p.6
Reabsorption of Salt and Water
What is the function of the collecting duct?
Final concentration of urine and regulation of water reabsorption.
p.35
Regulation of Electrolyte and Acid-Base Balance
How do the kidneys contribute to acid-base balance?
By excreting hydrogen ions and reabsorbing bicarbonate.
p.23
Reabsorption of Salt and Water
How is Na+ transported across the basolateral membrane in the proximal tubule?
By primary active transport using the Na+/K+ pump.
p.10
Nephron as the Functional Unit
Where does the filtrate pass after the glomerular filtration?
Into the proximal convoluted tubule.
p.39
Nephron as the Functional Unit
What is the Juxtaglomerular Complex?
A specialized region in each nephron.
p.4
Gross Structure of the Urinary System
What does the cortex of the kidney contain?
Many capillaries and the outer parts of nephrons.
p.13
Glomerular Filtration and Rate (GFR)
What forms the filter for blood in the glomerulus?
Glomerular capillaries and Bowman's capsule.
p.24
Reabsorption of Salt and Water
How does water reabsorption occur in the proximal tubules?
Water follows salt by osmosis.
p.36
Regulation of Electrolyte and Acid-Base Balance
What ions do the kidneys regulate for electrolyte balance?
Na+, K+, H+, HCO3-, Cl-, and PO4-3.
p.6
Regulation of Electrolyte and Acid-Base Balance
What is the role of the distal tubule?
Regulation of electrolyte balance and pH.
p.46
Nephron as the Functional Unit
What is the primary function of the glomerulus?
To filter blood and form urine.
p.29
Countercurrent Multiplier System
What is the role of the vasa recta in the countercurrent multiplier system?
It is an important component that helps maintain the concentration gradient in the medulla.
p.16
Glomerular Filtration and Rate (GFR)
What does Glomerular Filtration Rate (GFR) measure?
The volume of filtrate produced by both kidneys per minute.
p.13
Glomerular Filtration and Rate (GFR)
How much more permeable are glomerular capillaries compared to other capillaries?
100-400 times more permeable.
p.36
Regulation of Electrolyte and Acid-Base Balance
How do kidneys maintain electrolyte balance?
By matching excretion to ingestion.
p.20
Reabsorption of Salt and Water
Where does most reabsorption of molecules and water occur in the nephron?
In the proximal convoluted tubule.
p.40
Renin-Angiotensin-Aldosterone System
How is angiotensin I converted to angiotensin II?
By angiotensin-converting enzyme (ACE) in the lungs.
p.35
Regulation of Electrolyte and Acid-Base Balance
What is the effect of antidiuretic hormone (ADH) on electrolyte balance?
It increases water reabsorption, which can dilute electrolytes in the blood.
p.14
Glomerular Filtration and Rate (GFR)
What must filtrate pass through to enter the tubule?
Narrow slit diaphragms formed between pedicels of podocytes.
p.12
Glomerular Filtration and Rate (GFR)
What is the primary function of glomerular filtration?
To form urine by filtering blood plasma.
p.20
Reabsorption of Salt and Water
How does urine volume vary?
According to the needs of the body.
p.9
Nephron as the Functional Unit
What is the final part of the nephron tubules before it empties into the collecting duct?
Distal convoluted tubule.
p.41
Renin-Angiotensin-Aldosterone System
What role do arterial baroreceptors play in renin secretion?
They initiate sympathetic activity that stimulates renin release.
p.38
Reabsorption of Salt and Water
What is the source of all K+ in urine?
Secretion rather than filtration.
p.15
Glomerular Filtration and Rate (GFR)
Why are plasma proteins mostly excluded from the glomerular filtrate?
Due to their large size and negative charge.
p.1
Kidney Function and Urine Formation
How do kidneys contribute to blood pressure?
By regulating the volume of blood plasma.
p.19
Reabsorption of Salt and Water
Where does the majority of salt and water reabsorption occur in the nephron?
In the proximal convoluted tubule.
p.33
Kidney Function and Urine Formation
How is renal plasma clearance measured?
By determining the concentration of a substance in urine and plasma over a specific time period.
p.21
Reabsorption of Salt and Water
How does water move during the reabsorption process?
Water follows other molecules by osmosis.
p.43
Glomerular Filtration and Rate (GFR)
What is the function of the Macula Densa?
Acts as a sensor for tubuloglomerular feedback; needed for autoregulation of GFR.
p.33
Kidney Function and Urine Formation
What is renal plasma clearance?
The volume of plasma from which a substance is completely removed by the kidneys per unit time.
p.21
Reabsorption of Salt and Water
Is water actively transported during reabsorption?
No, water is never transported actively.
p.3
Gross Structure of the Urinary System
What is the pathway of urine flow from the kidneys?
Urine flows from the kidneys into the ureters, which empty into the bladder.
p.2
Gross Structure of the Urinary System
What are the main components of the urinary system?
Kidneys, ureters, bladder, and urethra.
p.34
Nephron as the Functional Unit
How does secretion differ from reabsorption?
Secretion is opposite in direction to reabsorption.
p.31
Regulation of Electrolyte and Acid-Base Balance
What hormone maintains homeostasis of plasma concentration?
Antidiuretic hormone (ADH).
p.37
Reabsorption of Salt and Water
What happens to Na+ reabsorption in the absence of aldosterone?
80% of remaining Na+ is reabsorbed.
p.37
Renin-Angiotensin-Aldosterone System
What occurs when aldosterone levels are high?
All remaining Na+ is reabsorbed.
p.42
Regulation of Electrolyte and Acid-Base Balance
What effect does decreased ADH have on water reabsorption?
It decreases water reabsorption in the collecting ducts.
p.1
Kidney Function and Urine Formation
What waste products do kidneys help regulate in plasma?
Waste products in plasma.
p.6
Countercurrent Multiplier System
What occurs in the loop of Henle?
Concentration of urine through countercurrent multiplication.
p.8
Nephron as the Functional Unit
What are glomeruli?
Masses of capillaries inside the glomerular capsule that produce filtrate for the nephron tubule.
p.35
Renin-Angiotensin-Aldosterone System
What role does aldosterone play in electrolyte balance?
It promotes sodium reabsorption and potassium excretion in the kidneys.
p.37
Reabsorption of Salt and Water
Where is the remaining Na+ and K+ variably reabsorbed?
In the distal tubule and cortical collecting duct.
p.45
Glomerular Filtration and Rate (GFR)
What is the role of the glomerulus?
To facilitate the filtration of blood.
p.41
Renin-Angiotensin-Aldosterone System
What effect does inadequate intake of NaCl have on blood volume?
It causes a decrease in blood volume.
p.34
Nephron as the Functional Unit
What effect does reabsorption have on renal clearance?
Reabsorption decreases renal clearance.
p.34
Nephron as the Functional Unit
What effect does secretion have on renal clearance?
Secretion increases renal clearance.
p.34
Nephron as the Functional Unit
How is the excretion rate calculated?
Excretion rate = (filtration rate + secretion rate) - reabsorption rate.
p.31
Reabsorption of Salt and Water
What happens to water when ADH levels are high?
Water is drawn out of the collecting duct and reabsorbed by the vasa recta.
p.31
Regulation of Electrolyte and Acid-Base Balance
What type of feedback mechanism controls ADH secretion?
Negative feedback control.
p.42
Regulation of Electrolyte and Acid-Base Balance
What is the effect of low plasma [Na+] on blood volume?
It decreases blood volume.
p.4
Gross Structure of the Urinary System
What do the renal pyramids contain?
Minor calyces, which unite to form a major calyx.
p.19
Reabsorption of Salt and Water
What is the primary function of reabsorption in the kidneys?
To reclaim salt and water from the filtrate back into the bloodstream.
p.36
Regulation of Electrolyte and Acid-Base Balance
What is the significance of controlling plasma K+ levels?
It is important for the proper function of cardiac and skeletal muscles.
p.3
Gross Structure of the Urinary System
Where are the paired kidneys located in the body?
On either side of the vertebral column below the diaphragm.
p.45
Kidney Function and Urine Formation
What is the primary function of the kidneys?
To filter blood and produce urine.
p.2
Gross Structure of the Urinary System
What is the function of the ureters?
To transport urine from the kidneys to the bladder.
p.45
Gross Structure of the Urinary System
What is the significance of the renal pelvis?
It collects urine from the renal calyces before it moves to the ureter.
p.29
Countercurrent Multiplier System
How does the vasa recta contribute to the trapping of salt?
By recirculating salt and trapping some in the medulla interstitial fluid.
p.44
Urinary Buffers and pH Regulation
How does the nephron excrete more H+?
By buffering H+ with HPO4-2 or NH3 before excretion.
p.17
Glomerular Filtration and Rate (GFR)
How does vasoconstriction or dilation of afferent arterioles affect GFR?
It affects the rate of blood flow to glomeruli and thus GFR.
p.5
Nephron as the Functional Unit
Which nervous system controls the bladder?
Parasympathetic nervous system.
p.11
Reabsorption of Salt and Water
What substances are reabsorbed in the Proximal Convoluted Tubule?
Salt, water, and other molecules needed by the body.
p.1
Kidney Function and Urine Formation
Which electrolytes do kidneys help regulate?
Na+, K+, HCO3-, and others.
p.35
Regulation of Electrolyte and Acid-Base Balance
What is the primary function of the kidneys in relation to electrolytes?
To regulate electrolyte balance in the body.
p.16
Reabsorption of Salt and Water
Why must most filtered water be reabsorbed?
To prevent death from excessive water loss through urination.
p.2
Gross Structure of the Urinary System
What is the primary function of the urinary system?
To remove waste products from the body and regulate water and electrolyte balance.
p.3
Gross Structure of the Urinary System
What is the function of the urethra in the urinary system?
The urethra drains urine from the bladder.
p.23
Reabsorption of Salt and Water
How is glucose transported out of the cell in the proximal tubule?
By facilitated diffusion.
p.9
Nephron as the Functional Unit
What follows the glomerular capsule in the nephron tubules?
Proximal convoluted tubule.
p.26
Countercurrent Multiplier System
How does salt pumping in the thick ascending limb affect the descending limb?
It raises the osmolality around the descending limb, causing more water to diffuse out of the filtrate.
p.2
Gross Structure of the Urinary System
What is the purpose of the bladder?
To store urine until it is excreted.
p.41
Renin-Angiotensin-Aldosterone System
What stimulates renin release?
Low blood volume and renal blood flow.
p.18
Regulation of Electrolyte and Acid-Base Balance
What is the effect of increased sympathetic nerve activity on cardiac output?
It increases cardiac output.
p.31
Regulation of Electrolyte and Acid-Base Balance
What role do osmoreceptors in the hypothalamus play in ADH regulation?
They detect increased plasma osmolality and stimulate the posterior pituitary to release ADH.
p.44
Urinary Buffers and pH Regulation
What is the buffering reaction involving ammonia?
NH3 + H+ → NH4+ (ammonium ion).
p.42
Regulation of Electrolyte and Acid-Base Balance
What is the overall effect of increased Na+ reabsorption on blood?
It increases Na+ retention in blood.
p.39
Nephron as the Functional Unit
Where does the afferent arteriole come in contact within the nephron?
With the thick ascending limb.
p.4
Gross Structure of the Urinary System
What is the structure of the medulla in the kidney?
It consists of renal pyramids separated by renal columns.
p.6
Nephron as the Functional Unit
What are the main components of a nephron?
The glomerulus, Bowman's capsule, proximal tubule, loop of Henle, distal tubule, and collecting duct.
p.19
Reabsorption of Salt and Water
What hormone regulates the reabsorption of water in the kidneys?
Antidiuretic hormone (ADH).
p.19
Reabsorption of Salt and Water
How does aldosterone affect salt reabsorption?
It increases sodium reabsorption in the distal convoluted tubule and collecting duct.
p.33
Kidney Function and Urine Formation
What factors can affect renal plasma clearance?
Factors include blood flow to the kidneys, glomerular filtration rate, and tubular secretion and reabsorption.
p.12
Glomerular Filtration and Rate (GFR)
Where does glomerular filtration occur?
In the glomeruli of the kidneys.
p.29
Countercurrent Multiplier System
What substances are the vasa recta permeable to?
Salt, water (via aquaporins), and urea.
p.46
Reabsorption of Salt and Water
What is the main function of the distal convoluted tubule?
To further adjust the composition of urine by reabsorbing sodium and water.
p.2
Gross Structure of the Urinary System
What is the function of the urethra?
To carry urine from the bladder to the outside of the body.
p.41
Renin-Angiotensin-Aldosterone System
How do blood pressure changes affect juxtaglomerular cells?
Direct effects of blood pressure stimulate renin release.
p.13
Glomerular Filtration and Rate (GFR)
What type of structure do glomerular capillaries have?
Fenestrated structure with large pores.
p.5
Nephron as the Functional Unit
What type of receptors do drugs for overactive bladders target?
Muscarinic acetylcholine receptors.
p.40
Renin-Angiotensin-Aldosterone System
What activates the Renin-Angiotensin-Aldosterone System?
Release of renin from juxtaglomerular cells.
p.3
Gross Structure of the Urinary System
What is the approximate size of the kidneys?
About the size of a fist.
p.19
Reabsorption of Salt and Water
What is the role of the loop of Henle in reabsorption?
It creates a concentration gradient that facilitates the reabsorption of water and salts.
p.12
Glomerular Filtration and Rate (GFR)
What is glomerular filtration?
The process by which the kidneys filter blood, removing excess waste and fluids.
p.46
Reabsorption of Salt and Water
What role does the proximal convoluted tubule play in kidney function?
It reabsorbs nutrients, water, and electrolytes from the filtrate.
p.26
Countercurrent Multiplier System
What is the role of countercurrent flow in the Loop of Henle?
It allows the descending and ascending limbs to interact, building osmolality in the medulla.
p.41
Renin-Angiotensin-Aldosterone System
How does lower osmolality affect ADH?
It inhibits ADH, causing less H2O reabsorption.
p.25
Reabsorption of Salt and Water
What percentage of filtered water and salt is reabsorbed variably?
The remaining 15%, depending on hydration levels.
p.46
Reabsorption of Salt and Water
What is the role of the collecting duct in the kidney?
To collect urine from multiple nephrons and regulate water reabsorption.
p.42
Renin-Angiotensin-Aldosterone System
What is the effect of increased Renin on Angiotensin II levels?
It increases Angiotensin II levels.
p.6
Reabsorption of Salt and Water
What is the function of the proximal tubule?
Reabsorption of water, ions, and nutrients.
p.33
Kidney Function and Urine Formation
What is the significance of renal plasma clearance in clinical settings?
It helps assess kidney function and the effectiveness of drug elimination.
p.7
Nephron as the Functional Unit
What are the main components of a nephron?
Small tubes and associated small blood vessels.
p.8
Nephron as the Functional Unit
Where does the efferent arteriole deliver blood?
To the peritubular capillaries (vasa recta).
p.2
Gross Structure of the Urinary System
What is the role of the kidneys in the urinary system?
To filter blood and produce urine.
p.46
Countercurrent Multiplier System
What is the function of the loop of Henle?
To create a concentration gradient in the medulla for water reabsorption.
p.12
Glomerular Filtration and Rate (GFR)
What factors can affect the rate of glomerular filtration?
Blood pressure, blood flow, and the permeability of the glomerular membrane.
p.18
Regulation of Electrolyte and Acid-Base Balance
What is the role of negative feedback control in sympathetic effects?
It helps regulate blood pressure and volume.
p.1
Kidney Function and Urine Formation
What is the primary function of the kidneys?
To regulate plasma and interstitial fluid by formation of urine.
p.15
Glomerular Filtration and Rate (GFR)
What role do slit diaphragms play in glomerular filtration?
They are lined with negative charges that repel negatively-charged proteins.
p.6
Glomerular Filtration and Rate (GFR)
What is the role of the glomerulus in the kidney?
It filters blood to form urine.
p.11
Reabsorption of Salt and Water
How are substances transported during reabsorption in the Proximal Convoluted Tubule?
From the lumen through the tubular cells into surrounding peritubular capillaries.
p.43
Nephron as the Functional Unit
Where is the Macula Densa located?
Where tubule cells make contact with juxtaglomerular cells.
p.14
Glomerular Filtration and Rate (GFR)
What are pedicels?
Foot processes of podocytes in the glomerular capsule.
p.14
Glomerular Filtration and Rate (GFR)
What is the role of podocytes in glomerular filtration?
They form slit diaphragms that filtrate must pass through.
p.9
Nephron as the Functional Unit
Where do the nephron tubules empty?
Into the collecting duct.
p.42
Regulation of Electrolyte and Acid-Base Balance
What type of feedback mechanism is involved in this regulatory process?
Negative feedback control.
p.17
Glomerular Filtration and Rate (GFR)
What mechanisms control the regulation of Glomerular Filtration Rate (GFR)?
Extrinsic and intrinsic (autoregulation) mechanisms.
p.36
Regulation of Electrolyte and Acid-Base Balance
Why is the control of plasma Na+ important?
It is crucial for the regulation of blood volume and pressure.
p.15
Glomerular Filtration and Rate (GFR)
How is most protein reabsorbed after entering the filtrate?
By receptor-mediated endocytosis.
p.33
Kidney Function and Urine Formation
What does a high renal plasma clearance indicate?
It indicates efficient removal of a substance from the plasma by the kidneys.
p.45
Reabsorption of Salt and Water
What is the function of the renal tubule?
To reabsorb water and essential nutrients from the filtrate.
p.9
Nephron as the Functional Unit
What are the two limbs of the Loop of Henle in the nephron?
Descending and ascending limbs.
p.20
Reabsorption of Salt and Water
What is the minimum urine volume necessary to excrete metabolic wastes?
400 ml/day (obligatory water loss).
p.31
Nephron as the Functional Unit
What effect does ADH have on the collecting duct?
Stimulates the insertion of aquaporins into the plasma membrane.
p.31
Reabsorption of Salt and Water
What is the overall effect of ADH on urine output?
Less water is excreted in urine.
p.42
Renin-Angiotensin-Aldosterone System
What role does the juxtaglomerular complex play in response to low Na+ intake?
It increases Renin production.
p.25
Reabsorption of Salt and Water
Is the reabsorption in the proximal tubule dependent on hydration levels?
No, it is constant and independent of hydration levels.
p.43
Renin-Angiotensin-Aldosterone System
What happens when blood Na+ levels increase?
The Macula Densa signals juxtaglomerular cells to decrease secretion of renin.
p.35
Regulation of Electrolyte and Acid-Base Balance
What happens to bicarbonate levels during acidosis?
The kidneys increase bicarbonate reabsorption to help neutralize acidity.
p.31
Regulation of Electrolyte and Acid-Base Balance
Where is ADH secreted from?
The posterior pituitary gland.
p.12
Glomerular Filtration and Rate (GFR)
What is the normal range for the glomerular filtration rate (GFR)?
Approximately 90 to 120 mL/min.
p.46
Gross Structure of the Urinary System
How does the renal pelvis contribute to kidney function?
It collects urine from the collecting ducts and channels it to the ureter.
p.44
Urinary Buffers and pH Regulation
How is ammonia produced in the tubule?
By deaminating amino acids.
p.23
Reabsorption of Salt and Water
What happens to glucose after it is transported out of the cell in the proximal tubule?
It is reabsorbed into the blood.
p.18
Regulation of Electrolyte and Acid-Base Balance
What effect does sympathetic activity have on the afferent arteriole?
It constricts the afferent arteriole.
p.18
Regulation of Electrolyte and Acid-Base Balance
How does sympathetic activity help maintain blood pressure?
By shunting blood to the heart and muscles.
p.18
Glomerular Filtration and Rate (GFR)
What is the result of vasoconstriction of afferent arterioles in the kidneys?
Decreased glomerular filtration rate (GFR) and urine production.
p.25
Reabsorption of Salt and Water
What is the energy cost of reabsorption in the proximal tubule?
6% of calories consumed at rest.
p.35
Regulation of Electrolyte and Acid-Base Balance
What is the significance of potassium regulation by the kidneys?
It prevents hyperkalemia, which can lead to cardiac issues.
p.26
Countercurrent Multiplier System
What happens to the filtrate in the descending limb as osmolality increases?
The osmolality of the filtrate in the descending limb increases, delivering more concentrated filtrate to the ascending limb.
p.26
Countercurrent Multiplier System
What effect does the concentrated filtrate have on the ascending limb?
It undergoes active transport of salts, raising the osmolality around the descending limb, creating a positive feedback loop.
p.31
Regulation of Electrolyte and Acid-Base Balance
What physiological change occurs with low water intake?
Increased plasma osmolality.
p.42
Renin-Angiotensin-Aldosterone System
What is the effect of Aldosterone on Na+ reabsorption?
It increases Na+ reabsorption in the cortical collecting duct.
