What structures are involved in urine production in the nephron?
Bowman's capsule, PCT, Loop of Henle (LOH), DCT, Collecting duct (CD)
What structures transport urine through the renal system?
Papillary duct, minor calyx, major calyx, renal pelvis, ureter, bladder, urethra
What occurs in Bowman's capsule?
Contains glomerular capillaries where filtration occurs.
What initiates the micturition reflex?
Stretch receptors in the bladder wall transmit sensory impulses to the spinal cord.
What is the reflexive component of micturition?
PNS fibers activate for relaxation of internal urethral sphincter and contraction of detrusor muscle.
What is the voluntary component of micturition?
Signals travel to cerebral cortex, allowing control over external urethral sphincter relaxation.
What are the tubular parts of a nephron?
Renal corpuscle, PCT, descending limb, Loop of Henle, ascending limb, DCT, CD.
What are the types of nephrons and their functions?
Cortical nephron (80%) helps reabsorb essential substances; Juxtamedullary nephron (20%) adjusts urine volume and concentration.
What is the flow of blood to/from the nephron?
Renal artery > afferent arterioles > glomerular capillaries > efferent arterioles > peritubular capillaries > renal vein > inferior vena cava > right atrium.
What is filtration in the renal system?
Moving fluids and solutes from glomerulus to tubules where it becomes filtrate.
What is reabsorption in the renal system?
Occurs along renal tubules, reclaiming wanted substances into peritubular capillaries.
What is secretion in the renal system?
Moves unwanted substances from peritubular capillaries to renal tubules for elimination.
What is excretion in the renal system?
Urine, which is filtrate minus wanted substances plus unwanted substances.
How does blood differ from filtrate?
Blood contains proteins and cells; filtrate does not contain proteins and cells in healthy individuals.
How does filtrate differ from urine?
Filtrate contains fluids and solutes; urine is filtrate minus reabsorbed substances plus secreted substances.
What is the function of the filtration barrier?
Prevents proteins and cells from entering the filtrate during the filtration process.
What problems arise in renal failure?
Anemia (low RBC count) and edema (due to low plasma proteins) develop due to impaired filtration.
What are Mesangial cells?
Cells interspersed between capillaries that regulate surface area for filtration by contracting or relaxing.
What does the basement membrane contain?
Negatively charged proteoglycans that prevent filtration of negatively charged proteins.
What are podocytes?
Cells forming the inner layer of Bowman's capsule, wrapping around glomerular capillaries and forming filtration slits.
How does the breakdown of GFB lead to renal failure?
Loss of podocytes allows large proteins and cells in urine, causing anemia and edema.
What opposes filtration in the kidneys?
Capsular hydrostatic pressure and glomerular capillary colloid osmotic pressure.
What promotes filtration in the kidneys?
Glomerular capillary hydrostatic pressure, adjusted by arterioles' radius. Constriction of arterieols=causes a lower GFR and dilation of arterioles= higher GFR
What is the juxtaglomerular apparatus?
Specialized cells that regulate GFR and blood pressure, located between afferent and efferent arterioles.
What is the function of macula densa cells?
Located in the DCT, they act as chemoreceptors tracking salts and GFR, releasing vasoconstrictors.
What do juxtaglomerular cells do?
Located in afferent arterioles, they detect wall stretch and release renin if stretch is too low. renin produces AngII to increase BP and BF
What is GFR?
The amount of fluid filtered from blood into the tubules.
What is a typical GFR?
125 ml/min or 180 L/day.
Why should GFR be maintained?
To keep blood pressure and sugar levels within target ranges, preventing kidney damage.
What is the myogenic feedback mechanism?
Increased MAP causes arteriole constriction, decreasing blood flow and normalizing filtration.
What is the tubuloglomerular feedback mechanism?
Increased MAP leads to increased filtration, triggering macula densa to release vasoconstrictors.
What is the end goal of intrinsic regulation in kidneys?
To keep GFR constant even when MAP changes between 80 and 180 mmHg.
What is the end goal of intrinsic regulation in the kidneys?
To keep GFR constant even when MAP changes between 80 and 180 mmHg.
What happens when MAP is too low?
The R-A-A-S is activated, releases ANG II and it decreases GFR and urine output.
What hormone is released when MAP is too high?
ANP (atrial natriuretic peptide).
What is the role of ANP?
It increases GFR and urine output to lower MAP.
Where does renin come from?
Renin is released by the kidneys.
What does angiotensin II do?
It raises MAP by decreasing GFR and urine output.
What is obligatory reabsorption?
Reabsorption in the PCT and LOH that is not regulated by hormones.
What is facilitated reabsorption?
Reabsorption in DCT and CD regulated by hormones ADH and Aldosterone.
Which nephron segments respond to ADH and Aldosterone?
DCT and CD.
What occurs in the PCT?
Bulk reabsorption and 100% glucose reabsorption via secondary active transport.
What is diabetes mellitus?
Insulin is not produced, causing high blood glucose and osmotic diuresis.
What are the symptoms of diabetes mellitus?
Increased thirst, increased urine, ketoacidosis, sweet-smelling urine.
What causes diabetes insipidus?
Impaired ADH release leading to large amounts of dilute urine.
How do diabetes mellitus and diabetes insipidus compare?
Both cause increased urine output but have different mechanisms.
What stimulates the release of angiotensin II?
Low MAP triggers the release of renin, leading to angiotensin II production.
What stimulates the release of Ang II?
Low MAP (Mean Arterial Pressure) stimulates the release of Ang II.
What is the origin of Ang II?
Ang II is formed from renin (kidney) and ACE (pulmonary blood enzymes).
What effect does Ang II have on urine output?
Ang II decreases GFR, leading to decreased urine output.
What stimulates the release of ANP?
ANP is stimulated by stretch in the right atrium.
What is the effect of ANP on blood pressure?
ANP decreases blood pressure by increasing GFR and urine output.
What stimulates the release of ADH?
ADH release is activated by Ang II and acts on principal cells.
What is the role of ADH in the kidneys?
ADH increases water reabsorption by adding aquaporin channels in DCT and CD.
What stimulates the release of Aldosterone?
Aldosterone is stimulated by low blood volume or low MAP.
What is the action of Aldosterone in the kidneys?
Aldosterone increases NaCl reabsorption and K+ secretion in DCT and CD.
How does ADH affect urine volume and concentration?
ADH increases water reabsorption, decreasing urine volume and increasing concentration.
How does Aldosterone affect blood volume?
Aldosterone increases blood volume by reabsorbing NaCl, which retains water.
What is the effect of loop diuretics on urine output?
Loop diuretics increase urine output by inhibiting salt transport in the loop of Henle.
How does alcohol affect ADH release?
Alcohol inhibits ADH release, leading to increased urine output.
What causes diabetes insipidus?
Diabetes insipidus is caused by a lack of ADH, leading to diluted urine.
What effect does diabetes mellitus have on urine?
Diabetes mellitus causes increased glucose in filtrate, leading to sweet urine.
What is the role of Aldosterone in salt reabsorption?
Aldosterone promotes NaCl reabsorption and K+ secretion in the kidneys.
What is the impact of increased salt reabsorption on blood volume?
Increased salt reabsorption raises blood volume by increasing osmolarity.
What hormones are released for a large volume of dilute urine?
ADH is not released, while Aldosterone is released for dilute urine.
When would you want to produce a large volume of dilute urine?
A large volume of dilute urine is produced when overhydrated.
What type of urine is produced with large volume and dilute?
ADH not released, ALDO released. Occurs when overhydrated.
What type of urine is produced with small volume and concentrated?
ADH released, ALDO not released. Occurs when dehydrated.
How does filtrate osmolarity change in the descending limb?
Osmolarity increases as water is reabsorbed; permeable to water, not solutes.
How does filtrate osmolarity change in the ascending limb?
Osmolarity decreases; impermeable to water, actively reabsorbs ions.
What is the osmolarity in the PCT?
300 mOsm/L.
What is the osmolarity in the Loop of Henle (LOH)?
1200 mOsm/L.
What is the osmolarity in the DCT?
100 mOsm/L.
What is the osmolarity in the collecting duct (CD)?
1200 mOsm/L.
What structures are involved in urine production in the nephron?
Bowman's capsule, PCT, Loop of Henle (LOH), DCT, Collecting duct (CD)
What structures transport urine through the renal system?
Papillary duct, minor calyx, major calyx, renal pelvis, ureter, bladder, urethra
What initiates the micturition reflex?
Stretch receptors in the bladder wall transmit sensory impulses to the spinal cord.
What is the reflexive component of micturition?
PNS fibers activate for relaxation of internal urethral sphincter and contraction of detrusor muscle.
What is the voluntary component of micturition?
Signals travel to cerebral cortex, allowing control over external urethral sphincter relaxation.
What are the tubular parts of a nephron?
Renal corpuscle, PCT, descending limb, Loop of Henle, ascending limb, DCT, CD.
What are the types of nephrons and their functions?
Cortical nephron (80%) helps reabsorb essential substances; Juxtamedullary nephron (20%) adjusts urine volume and concentration.
What is the flow of blood to/from the nephron?
Renal artery > afferent arterioles > glomerular capillaries > efferent arterioles > peritubular capillaries > renal vein > inferior vena cava > right atrium.
What is filtration in the renal system?
Moving fluids and solutes from glomerulus to tubules where it becomes filtrate.
What is reabsorption in the renal system?
Occurs along renal tubules, reclaiming wanted substances into peritubular capillaries.
What is secretion in the renal system?
Moves unwanted substances from peritubular capillaries to renal tubules for elimination.
What is excretion in the renal system?
Urine, which is filtrate minus wanted substances plus unwanted substances.
How does blood differ from filtrate?
Blood contains proteins and cells; filtrate does not contain proteins and cells in healthy individuals.
How does filtrate differ from urine?
Filtrate contains fluids and solutes; urine is filtrate minus reabsorbed substances plus secreted substances.
What is the function of the filtration barrier?
Prevents proteins and cells from entering the filtrate during the filtration process.
What problems arise in renal failure?
Anemia (low RBC count) and edema (due to low plasma proteins) develop due to impaired filtration.
What are Mesangial cells?
Cells interspersed between capillaries that regulate surface area for filtration by contracting or relaxing.
What does the basement membrane contain?
Negatively charged proteoglycans that prevent filtration of negatively charged proteins.
What are podocytes?
Cells forming the inner layer of Bowman's capsule, wrapping around glomerular capillaries and forming filtration slits.
How does the breakdown of GFB lead to renal failure?
Loss of podocytes allows large proteins and cells in urine, causing anemia and edema.
What opposes filtration in the kidneys?
Capsular hydrostatic pressure and glomerular capillary colloid osmotic pressure.
What promotes filtration in the kidneys?
Glomerular capillary hydrostatic pressure, adjusted by arterioles' radius. Constriction of arterieols=causes a lower GFR and dilation of arterioles= higher GFR
What is the juxtaglomerular apparatus?
Specialized cells that regulate GFR and blood pressure, located between afferent and efferent arterioles.
What is the function of macula densa cells?
Located in the DCT, they act as chemoreceptors tracking salts and GFR, releasing vasoconstrictors.
What do juxtaglomerular cells do?
Located in afferent arterioles, they detect wall stretch and release renin if stretch is too low. renin produces AngII to increase BP and BF
Why should GFR be maintained?
To keep blood pressure and sugar levels within target ranges, preventing kidney damage.
What is the myogenic feedback mechanism?
Increased MAP causes arteriole constriction, decreasing blood flow and normalizing filtration.
What is the tubuloglomerular feedback mechanism?
Increased MAP leads to increased filtration, triggering macula densa to release vasoconstrictors.
What is the end goal of intrinsic regulation in kidneys?
To keep GFR constant even when MAP changes between 80 and 180 mmHg.
What is the end goal of intrinsic regulation in the kidneys?
To keep GFR constant even when MAP changes between 80 and 180 mmHg.
What happens when MAP is too low?
The R-A-A-S is activated, releases ANG II and it decreases GFR and urine output.
What is facilitated reabsorption?
Reabsorption in DCT and CD regulated by hormones ADH and Aldosterone.
What occurs in the PCT?
Bulk reabsorption and 100% glucose reabsorption via secondary active transport.
What is diabetes mellitus?
Insulin is not produced, causing high blood glucose and osmotic diuresis.
What are the symptoms of diabetes mellitus?
Increased thirst, increased urine, ketoacidosis, sweet-smelling urine.
How do diabetes mellitus and diabetes insipidus compare?
Both cause increased urine output but have different mechanisms.
What stimulates the release of angiotensin II?
Low MAP triggers the release of renin, leading to angiotensin II production.
What stimulates the release of Ang II?
Low MAP (Mean Arterial Pressure) stimulates the release of Ang II.
What is the origin of Ang II?
Ang II is formed from renin (kidney) and ACE (pulmonary blood enzymes).
What effect does Ang II have on urine output?
Ang II decreases GFR, leading to decreased urine output.
What is the effect of ANP on blood pressure?
ANP decreases blood pressure by increasing GFR and urine output.
What is the role of ADH in the kidneys?
ADH increases water reabsorption by adding aquaporin channels in DCT and CD.
What stimulates the release of Aldosterone?
Aldosterone is stimulated by low blood volume or low MAP.
What is the action of Aldosterone in the kidneys?
Aldosterone increases NaCl reabsorption and K+ secretion in DCT and CD.
How does ADH affect urine volume and concentration?
ADH increases water reabsorption, decreasing urine volume and increasing concentration.
How does Aldosterone affect blood volume?
Aldosterone increases blood volume by reabsorbing NaCl, which retains water.
What is the effect of loop diuretics on urine output?
Loop diuretics increase urine output by inhibiting salt transport in the loop of Henle.
How does alcohol affect ADH release?
Alcohol inhibits ADH release, leading to increased urine output.
What causes diabetes insipidus?
Diabetes insipidus is caused by a lack of ADH, leading to diluted urine.
What effect does diabetes mellitus have on urine?
Diabetes mellitus causes increased glucose in filtrate, leading to sweet urine.
What is the role of Aldosterone in salt reabsorption?
Aldosterone promotes NaCl reabsorption and K+ secretion in the kidneys.
What is the impact of increased salt reabsorption on blood volume?
Increased salt reabsorption raises blood volume by increasing osmolarity.
What hormones are released for a large volume of dilute urine?
ADH is not released, while Aldosterone is released for dilute urine.
When would you want to produce a large volume of dilute urine?
A large volume of dilute urine is produced when overhydrated.
What type of urine is produced with large volume and dilute?
ADH not released, ALDO released. Occurs when overhydrated.
What type of urine is produced with small volume and concentrated?
ADH released, ALDO not released. Occurs when dehydrated.
How does filtrate osmolarity change in the descending limb?
Osmolarity increases as water is reabsorbed; permeable to water, not solutes.
How does filtrate osmolarity change in the ascending limb?
Osmolarity decreases; impermeable to water, actively reabsorbs ions.
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