p.12
Glomerular Filtration Process
Where are the podocytes located?
In the glomerular capsule.
p.7
Nephron Anatomy and Function
What does a nephron consist of?
Small tubes and associated small blood vessels.
p.13
Glomerular Filtration Process
Why are plasma proteins mostly excluded from the filtrate?
Due to their large size and negative charge.
p.12
Glomerular Filtration Process
What must filtrate pass through to enter the tubule?
Narrow slit diaphragms formed between pedicels of podocytes.
p.3
Structure of the Urinary System
What does the cortex of the kidney contain?
Many capillaries and outer parts of nephrons.
p.3
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.22
Reabsorption Mechanisms in the Proximal Convoluted Tubule
How does water reabsorption occur in the proximal tubules?
Water follows salt by osmosis.
p.32
Regulation of Glomerular Filtration Rate (GFR)
What are the two main mechanisms that regulate Glomerular Filtration Rate (GFR)?
Extrinsic and intrinsic (autoregulation) mechanisms.
p.41
Renin-Angiotensin-Aldosterone System
What activates the Renin-Angiotensin-Aldosterone System?
Release of renin from granular cells within the afferent arteriole.
p.13
Glomerular Filtration Process
What role do slit diaphragms play in glomerular filtration?
They are lined with negative charges that repel negatively-charged proteins.
p.18
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What is the primary function of the Proximal Convoluted Tubule (PCT) in the kidneys?
Reabsorption of most molecules and water from filtrate back to peritubular capillaries.
p.3
Structure of the Urinary System
What do the renal pyramids in the kidney contain?
Minor calyces which unite to form a major calyx.
p.13
Glomerular Filtration Process
What happens to some proteins, like albumin, during glomerular filtration?
They normally enter the filtrate but most is reabsorbed by receptor-mediated endocytosis.
p.18
Reabsorption Mechanisms in the Proximal Convoluted Tubule
How much ultrafiltrate is produced daily by the kidneys?
About 180 liters per day.
p.32
Regulation of Glomerular Filtration 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.11
Glomerular Filtration Process
What forms the filter for blood in the glomerular filtration process?
Glomerular capillaries and Bowman's capsule.
p.34
Nephron Anatomy and Function
Where is the Macula Densa located?
Where tubule cells make contact with granular cells.
p.8
Nephron Anatomy and Function
What is the function of glomeruli?
They are a mass of capillaries that give rise to filtrate entering the nephron tubule.
p.34
Regulation of Glomerular Filtration Rate (GFR)
What is the function of the Macula Densa?
Acts as a sensor for tubuloglomerular feedback; needed for autoregulation of GFR.
p.19
Reabsorption Mechanisms in the Proximal Convoluted Tubule
How does water move during the reabsorption process?
Water follows other molecules by osmosis.
p.21
Reabsorption Mechanisms in the Proximal Convoluted Tubule
How is glucose transported out of the cell after being reabsorbed in the proximal tubule?
By facilitated diffusion.
What is the primary function of the kidneys?
To filter blood and produce urine.
p.48
Electrolyte and Acid-Base Balance
What happens to bicarbonate in the kidneys during acid-base balance?
Bicarbonate is reabsorbed to help neutralize acids.
p.24
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.33
Regulation of Glomerular Filtration Rate (GFR)
What is the role of mesangial cells in response to decreased GFR?
Contraction of mesangial cells.
p.37
Regulation of Glomerular Filtration Rate (GFR)
What physiological change occurs with low water intake?
Increased plasma osmolality.
p.14
Nephron Anatomy and Function
What is the Juxtaglomerular Complex?
A specialized region in each nephron.
p.41
Renin-Angiotensin-Aldosterone System
How is angiotensin I converted to angiotensin II?
By angiotensin-converting enzyme (ACE) in the lungs.
p.49
Electrolyte and Acid-Base Balance
How do kidneys maintain electrolyte balance?
By matching excretion to ingestion.
p.25
Nephron Anatomy and Function
What is the function of the thin descending limb in the nephron?
It is permeable to water but impermeable to solutes.
p.47
Reabsorption Mechanisms in the Proximal Convoluted Tubule
How does secretion differ from reabsorption?
Secretion is opposite in direction to reabsorption.
p.48
Electrolyte and Acid-Base Balance
How do the kidneys contribute to acid-base balance?
By excreting hydrogen ions and reabsorbing bicarbonate.
p.47
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What effect does secretion have on renal clearance?
Secretion increases renal clearance.
p.47
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What is the formula for excretion rate?
Excretion rate = (filtration rate + secretion rate) - reabsorption rate.
p.25
Nephron Anatomy and Function
What is the variable permeability of the nephron related to?
It relates to urea and water in different segments.
p.36
Regulation of Glomerular Filtration Rate (GFR)
How does sympathetic activity help maintain blood pressure?
By shunting blood to the heart and muscles.
p.43
Regulation of Glomerular Filtration Rate (GFR)
How does low Na+ intake affect blood volume?
It decreases blood volume.
p.33
Regulation of Glomerular Filtration Rate (GFR)
What occurs if GFR is decreased sufficiently?
Decreased filtrate and urine production.
p.43
Renin-Angiotensin-Aldosterone System
What effect does Aldosterone have on Na+ reabsorption?
It increases Na+ reabsorption in the cortical collecting duct.
What is renal plasma clearance?
The volume of plasma from which a substance is completely removed by the kidneys per unit time.
How is renal plasma clearance measured?
By calculating the amount of a substance excreted in urine over time relative to its plasma concentration.
What do drugs for overactive bladders target?
Muscarinic ACh receptors.
p.19
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What happens to other molecules during the reabsorption process?
They are transported, and water follows by osmosis.
What does a low renal plasma clearance suggest?
It suggests poor kidney function or reabsorption of the substance.
p.21
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What happens to glucose after it is transported out of the proximal tubule cell?
It is reabsorbed into the blood.
p.9
Nephron Anatomy and Function
What is the last part of the nephron tubules before it empties into the collecting duct?
Distal convoluted tubule (DCT).
p.9
Nephron Anatomy and Function
Where does the tubular part of the nephron end?
It empties into the collecting duct (CD).
p.54
Nephron Anatomy and Function
What is the main function of the distal convoluted tubule?
To further adjust the composition of urine through selective reabsorption and secretion.
p.24
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.33
Regulation of Glomerular Filtration Rate (GFR)
What occurs to the afferent arterioles during the response to reduced GFR?
Dilation of afferent arterioles.
p.43
Renin-Angiotensin-Aldosterone System
What does the juxtaglomerular apparatus do in response to low Na+?
It increases Renin secretion.
p.52
Electrolyte and Acid-Base Balance
What is the source of all K+ in urine?
Secretion rather than filtration.
What is the primary function of the kidneys?
To regulate plasma and interstitial fluid by formation of urine.
p.9
Nephron Anatomy and Function
What follows the glomerular capsule in the nephron tubules?
Proximal convoluted tubule (PCT).
How does the volume of blood plasma relate to blood pressure?
It contributes to blood pressure (BP).
p.54
Nephron Anatomy and Function
What is the primary function of the renal corpuscle?
To filter blood and form urine.
p.54
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What role does the proximal convoluted tubule play in the nephron?
It reabsorbs nutrients, electrolytes, and water from the filtrate.
p.25
Nephron Anatomy and Function
What is the permeability of the ascending thick limb to water?
It is impermeable to water.
p.50
Renin-Angiotensin-Aldosterone System
What occurs when aldosterone levels are high?
All remaining Na+ is reabsorbed.
p.36
Regulation of Glomerular Filtration Rate (GFR)
What effect does sympathetic activity have on the afferent arteriole?
It constricts the afferent arteriole.
What is the effect of relaxing the external urethral sphincter?
It causes relaxation of the internal urethral sphincter.
p.2
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.23
Reabsorption Mechanisms in the Proximal Convoluted Tubule
Is the reabsorption of 85% of filtered H2O and salt dependent on hydration levels?
No, it is constant and independent of hydration levels.
p.37
Regulation of Glomerular Filtration Rate (GFR)
What role do osmoreceptors in the hypothalamus play?
They detect increased plasma osmolality and stimulate ADH release.
p.11
Glomerular Filtration Process
What type of structure are glomerular capillaries?
Fenestrated, meaning they have large pores between endothelial cells.
p.11
Glomerular Filtration Process
How much more permeable are glomerular capillaries compared to other capillaries?
100-400 times more permeable.
p.25
Nephron Anatomy and Function
What is the characteristic of the thick ascending limb?
It is impermeable to water and actively transports solutes.
p.25
Countercurrent Multiplier System
What happens to NaCl in the thick ascending limb?
Its transport results in the movement of water from the descending limb.
p.54
Countercurrent Multiplier System
What is the function of the loop of Henle?
To create a concentration gradient in the medulla for water reabsorption.
p.42
Renin-Angiotensin-Aldosterone System
What stimulates renin release in the kidneys?
Low blood volume and renal blood flow.
p.2
Structure of the Urinary System
Where are the paired kidneys located?
On either side of the vertebral column, below the diaphragm.
p.53
Structure of the Urinary System
What is the role of the urethra?
To carry urine from the bladder to the outside of the body.
p.24
Countercurrent Multiplier System
What occurs during the positive feedback loop in the countercurrent multiplier system?
The process repeats, causing even higher osmolality around the descending limb until equilibrium is reached.
p.36
Regulation of Glomerular Filtration Rate (GFR)
What is the result of vasoconstriction of afferent arterioles in the kidneys?
Decreased glomerular filtration rate (GFR) and urine production.
p.43
Renin-Angiotensin-Aldosterone System
What is the result of increased Na+ retention in the blood?
It helps to restore blood volume.
p.14
Nephron Anatomy and Function
Where does the Juxtaglomerular Complex form?
Where the afferent arteriole comes in contact with the thick ascending limb.
p.50
Renin-Angiotensin-Aldosterone System
What is the primary role of aldosterone in the body?
To regulate Na+ reabsorption and K+ secretion.
p.10
Nephron Anatomy and Function
Where does the filtrate pass after the glomerular filtration?
Into the proximal convoluted tubule.
Which electrolytes do the kidneys help to regulate?
Sodium (Na+), Potassium (K+), Bicarbonate (HCO3-), and others.
p.16
Reabsorption Mechanisms in the Proximal Convoluted Tubule
Where do the reabsorbed substances go after being transported through the tubular cells?
Into surrounding peritubular capillaries.
p.42
Renin-Angiotensin-Aldosterone System
How does lower osmolality affect ADH secretion?
It inhibits ADH, causing less H2O reabsorption.
What happens to the external urethral sphincter during urination?
Voluntary relaxation occurs.
p.2
Structure of the Urinary System
What is the approximate size of the kidneys?
About the size of a fist.
p.36
Regulation of Glomerular Filtration Rate (GFR)
What is the effect of increased sympathetic nerve activity on cardiac output?
It increases cardiac output.
p.37
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What happens to water when ADH levels are high?
Water is drawn out of the collecting duct and reabsorbed by the vasa recta.
p.37
Regulation of Glomerular Filtration Rate (GFR)
What is the overall effect of increased ADH on urine output?
Less water is excreted in urine.
p.19
Reabsorption Mechanisms in the Proximal Convoluted Tubule
Is water actively transported during reabsorption?
No, water is never transported actively.
p.8
Nephron Anatomy and Function
Where does the blood from the efferent arteriole go?
To the peritubular capillaries (vasa recta).
p.26
Countercurrent Multiplier System
What is the role of the vasa recta in the countercurrent exchange?
It is an important component of the countercurrent multiplier.
What is the significance of renal plasma clearance in clinical settings?
It helps assess kidney function and the effectiveness of drug elimination.
p.42
Renin-Angiotensin-Aldosterone System
What effect does inadequate intake of NaCl have on blood volume?
It causes decreased blood volume.
p.50
Renin-Angiotensin-Aldosterone System
What happens to Na+ reabsorption in the absence of aldosterone?
80% of remaining Na+ is reabsorbed.
p.24
Countercurrent Multiplier System
What is the primary function of the countercurrent multiplier system?
To build osmolality in the medulla through interaction between the descending and ascending limbs of the Loop of Henle.
p.43
Regulation of Glomerular Filtration Rate (GFR)
What effect does decreased ADH have on water reabsorption?
It decreases water reabsorption in the collecting ducts.
p.44
Renin-Angiotensin-Aldosterone System
How is angiotensin I activated to angiotensin II?
By angiotensin converting enzyme (ACE) in the capillaries of the lungs.
p.36
Regulation of Glomerular Filtration Rate (GFR)
What is the overall effect of sympathetic activity on blood volume?
It increases blood volume.
p.44
Electrolyte and Acid-Base Balance
What does increased ADH production lead to?
Increased water retention.
Which part of the brain delivers sensation to the cerebral cortex during the micturition reflex?
Projection fibers from the thalamus.
What does a high renal plasma clearance indicate?
It indicates efficient removal of a substance from the plasma by the kidneys.
What do the afferent fibers stimulate in the micturition reflex?
Neurons involved with a local pathway and a central pathway.
p.16
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What substances are reabsorbed from the lumen in the Proximal Convoluted Tubule?
Salt, water, and other molecules needed by the body.
What is one of the waste products that kidneys help to manage?
Waste products in plasma.
What do postganglionic neurons in intramural ganglia stimulate?
Contraction of the detrusor muscle.
p.53
Structure of the Urinary System
What is the main function of the bladder?
To store urine until it is excreted.
p.24
Countercurrent Multiplier System
What role does active transport of salts play in the countercurrent multiplier system?
It subjects the concentrated filtrate in the ascending limb to active transport, raising the osmolality around the descending limb.
p.37
Regulation of Glomerular Filtration Rate (GFR)
Where is ADH secreted from?
The posterior pituitary gland.
p.43
Renin-Angiotensin-Aldosterone System
What is the role of Angiotensin II in the body?
It stimulates the adrenal cortex to increase Aldosterone secretion.
Which nervous system innervates and controls the bladder?
Parasympathetic nervous system.
p.15
Glomerular Filtration Process
What does Glomerular Filtration Rate (GFR) measure?
The volume of filtrate produced by both kidneys per minute.
p.49
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.9
Nephron Anatomy and Function
What are the two limbs of the Loop of Henle?
Descending and ascending limbs.
p.15
Reabsorption Mechanisms in the Proximal Convoluted Tubule
Why must most filtered water be reabsorbed?
To prevent death from water loss through urination.
What type of fibers are involved in the micturition reflex?
Sensory fibers in pelvic nerves and parasympathetic preganglionic motor fibers.
p.53
Structure of the Urinary System
What is the function of the ureters?
To transport urine from the kidneys to the bladder.
p.54
Structure of the Urinary System
How does the renal pelvis function in the urinary system?
It collects urine from the collecting ducts and channels it into the ureters.
p.33
Regulation of Glomerular Filtration Rate (GFR)
What is restored after the autoregulation response to decreased GFR?
Homeostasis and normal GFR.
p.43
Regulation of Glomerular Filtration Rate (GFR)
What type of feedback control is involved in this process?
Negative feedback control.
p.49
Electrolyte and Acid-Base Balance
What ions do the kidneys regulate for electrolyte balance?
Na+, K+, H+, HCO3-, Cl-, and PO4-3.
p.18
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What is the minimum urine volume necessary to excrete metabolic wastes?
400 ml per day (obligatory water loss).
p.34
Renin-Angiotensin-Aldosterone System
What does the Macula Densa signal granular cells to decrease?
Secretion of renin when blood Na+ is increased.
p.48
Electrolyte and Acid-Base Balance
What is the primary function of the kidneys in electrolyte balance?
To regulate the levels of electrolytes in the body.
p.47
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What effect does reabsorption have on renal clearance?
Reabsorption decreases renal clearance.
p.26
Countercurrent Multiplier System
What does the descending section of the vasa recta reabsorb?
H2O coming out of the descending limb.
p.48
Electrolyte and Acid-Base Balance
What is the effect of aldosterone on the kidneys?
It increases sodium reabsorption and potassium excretion.
p.54
Nephron Anatomy and Function
What is the role of the collecting duct in the nephron?
To collect urine from multiple nephrons and concentrate it under the influence of hormones.
p.37
Regulation of Glomerular Filtration Rate (GFR)
What hormone is responsible for maintaining plasma concentration?
ADH (Antidiuretic Hormone).
p.33
Regulation of Glomerular Filtration Rate (GFR)
What happens to the efferent arterioles during the autoregulation process?
Constriction of efferent arterioles.
p.36
Regulation of Glomerular Filtration Rate (GFR)
What areas experience vasoconstriction during sympathetic activity?
Skin and gastrointestinal (GI) tract.
p.37
Regulation of Glomerular Filtration Rate (GFR)
What type of feedback mechanism is involved in the regulation of ADH?
Negative feedback control.
What do the kidneys regulate in the process of urine formation?
Volume of blood plasma, waste products in plasma, concentration of electrolytes, and plasma pH.
p.26
Countercurrent Multiplier System
What substances are the vasa recta permeable to?
Salt, H2O (via aquaporins), and urea.
p.26
Countercurrent Multiplier System
How does the vasa recta contribute to the medulla interstitial fluid?
It recirculates salt, trapping some in the medulla interstitial fluid.
What initiates the micturition reflex?
Distortion of stretch receptors in the urinary bladder.
p.53
Structure of the Urinary System
What is the role of the renal pelvis?
To collect urine from the kidneys before it moves to the ureters.
p.48
Electrolyte and Acid-Base Balance
What is the significance of the renal tubules in electrolyte balance?
They are responsible for the reabsorption and secretion of electrolytes.
p.36
Regulation of Glomerular Filtration Rate (GFR)
What happens to blood pressure during exercise?
It decreases due to increased sympathetic nerve activity.
p.43
Regulation of Glomerular Filtration Rate (GFR)
What is the effect of low blood volume on sympathetic nerve activity?
It increases sympathetic nerve activity.
p.36
Regulation of Glomerular Filtration Rate (GFR)
What mechanism is involved in controlling the effects of sympathetic activity?
Negative feedback control.
What role does the interneuron play in the micturition reflex?
It relays sensation to the thalamus.
p.8
Nephron Anatomy and Function
What happens to blood from the peritubular capillaries?
It enters interlobular veins.
p.49
Electrolyte and Acid-Base Balance
Why is the control of plasma K+ important?
It is essential for the proper function of cardiac and skeletal muscles.
p.50
Regulation of Glomerular Filtration Rate (GFR)
How is the remaining Na+ and K+ reabsorbed in the distal tubule and cortical collecting duct?
Variably, according to bodily needs.
p.48
Electrolyte and Acid-Base Balance
What role do hormones play in renal control of electrolytes?
Hormones like aldosterone regulate sodium and potassium levels.
p.25
Nephron Anatomy and Function
What is the permeability of the descending limb to solutes?
It is impermeable to solutes.
p.42
Renin-Angiotensin-Aldosterone System
What are the two mechanisms that stimulate renin release?
Direct effects of blood pressure on granular cells and sympathetic activity initiated by arterial baroreceptor reflex.
p.44
Regulation of Glomerular Filtration Rate (GFR)
What system is activated in response to a reduction in the GFR?
Renin–Angiotensin-Aldosterone System.
p.2
Structure of the Urinary System
What is the function of the urethra in the urinary system?
The urethra drains urine from the bladder.
p.37
Reabsorption Mechanisms in the Proximal Convoluted Tubule
What effect does ADH have on the collecting duct?
Stimulates the insertion of aquaporins into the plasma membrane.
p.44
Regulation of Glomerular Filtration Rate (GFR)
What are the effects of angiotensin II and sympathetic activation?
They stimulate peripheral vasoconstriction.
