Urinary System Flashcards
What are the three layers of the urinary bladder?
– Covered by parietal peritoneum, superiorly, and by fibrous adventitia elsewhere – Muscularis: detrusor: three layers of smooth muscle – Mucosa: transitional epithelium
What are some causes of kidney stones?
hypercalcemia, dehydration, pH imbalances,
frequent urinary tract infections, or enlarged prostate causing urine
retention
When is filtrate considered urine?
once it enters the collecting duct
what are the three layers of the filtration membrane?
- Fenestrated endothelium of glomerular capillaries
- Basement membrane
- Filtration sits
What three factors promote osmosis into the peritubular capillaries
– High interstitial fluid pressure due to accumulation of
reabsorbed fluid in extracellular space
– Low blood hydrostatic pressure in peritubular capillaries
due to narrowness of efferent arterioles
– High colloid osmotic pressure in blood due to presence of
proteins that were not filtered
Trace renal blood flow from the renal artery to glomerulus
- Renal artery
- interlobar arteries(up renal columns)
- Arcuate arteries(over pyramids)
- Cortical radiate arteries(up into cortex)
- Afferent arterioles
- Glomerulus
How do the kidneys respond to falling blood pressure?
they produce renin
Blood flows out of the glomerulus via?
efferent arterial’s
What are rugae?
conspicuous wrinkles in empty
bladder
what occurs with sympathetic stimulation of the renal plexus
-Reduction in glomerular blood flow and rate of urine production
A flap of ___ acts as a valve at the enterance of the uerter to the bladder. What does this valve prevent?
Mucosa
Re-flux of urine into the ureter
After the proximal convoluted tube comes the ___
nephron loop
What is the function of the principal cells in the DCT?
- Receptor sites for hormones
- Salt/water balance
The function of the collecting ducts is to _____ Water
Conserve
What is nitrogenous waste?
Metabolic waste products that contain high amounts of nitrogen
What is the urinary pole of the renal corpuscle?
The side where the renal tubule begins
What is renal auto-regulation?
The ability of the nephrons to adjust their own blood flow and GFR
How does angiotensin II induce sodium retention?
3 ways
- Lowers BP in peritubular Capillaries increasing reabsorption of sodium
- Stimulates adrenal cortex to release aldosterone promoting Na+ reabsorption in the DCT
- Stimulates Na+ reabsorption in the PCT
How long is the male urethra?
18cm long
Does the counter current exchange of salt and water in the vasa recta effect the osmolarity of the medulla?
No, because the exchange is equal
If mean arterial pressure drops below ___mm Hg then filtration and urine output cease
70 mm Hg
What is the function of ADH?
Makes the collecting ducts of the kidneys more permeable to water allowing water to be reabsorbed into the blood
What is a BUN level and what does BUN stand for?
BUN stands for Blood Urea Nitrogen
its value signifies the level of nitrogenous wastes in the blood
How does the Tubuloglomerular feedback mechanism carry out its function?
Via the juxtaglomerular apparatus
The thin segment of the nephron loop ___ water the ____ the urine
- Secretes water
- Concentrates
efferent vessels from the glomerulus lead to one of which two vessels?
Peritubular capillaries(cortex) Vasa recta(Medulla)
What is a nephron?
The functional filtration unit of the kidney
What are the two regions of the renal parenchyma?
- the outer renal cortex
- inner renal medulla
What is the vasa recta? where does it supply blood to?
—capillary branching off efferent arteriole in medulla
– Provides blood supply to medulla and does not remove NaCl and urea from medullary ECF
What is the average capacity of the urinary bladder?
moderate fullness-500mL
Max 700-800 mL
What is the renal pelvis?
the convergence of the major calyces of the kidney into one main urine collecting body
What is the myogenic mechanism based on?
the tendency of smooth muscle to contract when stretched
What are some functions of the kidneys?
- Filtration
- Regulation of: Blood volume, pressure,and osmolarity. Electrolytes, acid-base balance, Calcium
- Hormone clearance
- Glucose synthesis during starvation
What are the two routes of tubular reabsorption?
- Transcellular-through cytoplasm
- Paracellular-through tight junctions
a minor calyx of the kidney is?
A cup that nestles the papilla of a renal pyramid and collects its urine
Why does dehydration cause hypertonic urine?
- Dehydration causes high blood osmolarity
- High blood osmolarity causes the release of ADH
- ADH creates more aquaporin channels in renal tubules
- more water is reabsorbed by collecting duct
- urine is concentrated
What is the function of filtration slits in the filtration membrane?
- They are extensions of podocyte cells visceral layer of the glomerular capsule
- Leave a gap after the basement membrane
- Negatively charged
Transport maximum is reached when___
transporters are saturated
The thick segment of the nephron loop is composed of ___ ET which is heavily engaged in___
Simple cuboital
Active transport of salts
what is obligatory water reabsorption?
PCT, water is reabsorbed at constant rate
What molecules can pass through the filtration membrane?
almost any unbound molecules smaller than 3nm
Water, electrolytes, glucose, fatty acids, amino acids, nitrogenous wastes, vitamins
The Nephron loop has two segments the ___ and the ___
Thick and thin segments
How is GFR controlled?
By adjusting glomerular blood pressure moment to moment
What are the portions of the glomerular capsule? what are the composed of?
- Outer parietal layer(simple squam)
- Inner visceral layer(podocytes that wrap around glomerulus)
- capsular space
What is the urinary bladder?
—muscular sac
located on floor of the pelvic cavity
What is the urethra?
tube that conveys urine out of body
The renal plexus carries _____ innervation from the _____ plexus
Sympathetic
abdominal aortic
The thick segment of the nephron loop___ solutes but not ____ thus it ____the urine
- Reabsorbs Solutes
- Water
- dilutes urine
What is the spongy urethra?
The portion of the male urethra that passes through the penis
How do granular cells respond to low blood pressure?
by secreting renin
What is the internal urethral sphincter?
the thickening of the detrusor muscles. found only in males
What is Excretion?
Separating wastes from body fluids and eliminating them
The proximal convoluted tube is composed of ____ epithelium with prominent____which allow for maximum surface area for absorption
- Simple cuboidal
- Microvilli
what alterations does urine undergo?
only changes to water content
What is the function of the PCT?
- Reabsorbs 65% of glomerular filtrate
- removes substances from the blood and secretes them into filtrate
- Has microvilli
- abundant mitochondria for active transport
What are the three steps involved in converting filtrate into urine?
- Tubular reabsorption
- Tubular secretion
- Water conservation
What are the cell times within the DCT?
- Principal cells
- intercalated cells
What are the three regions of the male urethra?
- Prostatic
- Membranous
- Spongy
What four body systems carry out excretion?
- Respiratory system
- Integumentary system
- Digestive system
- Urinary System
Collecting duct (CD) begins in the
_____ where it receives tubular fluid
from several _____
Cortex
Nephrons
What is the function of the fenestrated endothelium of the glomerular capillaries?
- It is the initial filtration
- a series of small filtration pores
The thin segment of the nephron loop is composed of ___ which is very permeable to ___
Simple Squamish
What is tubular secretion?
renal tubule extracts chemicals from
capillary blood and secretes them into tubular fluid
What are Natriutetic peptides released?
in response to high BP
What are the four actions of ANP that resalt in the excretion of salt and water?
– Dilates afferent arteriole, constricts efferent arteriole:
raising GFR
– Inhibits renin and aldosterone secretion
– Inhibits secretion of ADH
– Inhibits NaCl reabsorption by collecting duct
What is the prostatic urethra?
The portion of the male urethra that passes through the prostate
Juxtamedullary nephrons maintain ____gradients and have efferent arterioles that branch into ____ around their nephron loops
salinity gradients
Vasa Recta
How long is the female urethra?
3-4 cm long
What is azotemia and what does it indicate?
Elevated BUN levels
indicates renal insufficency
What is the function of the Tubuloglomerular feedback mechanism of renal auto-regulation?
It receives feedback on the status downstream tubular fluid and adjusts filtration rate in the glomerulus accordingly
What are the triggers of aldosterone?
- It is a steroid released by the adrenal cortex
- triggered by: Low blood Na+, High K+, low blood pressure via the rennin-angiotensin-aldosterone
What is glomerular filtrate?
The fluid in the capsular space
Once the mesangial cells produce adenosine, where does it go next?
to the granular cells
How concentrated the urine becomes depends on
body’s state of_____
Hydration
What are ureters?
retroperitoneal, muscular tubes that extend from each kidney to the urinary bladder
What are the two mechanisms of renal auto-regulation?
- Myogenic mechanism
- Tubuloglomerular feedback
What are kidney stones?
-Renal calculus, hard granule of calcium phosphate,
calcium oxalate, uric acid, or a magnesium salt called struvite
What occurs in the ascending capillaries of the vasa recta?
The exchange salt for water
How is Creatinine produced?
As a product of Creatine phosphate catabolism
What is the external urethral sphincter?
– Where urethra passes through the pelvic floor
– Skeletal muscle - voluntary control
Aldosterone is the ____ hormone
Salt retaining
What are the four types of nitrogenous wastes found in the body?
- Ammonia
- Urea
- Uric Acid
- Creatinine
fluid entering the DCT contains ___% of the water and ___% of the salts from the glomerular filtrate
- 20%
- 7%
What is Proteinuria and what can cause it?
- Presence of protein in the urine
- Damage or infection to the kidneys
- Prolonged strenuous physical activity
What are the four principle organs of the urinary system?
Kidneys
Ureters
Urinary bladder
urethra
What are the effects of parathyroid hormone?
- Responds to low calcium
- Causes increased calcium reabsorption in the ascending limb of the nephron loop and the DCT
- Increases phosphate excretion
- this reduces calcium precipitation into bone and allows the levels in the blood to rise
The two types of nephrons are the ____ and the ____
- Juxtamedullary Nephrons
- Cortical Nephrons
What are normal BUN levels?
10 to 20 mg/dL
explain the process of Rennin to angiotensin II
- Baroreceptors detect ow BP and stimulate the sympathetic NS
- Sympathetic fibers cause the release of renin
- renin convets angiotensinogen into angiotensin I
- Angiotensin I is converted to angeotensin II in the lunce by the ACE in the lungs and kidneys
What are the three purposes of tubular secretion?
- Acid-base balance-H+ and HCO3 ions
- Waste removal-nitrogenous
- Clearance of drugs and contaminants-Morphine, penicillin, asprin
What is micturition?
the act of urinating
What is the renal parenchyma?
The function tissue of the kidney-produces urine
How is uric acid produced?
As a product of nucleic acid catabolism
What is the counter current exchange system?
a system formed by blood flowing in opposite directions in adjacent
parallel capillaries
The ____ kidney is slightly lower due to ____
Right
Large right lobe of the liver
What are the three layers of the ureter?
- outer layer-Adventitia
- –Connective tissue
- middle layer-Muscularis
- —Layers of smooth muscle
- Deep layer-Mucosa
- –Transitional epithelium
The PTC reabsorbs ___ of the water in filtrate?
2/3
What is the Macula densa and what is its function?
- A patch of slender, closely spaced sensory cells in the nephron loop
- When NaCl levels are high it communicates with the mesangial cells which intern communicate with the Granular cells to carry out their function
What are the functions of Angiotensin II?
- Vasoconstrictor
- Salt retention
- Stimulates aldosterone
- water retention
- thirst stimulation
What is the transport maximum?
the maximum amount of a solute that can be reabsorbed by the transport proteins in the tubule cells
Cortical nephrons have efferent arterioles that branch into _____ around the ___ and ___
peritubuar capillaries
PCT and DCT
What is the renal pelvis?
cavity that contains blood and lymphatic vessels,nerves, and urine collecting structures
Filtrate is similar to blood plasma except
It has almost no protein
What is the filtration membrane?
A series of three barriers that fluid must pass through during glomerular filtration
Explain the Countercurrent multiplyer
- Depended on the salinity gradient in the renal medulla
- Decending limb is permeable to water, water is drawn out by high salt of the ECF in the medulla
- Ascending limb is permeable to solutes but not water, salt and others are reabsorbed
- salt absorbed in the ascending limb maintains the salinity gradient
What two components make up the renal corpuscle?
- The glomerulus
- glomerular capsule(2 layers) enclosing the glomerulus
What is the Rennin-Angiotensin-Aldosterone Mechanism?
A system of hormones that helps control BP and GFR
follow the Flow of fluid from the point where the glomerular filtrate is formed to the point where urine leaves the body
-glomerular capsule
-proximal convoluted
tubule
-nephron loop
-distal convoluted
tubule
-collecting duct
-papillary duct
-minor calyx
-major calyx
-renal pelvis
-ureter
-urinary bladder
-urethra
What is glomerular filtration?
An instance of capillary fluid exchange where water and solutes pass from the capillaries of the glomerulus to the capsular space in the nephron
What occurs in the decending capillaries of the vasa recta?
They exchange water for salt
What are the three protective connective tissue layers of the kidneys? from superficial to deep
- Renal fascia
- Perirenal Fat Capsule
- Fibrous Capsule
What is Hematura and what causes it?
- Blood in the urine
- Damage or infection to the kidneys
- Prolonged strenuous physical activity
What three homeostatic mechanisms control GFR?
- Renal auto regulation
- Sympathetic control
- Hormonal Control
What are general GFR’s for men and women?
180L/day for men
150L/day for women
What occurs if GFR is too low?
- Waste products are reabsorbed
- Azotemia may occur
What are the four stages in urine formation?
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
- Water Conservation
What are the components of the juxtaglomerular apparatus?
- The macula densa
- Granular(juxtaglomerular) cells
- Mesangial cells
The functions of the DCT are regullated by___
Various hormones
- Aldosterone
- ANP
- ADH
- Parathyroid hormone
What are the functions of Adosterone?
- Acts on the thick seg of the Neph. loop
- Stimulates reabsorption of Na+ and secretion of K+
- Water and Cl- follow Na+
- urine volume is reduced
- body retains NaCl and water
The Juxtamedullary nephrons make up ___ of all nephrons
15%
How does the myogenic mechanism work with rise and falls of arterial blood pressure?
- BP go up, aff. arteriole is stretched, aff. arteriole constricts
- -BP go down, aff. arteriole is relaxed, aff. arteriole dilates
What is a major calyces of the kidney?
a convergence of 2 or 3 major calyxs
One lobe of the kidney consists of?
one pyramid and its cortex
What is the vascular pole of the renal corpuscle?
The side where afferent arterioles enter and efferent arterioles leave
What is the primary function of the nephron loop?
To generate a salinity grasient that enables collecting duct to concentrate urine and conserve water
When does the Distal convoluted tubule begin?
After the ascending limb of the nephron loop reenters the cortex
Renal innervation comes from the?
Renal Plexus
What are the two principal parts of a nephron?
- The renal corpuscle
- Renal Tubule
How does the Macula densa communicate with nearby mesangial cells?
- The macula densa produces ATP when it absorbs excess NaCl
- The ATP is metabolized by the nearby mesangial cells which produce Adenosine
What triggers the release of ADH?
– Dehydration, loss of blood volume, and rising blood
osmolarity stimulate arterial baroreceptors and
hypothalamic osmoreceptors
Kidneys receive ____ of cardiac output. This is called the renal ___
21%
Fraction
The key electrolyte to be reabsorbed is___
Why?
- sodium
- Creates electrical and osmotic gradients that drive the reabsorption of other solutes
How do sympathetic nerves effect GFR
when they are stimulated they constrict afferent arterioles
What is tubular fluid?
fluid present within the PCT, Nephron loop, and DCT
What is Water diuresis
drinking large volumes of water will
produce a large volume of hypotonic urine
How do the kidneys regulate calcium levels?
Via calcitriol synthesis
What are granular (juxtaglomerular) cells and what are their functions?
- Modified smooth muscle cells that wrap around the arterioles
- The respond to adenosine by constricting afferent arterioles thus reducing blood flow, correcting GFR
What is the trigone of the urinary bladder?
smooth-surfaced triangular area on bladder
floor that is marked with openings of ureters and
urethra
Why does water diuresis creat hypotonic urine?
Because When the urine passes through the cortical portion of the CD it only absorbs NaCl and not water so salt is taken out but not water leading to urine with very low concentration
Trace the flow of blood in the kidneys after the Peritubular capillaries/Vasa recta to the renal vein
- Peritubular capillaries/Vasa recta
- Cortical radiate veins
- or/then into Arcuate veins
- interlobar veins
- renal vein
What is glomerular filtration rate?GFR
The amount of filtrate formed per minute by the two kidneys combined
How is urea formed?
- Proteins break down into amino acids
- amino acids into ammonia once NH2 is removed\
- ammonia is converted into urea in the liver
What occurs if GFR is too high?
- Flow is to rapid for proper reabsorbtion
- increased urine output
- dehydration and electrolyte depletion
How much of the nitrogenous waste is reabsorbed in the nephrons?
1/2
Where do kidney stones form?
in the renal pelvis
How does the vaso constriction action of angiotensin II effect GFR?
-Restriction of the efferent arterioles raises GFR by increasing pressure
What are the four parts of the renal tubule?
- Proximal convoluted tube
- Nephron Loop
- Distal Convoluted tubule
- Collecting duct
What is the membranous urethra?
the portion of the male urethra that passes through the muscular floor of the pelvic cavity
Explain the involuntary micturition reflex
- Stretch receptors detect fullness and signal to spinal cord
- parasympathetic nerves respond and excite detrusor muscles
- signals relax internal sphincter in males
- urine is voided
What occurs to the filtrate as it passes through the tubules?
it gets modified as needed by the body
What is the function of the basement membrane in the filtration membrane?
- A negatively charged proteoglycan gel that repels proteins
* only .03% of filtrate is protein compared to 7% in blood plasma*
Why is blood hydrostatic pressure high inside the glomerular capillaries?
Due to the afferent arteriole being larger than the efferent arteriole
What is the function of the interculated cells within the DCT?
Involved in acid base balance
How do the kidneys regulate blood levels?
by producing erythropoietin which stimulates red bone marrow to produce erythrocytes
The function of the DCT is to_____
Reabsorb varying amounts of water and salts
What is Uremia and how is it treated?
- A syndrome of diarrhea, vomiting, dyspnea, and cardiac arrhythmia stemming from the toxicity of nitrogenous waste
- Treated using dialysis or organ transplant
