zzz Watson Urinary Flashcards
filter blood to remove metabolic waste products
Kidneys
modify resulting for- Fluid and electrolyte homeostasis AND Acid-base and blood pressure homeostasis
Kidneys
Both kidneys are found
Retroperitoneal
Right kidney is found in a slightly ___ position due to liver
Inferior
3 layers of urinary tract
Adventitia, muscularis, mucosa
Urinary bladder held in place by ___ ____
parietal peritoneum
muscularis layer of the bladder
Detrusor muscle
A second sphincter that allows for voluntary control of urination: the ____ urethral sphincter
external
A second external urethral sphincter is formed by ___ ___ muscle
levator ani
Micturition reflex – reflex arc mediated by ___ nervous system
Parasympathetic
Micturition center – found in
Pons
Kidney layer; dense irregular connective tissue; anchors each kidney to peritoneum and musculature of posterior abdominal wall
Renal fascia
Kidney layer; thickest layer; wedges each kidney in place and shields them from physical shock
Adipose capsule
Kidney layer; thin layer of dense irregular connective tissue; covers exterior of each kidney; protects it from infection and physical trauma
Renal capsule
opening on medial surface of kidney
Hilum
Hilum opens into renal ___
renal sinus
Three distinct regions of kidney: renal cortex, middle renal medulla,
and innermost renal ___
pelvis
Renal ___ and the renal ___ make up
urine-forming portion of kidney
Cortex, medulla
Renal ___ and its associated structures drain urine formed in cortex and medulla
Pelvis
extensions of renal cortex; pass through
renal medulla toward renal pelvis
Renal columns
Globe-shaped renal ___ found in renal cortex
Corpuscle
renal ___ are found within renal medulla separated by renal columns on either side
pyramids
Each renal pyramid tapers into a slender
papilla
Each papilla borders on a cup-shaped tube (__ calyx); first urine-draining structure
Minor
Three to four minor calyces drain into a larger urine-draining structure (___ calyx)
major
Two to three major calyces drain into a large urine collecting chamber (renal ___) which leads to ureter
Pelvis
Calyces and renal pelvis are found in renal
sinus
Left and right renal arteries are branches of abdominal
aorta
ball-shaped capillary bed
glomerulus
Efferent arteriole feeds into a second capillary bed
peritubular capillaries
Venous blood exits kidney parallel to arterial pathway beginning with peritubular venules that drain ___ ___ beds
peritubular capillary beds
Nephron – two main divisions; renal corpuscle and renal
Tubule
group of looping fenestrated capillaries; extremely “leaky”, or permeable
Glomerulus
double-layered outer sheath of epithelial tissue; consists of outer parietal and inner visceral layer
Glomerular capsule (Bowman’s capsule)
composed of both macula densa and juxtaglomerular (JG) cells
Juxtaglomerular apparatus (JGA)
a group of cells in contact with modified smooth muscle cells (juxtaglomerular (JG) cells) found in walls of both afferent and efferent arterioles
Macula densa
regulates blood pressure and glomerular filtration rate
JGA
Several medullary collecting ducts merge to form a ___ duct
Papillary duct
Once filtrate enters papillary duct it is known as ___, not filtrate
Urine
Urine exits papillary duct
at papilla of renal pyramid
into a ___ ___
minor calyx
___ nephrons make up about 80% of nephrons in kidneys
Cortical
Cortical portion of nephron is surrounded by ____ capillary branches from neighboring cortical nephrons; nephron loop is surrounded by a ladder-like network of capillaries called the ___ ___
Peritubular, vasa recta
Unique capillary structural arrangement allows juxtamedullary nephrons to
control volume and concentration of urine
Reabsorption in distal tubule and collecting duct is more
Precise
Tubular ___ – process where substances are added into filtrate from peritubular capillaries for excretion from body
Secretion
Includes fenestrated glomerular capillary endothelial cells, basal lamina, and podocytes
Filtration membrane
thin layer of extracellular matrix gel; makes up second layer that separates glomerular endothelial cells from podocytes
Basal lamina
group of small substances that are readily filtered; include:
urea, ammonia, creatine kinase
Amount of filtrate formed by both kidneys in __ minute is known as glomerular filtration rate (GFR)
1
Pressure (not colloid osmotic pressure) that opposes filtration
Capsular hydrostatic pressure
internal kidney mechanisms that work together to maintain GFR within normal range
Autoregulation
similar to constriction of smooth muscle in blood vessel walls in response to increases in blood pressure
Myogenic mechanism
Myogenic mechanism: ___ systemic blood pressure stretches afferent arteriole less, reducing GFR; triggers smooth muscle ____, increasing blood flow through glomerulus, causing an increase in GFR back toward normal range
Decreased, relaxation
Mechanism works best for systemic blood pressure changes between __ and __ mm Hg to rapidly restore GFR back to normal
80 and 180
Tubuloglomerular feedback – second autoregulation mechanism; involves __ __
macula densa
macula densa are in the ___ renal tubule
distal renal tubule
Tubuloglomerular feedback – negative feedback loop controls pressure in glomerulus in response to __ concentration of filtrate
NaCl
As GFR increases, volume of filtrate flowing through renal tubule ___, and more sodium and chloride ions are absorbed into macula densa
Increases
Macula densa responds to increases in ___ concentration by releasing chemicals that cause afferent arteriole to constrict
NaCl
Tubuloglomerular feedback (continued): Macula densa also signals JG cell causing a reduction in release of hormones, ___ and ____, when reduced allow efferent arteriole to dilate causing a decrease in GFR towards normal
renin and angiotensin-II
Decreases in GFR reduces sodium and chloride ions absorbed by macula densa, which triggers ___ of afferent arteriole and constriction of efferent arteriole, which increase glomerular hydrostatic pressure to restore GFR
Dilation
RAAS responds to combination of three conditions: stimulation by sympathetic nervous system, low glomerular hydrostatic pressure, and stimulation from ___ ___
macula densa
Neural regulation of GFR primarily involves sympathetic division of autonomic nervous system and its hormone ____
norepinephrine
Increased sympathetic activity causes ____ of afferent arterioles like most systemic blood vessels; increases systemic blood pressure
Constriction
Low levels of sympathetic stimulation trigger JG cells to release ____, ultimately leading to formation of angiotensin-II; raises systemic blood pressure and increases GFR
Renin
High levels of sympathetic stimulation leads to high levels of ____; constricts both afferent and efferent arterioles, decreasing GFR to minimize fluid loss, preserve blood volume, and maintain blood pressure
angiotensin-II
Transcellular route – substances such as ___ and amino acids must move through tubule cells
Glucose
Most substances either reabsorbed or secreted via transcellular route do so by ___-___ transport in one of the following processes: Facilitated diffusion or Active transport
carrier-mediated
a concentration gradient set up by a primary active transport pump is used to drive the transport of a second substance against its concentration gradient via another carrier protein:
Secondary active transport
bring sodium ions into cell from filtrate and secrete hydrogen ions into filtrate
Na+/H+ antiporters
steroid hormone made by and released from adrenal cortex; increases reabsorption of sodium ions from filtrate and secretion of potassium ions into filtrate
Aldosterone
made by hypothalamus and secreted by posterior pituitary; causes water reabsorption; reduces urine output
ADH
stimulates urinary excretion of sodium ions while it also inhibits release of both aldosterone and ADH; results in more water and sodium excretion
ANP
last chance for regulation of fluid, electrolyte, and acid-base balance before filtrate becomes urine
Medullary collecting system
Medullary collecting system is impermeable to water in absence of
ADH
Medullary collecting system is permeable to ___; allows it to be reabsorbed passively into interstitial fluid
Urea
If blood pH increases, tubule cells reabsorb less ___ ions from filtrate; lowers blood pH as these ions are excreted in urine
Bicarbonate
Reabsorption of organic solutes and ions occurs in __ half of proximal tubule
First
Na+/glucose symporters use the sodium ion gradient to move both sodium ions and glucose molecules, by secondary ___ transport, into tubule cell
Active
Amino acids, lactic acid, sulfate ions, and phosphate ions are also transported by ___ ___ transport in this fashion
secondary active
Bicarbonate ion reabsorption occurs as result of ___ antiporter activity and a reversible chemical reaction: CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3−
Na+/H+
Hydrogen ions secreted into filtrate combine with bicarbonate ions forming
carbonic acid
Carbonic acid is converted to CO2 and H2O by enzyme
carbonic anhydrase
Bicarbonate ion reabsorption is ___ as hydrogen ions are again secreted back into tubular lumen
Continual
Obligatory water reabsorption Occurs in ___ half of proximal tubule where sodium ions, glucose, and other organic molecules have already been reabsorbed; water is “obliged” to follow reabsorbed substances
Second
passive movement of water out of filtrate happens by osmosis through ____ and ___ routes
paracellular and transcellular
___ in proximal tubule includes hydrogen ions (discussed previously), many drugs, and various nitrogenous wastes
Secretion
In first half of proximal tubule, most of __ acid in filtrate is reabsorbed; nearly all of it is secreted back into filtrate in second half of the tubule
Uric
last chance for regulation of fluid, electrolyte, and acid-base balance before filtrate becomes urine: ___ ___ __
Medullary collecting system
Medullary collecting system is ___ to water in absence of ADH
Impermeable
Medullary collecting system is ___ to urea; allows urea to be reabsorbed passively into interstitial fluid
Permeable
Local ___ cells secrete hydrogen ions into filtrate against a steep concentration gradient, increasing H+ concentration in filtrate by as much as 900 times
Intercalated
Cells of proximal tubule secrete ___ ions as a mechanism for reabsorbing bicarbonate ions while cells of distal tubule secrete hydrogen ions under direction of ___
Hydrogen, aldosterone
Production of Dilute Urine: Facultative water reabsorption is turned off as ADH hormone release is
Suppressed
creates and maintains medullary osmotic gradient: ___ mechanism
Countercurrent mechanism
Countercurrent mechanism creates and maintains medullary osmotic gradient by exchanging materials in opposite directions between ___ and ___ fluids
filtrate and interstitial fluids
Countercurrent mechanism involves three factors:
• ___ multiplier system in nephron loops of juxtamedullary nephrons
• Recycling of ___ in medullary collecting ducts
• Countercurrent exchanger in ___ ___
Countercurrent, urea, vasa recta
Countercurrent multiplier proceeds in following steps: ___ is actively transported from thick ascending limb filtrate into interstitial fluid, raising NaCl concentration outside nephron
NaCl
NaCl in interstitial fluid pulls water out of filtrate in thin ___ limb by osmosis
Descending
As NaCl continues to be removed from filtrate, water continues to follow making filtrate more
Concentrated
Last part of Countercurrent multiplier: High NaCl concentration in filtrate allows for continued NaCl reabsorption into
interstitial fluid
Countercurrent mechanism (continued): Permeability of medullary collecting system to urea is another important factor in establishment of medullary osmotic gradient. As water is reabsorbed from filtrate, urea becomes more concentrated in remaining fluid. In medullary collecting ducts and papillary ducts, urea follows concentration gradient and passively diffuses out of filtrate and into interstitial fluid; further ___ medullary interstitial fluid
Concentrates
Some urea enters thin descending limb, so ___ recycles
Continuously
Note that urea diffusing out of collecting duct constitutes only a ___ amount of total urea; much of urea remains in filtrate and is excreted in urine
Small
Medullary osmotic gradient created by countercurrent multiplier and urea recycling is maintained by vasa recta (vessels surrounding juxtamedullary loops) acting as
countercurrent exchanger
Countercurrent exchanger (continued): By the time vasa recta exit renal medulla, blood has approximately __ concentration (about 300 mOsm) it had upon entering renal medulla
Same
Countercurrent exchanger (continued): Return of blood to its initial osmolarity is critical; allows vasa recta to deliver oxygen and nutrients to cells of medulla without ___ medullary osmotic gradient necessary for water reabsorption and production of concentrated urine
Depleting
Measurement of rate at which kidneys remove a substance from blood; can be used to estimate glomerular filtration rate; both measured in milliliters of plasma per minute
Renal clearance
accurate assessment of GFR can be obtained using
inulin
condition that can develop when GFR is less than 50% of normal
Uremia
when GRF decreases, the macula densa releases chemicals to ___ the afferent arteriole
dilate
The sympathetic nervous system ___ the blood vessels supplying the kidney to ___ the GFR
constricts; reduce
The enzyme ___ is released by JG cells in response to a decrease in the GFR
renin
The enzyme ___ converts angiotensin 1 to angiotensin 2
angiotensin-converting enzyme
Generally, angiotensin 2 ___ systemic blood pressure while ___ the GFR
increases; maintaining
the distal tubule reabsorbs sodium ions and secretes potassium and hydrogen ions in response to
aldosterone
___ ion reabsorption creates a gradient that helps drive the reabsorption of water and many other solutes from the proximal tubule
sodium
ADH triggers water reabsorption from the __ __ and the __ __
distal tubule
collecting duct
___ water reabsorption occurs in the distal tubule and collecting duct
facultative
Which of the following foes not contribute to the creation/maintenance of the medullary osmotic gradient
the countercurrent multiplier of the nephron loops of cortical nephrons
the kidneys produce ___ urine when the osmolarity of the body’s fluids increases. The produce ___ urine when the osmolarity of the body’s fluids decreases
concentrated; dilute
GFR can be estimated by measuring the rate at which certain substances are removed from the blood, which is known as ___ clearance
renal clearance
the process by which urine is eliminated is called ____, and it is mediated by reflexes involving the ___ nervous system
micturition; parasympathetic
