Where are the 3 constriction locations in the urinary tract?
- Right outside kidneys
- middle of ureter
- At entrance to bladder
The outside of the bladder is protected by _______________
The inner layer of the bladder is lined w/ a mucosal membrane consisting of _____________,_______________, _______________ , and ______________
Surface glycocalyx, basement membrane, lamina propria, and urothelium
Which type of cells act as a barrier to ions, water, and solutes?
The bladder is flexible, but impermeable, because of _______________
What does the pudenal nerve innervate?
The ____________ nerve is not fully developed until a child reaches ~3-4 years of age
List 8 ways the kidneys maintain the body's internal environment
- Excretion of metabolic wastes and foreign substances
- Regulation of total water volume in the body and osmolarity
- Regulation of ion concentrations in extracellular fluids
- Regulation of arterial P
- Long-term acid-base balance
- Production of erythropoietin and renin
- Conversion of vitamin D to its active form
- Carrying out gluconeogenesis during prolonged fasting
Approximately how much blood is filtered through the kidneys each day?
How many liters of plasma is filtered per day?
How much plasma enters the glomerular capillaries per minute?
How many liters of filtrate is reabsorbed per day?
How many liters of urine are excreted per day?
The outermost layer of the kidney where majority of reabsorption and secretion take place
Middle layer of the kidney where urine concentration and dilution occur
The medulla consists of multiple pyramidal tissue masses, called the ___________
In between renal pyramids are spaces called ___________ through which the blood vessels pass. These structures nourish the kidneys
The tip of the renal pyramid that points toward the renal pelvis
Innermost layer of the kidney, which is a collection of channels cushioned on fat tissue
Channels through which urine passes to the pelvis
Major and minor calyces
Urine passes through the renal papilla into the _____________
2-3 minor calyces merge to form _______________, through which urine passes through the renal pelvis into the ureter
Fatty cavity underneath renal pelvis through which blood vessels, nerves and lymphatics pass
Thin membrane sheath covering outer surface of kidney. Consists of tough fibers containing collagen and elastin that protect kidneys from injury and infecton
Concave part of the bean-shape where blood vessels and nerves enter and exit the kidney; also the point of exit for the ureter
Urine formation through kidney:
Cortex --> Medulla --> Papilla --> Minor calyx --> major calyx --> Pelvis --> ureter --> urinary bladder
What is the functional unit of the kidney?
Major structures of the nephrons:
Glomerulus and tubules
What structure is the primary site for reabsorption?
Proximal convoluted tubule
The thin segment of the loop of Henle reabsorbs ________ only
The thick segment of the loop of Henle reabsorbs ________ only
Glomerular capillaries are mostly located where?
Macula densa has a ______ sensing mechanism
Where do thiazide diuretics work?
Distal convoluted tubule
Peritubular capillaries are located in which type of nephron?
Vasa recta is located in which type of nephron?
Which type of nephron has short loops of henle?
Where is the glomeruli located in Cortical nephrons?
Cortical nephrons comprise what percentage of total nephrons?
Juxtamedullary nephrons comprise what percentage of total nephrons?
Where is the glomeruli located in juxtamedullary nephrons?
deep w/in renal cortex
Which type of nephrons have long loops of henle that set up an osmotic gradient by increasing Na reabsorption, promoting water reabsorption?
What cell types are found in the Juxtamedullary complex?
- Macula densa cells
- Extraglomerular mesangial cells
- JG cells
Cells of the Juxtamedullary complex that respond to changes in the NaCl levels in the distal tubule of the nephron via tubuglomerular feedback (TGF)
Macula densa cells
Cells of the Juxtamedullary complex that are located in the jxn b/w afferent and efferent arterioles
Extraglomerular mesangial cells
Cells of the Juxtamedullary complex that are specialized cells located on either side of the afferent arteriole; secrete renin
What is the primary fxn of glomerular mesangial cells?
Remove trapped residues and aggregated ptns from the basement membrane to keep filter unclogged
Function of podocytes:
Form filtration barrier (along w/ glomerular capillary endothelial cells and glomerular basement membrane)
Autonomic innervation to the kidneys is entirely ___________, with nerves originating from the ________________
Sympathetic; celiac plexus
What are the 3 major effects of sympathetic stimulation of the kidneys?
- Catecholamines cause vasoconstriction (mostly α1A, some α1B)
- Catecholamines enhance Na reabsorption in proximal tubules (α1B)
- Increased nerve activity dramatically increases renin secretion from JG cells (β1)
Renal nerves also include ___________ (afferent/efferent) fibers to conduct chemoreceptor and baroreceptor impulses from the kidney
Which process of the kidney occurs in the renal corpuscle and produces cell- and ptn-free filtrate?
Which process of the kidney occurs in the renal tubules and collecting ducts and selectively moves substances from filtrate into the blood (based on pressures)?
Which process of the kidney occurs in the renal tubules and collecting ducts and selectively moves substances from the blood to the filtrate, utilizing active transport?
T/F: If a substance is freely filtered, the concentration in the glomerular capsule is equal to the concentration in the urine.
If only filtration and reabsorption is occurring and 100 molecules of a substance comes to the glomerulus, approximately what volume of the substance would be found in the urine (assuming this substance can be reabsorbed)?
List molecules that can be partially absorbed
List molecules that can be completely absorbed
If only filtration and secretion is occurring and 100 molecules of a substance comes to the glomerulus, approximately what volume of the substance would be found in the urine (assuming this substance can be secreted)?
List molecules that can be partially secreted
List molecules that can be completely secreted
Para-aminohippuric acid (PAH)
List molecules that can be partially reabsorbed and secreted
- Uric acid
T/F: Glomerular filtration is an active process in which hydrostatic P forces fluids and solutes through the filtration membrane
Where is the filtration membrane located?
B/w the blood and the interior of the glomerular capsule
What 3 layers make up the filtration membrane?
- Fenestrated endothelium of the glomerular capsule
- Basement membrane
- Foot processes of podocytes of the glomerular capsule
_____________ of the glomerular capillary endothelium filter by size
The basement membrane of the filtration membrane is composed of:
Collagen and proteoglycan
T/F: Collagen filters by charge and proteoglycan filters by size
If albumin is 6.9 nm in diameter, but glomerular membrane pores are 7-8 nm in diameter, why doesn't albumin get through?
Charge on albumin is negative = repelled by negative charge on proteoglycan
Defined as the volume of filtrate formed each minute by the glomeruli of the kidneys
Defined as the fraction of the renal plasma flow that is filtered
How much plasma is filtered every minute?
About ______% of plasma flowing through the kidney is filtered through the glomerular capillaries
GFR is directly proportional to:
- Net filtration P
- Total surface area available for filtration
- Filtration membrane permeability
Net filtration P =
Outward P - Inward P
A vascular P of ~______ mm Hg is needed for filtration to occur
A vascular P of ~______ mm Hg is needed for reabsorption and secretion to occur
What kind of pressure is created by the amount of liquid present?
What kind of pressure is created by the amount of dissolved solute (i.e. albumin)
T/F: Kf cannot be measured directly, so it must be calculated
The glomerular capillary filtration coefficient (Kf) is calculated by:
hydraulic conductivity x SA of glomerular capillaries
T/F: the Kf value for the glomerular capillaries is ~200x higher than the Kf for most other capillary systems i the body
T/F: Maintenance of GFR is likely due to changes in Kf
In chronic uncontrolled HTN and DM, thickening of the basement membrane occurs, which ultimately damages the capillaries. How does this affect Kf and GFR?
How can obstructions lodged in the urinary tract affect HPcs, NFP, and GFR?
Increase; decrease; decrease
Defined as distention and dilation of the renal pelvis and calices
Defined as the volume of plasma that is completely cleared of a substance by the kidneys per unit of time
Renal clearance equation:
Cs x Ps = Us x V
T/F: If a substance is freely filtered and is not reabsorbed/secreted, then the rate at which the substance is excreted in urine = the filtration rate of the substance by the kidneys.
T/F: Inulin is freely filtered
What equation could you use to calculate GFR using inulin?
GFR = (Us x V) / Ps
__________ is a byproduct of muscle metabolism
T/F: Creatinine is not cleared by the body via glomerular filtration and requires IV infusion to measure
How would an increase in HPgc affect GFR?
How would an increase in HPcs affect GFR?
How would a decrease in OPgc affect GFR?
How would a decrease in Kf affect GFR?
How would an increase in arterial P affect HPgc ?
Increase (only small effect)
How would an increase in efferent arteriolar resistance affect HPgc ?
How would a decrease in afferent arteriolar resistance affect HPgc ?
T/F: severe increases in efferent resistance causes decrease in renal BF.
Ang II ______________(increases/decreases) efferent arteriole resistance
T/F: A decrease in afferent arteriolar resistance will restrict renal BF and decrease HPgc
_________ cells causes contraction of basement membrane of glomerular capillaries, leading to decreased SA and decreased GFR
RBF is determined by:
P gradient across the renal vasculature divided by total vascular resistance
List mechanisms for intrinsic control of GFR:
- Myogenic response
- Tubuloglomerular feedback
- Intrarenal baroreceptor pathway
List mechanisms for extrinsic control of GFR:
How does the myogenic response regulate HP and GFR if there is an increase in systemic BP?
--> ↑stretch of vasc. SMC; ↑Ca --> constriction of afferent arterioles --> ↓ renal BF to glomerulus --> ↓ HP ↓GFR
How does the myogenic response regulate HP and GFR if there is a decrease in systemic BP?
--> ↓stretch of vasc. SMC; no Ca accumulation --> relaxation of afferent arterioles --> ↑ renal BF to glomerulus --> ↑ HP ↑GFR
Which type of regulation is flow-dependent and directed by cells of the macula densa?
How is the [Na] in the tubule affected if there is high GFR?
Less time for Na reabsorption = high [Na] in tubule
T/F: If there is high [Na] in tubule, there will be vasodilation of the afferent arteriole in order to increase the amount of water coming into the tuble
How is the [Na] in the tubule affected if there is low GFR?
more time for Na reabsorption = low [Na] in tubule
If there is high [Na] in tubule, what will happen to the afferent arteriole?
Describe the overall tubularglomerular feedback mechanism when BP is high
- ↑ BP and RBF
- ↑ GFR
- ↑ speed of filtrate flow through tubules
- ↓ contact time b/w filtrate and tubule cells
- ↑ apical Na entry into macula densa cells via NKCC
- ↑ Na transport across basolateral via Na/K atpase
- ↑ATP to AD conversion and A1 receptor binding
- ↑ Ca in SMC and ↑ Ca in JG cells
- Afferent arteriole constriction and ↓ RBF and ↓ renin secretion, ↓BP
Describe the overall tubularglomerular feedback mechanism when BP is low
- ↓ BP and RBF
- ↓ GFR
- ↓ speed of filtrate flow through tubules
- ↑ contact time b/w filtrate and tubule cells
- ↓ apical Na entry into macula densa cells via NKCC
- ↓ Na transport across basolateral via Na/K atpase
- ↑ NO and PG production
- ↑ NO action in SMC and ↑ PG action in JG cells
- Afferent arteriole dilation, ↑ RBF and ↑ renin secretion, ↑BP
Describe the inrarenal baroreceptor pathway if renal P is high in afferent arterioles
↓ prostaglandins --> ↓ renin release
Describe the inrarenal baroreceptor pathway if renal P is low in afferent arterioles
↑ prostaglandins --> ↑ renin release
When would neuronal control take over extrinsic control?
Extreme circumstances (low extracel. fluid / hypovolemic shock from severe hemorrhage)
What are the effects of neural control?
- Constriction of efferent and afferent arterioles causing a reduction in RBF and GFR
- ↑ secretion of renin via tubuloglomerular feedback
- Stimulation of β1 on juxtaglomerular cells leading to additional renin secretion
What 3 mechanisms can stimulate renin release?
- Sympathetic nerve
- Macula densa
Which of the 3 mechanisms that stimulate renin release utilize prostaglandin?
- Macula densa
How does the intrarenal baroreceptor mechanism release renin when stimulated?
↓ in renal perfusion in afferent arteriole stimulates synthesis and release of prostaglandins = renin release
How does the sympathetic nerve mechanism release renin when stimulated?
↑ activity of SNS = release NE and/or E = stimulates β1 on JG cells = renin release
How does the macula densa mechanism release renin when stimulated?
↓ in Na reaching MD = MD synthesizes and releases prostaglandins = renin release from JG cells