reabsorption?
active transport and passive transport
For active transport to occur, the substance to be reabsorbed must combine with a _______ contained in the membranes of the renal tubular epithelial cells.
carrier protein
TRUE OR FALSE.
In passive transport, the movement of a substance from an area of LOWER concentration to one of HIGHER concentration
HIGHER to LOWER
Passive reabsorption of water takes place in all parts of the nephron except the ________
Ascending loop of Henle
Sodium is actively transport in all part of the nephron except in the _________
Ascending loop of henle
Denoted Tm, the maximal rate of reabsorption of a solute by the tubular epithelium per minute (milligrams per minute).
Maximal Tubular reabsorptive capacity
The plasma concentration at which active transport stops is termed the ________ .
renal threshold
What is the plasma renal threshold for glucose?
160 to 180 mg/dL
What is the sodium renal threshold?
110 to 130 mmol/L
Renal concentration begins in the ________ and the final concentration of urine continues to the __________ .
descending and ascending loop of henle ; Collecting Duct
Water is removed by ________ in the descending loop of Henle, and sodium and chloride are reabsorbed in the ascending loop.
osmosis
Act of the adrenal medulla that functions to maintain osmotic gradient of the medulla
countercurrent mechanism
Vasopressin is also known as the _______.
ADH
This is determined by the state of body hydration.
ADH or Vasopressin
Increase body hydration would result to an:
Decrease ADH
Decrease reabsorption of H2O
Increase urine volume
Decrease body hydration would result to an:
Increase ADH
Increase reabsorption of H2O
Decrease urine volume
Tubular secretion serves two major functions:
- eliminating waste products not filtered by the glomerulus
- regulating the acid–base balance in the body through the se- cretion of hydrogen ions
The major site for removal of nonfiltered substances is the ________.
PCT or proximal convoluted tubule
BEST INDICATOR OF OVERALL GLOMERULAR FUNCTION
Clearance test
Standard tests used to measure the filtering capacity of the glomeruli are termed __________.
clearance tests
What are the different clearance tests?
- Inulin clearance test
- Creatinine clearance test
- Cystatin C
- Beta 2 microglobulin
- Radioisotopes
- Urea clearance test
This is a polymer of fructose and is extremely stable substance that is not reabsorbed or secreted by the tubules. It is not a normal body constituent, however, and must be infused by IV at a constant rate throughout the testing period.
Inulin
The original reference method for clearance tests
Inulin
Earliest clearance test
Urea clearance test
Formula for the computation of GFR using the creatinine clearance test
C = (Urine creatinine/ plasma creatinine) X volume of urine per 24hours x (1.73/A)
This is a waste product of muscle metabolism
Creatinine
TRUE OR FALSE
Creatinine provides the laboratory with an EXOGENOUS procedure for evaluating glomerular function
False - Endogenous
TRUE OR FALSE
A diet heavy in meat consumed during collection of a 24-hour urine specimen will influence the results if the plasma specimen is drawn before the collection period = FALSE INCREASE RESULTS
True
What is the greatest source of error in any clearance procedure utilizing urine?
Use of improperly timed urine specimens
Its plasma concentration is inversely related to GFR.
Cystatin C
TRUE OR FALSE
Increase plasma cystatin C = decrease GFR
TRUE
TRUE OR FALSE
The rate of cystatin C production is not affected by muscle mass, sex, or race
True
________ is a better marker of reduced renal tubular function than of glomerular function.
BETA-2-MICROGLOBULIN
What is MDRD?
MDRD = Modification of Diet in Renal Disease
This test measures only the number of particles on solution.
Osmolality Test
What is the normal urine to serum ratio?
1:1 to 3:1 (after controlled fluid intake)
Measures the number and size of particles on solution.
Specific gravity
In this test, patients deprived of fluids for 24 hours before measuring Specific Gravity.
Fishberg Test
In this test, volume and S.G of day and night urine samples are compared.
Mosenthal test
The calculation of the ___________ is used to determine the ability of the kidney to respond to the state of body hydration.
free water clearance
What is the obselete test for renal secretion and blood flow?
PSP (phenolsulfonphthalein) dye excretion test
