The Kidney and Urine Formation Flashcards
The ____ is a very vital organ, which the main fuction is to filter blood and remove toxic wastes.
Kidney
Main Functions of the Urinary System
- Regulate blood
- Regulate volume of blood
- Regulate amount of solute
____ is the major organ of the excretory system.
Kidney
____ is a bean-shaped organ.
Kidney
The kidney is a ____-shaped organ.
bean
Order of Urine Formation
- Glomerulus
- Renal tubules
- PCT
- Loop of Henle
- DCT
- Collecting duct
- Renal pelvis
- Ureter
- Urinary bladder
- Urethra
____ is the functional unit of the kidney.
Nephron
____ is responsible for the urine formation.
Nephron
Each kidney contains approximately ____ nephrons.
1 to 1.5 million
Both kidneys contain ____ nephrons.
2 to 3 million
2 Distinct Areas of the Kidney
- Renal Cortex
- Renal Medulla
The ____ is the lighter and outer portion of the kidney.
Renal Cortex
The ____ is the darker and inner portion of the kidney.
Renal Medulla
5 Distinct Areas of the Nephron
- Bowman’s Capsule
- Glomerulus
- Proximal Convoluted Tubule
- Distal Concoluted Tubule
- Loop of Henle
____ is responsible for the concentration of urine.
Loop of Henle
2 Types of Nephron
- Cortical
- Juxtamedullary
____ of nephrons are cortical nephrons.
85%
85% of nephrons are ____.
cortical nephrons
Which type of nephron is found on the cortex of the kidneys?
Cortical Nephron
Cortical nephron is found on the ____ of the kidneys.
cortex
The ____ functions in the removal of wastes and reabsorption of nutrients.
Cortical Nephron
____ of the nephrons are juxtamedullary nephrons.
15%
15% of the nephrons are ____.
juxtamedullary nephrons
____ have longer Loop of Henle that extend deep into the medulla of the kidney.
Juxtamedullary nephrons
____ function in the concentration of urine and maintenance of osmotic gradient.
Juxtamedullary nephrons
In the medulla, ____ have an increased amount. Therefore, it should be balanced.
water and salt
Water and salt have an increased amount in the ____.
medulla
Four Renal Functions
- Renal blood flow
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
The ____ supplies blood to the kidney.
Renal artery
The kidneys receive approximately ____ of the blood from the heart.
25%
Renal Blood Flow Pattern
- Renal artery
- Afferent arteriole
- Glomerulus
- Efferent arteriole
- Peritubular capillaries
- Vasa recta
- Renal vein
The varying sizes of the arterioles helps in ____.
- Creating hydrostatic pressure
- Maintaining consistency of glomerular capillary pressure and renal blood flow
Smaller size of efferent arteriole increases the ____.
glomerular capillary pressure
Smaller size of efferent arteriole ____ the glomerular capillary pressure.
increases
The ____ surrounds the proximal and distal convoluted tubules.
Peritubular capillaries
____ function in immediate reabsorption of essential substances, and final adjustment of the urinary composition.
Peritubular capillaries
The ____ are located in the Loop of Henle.
Vasa recta
Peritubular capillaries are found in the ____.
renal tubules
Vasa recta is found in the ____.
Loop of Henle
____ functions in the exchange of water and salt.
Vasa recta
Vasa recta functions in the exchange of ____.
water and salt
Total renal blood flow
1,200 mL/min
Total renal plasma flow
600 - 700 mL/min
The glomerulus consists of a coil of approximately ____.
8 capillary lobes
The glomerulus is located within the ____.
Bowman’s capsule
The ____ forms the beginning of the renal tubule.
Bowman’s capsule
TRUE OR FALSE.
Bowman’s capsule is a part of the glomerulus
False
Reason: It is a part of the renal tubules
The glomerulus serves as a ____ of blood.
non-selective filter
The ____ serves as a non-selective filter of blood.
Glomerulus
Glomerulus filters blood with molecular weights ____.
less than 70,000 Daltons
Can amino acid be filtered?
Yes, but 100% is reabsorbed because it is essential
Can urea be filtered?
Yes
____% of urea is reabsorbed.
40
____% of urea is excreted.
60
Can protein be filtered?
- Based on size yes, because it weighs 69k Daltons.
- Based on charge no, because it is negative, and the glomerulus has a shield of negativity. Therefore, it will repel.
Fluid as it leaves the glomerulus shows the filtrate to have a specific gravity of ____.
1.010
Cellular Structure of the Glomerulus
- Capillary wall membrane (endothelial cells)
- Basement membrane (basal lamina)
- Visceral epithelium of the Bowman’s Capsule
____ are different from other capillary walls because they have pores.
Endothelial cells
Endothelial cells differ from other capillary walls because they have ____.
Pores (fenestrated endothelium)
____ increase cellular permeability but do not allow large molecules and blood cells.
Pores
____ are foot processes on the inner layer of Bowman’s capsule.
Podocytes
Podocytes are found in the ____.
inner layer of Bowman’s Capsule
____ is a force that pushes the fluid out of the blood capilaries.
Hydrostatic Pressure
____ resist the hydrostatic pressure. It pushes the fluid into the blood capillaries.
Oncotic Pressure
Our oncotic pressure is the ____.
Albumin
An autoregulatory mechanism is found within the ____.
Juxtaglomerular apparatus
An ____ is found within the juxtaglomerular apparatus.
autoregulatory mechanism
Autoregulatory Mechanisms
- Juxtaglomerular cells (JG cells)
- Macula Densa
____ is found on the afferent arteriole.
Juxtaglomerular cells (JG cells)
____ produces the hormone renin when blood pressure is low.
Juxtaglomerular cells (JG cells)
JG cells produce ____ when blood pressure is low.
renin
When do JG cells produce the hormone renin?
When the blood pressure is low
When BP is high, the JG cells ____ the afferent arteriole.
constrict
When BP is low, the JG cells ____ the afferent arteriole.
dilate
JG cells are found on the ___.
afferent arteriole
____ is found on the distal convoluted tubule.
Macula Densa
Macula Densa is found on the ____.
Distal Convoluted Tubule (DCT)
____ sense the changes in blood pressure, especially when decreased.
Macula Densa
____ sends signal to JG cells to produce hormone.
Macula Densa
What will happen without Oncotic pressure?
All fluid will come out of our body and may lead to Edema
What is the difference between the compositions of the filtrate and plasma?
The absence of protein
____ is a hormone system within the body that is essential for the regulation of blood pressure and fluid balance.
Renin-Angiotensin-Aldosternone System (RAAS)
RAAS is mainly comprised of three hormones: ____.
- Renin
- Angiotensin
- Aldosterone
RAAS will be activated if the body has ____.
Decreased:
* Blood pressure
* Sodium concentration
* Water
Low plasma sodium content ____ water retention within the circulatory system.
decreases
Changes in blood pressure and plasma sodium content are monitored by ____.
- Juxtaglomerular cells (afferent arteriole)
- Macula densa (DCT)
The activation of RAAS should be inhibited when blood pressure is high by taking ____.
Losartan
RAAS Cascade of Reaction
- Renin reacts with Angiotensinogen to produce the inactive hormone called Angiotensin I.
- Angiotensin I passes through the lungs and Angiotensin-converting enzyme activates it.
- Angiotensin II corrects renal blood flow by either of the following:
* Dilate afferent arteriole, constrict efferent arteriole
* Stimulate sodium reabsorption
* Triggers adrenal cortex to release Aldosterone
* Triggers hypothalamus to produce ADH
How will RAAS act?
Decreased BP
Dilation of afferent arteriole and constriction of efferent arteriole
How will RAAS act?
Decreased salt concentration
Triggers adrenal cortex to relsease Aldosterone
How will RAAS act?
Decreased water content
Triggers the hypothalamus to produce Antidiuretic hormone
The molecules that were filtered by the glomerulus will come back to the circulation and will be reabsorbed in the ____.
proximal convoluted tubule
Cellular Mechanisms Involved in Tubular Reabsorption
- Active Transport
- Passive Transport
____ requires energy to transport important substances from the renal tubule going to the peritubular capillaries.
Active transport
For active transport to occur, the substance to be reabsorbed must ____.
combine with a carrier protein
Active transport is responsible for the reabsorption of the following substances: ____.
- Glucose, amino acids, salts (PCT)
- Chloride (Ascending loop)
- Sodium (PCT and DCT)
Determine which location is the substance reabsorbed
Glucose
PCT
Determine which location is the substance reabsorbed
Amino acid
PCT
Determine which location is the substance reabsorbed
Salt
PCT
Determine which location is the substance reabsorbed
Chloride
Ascending Loop of Henle
Determine which location is the substance reabsorbed
Sodium (via active transport)
PCT and DCT
Through ____, the substance moves from a low concentration to a higher concentration.
active transport
In the ____ mechanism, substances move from high concentration to a lower concentration.
Passive transport
The movement of molecules across a membrane as a result of differences in their concentration or electric potential is called ____.
gradient
____ is the plasma concentration at which active transport stops.
Renal threshold (maximal reabsorptive capacity)
Can we maintain the specific gravity of 1.010 once it leaves the PCT?
Yes
Renal concentration begins in the ____.
descending and ascending loops of Henle
____ is where the filtrate exposed to the high osmotic gradient of the renal medulla.
descending and ascending loops of Henle
Loop of Henle is important in the ____.
reabsorption of water and sodium (salt)
____ is reabsorbed in the descending loop of Henle.
water
Water is reabsorbed in the ____.
descending loop of Henle
____ is reabsorbed in the ascending loop of Henle.
Salt
Salt is reabsorbed in the ____.
ascending loop of Henle
Passive reabsorption of water takes place in all parts of the nephron except the ____.
ascending loop of Henle
The walls of the ____ is impermeable to water.
ascending loop of Henle
The walls of the ascending loop of Henle is impermeable to ____.
water
Why is the ascending loop of Henle impermeable to water?
To maintain the osmotic gradient within the medulla
As the filtrate goes down to the descending loop, the osmolarity ____ because water is reabsorbed.
increases
As the filtrate goes up to the ascending loop of Henle, the osmolarity ____ because salt is reabsorbed.
decreases (goes back to normal)
____ is the selective reabsorption process to maintain the osmotic gradient of the medulla.
Countercurrent mechanism
Passive transport is responsible for the reabsorption of the following substances: ____.
- Water (PCT, Descending loop, Collecting ducts)
- Urea (PCT, Ascending loop)
- Sodium (Ascending loop)
Determine which location is the substance reabsorbed
Water
- PCT
- Descending loop of Henle
- Collecting ducts
Determine which location is the substance reabsorbed
Urea
- PCT
- Ascending loop of Henle
Determine which location is the substance reabsorbed
Sodium (via passive transport)
Ascending loop of Henle
The final concentration of the filtrate through the reabsorption of water begins in the ____ and continues in the ____.
late distal convoluted tubule; collecting duct
Reabsorption depends on the ____.
- Osmotic gradient in the medulla
- Antidiuretic hormone (ADH) or Vasopressin
Production of ADH is determined by ____.
the state of body’s hydration
Saan nagi-instruct na mag-conserve ng water?
hshshhsh hindi q alam paano i-english censya n guys….
Collecting ducts
____ are receptors of Antidiuretic hormone (ADH).
Aquaporins
If the body is hydrated, aquaporins are ___.
closed
If the body is dehydrated, aquaporins are ____.
opened
Deficiency in antidiuretic hormone is clinically known as ____.
Diabetes Insipidus
Types of Diabetes Insipidus
- Nephrogenic
- Hypothalamic
Which Type of Diabetes Insipidus?
Aquaporins are not responsive, but the body produces enough ADH.
Nephrogenic
Which Type of Diabetes Insipidus?
The problem is in the hypothalamus; complete deficiency.
Hypothalamic
Type 2 diabetes insipidus lead to ____.
Polyuria
In diabetes insipidus, the body’s hydration is ____, ADH levels are ____, and urine volume is _____.
decreased, decreased, increased
Concept of ADH Control
Increased body hydration
Decreased ADH + Increased Urine Volume
Concept of ADH Control
Decreased body hydration
Increased ADH + Decreased Urine Volume
____ involves the passage of substances from the blood in the peritubullar capillaries to the tubular filtrate.
Tubular Secretion
Major Functions of Tubular Secretion
- Elimination of waste products not filtered by glomerulus
- Regulate acid-base balance by secreting Hydrogen ions
Why can’t some substances be filtered by the glomerulus?
Because they are bound to plasma proteins
When protein-bound substances enter the peritibular capillaries, they develop a high affinity for the ____, and dissociate from their carrier proteins.
tubular cells
The major site for removal of non-filtered substances is the ____.
Proximal convoluted tubule
How do our kidneys regulate acidosis via tubular secretion?
By secreting Hydrogen ions into the urine
How do our kidneys regulate alkalosis via tubular secretion?
By excreting bicarbonate in the urine (or secreting hydrogen ions)
The standard tests used to measure the filtering capacity of the glomeruli is the ____.
Clearance Tests
A ____ measures the rate at which the kidneys are able to remove a filterable substance from the blood.
Clearance test
____ is the most common test that determines which particular kidney function has a problem.
Clearance test
____ is the earliest glomerular filtration test because of its presence in all urine specimens.
Urea clearance
____ is a polymer of fructose.
Inulin
____ is not a normal body constituent because it is exogenous.
Inulin
____ is the gold standard. Although it was the original reference method for clearance tests, it is currently not used for glomerular filtration testing.
Inulin clearance
____ is a very common clearance test.
Creatinine clearance
What specimen is required for creatinine clearance test?
24 hour urine
____ present in human plasma react in the chemical analysis.
Chromogens
____ may help counteract the falsely elevated rates caused by tubular secretion.
Chromogens
____ inhibit tubular secretion of creatinine, thus causing falsely low serum levels.
Medications
Ex. gentamicin, cephalosphorins, and cimetidine
Creatinine clearance formula
Urine Creatinine (mg/dL) x Urine Volume (mL/min) / Plasma Creatinine (mg/dL)
Normal values of creatinine clearance in Males
107 - 139 mL/min
Normal values of creatinine clearance in Females
87 - 107 mL/min
Calculated Glomerular Filtration Estimates
Cockroft and Gault
Cockroft and Gault variables
- Age
- Weight
- Gender (if female, multiply the computed value by 0.85)
Cockroft and Gault formula
(140-age)(weight in kg) / 72 x serum creatinine (mg/dL)
Modification of Diet in Renal Disease (MDRD) variables
- Age
- Gender
- Ethnicity (if black, multiply the computed value by 1.1880)
- BUN
- Serum albumin
Renal function test
- Injection of radionucleotides such as, 125I-iothalamate
- Beta 2 microglobulin
- Cystatin C
Tubular reabsorption tests
- Fishberg test (water deprivation test)
- Mosenthal test
Both are now OBSOLETE
The ____ deprives the patient of water for 24 hours.
Fishberg test
Specific gravity for Fisheberg test
greater than or equal to 1.025
The ____ compare the day and night urine specific gravity and volume.
Mosenthal test
Renal concentration ability
- Osmolarity
- Specific gravity
____ is affected only by the number of particles present.
Osmolarity
____ depends on the number of particles present in a solution and the density of these particles.
Specific gravity
____ determine the freezing point if any solution by supercooling and measuring the amount of sample to approximately 27 C.
Freezing point osmometer
____ measures the due point.
Vapor pressure osmometer
____ is the temperature at which water vapor will be condensed to a liquid.
Due point
Factors to consider because of their influence on true osmolarity readings
- Lipemic serum
- Lactic acid
- Volatile substances
Lipemic serum
Produces erroneous results with both vapor pressure and freezing point osmometers
Mas matagal mag-condense and freeze
Lactic acid
Falsely elevated if serum samples are not separated or refrigerated within 20 minutes
Volatile substances
Vapor pressure osmometers do not detect the presence of volatile substances
Tubular secretion and renal blood flow tests
- P-aminohippuric acid (PAH) test
- Phenolsulfonphthalein (PSP) dye
Both should be excreted
- Exogenous
- Loosely bound to plasma proteins, which permits its complete removal as the blood passes through the peritubular capillaries.
PAH Test
The ability of the kidney to produce an acid urine depends on the tubular secretion of hydrogen ions and production and secretion of ammonia by the cells of the distal convoluted tubule.
Titratable acidity and Urinary Ammonia
