155 Questions
What is the main mechanism by which autoregulation of renal blood flow and glomerular filtration rate occurs?
Tubuloglomerular feedback
When sodium filtration increases, what happens to glomerular filtration rate (GFR)?
GFR decreases
What is the effect of sympathetic nervous system activation on renal blood flow and GFR?
Decreases renal blood flow and GFR
What is the effect of severe hypoxia on renal blood flow?
Decreases renal blood flow
What is the effect of inhibition of the sympathetic nervous system on renal blood flow and GFR?
Increases renal blood flow and GFR
What is the effect of decreased sodium filtration on glomerular filtration rate (GFR)?
GFR increases
What is the effect of exercise and changes in body position on renal blood flow and GFR?
Decreases renal blood flow and GFR
What is the role of the macula densa cells in the tubuloglomerular feedback mechanism?
They release vasodilatory substances like PGI2 and NO
Which of the following structures is responsible for detecting changes in blood pressure and regulating the glomerular filtration rate?
Granular cells (Juxtaglomerular cells)
What is the normal filtration fraction (FF) of the kidneys?
20%
What is the relationship between mean arterial pressure and renal blood flow (RBF)?
Depends on the vascular resistance
Which of the following is the primary function of the kidney?
Glomerular filtration rate (GFR)
What is the main mechanism responsible for the autoregulation of renal blood flow and glomerular filtration rate?
Myogenic mechanism
What is the relationship between the glomerular filtration rate (GFR) and the renal plasma flow (RPF)?
GFR is 20% of RPF
What is the approximate range of the glomerular filtration rate (GFR) in a healthy individual?
120-140 ml/min
Which of the following structures is responsible for the efferent arteriole constriction in response to increased blood pressure?
Myocytes (smooth muscle)
Which of the following occurs during glomerular filtration?
Water and small solutes move from the blood plasma into the glomerular capsule and renal tubules
What is the primary function of tubular reabsorption?
To return useful solutes and water from the renal tubules back into the blood
Which hormone stimulates the reabsorption of calcium ions in the renal tubules?
Parathyroid hormone (PTH)
Which structure in the nephron is responsible for fine-tuning the osmolarity of the blood?
Loop of Henle
Which process allows for the paracellular transport of solutes in the proximal convoluted tubule?
Claudin proteins
What is the primary function of tubular secretion?
To secrete waste products, drugs, and excess ions into the renal tubules
Which hormone regulates water reabsorption in the collecting duct?
Antidiuretic hormone (ADH)
How does urine concentration vary with fluid intake?
High fluid intake results in dilute urine of high volume, while low fluid intake results in concentrated urine of low volume
What is the best estimate for the functioning of renal tissue?
Inulin
Which substance provides a good estimate of GFR since only a small amount enters urine?
Creatinine
What does Plasma Urea Nitrogen (BUN) measure to monitor in renal patients?
Progressive renal dysfunction
What does Para-aminohippuric acid (PAH) clearance primarily determine in the kidney?
Renal plasma flow and blood flow
Which substance requires constant infusion to maintain a stable plasma level since all filtered content is excreted in urine?
Inulin
What is the normal range for Plasma Creatinine concentration?
0.6 to 1.2 mg/dl
What is the main function of Renal Clearance techniques?
Indirectly measure GFR, tubular secretion, tubular reabsorption, and RBF
Which of the following is responsible for supplying the glomerular capillaries?
Afferent arterioles
What is the role of the vasa recta?
To influence the osmolar concentration of the medullary extracellular fluid
What percentage of the total nephrons are superficial cortical nephrons?
85%
What is the function of the efferent arterioles?
To convey blood to a second capillary bed
What is the percentage of the body's resting cardiac output that the kidneys receive?
20-25%
What is the role of the peritubular capillaries?
To surround the proximal and distal convoluted tubules and be the site of the filtration loop of Henle
What is the main function of the juxtamedullary nephrons?
To secrete renin
What is the primary role of the renal corpuscle?
Filtration from blood plasma into the nephron
What is the primary function of the renal cortex?
It contains all of the glomeruli and most of the proximal tubules.
What is the function of the renal pelvis?
It joins the proximal end of the ureter.
What is the function of the minor calyx?
It receives urine from the collecting ducts through the renal papilla.
What is the function of the renal fascia?
It attaches and suspends the kidney to the posterior abdominal wall.
What is the function of the adipose capsule?
It surrounds each kidney with a layer of fat.
What is the function of the renal capsule?
It covers the kidney with a tightly adhering capsule.
What substance is often used to provide the best estimate of the functioning of renal tissue?
Inulin
Which substance is most valuable for monitoring the progress of chronic renal disease?
Creatinine
What is the main purpose of measuring Plasma Urea Nitrogen (BUN) levels in kidney failure?
To measure progressive renal dysfunction
Which technique permits an indirect measure of Glomerular Filtration Rate (GFR), tubular secretion, tubular reabsorption, and Renal Blood Flow (RBF)?
Renal clearance
What is the primary function of Para-aminohippuric acid (PAH) clearance in the kidney?
To estimate blood flow in kidneys
Why is constant infusion required to maintain stable plasma levels of inulin during testing?
Inulin is completely excreted in urine
What is the primary function of the glomerular filtration membrane?
To filter out large proteins and blood cells from the blood
What is the role of the mesangial cells in the glomerulus?
To support the structure of the glomerulus and regulate blood flow
What is the function of the macula densa in the juxtaglomerular apparatus?
To detect changes in sodium and chloride levels in the filtrate
What is the primary function of the juxtaglomerular cells?
To secrete renin and regulate renal blood flow and glomerular filtration rate
What is the primary function of the podocytes in the glomerulus?
To prevent the filtration of large proteins and blood cells
What is the function of the negative charge on the basement membrane of the glomerulus?
To repel the filtration of negatively charged proteins (anionic proteins)
What happens to the glomerular filtration rate (GFR) when arterial pressure drops?
GFR increases due to afferent arteriole dilation
Which receptor is involved in the vasoconstriction of the afferent arteriole during tubuloglomerular feedback?
A1A receptor
What is the primary mechanism by which increased sodium filtration leads to a decrease in GFR?
Adenosine release from macula densa cells causes afferent arteriole constriction
What is the effect of sympathetic nervous system stimulation on renal blood flow and GFR?
Decreases renal blood flow and GFR
What is the effect of exercise and changes in body position on renal blood flow and GFR?
Causes mild vasoconstriction, decreasing renal blood flow and GFR
What is the primary mechanism by which severe hypoxia decreases renal blood flow?
Stimulation of chemoreceptors, leading to sympathetic stimulation
What is the primary mechanism by which the afferent arterioles constrict in response to increased blood pressure?
Myogenic response due to stretch-activated ion channels
What is the primary determinant of the filtration fraction (FF) in the kidneys?
Afferent arteriolar resistance
If the mean arterial pressure decreases, what is the expected effect on the renal blood flow (RBF) and the glomerular filtration rate (GFR)?
Both RBF and GFR decrease
Which of the following structures plays a key role in the tubuloglomerular feedback mechanism?
Macula densa
What is the approximate range of the renal plasma flow (RPF) in a healthy individual?
600-700 ml/min
What is the relationship between the glomerular filtration rate (GFR) and the renal plasma flow (RPF)?
GFR is approximately 20% of RPF
Renin is an enzyme formed and stored in the granular cells of the ______ apparatus.
juxtaglomerular
In the presence of angiotensin-converting enzyme (ACE), angiotensin I is converted to angiotensin ______.
II
Angiotensin II stimulates the secretion of ______ by the adrenal cortex.
aldosterone
Atrial natriuretic peptide (ANP) is secreted from myocardial cells in the ______.
atria
Brain natriuretic peptide (BNP) is secreted from myocardial cells in the ______.
ventricles
ANP and BNP inhibit sodium and therefore water reabsorption by kidney ______.
tubules
ANP and BNP inhibit secretion of ______ and aldosterone.
renin
Vasodilation of the afferent arterioles and constriction of the efferent arterioles is caused by ANP and BNP to increase ______ output.
urine
Natriuretic peptides promote sodium and water ______.
loss
Renin-angiotensin-aldosterone system (RAAS) increases systemic arterial pressure and increases ______ reabsorption.
sodium
Renin is physiologically inactive until it is converted to angiotensin II by angiotensin-converting enzyme (ACE).
True
Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) stimulate the secretion of aldosterone by the adrenal cortex.
False
Angiotensin II promotes sodium and water loss in the body.
False
Vasodilation of afferent arterioles is one of the effects of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP).
True
Renin is secreted from myocardial cells in the atria.
False
Match the following hormones with their effects on sodium and water reabsorption:
Renin = Increases sodium reabsorption Angiotensin II = Stimulates water retention Atrial natriuretic peptide (ANP) = Inhibits sodium and water reabsorption Antidiuretic hormone (ADH) = Stimulates water retention
Match the following peptides with their actions in the kidney tubules:
Atrial natriuretic peptide (ANP) = Vasodilates afferent arterioles Brain natriuretic peptide (BNP) = Promotes sodium and water loss
Match the following terms with their functions:
Juxtaglomerular apparatus = Location where renin is formed and stored Glomerular filtration rate (GFR) = Indirect measure of renal function Vasa recta = Supplying the glomerular capillaries Renal pelvis = Collecting urine from the kidneys
Match the following regulatory mechanisms with their effects on blood pressure:
Renin-angiotensin-aldosterone system (RAAS) = Increases systemic arterial pressure Natriuretic peptides = Decrease blood volume and blood pressure Aldosterone = Promotes sodium retention and water reabsorption Antidiuretic hormone (ADH) = Increases blood volume and blood pressure
Match the following vasoactive substances with their effects on arterioles:
Angiotensin II = Potent vasoconstrictor Atrial natriuretic peptide (ANP) = Vasodilates afferent arterioles Brain natriuretic peptide (BNP) = Constricts efferent arterioles Renal fascia = Supports renal structures
Match the following hormones with their effects on sodium and water reabsorption:
Angiotensin II = Promotes sodium and water retention Atrial natriuretic peptide (ANP) = Inhibits sodium and water reabsorption Brain natriuretic peptide (BNP) = Inhibits sodium and water reabsorption Antidiuretic hormone (ADH) = Promotes water reabsorption
Match the following peptides with their actions in the kidney tubules:
Atrial natriuretic peptide (ANP) = Inhibits sodium and water reabsorption Brain natriuretic peptide (BNP) = Inhibits sodium and water reabsorption Renin = Stimulates aldosterone secretion Angiotensin II = Promotes sodium reabsorption
Match the following regulatory mechanisms with their effects on blood pressure:
Renin-angiotensin-aldosterone system (RAAS) = Increases systemic arterial pressure Atrial natriuretic peptide (ANP) and Brain natriuretic peptide (BNP) = Decrease blood pressure Antidiuretic hormone (ADH) = Promotes vasoconstriction Natriuretic peptides = Vasodilate arterioles
Match the following terms with their functions:
Peritubular capillaries = Reabsorb solutes from tubules Vasa recta = Maintain osmotic gradient in medulla Juxtaglomerular apparatus = Regulate glomerular filtration rate Renal capsule = Protect and support kidney
Match the following structures with their roles:
Efferent arterioles = Constrict in response to increased blood pressure Afferent arterioles = Regulate renal blood flow by resistance changes Renal fascia = Anchors kidney to surrounding structures Renal pelvis = Collects urine from major calyces
What is the primary function of the kidney in maintaining a stable internal environment?
Regulation of blood volume and blood pressure
Which of the following electrolytes is NOT primarily regulated by the kidneys?
Glucose
What is the main mechanism responsible for the autoregulation of renal blood flow and glomerular filtration rate?
Tubuloglomerular feedback
Which hormone is responsible for stimulating the production of red blood cells (erythropoiesis) in the kidneys?
Erythropoietin
What is the primary function of the renal cortex?
Filtering blood and forming urine
Which of the following is the best estimate of the functioning of renal tissue?
Glomerular filtration rate (GFR)
What is the primary function of the renal pelvis?
To allow the passage of urine from the kidneys to the ureters
Which of the following best describes the role of the mesangial cells in the glomerulus?
They provide structural support and help regulate the filtration surface area.
What is the primary mechanism by which the afferent arterioles constrict in response to increased blood pressure?
Triggering of the tubuloglomerular feedback mechanism
What is the effect of exercise and changes in body position on renal blood flow and GFR?
Exercise decreases renal blood flow and GFR, while changes in body position have no effect.
What is the main purpose of measuring Plasma Urea Nitrogen (BUN) levels in kidney failure?
To evaluate the severity of kidney damage
What is the primary mechanism by which severe hypoxia decreases renal blood flow?
Constriction of the afferent arterioles
What causes the detrusor muscle to contract during micturition?
Parasympathetic fibers
What is the role of the external urethral sphincter in micturition?
Relaxing to allow urine flow
What is the main trigger for initiating a desire to urinate?
Bladder fullness
Which part of the brain is responsible for conscious control of micturition?
Cerebral cortex
What type of muscle controls the external urethral sphincter?
Striated skeletal muscle
Which fiber type causes relaxation of the internal urethral sphincter during micturition?
Parasympathetic fibers
What is the primary function of the podocytes in the glomerulus?
To form an elaborate network of intercellular clefts called filtration slits and modulate filtration
What is the primary mechanism by which increased sodium filtration leads to a decrease in glomerular filtration rate (GFR)?
Increased sodium filtration activates the tubuloglomerular feedback mechanism, leading to vasoconstriction of the afferent arteriole
What is the role of the vasa recta in the kidney?
To maintain the osmotic gradient in the renal medulla and facilitate water reabsorption
What is the main function of the glomerular filtration membrane?
To selectively filter substances from the blood based on their size, charge, and molecular characteristics
What is the effect of sympathetic nervous system stimulation on renal blood flow and glomerular filtration rate (GFR)?
Sympathetic stimulation decreases renal blood flow and GFR
What is the relationship between the glomerular filtration rate (GFR) and the renal plasma flow (RPF)?
GFR is approximately 20% of RPF, as only a fraction of the renal plasma flow is filtered
What is the main purpose of measuring Plasma Urea Nitrogen (BUN) levels in kidney failure?
To monitor the functioning of the renal tissue and the glomerular filtration rate
What is the primary mechanism by which increased sodium filtration leads to a decrease in glomerular filtration rate (GFR)?
Increased sodium filtration stimulates the macula densa cells to release adenosine, which causes vasoconstriction of the afferent arteriole and vasodilation of the efferent arteriole, leading to a decrease in GFR.
What is the effect of sympathetic nervous system stimulation on renal blood flow and glomerular filtration rate (GFR)?
Sympathetic stimulation causes vasoconstriction of the afferent arteriole, leading to a decrease in renal blood flow and GFR.
What is the primary mechanism by which autoregulation of renal blood flow and glomerular filtration rate (GFR) occurs?
Autoregulation is primarily mediated by the tubuloglomerular feedback mechanism, where changes in sodium chloride content are detected by the macula densa cells.
What is the role of the macula densa cells in the tubuloglomerular feedback mechanism?
The macula densa cells release adenosine, which stimulates vasoconstriction of the afferent arteriole and vasodilation of the efferent arteriole, leading to a decrease in GFR.
What is the effect of inhibition of the sympathetic nervous system on renal blood flow and glomerular filtration rate (GFR)?
Inhibition of the sympathetic nervous system causes vasodilation of the afferent arteriole, leading to an increase in renal blood flow and GFR.
What is the primary function of the juxtaglomerular cells?
The juxtaglomerular cells secrete renin, which is the first step in the renin-angiotensin-aldosterone system (RAAS) that regulates blood pressure and fluid balance.
What is the primary function of the juxtaglomerular apparatus?
Regulating blood pressure
Which hormone is primarily responsible for calcium homeostasis?
Calcitriol
What is the main function of mesangial cells in the glomerulus?
Supporting and contracting the glomerular tuft
How does retention of water by the kidneys affect blood pressure?
Increases blood pressure
What is the primary role of the renal corpuscle in kidney function?
Filtering blood
What is the primary function of the negative charge on the basement membrane of the glomerulus?
To repel anionic proteins and prevent their filtration
What is the primary role of the macula densa in the juxtaglomerular apparatus?
To sense high filtrate rate in the distal convoluted tubule and trigger vasoconstriction
Which of the following structures in the juxtaglomerular apparatus is responsible for controlling renal blood flow, glomerular filtration, and renin secretion?
Juxtaglomerular cells
What is the primary function of the mesangial cells in the glomerulus?
To provide structural support and help regulate glomerular blood flow
What is the primary mechanism by which the afferent arterioles constrict in response to increased blood pressure?
Decreased production of nitric oxide by the macula densa
What is the primary mechanism that allows for the production of dilute urine?
Countercurrent mechanism creating a concentration gradient in the renal medulla
What is the primary driving force for glomerular filtration?
Blood pressure within the glomerular capillaries
Which cells are responsible for regulating the filtration surface area in the glomerulus?
Podocytes
What is the primary function of the mesangial cells in the glomerulus?
Support the glomerular capillaries and respond to changes in blood pressure
What is the primary function of the glomerular endothelial cells?
Synthesize nitric oxide, a vasodilator, and endothelin-1, a vasoconstrictor
What triggers the micturition reflex?
Stretch receptors signaling the spinal cord when bladder volume exceeds 250-300 mL
Which muscle is responsible for voluntary control of urination?
External urethral sphincter
What is the primary function of the micturition center in the sacral spinal cord?
Triggering the micturition reflex
Which of the following arteries directly supplies blood to the kidney?
Renal arteries
What is the primary function of the arcuate arteries in the kidney?
Arching over the base of the renal pyramids
What is the primary function of measuring plasma creatinine concentration?
To estimate the glomerular filtration rate (GFR)
Which of the following substances is used to determine renal plasma flow and blood flow?
Para-aminohippuric acid (PAH)
What is the normal range for plasma cystatin C concentration?
0.52 to 0.98 mg/L
What is the primary purpose of measuring Blood Urea Nitrogen (BUN) levels in kidney failure?
To monitor the progress of chronic renal disease
What substance is often used to provide the best estimate of the functioning of renal tissue?
Inulin
Which enzyme is stored in the granular cells of the juxtaglomerular apparatus?
Renin
What is the physiological action of angiotensin II in the body?
Stimulate aldosterone secretion
Which hormone inhibits both renin and aldosterone secretion in the body?
Atrial natriuretic peptide (ANP)
What is the main physiological effect of natriuretic peptides on afferent and efferent arterioles?
Vasodilation of afferent arterioles and constriction of efferent arterioles
What is the ultimate result of the actions of natriuretic peptides on urine output and blood pressure?
Increase urine output, decrease blood volume
Study Notes
Regulation of Glomerular Filtration Rate (GFR)
- EPO (erythropoietin) does not affect GFR but increases oxygen delivery to the kidney
- Tests of renal function:
- Renal clearance: measures the amount of a substance cleared from the blood by the kidneys during a given unit of time
- Permits indirect measurement of GFR, tubular secretion, tubular reabsorption, and renal blood flow (RBF)
- Inulin (a fructose polysaccharide) is often used to measure GFR
- Creatinine: provides a good estimate of GFR since only a small amount enters urine (1.6g/Day)
Autoregulation of Renal Blood Flow and Glomerular Filtration Rate
- Tubuloglomerular feedback (sodium chloride content):
- If sodium filtration increases, GFR decreases
- Macula densa cells release Adenosine: stimulates afferent arteriole vasoconstriction (via A1AR receptors) and efferent arteriole vasodilation (via A2B receptors)
- Myogenic mechanism (pressure/stretch):
- If arterial pressure increases, stretch of the afferent arterioles increases, mechanical stretch channels open, and smooth muscle contracts to constrict afferent arteriole and perfusion decreases
Neural Regulation of Renal Blood Flow and Glomerular Filtration Rate
- Sympathetic nervous system:
- Sympathetic stimulation of afferent arterioles via alpha-1 (α-1) receptors causes vasoconstriction (decreases GFR)
- Inhibition of sympathetic nerves causes vasodilation (increases GFR)
- Exercise and change of body position: activate renal sympathetic neurons, causing mild vasoconstriction
- Severe hypoxia: stimulation of chemoreceptors decreases RBF by means of sympathetic stimulation
Structure and Function of the Kidney
- Renal corpuscle:
- Filtration from blood plasma into nephron
- Nephron:
- Functional unit of the kidney
- Consists of renal corpuscle and renal tubule
- Glomerulus:
- Tuft of capillaries surrounded by Bowman's capsule
- Juxtaglomerular apparatus:
- Controls renal blood flow, glomerular filtration, and renin secretion
Urinary System
- Functions of the urinary system:
- Electrolyte homeostasis
- Regulation of blood pH
- Regulation of blood volume/blood pressure
- Osmoregulation
- Produces hormones (calcitriol, erythropoietin, renin)
- Excretion of wastes (ammonia, urea, bilirubin, creatinine, uric acid)
- Performs gluconeogenesis
- Structures of the kidney:
- Renal capsule
- Adipose capsule
- Renal fascia
- Hilum
- Renal cortex
- Renal medulla
- Renal columns
- Minor calyx
- Major calyx
- Renal pelvis
- Ureter
Blood Flow through the Kidney
- Renal arteries: supply blood to the kidneys
- Segmental arteries: branches of the renal artery
- Interlobar arteries: travel between the pyramids
- Arcuate arteries: arch over the base of the pyramids
- Glomerular filtration: urine (contains excreted substances) and blood (contains reabsorbed substances)
Urine Production
- Fluid intake is highly variable
- Homeostasis requires maintenance of fluid volumes within specific limits
- Urine concentration varies with ADH### Renal Regulation and Function
-
Renin-Angiotensin-Aldosterone System (RAAS): Regulates blood pressure and sodium reabsorption.
- Renin: Enzyme formed in juxtaglomerular apparatus, converts to angiotensin I, then to angiotensin II with ACE.
- Angiotensin II: Stimulates aldosterone secretion, sodium retention, and water retention, and is a potent vasoconstrictor.
-
Natriuretic Peptides:
- Atrial Natriuretic Peptide (ANP): Secreted by atrial myocardial cells, inhibits sodium and water reabsorption, and renin and aldosterone secretion.
- Brain Natriuretic Peptide (BNP): Secreted by ventricular myocardial cells, inhibits sodium and water reabsorption, and renin and aldosterone secretion.
Renal Blood Flow and Glomerular Filtration Rate
-
Regulation of Renal Blood Flow (RBF):
- Autoregulation: Myogenic mechanism (pressure/stretch) and tubuloglomerular feedback (sodium chloride content) regulate RBF.
- Neural regulation: Sympathetic nervous system, exercise, and body position changes affect RBF.
- Hormonal regulation: RAAS, ANP, and BNP regulate RBF.
-
Glomerular Filtration Rate (GFR):
- 20% of renal plasma flow becomes filtrate, with an average rate of 125 ml/min in males and 105 ml/min in females.
- 180 Liters/day in males and 150 Liters/day in females, with 99% reabsorbed by the nephron.
Renal Anatomy
-
Kidney Structure:
- Renal capsule: Tightly adhering capsule covers the kidney.
- Adipose capsule: Fat capsule surrounds the kidney.
- Renal fascia: Fibrous tissue attaches the kidney to the posterior abdominal wall.
- Hilum: Medial indentation where renal blood vessels, nerves, lymphatic vessels, and ureter enter and exit the kidney.
-
Renal Cortex and Medulla:
- Renal cortex: Outer layer containing glomeruli, proximal and distal convoluted tubules, and some segments of the distal tubule.
- Renal medulla: Inner part containing tubules and the collecting duct, with regions called pyramids.
Nephron Structure and Function
-
Nephron:
- 1.2 million nephrons per kidney, with superficial cortical and juxtamedullary nephrons.
- Nephrons are the functional units of the kidney, regulating fluid and electrolyte balance.
-
Nephron Components:
- Afferent arteriole
- Glomerular capillaries
- Efferent arteriole
- Peritubular capillaries
- Renal tubule and collecting duct
- Minor calyx
- Major calyx
- Renal pelvis
- Ureter
- Bladder
- UrethraHere are the study notes:
Regulation of Renal Blood Flow and Glomerular Filtration Rate
- Autoregulation:
- When arterial pressure drops, afferent arterioles dilate to increase perfusion
- When sodium filtration increases, GFR decreases
- Macula densa cells release Adenosine, which stimulates afferent arteriol vasoconstriction and efferent arteriol vasodilation
- Neural Regulation:
- Sympathetic nervous system:
- Stimulates afferent arterioles, causing vasoconstriction and decreasing GFR
- Inhibition causes vasodilation and increases GFR
- Exercise and change of body position:
- Activate renal sympathetic neurons, causing mild vasoconstriction
- Severe hypoxia:
- Stimulation of chemoreceptors decreases RBF by means of sympathetic stimulation
- Sympathetic nervous system:
Hormonal Regulation
- Renin-Angiotensin-Aldosterone System (RAAS):
- Increases systemic arterial pressure and sodium reabsorption
- Renin: formed and stored in granular cells of the juxtaglomerular apparatus
- Angiotensin II:
- Stimulates secretion of aldosterone by the adrenal cortex
- Potent vasoconstrictor
- Stimulates antidiuretic hormone (ADH) secretion and thirst
- Natriuretic Peptides:
- Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP):
- Inhibit sodium and water reabsorption by kidney tubules
- Inhibit secretion of renin and aldosterone
- Vasodilate afferent arterioles and constrict efferent arterioles
- Increase urine output, leading to decreased blood volume and blood pressure; promote sodium and water loss
- Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP):
Functions of the Urinary System
- Primary Function: Maintain a stable internal environment for optimal cell and tissue metabolism
- Electrolyte homeostasis:
- Regulate Na+, K+, Ca2+, Cl-, and HPO42- levels
- Regulation of Blood pH:
- Removes H+ from blood and maintains bicarbonate ions (HCO3-) in blood
- Regulation of Blood Volume/Blood Pressure:
- Retention of water increases blood pressure, while elimination of water decreases blood pressure
- Osmoregulation:
- Maintains an osmolarity of 300 mOsm/L
- Production of Hormones:
- Calcitriol (form of Vitamin D) for calcium homeostasis
- Erythropoietin for RBC production
- Renin for blood pressure regulation
Test your knowledge on the pathway of renal blood supply, including interlobular arteries, afferent arterioles, glomerular capillaries, efferent arterioles, peritubular capillaries, and vasa recta. Understand how blood flows through different structures in the kidneys.
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