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All questions of Excretory System (BIO) for MCAT Exam
Which hormone is responsible for stimulating the production of red blood cells in the bone marrow?- a)Renin
- b)Aldosterone
- c)Erythropoietin
- d)Angiotensin II
Correct answer is option 'C'. Can you explain this answer?
Which hormone is responsible for stimulating the production of red blood cells in the bone marrow?
a)
Renin
b)
Aldosterone
c)
Erythropoietin
d)
Angiotensin II
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Orion Classes answered |
Erythropoietin is a hormone produced by the kidneys in response to low oxygen levels. It stimulates the production of red blood cells in the bone marrow, helping to increase oxygen-carrying capacity.
Which hormone is responsible for regulating water reabsorption in the kidney tubules?- a)Renin
- b)Aldosterone
- c)Antidiuretic hormone (ADH)
- d)Atrial natriuretic peptide (ANP)
Correct answer is option 'C'. Can you explain this answer?
Which hormone is responsible for regulating water reabsorption in the kidney tubules?
a)
Renin
b)
Aldosterone
c)
Antidiuretic hormone (ADH)
d)
Atrial natriuretic peptide (ANP)
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Orion Classes answered |
Antidiuretic hormone (ADH), also known as vasopressin, regulates water reabsorption in the kidney tubules. It acts on the collecting ducts to increase water permeability and reduce water loss in urine.
Which of the following is a mechanism of renal autoregulation that helps maintain a stable glomerular filtration rate (GFR) despite changes in blood pressure?- a)Tubuloglomerular feedback
- b)Sympathetic nervous system stimulation
- c)Activation of the renin-angiotensin-aldosterone system
- d)Release of atrial natriuretic peptide (ANP)
Correct answer is option 'A'. Can you explain this answer?
Which of the following is a mechanism of renal autoregulation that helps maintain a stable glomerular filtration rate (GFR) despite changes in blood pressure?
a)
Tubuloglomerular feedback
b)
Sympathetic nervous system stimulation
c)
Activation of the renin-angiotensin-aldosterone system
d)
Release of atrial natriuretic peptide (ANP)
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Orion Classes answered |
Tubuloglomerular feedback is a mechanism of renal autoregulation that involves communication between the macula densa cells in the distal convoluted tubule and the afferent arterioles of the glomerulus. If the glomerular filtration rate (GFR) is too high, the macula densa cells sense an increased flow of fluid and release vasoconstrictor signals to the afferent arterioles, reducing blood flow and maintaining a stable GFR. If the GFR is too low, the macula densa cells trigger vasodilation to increase blood flow and maintain adequate filtration.
Which of the following cell types release renin?- a)Extraglomerular mesangial cells
- b)Macula densa cells
- c)Alpha intercalated cells
- d)Juxta glomerular cells
Correct answer is option 'D'. Can you explain this answer?
Which of the following cell types release renin?
a)
Extraglomerular mesangial cells
b)
Macula densa cells
c)
Alpha intercalated cells
d)
Juxta glomerular cells
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Orion Classes answered |
Juxtaglomerular cells, also known as granular cells, are specialized cells located in the walls of the afferent arterioles of the kidney. These cells release renin in response to various signals, including low blood pressure or low blood volume. Renin plays a crucial role in the renin-angiotensin-aldosterone system (RAAS), initiating a cascade of events that ultimately regulate blood pressure and fluid balance.
Which part of the nephron is responsible for the majority of water reabsorption?- a)Glomerulus
- b)Proximal convoluted tubule
- c)Loop of Henle
- d)Distal convoluted tubule
Correct answer is option 'B'. Can you explain this answer?
Which part of the nephron is responsible for the majority of water reabsorption?
a)
Glomerulus
b)
Proximal convoluted tubule
c)
Loop of Henle
d)
Distal convoluted tubule
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Orion Classes answered |
The proximal convoluted tubule (PCT) is responsible for the majority of water reabsorption in the nephron. It reabsorbs water along with various solutes, including glucose, amino acids, and ions.
Which enzyme is released by the juxtaglomerular cells of the kidney in response to low blood pressure or low blood volume?- a)Renin
- b)Angiotensin-converting enzyme (ACE)
- c)Aldosterone synthase
- d)Antidiuretic hormone (ADH)
Correct answer is option 'A'. Can you explain this answer?
Which enzyme is released by the juxtaglomerular cells of the kidney in response to low blood pressure or low blood volume?
a)
Renin
b)
Angiotensin-converting enzyme (ACE)
c)
Aldosterone synthase
d)
Antidiuretic hormone (ADH)
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Orion Classes answered |
Juxtaglomerular cells, located in the walls of the afferent arterioles in the kidney, release renin in response to signals indicating low blood pressure or low blood volume. Renin initiates the renin-angiotensin-aldosterone system, leading to the production of angiotensin II and subsequent effects on blood pressure regulation.
How many nephrons does the average adult human kidney contain (a nephron is the main functional unit of the kidney)?- a)Exactly 1
- b)Roughly 100,000
- c)Roughly 1,000,000
- d)Roughly 1,000
Correct answer is option 'C'. Can you explain this answer?
How many nephrons does the average adult human kidney contain (a nephron is the main functional unit of the kidney)?
a)
Exactly 1
b)
Roughly 100,000
c)
Roughly 1,000,000
d)
Roughly 1,000
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Orion Classes answered |
The average adult human kidney contains approximately 1,000,000 nephrons. Nephrons are the functional units of the kidney responsible for filtering blood and producing urine. Each nephron consists of a glomerulus, which is a network of tiny blood vessels, and a tubule that carries the filtered fluid (urine) through various regions of the kidney for further processing. The large number of nephrons in each kidney allows for efficient filtration and processing of blood to maintain homeostasis.
Which of the following is least likely to be present in the glomerular filtrate (the filtrate produced by the nephron before it enters the loop of Henle) of a healthy adult nephron?- a)Amino acids
- b)Glucose
- c)Electrolytes
- d)Large molecular weight protein
Correct answer is option 'D'. Can you explain this answer?
Which of the following is least likely to be present in the glomerular filtrate (the filtrate produced by the nephron before it enters the loop of Henle) of a healthy adult nephron?
a)
Amino acids
b)
Glucose
c)
Electrolytes
d)
Large molecular weight protein
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Orion Classes answered |
In a healthy adult nephron, large molecular weight proteins are least likely to be present in the glomerular filtrate. The glomerular filtration process selectively allows the passage of small molecules and ions, while larger molecules such as proteins are usually excluded.
The glomerular filtration barrier consists of three layers: the fenestrated endothelium of the glomerular capillaries, the basement membrane, and the filtration slits formed by podocytes. This barrier acts as a sieve, allowing small molecules like water, ions, glucose, and amino acids to pass through, while preventing the passage of larger molecules, including most proteins.
Amino acids, glucose, and electrolytes are small molecules that are present in the glomerular filtrate. Amino acids are essential building blocks for protein synthesis, glucose is a vital energy source, and electrolytes are involved in various physiological processes.
Large molecular weight proteins, on the other hand, are normally retained within the bloodstream due to their size and charge. They are generally not filtered through the glomerular filtration barrier. Any presence of large proteins in the filtrate would indicate a malfunction or damage to the filtration barrier, which can occur in certain kidney diseases or conditions.
Therefore, option D, large molecular weight protein, is least likely to be present in the glomerular filtrate of a healthy adult nephron.
Which structure in the kidney is responsible for filtration of blood and formation of urine?- a)Glomerulus
- b)Loop of Henle
- c)Collecting duct
- d)Renal cortex
Correct answer is option 'A'. Can you explain this answer?
Which structure in the kidney is responsible for filtration of blood and formation of urine?
a)
Glomerulus
b)
Loop of Henle
c)
Collecting duct
d)
Renal cortex
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Orion Classes answered |
The glomerulus is a network of capillaries located within the renal corpuscle of the nephron. It is responsible for the filtration of blood, allowing small molecules and ions to pass through into the Bowman's capsule. This filtered fluid eventually becomes urine after undergoing further processing in the nephron.
Which of the following anatomical portions of a nephron connects the Bowman’s capsule to the loop of Henle?- a)Distal convoluted tubule
- b)Connecting tubule
- c)Proximal convoluted tubule
- d)Collecting duct
Correct answer is option 'C'. Can you explain this answer?
Which of the following anatomical portions of a nephron connects the Bowman’s capsule to the loop of Henle?
a)
Distal convoluted tubule
b)
Connecting tubule
c)
Proximal convoluted tubule
d)
Collecting duct
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Orion Classes answered |
The proximal convoluted tubule (PCT) is the portion of the nephron that connects the Bowman's capsule to the loop of Henle. It is located immediately after the glomerulus within the renal corpuscle. The PCT is responsible for reabsorbing the majority of filtered substances back into the bloodstream, such as water, glucose, amino acids, and electrolytes. After leaving the PCT, the filtrate enters the loop of Henle, which plays a critical role in concentrating the urine.
Which hormone plays a key role in the renal regulation of blood pressure by increasing sodium reabsorption and water retention?- a)Renin
- b)Angiotensin II
- c)Aldosterone
- d)Antidiuretic hormone (ADH)
Correct answer is option 'C'. Can you explain this answer?
Which hormone plays a key role in the renal regulation of blood pressure by increasing sodium reabsorption and water retention?
a)
Renin
b)
Angiotensin II
c)
Aldosterone
d)
Antidiuretic hormone (ADH)
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Orion Classes answered |
Aldosterone, produced by the adrenal cortex, acts on the distal tubules and collecting ducts of the nephron to enhance sodium reabsorption and potassium secretion. This results in increased water reabsorption and expansion of blood volume, leading to an increase in blood pressure.
Which of the following is the functional unit of the kidney responsible for filtration, reabsorption, and secretion?- a)Nephron
- b)Glomerulus
- c)Loop of Henle
- d)Collecting duct
Correct answer is option 'A'. Can you explain this answer?
Which of the following is the functional unit of the kidney responsible for filtration, reabsorption, and secretion?
a)
Nephron
b)
Glomerulus
c)
Loop of Henle
d)
Collecting duct
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Orion Classes answered |
The nephron is the structural and functional unit of the kidney. It is responsible for filtering the blood, reabsorbing useful substances, and secreting waste products to form urine.
Which of the following is the primary function of the loop of Henle?- a)Filtration of blood
- b)Reabsorption of water and sodium
- c)Secretion of waste products
- d)Regulation of blood pressure
Correct answer is option 'B'. Can you explain this answer?
Which of the following is the primary function of the loop of Henle?
a)
Filtration of blood
b)
Reabsorption of water and sodium
c)
Secretion of waste products
d)
Regulation of blood pressure
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Orion Classes answered |
The loop of Henle plays a critical role in reabsorbing water and sodium from the filtrate. It creates a concentration gradient in the interstitial fluid of the kidney, which allows for further water reabsorption in the collecting ducts.
Which of the following is a hormone released by the kidneys that acts on bone marrow to stimulate red blood cell production?- a)Renin
- b)Angiotensin II
- c)Erythropoietin
- d)Antidiuretic hormone (ADH)
Correct answer is option 'C'. Can you explain this answer?
Which of the following is a hormone released by the kidneys that acts on bone marrow to stimulate red blood cell production?
a)
Renin
b)
Angiotensin II
c)
Erythropoietin
d)
Antidiuretic hormone (ADH)
|
|
Orion Classes answered |
Erythropoietin is a hormone produced and released by the kidneys in response to low oxygen levels in the blood. It acts on the bone marrow, stimulating the production of red blood cells, which enhances the oxygen-carrying capacity of the blood.
The renal system does not play a direct role in regulating which of the following?- a)Blood solute concentrations
- b)Blood temperature
- c)Blood pressure
- d)Blood pH
Correct answer is option 'B'. Can you explain this answer?
The renal system does not play a direct role in regulating which of the following?
a)
Blood solute concentrations
b)
Blood temperature
c)
Blood pressure
d)
Blood pH
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Orion Classes answered |
The renal system is primarily responsible for regulating blood solute concentrations, blood pressure, and blood pH. It achieves these functions through processes such as filtration, reabsorption, and secretion in the nephrons. However, regulation of blood temperature is primarily carried out by other systems, such as the cardiovascular system and thermoregulatory mechanisms involving the skin and hypothalamus.
Which of the following hormones directly acts on the collecting duct of the nephron to enhance water reabsorption?- a)Aldosterone
- b)Antidiuretic hormone (ADH)
- c)Renin
- d)Atrial natriuretic peptide (ANP)
Correct answer is option 'B'. Can you explain this answer?
Which of the following hormones directly acts on the collecting duct of the nephron to enhance water reabsorption?
a)
Aldosterone
b)
Antidiuretic hormone (ADH)
c)
Renin
d)
Atrial natriuretic peptide (ANP)
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Orion Classes answered |
Antidiuretic hormone (ADH), also known as vasopressin, is produced by the hypothalamus and released by the posterior pituitary gland. It acts on the collecting duct of the nephron, increasing its permeability to water and promoting water reabsorption. This helps to concentrate the urine and conserve water in the body.
Which of the following substances is reabsorbed from the filtrate back into the bloodstream in the proximal convoluted tubule of the nephron?- a)Glucose
- b)Urea
- c)Creatinine
- d)Hydrogen ions
Correct answer is option 'A'. Can you explain this answer?
Which of the following substances is reabsorbed from the filtrate back into the bloodstream in the proximal convoluted tubule of the nephron?
a)
Glucose
b)
Urea
c)
Creatinine
d)
Hydrogen ions
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Orion Classes answered |
The proximal convoluted tubule is a section of the nephron where the majority of reabsorption takes place. Glucose is actively transported back into the bloodstream from the filtrate through specialized transport proteins in the apical membrane of the tubular cells. This prevents glucose loss in the urine and maintains its concentration in the blood.
Which of the following describes the role of the kidneys in long-term blood pressure regulation?- a)The kidneys regulate blood pressure by releasing hormones that directly affect vascular tone.
- b)The kidneys regulate blood pressure by adjusting heart rate and cardiac output.
- c)The kidneys regulate blood pressure by controlling blood volume through the regulation of sodium and water balance.
- d)The kidneys regulate blood pressure by increasing sympathetic nervous system activity.
Correct answer is option 'C'. Can you explain this answer?
Which of the following describes the role of the kidneys in long-term blood pressure regulation?
a)
The kidneys regulate blood pressure by releasing hormones that directly affect vascular tone.
b)
The kidneys regulate blood pressure by adjusting heart rate and cardiac output.
c)
The kidneys regulate blood pressure by controlling blood volume through the regulation of sodium and water balance.
d)
The kidneys regulate blood pressure by increasing sympathetic nervous system activity.
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Orion Classes answered |
The kidneys play a crucial role in long-term blood pressure regulation by controlling blood volume. They regulate blood pressure by adjusting the reabsorption and excretion of sodium and water, which directly impact blood volume. The renin-angiotensin-aldosterone system (RAAS) and other hormonal mechanisms controlled by the kidneys help maintain proper sodium and water balance, thus influencing blood pressure.
Urine is formed in a three-step process: which of the following gives the correct order in which these steps take place in the nephron?- a)Tubular secretion, tubular reabsorption, glomerular filtration
- b)Tubular reabsorption, tubular secretion, glomerular filtration
- c)Glomerular filtration, tubular reabsorption, tubular secretion
- d)Glomerular filtration, tubular secretion, tubular reabsorption
Correct answer is option 'C'. Can you explain this answer?
Urine is formed in a three-step process: which of the following gives the correct order in which these steps take place in the nephron?
a)
Tubular secretion, tubular reabsorption, glomerular filtration
b)
Tubular reabsorption, tubular secretion, glomerular filtration
c)
Glomerular filtration, tubular reabsorption, tubular secretion
d)
Glomerular filtration, tubular secretion, tubular reabsorption
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Orion Classes answered |
The correct order in which urine is formed in the nephron is glomerular filtration, tubular reabsorption, and tubular secretion.
- Glomerular filtration: This is the first step in urine formation and occurs in the glomerulus of the nephron. Blood pressure forces fluid and small solutes from the glomerular capillaries into the Bowman's capsule, forming the filtrate. Larger molecules like proteins and blood cells are not filtered.
- Tubular reabsorption: After filtration, the filtrate enters the renal tubules, where selective reabsorption takes place. Essential substances such as water, glucose, amino acids, and ions are reabsorbed from the tubules into the surrounding capillaries. This process helps maintain the body's fluid balance and reabsorb valuable substances.
- Tubular secretion: As the filtrate passes through the tubules, additional waste products, toxins, and excess ions are actively secreted from the blood into the tubules. This process further modifies the composition of the filtrate before it becomes urine.
Overall, the three steps of glomerular filtration, tubular reabsorption, and tubular secretion work together to produce urine and regulate the balance of water, ions, and other substances in the body
Which of the following best describes the role of the renin-angiotensin-aldosterone system (RAAS) in blood pressure regulation?- a)It promotes vasodilation and decreases blood pressure.
- b)It increases cardiac output and raises blood pressure.
- c)It stimulates sodium excretion and decreases blood pressure.
- d)It promotes vasoconstriction and increases blood pressure.
Correct answer is option 'D'. Can you explain this answer?
Which of the following best describes the role of the renin-angiotensin-aldosterone system (RAAS) in blood pressure regulation?
a)
It promotes vasodilation and decreases blood pressure.
b)
It increases cardiac output and raises blood pressure.
c)
It stimulates sodium excretion and decreases blood pressure.
d)
It promotes vasoconstriction and increases blood pressure.
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Orion Classes answered |
The renin-angiotensin-aldosterone system (RAAS) is an important hormonal cascade involved in blood pressure regulation. Angiotensin II, a key component of the RAAS, acts as a potent vasoconstrictor, causing narrowing of blood vessels. This vasoconstriction increases peripheral resistance and contributes to an increase in blood pressure.
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