The Urinary System Flashcards
Definition
A hormone that increases water reabsorption in the distal tubule and collecting duct.
Define
Antidiuretic Hormone (ADH)
Definition
The process where stretch receptors in the bladder send impulses to the spinal cord and brain as the bladder fills.
Define
Urinary Reflex Action
Definition
The blood vessel that supplies blood to the kidneys.
Define
Renal Artery
Definition
The part of the nephron that includes the glomerulus and Bowman’s capsule, where filtration begins.
Define
Renal Corpuscle
Definition
The cup-like structure that collects urine from the renal papillae.
Define
Minor Calyx
Define
Perirenal Fat
A layer of fat surrounding the kidneys, providing protection.
Define
Uric Acid
A nitrogenous waste from nucleic acid breakdown.
Define
Renal Pyramid
Structures in the renal medulla where collecting ducts end at the papillae.
Definition
The structure surrounding the glomerulus that collects the filtrate.
Define
Glomerular Capsule
Definition
The barrier between the glomerular capillaries and the glomerular capsule.
Define
Filtration Membrane
Define
Minor Calyx
The cup-like structure that collects urine from the renal papillae.
Define
Tubular Reabsorption
The process by which essential substances are reclaimed from the filtrate back into the blood.
Define
Renal Pelvis
The basin-like structure where urine collects before entering the ureter.
Define
Tubular Secretion
The process of adding substances from the blood into the filtrate.
Define
Ureter
The tube that transports urine from the renal pelvis to the bladder.
Define
Renal Vein
The blood vessel that drains blood away from the kidneys.
Definition
The small artery that carries blood toward the glomerulus in the nephron.
Define
Afferent Arteriole
Define
Short-term Controls
Quick adjustments to blood pressure, such as those that occur when changing positions or during acute stress.
Definition
A funnel-shaped structure in the kidney that collects urine from the nephrons and channels it to the ureter.
Define
Renal Pelvis
Definition
The primary organs of the urinary system, responsible for filtering blood, producing urine, and regulating various body functions.
Define
Kidneys
Define
Detrusor Muscle
Smooth muscle in the bladder wall that contracts to facilitate urination.
Define
Urinary Reflex Action
The process where stretch receptors in the bladder send impulses to the spinal cord and brain as the bladder fills.
Definition
Structures in the renal medulla where collecting ducts end at the papillae.
Define
Renal Pyramid
Define
Urinary System (Renal System)
The system responsible for producing, storing, and eliminating urine. It includes the kidneys, ureters, urinary bladder, and urethra.
Definition
A smooth muscle sphincter that controls the release of urine from the bladder.
Define
Internal Urethral Sphincter
Definition
The final segment of the renal tubule where hormonal regulation of water and solute reabsorption occurs.
Define
Collecting Duct
Define
Retroperitoneal
Refers to organs, such as the kidneys, that are located behind the peritoneal cavity.
Define
Renin-Angiotensin-Aldosterone System (RAAS)
A hormonal cascade initiated by low blood pressure.
Definition
Smooth muscle in the bladder wall that contracts to facilitate urination.
Define
Detrusor Muscle
Define
Osmotic Diuresis
A condition where high levels of solutes in the filtrate lead to increased urine production.
Definition
A hormone that increases peripheral vascular resistance and blood pressure.
Define
Angiotensin II
Definition
The organ that stores urine until it is excreted.
Define
Bladder
Define
Tubuloglomerular Feedback
A process where macula densa cells detect changes in filtrate solute concentration and flow rate.
Define
Renal Medulla
The inner region of the kidney, containing the renal pyramids and parts of the nephrons.
Define
Antidiuretic Hormone (ADH)
A hormone that increases water reabsorption in the distal tubule and collecting duct.
Define
Myogenic Mechanism
A response where vascular smooth muscle contracts in response to stretch from increased blood pressure, reducing GFR.
Define
Renal Pelvis
A funnel-shaped structure in the kidney that collects urine from the nephrons and channels it to the ureter.
Definition
The blood vessel that drains blood away from the kidneys.
Define
Renal Vein
Define
Intrinsic Mechanisms
The kidney’s internal mechanisms to regulate GFR.
Define
Kidneys
The primary organs of the urinary system, responsible for filtering blood, producing urine, and regulating various body functions.
Definition
The kidney’s internal mechanisms to regulate GFR.
Define
Intrinsic Mechanisms
Definition
Quick adjustments to blood pressure, such as those that occur when changing positions or during acute stress.
Define
Short-term Controls
Definition
A hormonal cascade initiated by low blood pressure.
Define
Renin-Angiotensin-Aldosterone System (RAAS)
Definition
The density of urine compared to water, reflecting the concentration of solutes.
Define
Specific Gravity
Definition
A metabolite from muscle activity.
Define
Creatinine
Definition
A tight collection of capillaries in the nephron where filtration of blood occurs, surrounded by the Bowman’s capsule.
Define
Glomerulus
Define
Glomerular Capsule
The structure surrounding the glomerulus that collects the filtrate.
Define
Urethra
The tube through which urine exits the body from the bladder.
Define
Internal Urethral Sphincter
A smooth muscle sphincter that controls the release of urine from the bladder.
Definition
Substances in urine that may indicate health issues:
Blood: Presence can indicate damage to glomerular capillaries or infections.
Bile: Presence can result in a brown color, often indicating liver disease or bile duct obstruction.
Glucose: Presence suggests poorly controlled diabetes mellitus.
Proteins: Their presence can indicate damage to the filtration membrane.
Define
Abnormal Constituents
Define
Major Calyx
Larger cup-like structures that collect urine from the minor calyces.
Define
Efferent Arteriole
The small artery that carries blood away from the glomerulus after filtration.
Define
Blood Pressure Regulation
The process of maintaining a constant blood pressure to ensure adequate delivery of oxygen and nutrients to cells and removal of waste.
Define
Abnormal Constituents
Substances in urine that may indicate health issues:
Blood: Presence can indicate damage to glomerular capillaries or infections.
Bile: Presence can result in a brown color, often indicating liver disease or bile duct obstruction.
Glucose: Presence suggests poorly controlled diabetes mellitus.
Proteins: Their presence can indicate damage to the filtration membrane.
Definition
The small artery that carries blood away from the glomerulus after filtration.
Define
Efferent Arteriole
Define
Atrial Natriuretic Peptide (ANP)
A hormone that inhibits sodium and water reabsorption in the distal tubule and collecting duct.
Define
Renal Artery
The blood vessel that supplies blood to the kidneys.
Define
External Urethral Sphincter
A skeletal muscle sphincter that controls the release of urine voluntarily.
Define
Aldosterone
A hormone that increases sodium reabsorption and potassium secretion in the distal tubule and collecting duct.
Define
Urinary Voluntary Control
The ability to consciously relax or contract the external sphincter to control urination.
Define
Filtration Membrane
The barrier between the glomerular capillaries and the glomerular capsule.
Definition
Larger cup-like structures that collect urine from the minor calyces.
Define
Major Calyx
Definition
Refers to organs, such as the kidneys, that are located behind the peritoneal cavity.
Define
Retroperitoneal
Definition
The ability to consciously relax or contract the external sphincter to control urination.
Define
Urinary Voluntary Control
Definition
The process of adding substances from the blood into the filtrate.
Define
Tubular Secretion
Definition
A major solute in urine, produced from the breakdown of amino acids.
Define
Urea
Definition
A response where vascular smooth muscle contracts in response to stretch from increased blood pressure, reducing GFR.
Define
Myogenic Mechanism
Define
Extrinsic Mechanisms
External regulatory mechanisms that influence GFR.
Definition
The inner region of the kidney, containing the renal pyramids and parts of the nephrons.
Define
Renal Medulla
Define
Angiotensin II
A hormone that increases peripheral vascular resistance and blood pressure.
Definition
A hormone that inhibits sodium and water reabsorption in the distal tubule and collecting duct.
Define
Atrial Natriuretic Peptide (ANP)
Definition
A process where macula densa cells detect changes in filtrate solute concentration and flow rate.
Define
Tubuloglomerular Feedback
Define
Creatinine
A metabolite from muscle activity.
Define
Renal Cortex
The outer region of the kidney, containing the majority of nephrons.
Definition
The process of maintaining a constant blood pressure to ensure adequate delivery of oxygen and nutrients to cells and removal of waste.
Define
Blood Pressure Regulation
Define
Nephron
The functional unit of the kidney responsible for filtering blood and forming urine, consisting of the glomerulus and renal tubule.
Definition
A nitrogenous waste from nucleic acid breakdown.
Define
Uric Acid
Define
Glomerular Filtration Rate (GFR)
The total volume of filtrate formed per minute by all renal nephrons in the kidneys.
Define
Specific Gravity
The density of urine compared to water, reflecting the concentration of solutes.
Define
Renal Corpuscle
The part of the nephron that includes the glomerulus and Bowman’s capsule, where filtration begins.
Define
Urea
A major solute in urine, produced from the breakdown of amino acids.
Definition
A skeletal muscle sphincter that controls the release of urine voluntarily.
Define
External Urethral Sphincter
Definition
External regulatory mechanisms that influence GFR.
Define
Extrinsic Mechanisms
Definition
The outer region of the kidney, containing the majority of nephrons.
Define
Renal Cortex
Definition
The total volume of filtrate formed per minute by all renal nephrons in the kidneys.
Define
Glomerular Filtration Rate (GFR)
Define
Glomerulus
A tight collection of capillaries in the nephron where filtration of blood occurs, surrounded by the Bowman’s capsule.
Definition
The system responsible for producing, storing, and eliminating urine. It includes the kidneys, ureters, urinary bladder, and urethra.
Define
Urinary System (Renal System)
Define
Collecting Duct
The final segment of the renal tubule where hormonal regulation of water and solute reabsorption occurs.
Define
Bladder
The organ that stores urine until it is excreted.
Definition
A condition where high levels of solutes in the filtrate lead to increased urine production.
Define
Osmotic Diuresis
Definition
The tube through which urine exits the body from the bladder.
Define
Urethra
Definition
The functional unit of the kidney responsible for filtering blood and forming urine, consisting of the glomerulus and renal tubule.
Define
Nephron
Definition
A hormone that increases sodium reabsorption and potassium secretion in the distal tubule and collecting duct.
Define
Aldosterone
Definition
The basin-like structure where urine collects before entering the ureter.
Define
Renal Pelvis
Definition
The tube that transports urine from the renal pelvis to the bladder.
Define
Ureter
Definition
The process by which essential substances are reclaimed from the filtrate back into the blood.
Define
Tubular Reabsorption
Define
Afferent Arteriole
The small artery that carries blood toward the glomerulus in the nephron.
Definition
A layer of fat surrounding the kidneys, providing protection.
Define
Perirenal Fat
What is another term commonly used to refer to the urinary system?
The renal system.
What are the primary organs of the urinary system?
Kidneys, ureters, urinary bladder, and urethra.
Where are the kidneys located in the body?
Between the T12 and L3 vertebrae, with the right kidney slightly lower than the left.
What protective structures surround each kidney?
A tough fibrous capsule and a layer of perirenal fat.
How much fluid do the kidneys filter from the bloodstream daily?
Nearly 200 liters.
What are the main functions of the kidneys besides urine production?
Regulating fluid and electrolyte balance, excreting metabolic wastes, maintaining acid-base balance, regulating blood pressure, and playing a role in erythropoiesis and vitamin D activation.
Which hormone produced by the kidneys regulates red blood cell production?
Erythropoietin
What role does the enzyme renin play in the renal system?
It regulates blood pressure by controlling blood volume.
What is the functional unit of the kidney?
The nephron.
Name the two main parts of a nephron.
The renal corpuscle and the renal tubule.
What are the three main processes involved in urine formation?
Glomerular filtration, tubular reabsorption, and tubular secretion.
What is the glomerulus, and what is its function?
A tightly packed collection of capillaries in the renal corpuscle, specialized for filtration.
Where does tubular reabsorption primarily occur?
In the proximal tubule of the nephron.
What percentage of nephrons are cortical nephrons?
About 85%.
Which type of nephron is primarily involved in forming concentrated urine?
Juxtamedullary nephrons.
Trace the pathway of urine from the kidney to outside the body.
Collecting ducts → Renal pelvis → Ureter → Urinary bladder → Urethra.
What hormones are involved in regulating urine output?
Aldosterone and antidiuretic hormone (ADH).
What is glomerular filtration rate (GFR), and why is it significant?
GFR is the rate at which the kidneys filter blood, and it’s significant because it reflects kidney function.
What percentage of the total cardiac output do the kidneys receive?
20 to 25%.
How much blood do the kidneys process per minute?
Approximately 1200 milliliters.
Through which vessels does blood enter and exit the kidneys?
Blood enters through the renal artery and exits through the renal vein.
What are the roles of the afferent and efferent arterioles in the nephron?
The afferent arteriole brings blood into the glomerulus, and the efferent arteriole carries blood away from the glomerulus.
What is the primary function of the glomerular capillaries?
To filter blood.
What drives the process of glomerular filtration?
High blood pressure within the glomerulus.
What are peritubular capillaries, and what is their role?
They are low-pressure, porous capillaries closely associated with renal tubules, responsible for absorbing solutes and water from the tubule cells.
What is the vasa recta, and why is it important?
The vasa recta are capillary networks associated with the nephron loops of juxtamedullary nephrons, playing a crucial role in forming concentrated urine.
What are the three major processes involved in urine production?
Glomerular filtration, tubular reabsorption, and tubular secretion.
What substances typically do not pass through the glomerular filtration barrier?
Proteins and red blood cells.
What is the difference between tubular reabsorption and tubular secretion?
Tubular reabsorption involves reabsorbing necessary substances back into the blood, while tubular secretion involves actively adding substances to the filtrate for excretion.
What type of process is glomerular filtration?
A passive process.
What is the main purpose of tubular reabsorption?
To reclaim necessary substances from the filtrate back into the bloodstream.
How does tubular secretion contribute to urine formation?
It actively adds waste and excess substances to the filtrate, which will become urine.
How does blood pressure within the glomerulus compare to that within the peritubular capillaries?
Blood pressure is high in the glomerulus and low in the peritubular capillaries.
What three structures make up the glomerular filtration membrane?
Glomerular capillaries, basement membrane, and podocytes.
What is unique about the endothelium of glomerular capillaries?
It is fenestrated, meaning it has small pores that allow certain substances to pass through.
What charge does the basement membrane have, and why is this important?
The basement membrane is negatively charged, which helps repel negatively charged particles such as most proteins.
What are podocytes, and what role do they play in glomerular filtration?
Podocytes are thin epithelial cells with filtration slits that help form the filtration barrier.
Which type of molecules can freely pass through the glomerular filtration membrane?
Small molecules.
What prevents large molecules like red blood cells and large proteins from passing into the glomerular capsule?
The size of the filtration membrane’s pores blocks large molecules.
Why are most proteins unable to pass through the glomerular filtration membrane?
They are large and negatively charged, which causes them to be repelled by the negatively charged basement membrane.
What substances are freely filtered into the glomerular capsule?
Water, ions, glucose, amino acids, small proteins, vitamins, and nitrogenous waste.
Why is glucose filtered into the glomerular capsule, and what must happen to it later?
Glucose is small enough to pass through the filtration membrane and needs to be reabsorbed later for energy.
What drives the process of glomerular filtration?
Hydrostatic pressure (blood pressure).
Does glomerular filtration require metabolic energy?
No, it relies on positive net filtration pressure.
What are the key pressures that influence glomerular filtration?
Glomerular hydrostatic pressure, glomerular colloid osmotic pressure, and capsular hydrostatic pressure.
Which pressure is the greatest force driving glomerular filtration?
Glomerular hydrostatic pressure.
How does glomerular colloid osmotic pressure affect filtration?
It opposes filtration by pulling water back into the capillaries.
What is capsular hydrostatic pressure, and what role does it play in filtration?
It is the pressure exerted by the filtrate in the capsular space and opposes filtration.
What is net filtration pressure, and why is it important?
Net filtration pressure is the sum of glomerular hydrostatic pressure, glomerular colloid osmotic pressure, and capsular hydrostatic pressure. It determines the force driving glomerular filtration.
What is the approximate value of net filtration pressure?
Approximately 10 mmHg.
What does GFR stand for, and what does it measure?
GFR stands for Glomerular Filtration Rate and measures the total volume of filtrate formed per minute by all glomeruli in the kidneys.
What is the typical GFR in a healthy person?
Around 120 milliliters per minute.
How many liters of filtrate are produced by the kidneys per day?
About 180 liters per day.
What factors determine GFR?
Net filtration pressure, total surface area available for filtration, and permeability of the filtration membrane.
How does a decrease in the number of functioning nephrons affect GFR?
It reduces the GFR.
What can affect the permeability of the filtration membrane?
Drugs, damage from infection, age, or disease.
Why is maintaining an adequate GFR essential?
It is crucial for efficient waste removal and maintaining homeostasis in the body.
Where does tubular reabsorption primarily occur?
In the proximal tubule of the renal tubule.
How do substances move during tubular reabsorption?
Substances move from the lumen of the tubule, through the tubular epithelium and capillary endothelium, back into the blood of the peritubular capillaries.
Which substances are commonly reabsorbed during tubular reabsorption?
Water, glucose, amino acids, and electrolytes.
What role does active transport play in tubular reabsorption?
Active transport is used to move sodium ions, the most abundant cations in the filtrate, which also facilitates the secondary active transport of other substances like glucose, amino acids, and some ions and vitamins.
What happens to glucose and amino acids during tubular reabsorption?
They are usually fully reabsorbed before reaching the nephron loop.
Why is the reabsorption of glucose and amino acids important?
It is vital for meeting the body’s energy needs.
How does water move during tubular reabsorption, and what facilitates this movement?
Water moves by osmosis into the peritubular capillaries, facilitated by concentration gradients created by sodium and other ions, as well as aquaporins in the proximal tubule.
What are transport maximums, and why are they significant?
Transport maximums refer to the maximum capacity of specific transport systems for solutes. When transporters are saturated, excess substances are excreted in the urine.
How does diabetes mellitus affect glucose reabsorption?
In diabetes mellitus, high blood glucose levels can saturate glucose transporters, leading to glucose appearing in the urine, which can cause osmotic diuresis.
What is osmotic diuresis, and how is it related to glucose in the filtrate?
Osmotic diuresis occurs when glucose in the filtrate draws water with it, leading to the production of large volumes of dilute urine.
What is the primary function of the descending limb of the nephron loop?
The descending limb primarily reabsorbs water due to the high number of aquaporins.
How does the ascending limb of the nephron loop differ from the descending limb in terms of reabsorption?
The ascending limb primarily reabsorbs solutes, both actively and passively, and does not couple water reabsorption with solute reabsorption due to fewer aquaporins.
Which hormones regulate reabsorption in the distal tubule and collecting duct?
Antidiuretic hormone (ADH), aldosterone, and atrial natriuretic peptide (ANP).
What effect does antidiuretic hormone (ADH) have on urine production?
ADH reduces urine production by promoting water reabsorption into the blood.
How does aldosterone influence tubular reabsorption?
Aldosterone stimulates the reabsorption of sodium in the distal tubule and collecting duct, leading to increased water reabsorption.
What role does atrial natriuretic peptide (ANP) play in tubular reabsorption?
ANP inhibits sodium and water reabsorption in the distal tubule and collecting duct, leading to increased urine production.
What is the purpose of tubular secretion?
To add unwanted substances to the filtrate, which will become urine, and help maintain blood pH and eliminate excess potassium.
Where is tubular secretion most prominent?
In the proximal tubule of the renal tubule.
Which substances are commonly secreted during tubular secretion?
Drugs, metabolites, urea, uric acid, creatinine, excess potassium, hydrogen ions, and organic acids and bases.
How does tubular secretion help maintain blood pH?
By removing hydrogen ions or organic acids and bases from the blood.
How is the total volume of urine produced calculated?
Urine production = Filtered substances + Secreted substances - Reabsorbed substances.
What is the typical daily volume of urine produced in a healthy person?
Approximately 1 to 2 liters per day.
How much filtrate is typically reabsorbed per day?
Approximately 177 to 179 liters per day.
What is Glomerular Filtration Rate (GFR)?
GFR is the total volume of filtrate formed by all renal nephrons in the kidneys.
How many nephrons are typically involved in GFR in a healthy individual?
About two million nephrons (one million per kidney).
Why is GFR important?
GFR is crucial for removing nitrogenous wastes, eliminating excess solutes and water, and maintaining constant blood volume and blood pressure.
What balancing act do the kidneys perform in relation to GFR?
The kidneys balance waste removal with the regulation of blood volume and pressure, which are potentially opposing requirements.
What is the purpose of intrinsic mechanisms in regulating GFR?
Intrinsic mechanisms (auto-regulation) maintain a constant GFR despite fluctuations in blood pressure.
What is the myogenic mechanism in GFR regulation?
The myogenic mechanism involves the contraction and relaxation of vascular smooth muscle in the arterial walls in response to changes in blood pressure.
How does the myogenic mechanism respond to increased blood pressure?
Increased blood pressure causes the afferent arterioles to constrict, reducing glomerular hydrostatic pressure and GFR.
What happens to the afferent arterioles when blood pressure decreases, according to the myogenic mechanism?
The afferent arterioles dilate, increasing GFR.
What is the tubuloglomerular feedback mechanism?
Tubuloglomerular feedback responds to changes in solute concentration in the filtrate and the flow rate through the tubule.
How does tubuloglomerular feedback respond to an increase in GFR?
High GFR leads to high sodium chloride concentration in the filtrate, detected by macula densa cells, which cause constriction of the afferent arterioles to decrease GFR.
What are the two main extrinsic mechanisms that regulate GFR?
Neural control and hormonal control.
When is neural control of GFR activated?
During low extracellular fluid volume or hypovolemic shock.
How does neural control affect GFR?
Noradrenaline release from sympathetic nerve fibers constricts afferent arterioles, decreasing GFR to maintain vital organ blood supply.
What is the function of the Renin-Angiotensin-Aldosterone System (RAAS) in GFR regulation?
RAAS maintains blood pressure and indirectly preserves GFR.
What triggers the release of renin in the RAAS?
Low blood pressure, sympathetic nervous system stimulation, low glomerular hydrostatic pressure, and activation of macula densa cells.
What is the role of angiotensin II in GFR regulation?
Angiotensin II increases peripheral vascular resistance, raising blood pressure and helping to preserve GFR.
What is the overall goal of the regulatory mechanisms of GFR?
To maintain homeostasis by ensuring proper filtration, reabsorption, and secretion, thereby preserving fluid balance and cell function.
How does the RAAS system indirectly help maintain GFR?
By raising blood pressure, the RAAS system helps maintain the hydrostatic pressure necessary for filtration in the glomeruli.
What cells detect changes in sodium chloride concentration in the filtrate during tubuloglomerular feedback?
Macula densa cells.
What are the primary consequences of a decrease in GFR?
Reduced waste removal, potential fluid and solute imbalances, and possible increases in blood volume and pressure.
Why is maintaining a constant GFR critical for kidney function?
A constant GFR ensures efficient waste removal and proper regulation of blood volume and pressure, which are essential for overall homeostasis.
What would happen if the kidneys could not regulate GFR effectively?
Imbalances in fluid, electrolytes, and blood pressure could occur, leading to potential damage to the kidneys and other organs.
What is the role of afferent arterioles in GFR regulation?
Afferent arterioles adjust their diameter to either increase or decrease blood flow into the glomerulus, thereby regulating GFR.
What happens to GFR during hypovolemic shock?
GFR decreases due to the constriction of afferent arterioles, preserving blood flow to vital organs.
How does the body ensure that GFR remains within a normal range despite changes in blood pressure?
Through intrinsic mechanisms like the myogenic mechanism and tubuloglomerular feedback, and extrinsic mechanisms like neural and hormonal control.
What pigment is responsible for the yellow color of urine?
Urochrome, a pigment from hemoglobin breakdown.
What can cause the color of urine to vary?
Diet, metabolism, hydration levels, and certain medical conditions.
Describe the typical odor of fresh urine.
Fresh urine is slightly aromatic.
What can cause urine to develop an ammonia smell over time?
Bacterial activity breaking down urea.
Name a food that can cause a distinct odor in urine.
Asparagus
What is the typical pH range of urine?
Urine is typically slightly acidic, with a pH range of 4.5 to 8, and an average of around 6.
What is specific gravity, and how does it relate to urine?
Specific gravity is a measure of urine density compared to water; it’s higher in urine due to the presence of solutes.
What percentage of urine is water?
Approximately 95%.
What are the main solutes found in urine?
Sodium, potassium, phosphate, calcium, magnesium, bicarbonate, urea, uric acid, and creatinine.
What is urea, and how is it formed?
Urea is the major nitrogenous waste in urine, formed from the breakdown of amino acids.
What might the presence of blood in urine indicate?
Potential issues like damage to glomerular capillaries, trauma, kidney stones, or infections.
What could cause urine to appear brown?
The presence of bile, which may indicate liver disease or bile duct obstruction.
What does the presence of glucose in urine typically indicate?
Poorly controlled diabetes mellitus.
Why might proteins appear in urine, and what does this suggest?
Proteins in urine suggest damage to the filtration membrane in the kidneys.
What happens to urine in the collecting ducts?
Urine formation is nearly complete, with minimal additional processing occurring.
Where does urine go after it leaves the collecting ducts?
Urine drains from the collecting ducts into the renal papillae, then into minor calyces.
Describe the pathway of urine from the renal pyramid to the ureter.
Urine flows from the renal papillae into minor calyces, then into major calyces, and finally collects in the renal pelvis before entering the ureter.
What is the function of the ureter?
The ureter transports urine from the renal pelvis to the bladder through peristaltic movements.
How much urine can the bladder typically store?
About 500 mL.
What is the difference between the internal and external urethral sphincters?
The internal urethral sphincter is under involuntary control (smooth muscle), while the external urethral sphincter is under voluntary control (skeletal muscle).
Explain the micturition reflex.
The micturition reflex involves the contraction of the detrusor muscle and the opening of the internal and external urethral sphincters, triggered by stretch receptors as the bladder fills.
What happens when the external urethral sphincter is voluntarily relaxed?
Urination occurs as the sphincter opens, allowing urine to pass from the bladder through the urethra.
How does the body prevent involuntary urination when the bladder is full?
The external urethral sphincter remains contracted to inhibit urination until voluntary control is exerted.
What could lead to involuntary urination despite voluntary effort to hold urine?
Increased bladder pressure over time may force the internal urethral sphincter open, leading to involuntary urination.
What could cause changes in the pH of urine?
Diet and metabolism can alter urine pH, making it more acidic or alkaline.
What role does creatinine play in urine, and where does it come from?
Creatinine is a nitrogenous waste product derived from muscle activity, excreted in urine.
Why might urine be checked for the presence of abnormal constituents like glucose or protein?
The presence of these substances can indicate underlying health issues, such as diabetes or kidney damage.
What is the role of peristalsis in the ureters?
Peristalsis propels urine from the renal pelvis to the bladder.
How does the urethra differ in length between males and females?
The urethra is longer in males than in females.
What happens to urine odor in the case of diabetes mellitus?
It may develop a sweet or fruity odor due to the presence of ketones.
Through which arteriole does blood enter the glomerulus?
The afferent arteriole.
Where does the filtration process in the kidney take place?
Filtration occurs between the glomerular capillaries and the glomerular capsule.
What structures make up the filtration membrane in the glomerulus?
The filtration membrane consists of two layers of cells, a basement membrane, fenestrations, and podocyte filtration slits.
After the filtrate is formed in the glomerular capsule, where does it go next?
The filtrate moves into the proximal tubule.
What percentage of water and sodium chloride is reabsorbed in the proximal tubule?
About 65% of water and sodium chloride.
Name two substances reabsorbed in the proximal tubule besides water and sodium chloride.
Glucose and amino acids.
What is the main function of secretion in the proximal tubule?
Secretion allows certain substances to be added to the filtrate from the blood.
In which part of the nephron is approximately 20% of water and sodium chloride reabsorbed?
The nephron loop (loop of Henle).
What hormone regulates sodium reabsorption and potassium secretion in the distal tubule?
Aldosterone
What hormone influences water reabsorption in the collecting duct?
Antidiuretic hormone (ADH).
What is the function of the collecting duct in maintaining blood pH?
The collecting duct secretes hydrogen ions and reabsorbs bicarbonate ions to regulate blood pH.
At what point in the urine formation process is the filtrate referred to as urine?
When it passes through the renal papillae into the minor calyx.
Describe the pathway of urine from the renal papillae to the bladder.
Urine passes through the minor calyx, major calyx, renal pelvis, and then into the ureters, which propel urine toward the bladder via peristalsis.
How does urine move from the renal pelvis to the bladder?
It drains into the ureters, which use peristalsis to move it to the bladder.
What is the final structure urine passes through before exiting the body?
The urethra.
What percentage of water can be reabsorbed in the collecting duct under the influence of ADH?
Up to 14%.
Which ions are involved in the pH regulation function of the collecting duct?
Hydrogen ions (H+) and bicarbonate ions (HCO3-).
What happens in the glomerulus if the afferent arteriole constricts?
Blood flow to the glomerulus decreases, reducing the glomerular filtration rate (GFR).
What is the primary role of the nephron loop in urine formation?
The nephron loop reabsorbs about 20% of the water and sodium chloride from the filtrate.
What role does aldosterone play in potassium balance?
Aldosterone regulates potassium levels by promoting either its reabsorption or secretion in the distal tubule.
How is glucose normally handled in the nephron?
Glucose is reabsorbed in the proximal tubule.
What might indicate a problem with the glomerular filtration membrane?
The presence of proteins or blood cells in the urine could indicate a problem with the filtration membrane.
What structural feature of the ureters helps propel urine to the bladder?
The smooth muscle in the ureter walls performs peristalsis.
Why is the filtrate called urine only after it reaches the minor calyx?
At this point, the filtrate has been fully processed, with reabsorption and secretion completed, making it urine.
What is the main function of the proximal tubule?
The proximal tubule is responsible for the reabsorption of water, sodium chloride, glucose, amino acids, and other ions, as well as the secretion of waste products into the filtrate.
What are short-term controls for blood pressure?
Quick adjustments to blood pressure, such as those made when standing up.
What are the two mechanisms involved in the renal regulation of blood pressure?
Direct renal mechanism and indirect renal mechanism (Renin-Angiotensin-Aldosterone System or RAAS).
What happens in the direct renal mechanism when blood pressure is high?
Increased blood pressure increases the rate of blood entering the glomerulus, speeding up filtration. This leads to increased urine output, decreased blood volume, and reduced blood pressure.
What is the outcome when blood pressure is low in the direct renal mechanism?
Low blood pressure slows the rate of blood entering the glomerulus, allowing more time for reabsorption. This reduces urine output, increases blood volume, and raises blood pressure.
Why is blood pressure regulation important?
To maintain a constant supply of oxygen and nutrients to every cell and to remove waste.
What is the main action of aldosterone in blood pressure regulation?
Aldosterone increases sodium reabsorption and potassium secretion in the distal tubule and collecting duct, leading to increased water reabsorption, which raises blood volume and blood pressure.
List three effects of angiotensin II.
Stimulates aldosterone release.
Promotes ADH secretion.
Causes vasoconstriction, increasing total peripheral resistance and blood pressure.
What is the role of renin in the RAAS pathway?
Renin initiates the RAAS cascade, leading to the formation of angiotensin II.
How does ADH affect urine output?
ADH increases water reabsorption in the distal tubule and collecting duct by making them more permeable to water, which decreases urine output and increases blood volume and pressure.
What triggers the release of renin in the indirect renal mechanism?
A decrease in arterial blood pressure.
What happens to urine output when aldosterone is released?
Urine output decreases due to increased sodium and water reabsorption.
How do alcohol and diuretics affect ADH?
Alcohol and diuretics inhibit ADH, leading to increased urine production.
What overall effect do aldosterone and ADH have on urine output?
Both hormones decrease urine output, which increases blood volume and pressure.
Describe the sequence of events in the RAAS pathway starting with renin release.
Renin is released in response to low blood pressure, which converts angiotensinogen to angiotensin I. Angiotensin I is then converted to angiotensin II, which:
Stimulates aldosterone release.
Promotes ADH secretion.
Activates the thirst center.
Causes vasoconstriction, raising blood pressure.
What is the impact of increased water reabsorption by aldosterone and ADH on blood pressure?
It leads to increased blood volume, which raises blood pressure.
How does the RAAS pathway help in regulating blood pressure over the long term?
By increasing blood volume through the reabsorption of water and sodium, the RAAS pathway helps maintain or raise blood pressure over the long term.
What role does the thirst center play in blood pressure regulation?
Angiotensin II activates the thirst center, leading to increased fluid intake, which helps increase blood volume and pressure.
How does vasoconstriction contribute to increased blood pressure?
Vasoconstriction caused by angiotensin II increases total peripheral resistance, which raises blood pressure.
What effect does aldosterone have on potassium levels?
Aldosterone promotes potassium secretion in the distal tubule and collecting duct, lowering blood potassium levels.
Summarize the impact of aldosterone and ADH on blood pressure regulation.
Aldosterone increases sodium and water reabsorption, while ADH increases water reabsorption. Both actions lead to decreased urine output and increased blood volume, ultimately raising blood pressure.
What happens when blood pressure drops significantly?
The body acts quickly to restore blood pressure. The kidneys release renin, triggering the RAAS (Renin-Angiotensin-Aldosterone System) cascade to raise blood pressure.
How does the RAAS system help restore blood pressure?
Renin release starts the RAAS cascade, leading to the formation of angiotensin II. Angiotensin II causes vasoconstriction, stimulates aldosterone and ADH release, and activates the thirst center, all of which help raise blood pressure.
What are the primary functions of the urinary system?
Urine production to maintain blood pressure and remove waste.
Excretion of metabolic wastes and foreign substances.
Regulation of acid-base balance.
Regulation of erythropoiesis (red blood cell production).
Activation of vitamin D.
Gluconeogenesis.
How does the urinary system activate vitamin D?
The kidneys convert inactive vitamin D into its active form, which is necessary for calcium absorption and bone health.
What is gluconeogenesis and how is it related to the urinary system?
Gluconeogenesis is the production of glucose from non-carbohydrate sources during fasting or starvation. The kidneys contribute to this process.
Which of the following is NOT a main function of the urinary system?
A) Regulation of blood pressure
B) Regulation of erythropoiesis
C) Production of digestive enzymes
D) Excretion of metabolic wastes
C) Production of digestive enzymes
What structure within the nephron is primarily responsible for filtration?
A) Proximal convoluted tubule
B) Glomerulus
C) Loop of Henle
D) Distal convoluted tubule
B) Glomerulus
Which part of the kidney contains the renal pyramids?
A) Renal cortex
B) Renal medulla
C) Renal pelvis
D) Renal capsule
B) Renal medulla
The main structural and functional unit of the kidney is the:
A) Nephron
B) Ureter
C) Glomerulus
D) Renal pelvis
A) Nephron
Which structure collects urine directly from the renal papillae?
A) Minor calyx
B) Major calyx
C) Renal pelvis
D) Ureter
A) Minor calyx
Glomerular filtration occurs in which part of the nephron?
A) Distal convoluted tubule
B) Proximal convoluted tubule
C) Glomerulus
D) Loop of Henle
C) Glomerulus
What is the primary force driving glomerular filtration?
A) Secretion in the distal tubule
B) Oncotic pressure in the Bowman’s capsule
C) Tubular reabsorption
D) Hydrostatic pressure in the glomerular capillaries
D) Hydrostatic pressure in the glomerular capillaries
What is the normal range for glomerular filtration rate (GFR) in a healthy adult?
A) 60-90 mL/min
B) 90-120 mL/min
C) 120-150 mL/min
D) 150-180 mL/min
B) 90-120 mL/min
Which of the following can cause a decrease in GFR?
A) Increased blood pressure
B) Constriction of the afferent arteriole
C) Dilation of the afferent arteriole
D) Increased glomerular hydrostatic pressure
B) Constriction of the afferent arteriole
What percentage of plasma entering the glomerulus is typically filtered into the Bowman’s capsule?
A) 10%
B) 50%
C) 30%
D) 20%
D) 20%
Where does the majority of tubular reabsorption occur?
A) Distal convoluted tubule
B) Loop of Henle
C) Proximal convoluted tubule
D) Collecting duct
C) Proximal convoluted tubule
Which of the following substances is typically secreted into the tubule?
A) Glucose
B) Sodium
C) Hydrogen ions
D) Water
C) Hydrogen ions
What percentage of sodium is reabsorbed in the proximal convoluted tubule?
A) 25%
B) 50%
C) 65%
D) 90%
C) 65%
Which part of the nephron is primarily responsible for creating the osmotic gradient in the kidney?
A) Proximal convoluted tubule
B) Loop of Henle
C) Distal convoluted tubule
D) Collecting duct
B) Loop of Henle
Tubular secretion is important for all the following EXCEPT:
A) Eliminating waste products
B) Regulating blood pH
C) Reabsorbing nutrients
D) Removing excess potassium
C) Reabsorbing nutrients
Which mechanism directly affects the glomerular filtration rate (GFR)?
A) Tubuloglomerular feedback
B) Myogenic response
C) RAAS activation
D) All of the above
D) All of the above
How does the constriction of the efferent arteriole affect GFR?
A) Decreases GFR
B) Increases GFR
C) Has no effect on GFR
D) Increases urine output
B) Increases GFR
The macula densa cells respond to changes in:
A) Blood pressure
B) Sodium concentration in the distal tubule
C) Blood glucose levels
D) Potassium concentration in the blood
B) Sodium concentration in the distal tubule
What effect does a high GFR have on the rate of filtrate reabsorption?
A) Increases reabsorption
B) Decreases reabsorption
C) Has no effect on reabsorption
D) Stops reabsorption altogether
B) Decreases reabsorption
Which of the following hormones is involved in the regulation of GFR?
A) Renin
B) Insulin
C) Glucagon
D) Thyroxine
A) Renin
What is the typical color of healthy urine?
A) Clear
B) Pale yellow
C) Dark brown
D) Red
B) Pale yellow
Which of the following structures does urine pass through immediately after the collecting ducts?
A) Renal pelvis
B) Minor calyx
C) Major calyx
D) Ureter
B) Minor calyx
Which structure stores urine until it is excreted?
A) Urethra
B) Ureter
C) Bladder
D) Renal pelvis
C) Bladder
What is the normal pH range of urine?
A) 3.0-4.5
B) 4.5-8.0
C) 7.0-9.5
D) 8.0-10.5
B) 4.5-8.0
Which structure serves as the final passage for urine to leave the body?
A) Collecting duct
B) Ureter
C) Renal pelvis
D) Urethra
D) Urethra
Which hormone increases sodium reabsorption in the distal convoluted tubule and collecting duct?
A) ADH
B) Aldosterone
C) Renin
D) Insulin
B) Aldosterone
What triggers the release of antidiuretic hormone (ADH)?
A) High blood pressure
B) Low blood osmolarity
C) High blood osmolarity
D) High blood glucose
C) High blood osmolarity
Which hormone directly causes vasoconstriction to increase blood pressure?
A) Angiotensin II
B) Aldosterone
C) ADH
D) Renin
A) Angiotensin II
What is the effect of alcohol on ADH secretion?
A) Increases ADH secretion
B) Decreases ADH secretion
C) Has no effect on ADH
D) Inhibits aldosterone secretion
B) Decreases ADH secretion
Aldosterone has the greatest effect on which of the following?
A) Potassium excretion
B) Glucose absorption
C) Calcium reabsorption
D) Blood glucose levels
A) Potassium excretion
In which part of a nephron does filtration occur?
Renal corpuscle
Which pressure drives filtration?
Glomerular hydrostatic pressure (GHP)
What doesn’t pass through the filtration membrane?
Blood cells & large proteins
In which part of a nephron does tubular reabsorption & secretion mainly occur?
Proximal tubule (PT)
Which hormone is required for the reabsorption of water from the DT & CD?
ADH
Which hormone is required for the reabsorption of Na+ (&water) from the DT & CD?
Aldosterone
How does tubular secretion help regulate blood pH?
By secreting H+ ions or HCO3- ions (kidneys can reabsorb excess H+ ions or HCO3- if needed)
Upon completion of these three processes what are the main constituents of normal urine?
Water, nitrogenous wastes, excess ions, drugs
Do you normally find glucose in urine? Why/why not?
No, glucose does move into filtrate but is reabsorbed
Do you normally find protein in urine? Why/why not?
No, because proteins are not filtered to begin with
The myogenic mechanism reflects the stretch response of vascular smooth muscle. This mechanism works to help regulate GFR.
(i) How does the myogenic mechanism act when blood pressure is increased?
↑ BP 🡪 afferent arteriole more stretched
🡪 Afferent arteriole constricts
🡪 ↓ glomerular blood flow
🡪 ↓ GHP 🡪 so no change in GFR
The myogenic mechanism reflects the stretch response of vascular smooth muscle. This mechanism works to help regulate GFR.
(ii) How does the myogenic mechanism act when blood pressure is decreased?
↓ BP 🡪 afferent arteriole less stretched
🡪 Afferent arteriole dilates
🡪 ↑ glomerular blood flow
🡪 ↑ GHP 🡪 so no change in GFR
The myogenic mechanism reflects the stretch response of vascular smooth muscle. This mechanism works to help regulate GFR.
(iii) What is the ultimate aim of the myogenic mechanism?
To maintain normal NFP & GFR
How does the Direct mechanism act to maintain blood pressure?
Direct renal mechanism alters blood volume independently of hormones. When either blood volume or blood pressure rises, the rate at which fluid filters from the blood stream into the kidney tubules speeds up. The kidneys cannot reabsorb filtrate fast enough and more of it leaves the body in urine. Resulting in blood pressure and blood volume falling. If BP increases, blood enters the glomerulus at a higher rate and filtrate moves through the tubules quicker. Not as much water and electrolytes are reabsorbed, increasing urine output which reduces blood volume and thus blood pressure. (Opposite for when there is a drop in blood pressure).
The Indirect mechanism is also involved in maintenance of blood pressure.
(i) When is it activated?
Decrease in blood volume/blood pressure
The Indirect mechanism is also involved in maintenance of blood pressure.
(ii) Identify and describe the indirect renal mechanism?
Renin-Angiotensin-Aldosterone –System RAAS
Annie suffers from hypertension (consistent high blood pressure). To treat her hypertension, Annie is prescribed a diuretic and a drug that inhibits the renin-angiotensin mechanism by blocking the action of angiotensin converting enzyme (ACE) and thus preventing the production of angiotensin II.
a. How will the diuretic lower Annie’s blood pressure?
🡩 urine output 🡪 🡫 BV = 🡫BP
Annie suffers from hypertension (consistent high blood pressure). To treat her hypertension, Annie is prescribed a diuretic and a drug that inhibits the renin-angiotensin mechanism by blocking the action of angiotensin converting enzyme (ACE) and thus preventing the production of angiotensin II.
b. How will the ACE inhibitor lower Annie’s blood pressure?
To prevent the production of angiotensin II if the 🡫BP achieved by the diuretic activates RAAS.
No angiotensin II:
🡪 Peripheral blood vessel will not constrict to 🡩 BP
🡪 no 🡩 ADH & aldosterone secretion = no 🡩 BV & BP
🡪 thirst will not be stimulated = no 🡩 BV & BP
The kidneys are organs making a significant contribution to whole body homeostasis. Beyond the formation of urine, involving the removal of nitrogenous wastes, toxins and drugs, list the “other” functions of the kidney and briefly describe how each contributes to the maintenance of the internal environment of the body.
Regulate total water volume 🡪 regulates BV & BP
Regulate ECF ion (H+ & HCO3- , Na+, K+) levels 🡪 regulates pH & osmolarity
Produce
EPO 🡪 regulates red blood cell production & BP
Renin 🡪 regulates BV & BP
Glucose (gluconeogenesis) 🡪 maintains BGL
Convert vitamin D to its active form (calcitrol) 🡪 regulates Ca2+ levels
