Chapter 24 Flashcards
Primary function of the urinary system is to filter ____ and convert the filtrate into urine.
blood
A major function of the urinary system function is ____ of metabolic wastes; urea, uric acids.
elimination
A major function of the urinary system is the _____ or ion levels; Na+, K+, Ca2+, PO43-
regulation
A major function of the urinary system is the ______ of acid-base balance; H+, HCO3-
regulation
A major function of the urinary system is the _____ of blood pressure; fluid balance, renin.
regulation
A major function of the urinary system is the____ of biologically active molecules; hormones, drugs.
elimination
The urinary system forms _____ which increases Ca2+ absorption, made from vitamin D3.
calcitriol
The urinary system produces and releases of _______ which is the production of erythrocytes due to low blood oxygen levels.
erythropoietin (EPO)
The urinary system has the potential to engage in ______, but only during extreme nutrient deprivation.
gluconeogenesis
The three interrelated processes of urine formation.
- glomerular filtration
- tubular reabsorption
- tubular secretion
_______ is the passive movement of water and dissolved solutes from blood plasma within the glomerular capillaries to capsular space of glomerular capsule.
glomerular filtration
_____ occurs due to pressure differences between the glomerulus and glomerular capsule.
glomerular filtration
Glomerular filtration is similar to the filtrate of plasma, but contains ________.
no proteins
Steps of urine formation
?
The filtration membrane is composed of endothelium, basement membrane, and _______.
mesangial cells found within the capillary loops
______ of glomerular capillaries blocks formed elements from leaving blood.
endothelium
________ of glomerular capillaries blocks smaller proteins from leaving blood.
basement membrane
Visceral layer of glomerular capsule (______) block smaller proteins from leaving blood.
podocytes
_______ found within the capillary loops that have phagocytic and contractile properties.
mesangial cells
Due to size of openings and negative charge across the filtration membrane, not all substance are ______.
filtered equally
Small substance are ___ filtered.
freely filtered
water, glucose, amino acids, ions, urea, some hormone, vitamins b, and ketones
Formed elements and large proteins are ____ filtered.
not
Intermediate size proteins are _______.
come through a limited filtration
normally not filtered due to size and negative charges, but some become part of filtrate.
Glomerular hydrostatic blood pressure is also known as ____.
HPg
HPg ____ filtration.
promotes
HPg has _____ blood pressure than other systemic capillaries.
higher
HPg has increased blood pressure due to afferent arteriole having a ______ than the efferent arteriole.
larger lumen
??? more volunderable to damage due to higher pressure.
???
Blood colloid osmotic pressure is ____.
OPg
___ is the osmotic pressure exerted by the plasma proteins within the blood.
Blood colloid osmotic pressure (OPg)
Omg drawn fluids into the ______.
glomerular capillaries
Typical value only slightly higher than colloid osmotic pressure within other _____.
systemic capillaries.
Capsular hydrostatic pressure is ____.
HPc
Hoc is pressure in the glomerular capsule due to the amount of filtrate already within _____.
capsular space
HPc impedes the movement of additional fluid from ______.
blood into the capsular space.
Slide 11
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_____ is tightly regulated to help monitor homeostasis.
GFR
A normal GFR is between ___ and ____ mL/min.
60-120
GFR is influenced by changing the luminal diameter of the afferent arteriole and by altering the surface area of the _____.
filtration membrane
________ (within the kidney) consists of renal auto regulation.
Intrinsic control
________ (external the kidney) involve nervous system or hormonal regulation.
Extrinsic controls
______ is the intrinsic ability of kidney to maintain a constant blood pressure and GFR despite changes in systemic arterial pressure.
renal autoregulation
Two mechanisms of renal auto regulation include myogenic response and _______.
tubuloglomerular feedback mechanism.
Vasodilation/constriction of afferent arteriole due to changes in blood pressure (________).
stretching of arteriole walls
The ______ is how arteries and arterioles react to an increase or decrease of blood pressure to keep the blood flow within the blood vessel constant.
myogenic response
With the myogenic response a decrease in blood pressure results in ____.
vasoconstriction
With the myogenic response a increase in blood pressure results in _____.
vasodilation
The ______ causes vasodilation/constriction of afferent arteriole due to changes in NaCl concentration.
tubuloglomerular feedback mechanism
_____ in the JG appartus detect NaCl levels in tubular fluid.
macula densa cells
With the tubuloglomerular feedback mechanism an increase in NaCl results in ____.
vasoconstriction
With the tubuloglomerular feedback mechanism a decrease in NaCl results in _______.
vasodilation
Renal autoregulation is only effective if systemic MAP stays between ___ and ___.
80 to 180 mm Hg
When the MAP is below ____ mm Hg, afferent arterioles maximally dilated GFR and urine production decrease.
80 mm Hg
When the MAP is above _____ mm Hg, afferent arterioles maximally contracted, GRF and urine production increase.
180 mm Hg
Review Renal autoregulation graph
?
The _____ division decreases GFR.
sympathetic division
The sympathic divison causes _____ of both afferent and efferent arterioles.
vasoconstriction
The sympathetic division stimulates the _______of the JG apparatus to release renin, which aids in the production of angiotensin II.
Granular cells
The sympathetic division stimulates the _____ cells to contract by angiotensin II decreasing surface area of filtration membrane.
mesangial
Vasoconstriction of afferent and efferent arterioles result in decreased blood flow into the ______.
glomerulus
Contraction of mesangial cells results in decreased filtration at _____.
glomerulus
Atrial natriuetic peptide (ANP) is a _____.
hormone
Atrial natriuretic peptide (ANP) increases ____.
GFR
Atrial natriuretic peptide (ANP) is released from atrial cardiac muscle cells due to ______.
increased stretch.
Atrial natriuretic peptide (ANP) causes relaxation of afferent arterioles and inhibits the release of ____, which causes relaxation of mesangial cells to increase filtration membrane surface area.
renin
Vasoldilation of afferent arteriole results in _____ blood flow into the glomerulus.
increased
Relaxation of mesangial cells results in _____ filtration at glomerulus.
increased
______ is the maximum amount of a substance that can be reabsorbed across the tubule epithelium in a given period of time.
Transport maximum (Tm)
The transport maximum (Tm) is dependent upon the ____ of transport proteins specific for the substance.
number
If tubular fluid contains more than the Tm, the excess is _____.
excreted in the urine
_____ is the max plasma concentration of a substance that can be transported in the blood without appearing in the urine.
renal threhold
If plasma concentration is greater than renal threshold, the excess will be _____.
lost in the urine.
Nutrients are reabsorbed completely in the ____.
proximal convoluted tubule (PCT)
Glucose Reabsorption
Concentration high within tubule cell, and low within tubular fluid and interstitial fluid
Transported across luminal membrane by Na+/glucose symporter protein
Na+ moving down its gradient creates enough energy to bring glucose in, moving against it’s gradient
Glucose then moves down it’s gradient and out the basolateral membrane by facilitated diffusion
Glucose then returns to the peritubular capillaries
Some small and medium sized peptides, such a insulin and angiotensin appear in _____
filtrate
Proteins undergo _____ changes while being reabsorbed
transformational
Proteins moved across luminal membrane by ______ or ______.
pinoctosis
receptor mediated endocytosis
Lysosomes digest the proteins into their amino acids which are then moved across the _____ by facilitated diffusion back into the blood
basolateral membrane
Angiotensin II is degraded by peptidases within the ______, the amino acids are then absorbed directly by tubule cell
luminal membrane
Na+ Reabsorption from tubular fluid varies from _______.
98-100%
Na+ reabsorption occurs entire length of ______ as well as collecting tubules and ducts
renal tubule
The majority of Na+ is reabsorbed in ________ and nephron loop (25%)
PCT (65%)
Na+ concentration _____ inside tubule cell and high within both tubular fluid and interstitial fluid due to Na+/K+ pumps.
low
Na+ _________ through a channel in the luminal membrane down it’s gradient into the cell.
passively diffused
Na+/K+ pumps move Na+ out of the cell through the basolateral membrane into the _______ and ultimately Na+ moves into the peritubular and vasa recta capillaries.
interstitial fluid
Na+/K+ pumps use up 80% of all energy invested in active transport within _____
nephrons
Amount of Na+ excreted in urine ranges from _____ of total filtered Na+
0-2%
Na+ reabsorption regulation is controlled by ______ and _____ hormones affecting cells in the PCT, DCT, CT and CD
aldosterone
ANP
_____ is a steroid produced by adrenal cortex.
aldosterone
_____ stimulates protein synthesis of Na+ channels and Na+/K+ pumps
aldosterone
In aldeosterones Na+ reabsorption regulation water follows Na+ by _______, resulting in reabsorption of isotonic fluid
osmosis (aldosterone)
In aldeosterones Na+ reabsorption regulation ____ is excreted in this process.
K+
ANP (atrial natriuretic peptide) role in Na+ reabsorption regulation ____ reabsorption of Na+ in PCT and CT and the release aldosterone
inhibits
_____ increases both the number of Na+ channels and Na+/K+ pumps, resulting in an increase in Na+ reabsorption.
aldosterone
Water movement occurs by either paracellular transport or by transcellular transport through ______.
aquaporins
Through water reabsorption _____ filtered per day, all but 1.5L reabsorbed
180L
Water reabsorption varies depending on _____ and excretion through other routes
fluid intake
____ of water is reabsorbed in the PCT.
65%
Ascending limb of nephron loop and ____ impermeable to water
DCT
_____ is the movement of water dependent on Na+ movement.
obligatory water reabsorption
Antidiuretic hormone (ADH) control reabsorption within the _____ and _____.
CT and CD
Causes migration of vesicles containing aquaporins to the luminal membrane is called ______.
facultative water reabsorption
Water reabsorption regulated by _____, not movement of Na+.
osmotic forces
As ADH increases, H20 absorption _____.
increases
An increase in urine concentration results in ____.
darker yellow color of urine
_____ increase the number of aquaporins, resulting in an increase of water absorption.
ADH
Postassium can be ____ and secreted.
reabsorbed
In PCT, ______ of K+ in tubular fluid is reabsorbed by paracellular transport which is dependent on ____ movement.
60-80%
Na+
10-20% of K+ reabsorbed in thick segment of _______ of nephron loop, both paracellular and transcellular transport.
ascending limb
In CT and CD type A intercalated cells reabsorb _____ continuously.
K+
In CT and CD _____ secrete K+ at varying rates based on aldosterone levels.
principal cells
Calcium and phosphate balance is regulated by the ______.
parathyroid hormone (PTH)
parathyroid hormone (PTH) ____ PO43- reabsorption in the PCT.
inhibits
parathyroid hormone (PTH) _____ Ca2+ reabsorption in DCT
stimulates
Calcium and phosphate balance is regulated by PTH. Additional PO43- is eliminated via urine so less is available to form ____.
calcium phosphate (major calcium salt in bones)
Calcium and phosphate regulation by PTH, Ca2+ increases in blood because it ____.
can’t be redeposited in bone
_____% of (Bicarbonate ions) HCO3- is ‘reclaimed’ from tubular fluid in PCT
80-90
The remaining 10-20% of Bicarbonate ions HCO3- is taken up in ______ of the nephron loop
thick segment of the ascending limb
Bicarbonate binds with H+ to form ______, which breaks into CO2 and H2O; CO2 diffuses into the tubule cell
carbonic anhydrase
CO2 binds with H2O within the cell, reforming carbonic anhydrase which turns around and breaks down into ____ and ____
HCO3- and H+
HCO3- leaves the tubule cell and enters the blood, the ____ reenters the tubular fluid
H+
pH of urine is regulated in ____.
CT
When blood ____ high, HCO2- reabsorbed into the blood by type A intercalated cells.
H+
When blood [H+] high, HCO3- reabsorbed into the blood by type A intercalated cells
It results in blood pH ______, urine pH _____
increase
decrease
Occurs due to more acidic diet (includes animal proteins and wheat)
pH of urine is ___.
6.0
When blood [H+] ____, type B intercalated cells reabsorb H+ into blood and secrete HCP3- into tubular fluid
low
When blood [H+] low, type B intercalated cells reabsorb H+ into blood and secrete HCP3- into tubular fluid. It results in pH ____ and urine pH ____.
decrease
increase
Occurs due to more alkaline diet, fruits/veggies primarily, little or no animal protein
____ is metabolic waste that contains nitrogen.
nitrogenous waste
____ is a nitrogenous waste that results from protein breakdown in liver.
urea
____ is a nitrogenous waste that results from nucleic acid breakdown in the liver
uric acid
____ is a nitrogenous waste that results in the breakdown of creatinine in muscle
creatine
____ and ____ both reabsorbed and secrete, creatinine only secreted.
urea and uric acid
____ is freely filtered, half reabsorbed in PCT but then secreted back into tubule fluid within nephron due to paracellular movement
urea
____ of nitrogenous waste reabsorbed at CT leaving 50% to be excreted.
50%
____ plays a role in establishing the concentration gradient in the interstitial fluid of the kidneys
urea
Elimination of drugs and bioactive substances typically occurs within the ____.
PCT
Certain drugs: antibiotics, morphine, chemotherapy drugs, and chemicals in marijuana are eliminated through _____.
urine
Other metabolic wastes: ________ (billirubin beakdown) and hormone metabolites.
urobilin
Some hormones: epinephrine, _____, and human chorionic gonadotropin (hCG) (realeased in urine when females are pregnant).
prostaglandins
_____ in the interstitial fluid surrounding the renal tubules exerts osmotic pull to move water from the tubular fluid into the interstitial fluid when necessary. ____ then moves into the capillaries.
concentration gradient
water
Concentration gradient est. and maintained by: 1. nephron loop via _____.
countercurrent multiplier
Concentration gradient est. and maintained by: 2. vasa recta via contercurrent _____.
exchange system
Concentration gradient est. and maintained by: 3. Urea ___.
recycling
The urea recycling when maintaining concentration gradient: urea makes up half of the solutes necessary for an ______ concentration gradient.
interstital fluid
The urea recycling when maintaining concentration gradient: Urea removed from tubular fluid in CD by urea uniporters, it then diffuses back in to tubular fluid in the ______.
thin segment of ascending limb
The countercurrent multiplier: Positive feedback mechanism in nephron loop Descending limb: \_\_\_\_\_\_ to water Impermeable to salt Water moves from tubular fluid to \_\_\_\_\_\_ Tubular fluid becomes more concentrated
Permeable
interstitial fluid
The countercurrent multiplier:
Positive feedback mechanism in nephron loop
Ascending limb:
______ to water
Permeable to salt
Water retained in tubular fluid, salt is moved into interstitial fluid
Tubular fluid becomes _______
Impermeable
less concentrated
In the countercurrent exchane system the concentration gradient is maintained in interstitial fluid by ______.
vasa recta
Blood flow in the countercurrent exchange system is opposite to _____ in the nephron loop.
tubular fluid
In the countercurrent exchange system blood flows near the _______, water moves out of vasa recta into interstitial fluid and salts are absorbed into blood. As a result, blood becomes more concentrated
ascending limb
As blood flows near descending limb, salts moves out of ______ into interstitial fluid and water is absorbed into the blood
Blood becomes less concentrated
vasa recta
Plasma filtration occurs in the ______.
glomerulus
Most substances are either reabsorbed or secreted into the ____.
PCT
Nephron loop surrounded by the vasa recta and the _______ from the CD to the ascending limb of the nephron loop, establishes the concentration gradient of the interstitial fluid. This is necessary for ADH function
recycling of urea
______, type A and type B intercalated cells within DCT, CR and CD aid in regulation of specific substances.
Principal cells
Urine composed of water and various dissolved substances including ____, waste products and perhaps drugs.
ions
Under normal circumstances, formed elements and _____ are not lost in urine
nutrients
Measuring the GFR is used to assess ____ function.
kidney
When measuring GFR ____ in injected in patient until blood plasma concentration is 1 mg/mL.
inulin
While measuring GFR, inulin is freely filtered, thus urine is collected and measured for ______ and ____.
volume and conectration
GFR = UV/P
concentration of inulin in urine x concentration of inulin in plasma / volume of urine produced per minute
GFR example
Urine concentration 125 mg/mL, urin volume 1 mL/ min, plasma concentration 1 mg/mL
125 x 1 mL / 1 mg/mL = 125 mL/min
This is a normal adult GFR, lower indicates kidney function.
Another way to assess kidney function is to measure ____.
renal plasma clearnace
Measures the volume of plasma that can be completely cleared of a substance in a given period of time (1 min). This can tell you if a substance is reabsorbed or secreted when trying to measure ____.
renal plasma clearance
Compared to GFR:
If substance is equal to GFR it has been neither reabsorbed nor filtered
If substance is reabsorbed, its renal plasma clearance will be lower than GFR because less of the substance is in the urine
Substances that are secreted have a higher renal plasma clearance
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Example:
Renal plasma clearance of urea is 70 mL/min
This means if urea is filtered at a rate of 125 mL/min, only 70 mL/min is cleared, the other 55 mL/min is reabsorbed
Renal plasma clearance of glucose is normally 0 mL/min
This means glucose is reabsorbed 100%
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_____ is the Expulsion of urine from bladder
micturition
Micturition is innervated by ____.
autonomic nervous system (ANS
Sympathetic _____ micturition.
inhibits
Parasympathetic _____ micturition.
stimulates
Somatic is ____ control of micturition.
voluntary
_______ is the relaxation of detrusor muscle, contraction of internal urethral sphincter
storage reflex
Micturition reflex
Volume of urine in bladder reaches 200-300 mL, baroreceptors in bladder become activated due to stretching of bladder walls
Micturition center in pons stimulated by incoming signals
Splanchnic nerve signals (parasympathetic) going to bladder are altered
Detrusor muscle contracts and internal urethral sphincter relaxes
Cerebral cortex sends signal through ______ to cause relaxation of external urethral sphincter in voluntary control of micturition
pudendal nerve
Expulsion of urine due to voluntary contraction of abdominal muscles and _______ muscles
expiratory
If urination doesn’t occur at time of first micturition reflex:
Detrusor muscle relaxes more due to ‘stress-relaxation response’ of smooth muscle
Bladder fills more, micturition reflex stimulated again after another 200-300 mL of urine has been added
Cycle continues until 500-600 mL of urine in bladder, conscious control no longer works
