Chapter 4: Urinary System

Select the correct answer:

1. Nephron, the functional unit of kidney is composed of all of the following except:

A) Bowman's capsules

B) Loop of Henle

C) glomerulus

D) ureter

Answer: D) ureter

Explanation: The nephron is the microscopic structural and functional unit of the kidney. It consists of the renal corpuscle

(Bowman's capsule and glomerulus) and the renal tubule (proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct). The ureter is a tube that carries urine from the kidney to the bladder and is not part of the nephron.

2. Osmoregulation involves:

A) active transport

B) diffusion

C) facilitated diffusion

D) osmosis

Answer: D) osmosis

Explanation: Osmoregulation is the active regulation of the osmotic pressure of bodily fluids to maintain homeostasis of the body's water content and electrolyte balance. It primarily involves osmosis, the movement of water across a semi-permeable membrane from an area of higher water potential to lower water potential. While active transport is involved in moving ions to create osmotic gradients, osmosis is the direct mechanism of water movement.

3. Urine passes from bladder to the:

A) medulla

B) urethra

C) ureter

D) cortex

Answer: B) urethra

Explanation: Urine flows from the kidneys through the ureters to the urinary bladder, where it is stored. When the bladder contracts during urination, urine passes out of the body through the urethra.

4. Where is urea produced?

A) urinary bladder

B) blood cells

C) kidney

D) liver

Answer: D) liver

Explanation: Urea is produced in the liver as a waste product of protein metabolism. The liver converts toxic ammonia (from the deamination of amino acids) into less toxic urea, which is then released into the bloodstream. The kidneys filter urea from the blood and excrete it in urine.

5. Which substance is present at a lower concentration in the renal artery than in the renal vein?

A) amino acid

B) carbon dioxide

C) glucose

D) urea

Answer: D) urea

Explanation: The renal artery brings blood to the kidney for filtration, and the renal vein carries filtered blood away. Since the kidney's function is to remove waste products like urea from the blood, the concentration of urea is lower in the renal vein (leaving the kidney) than in the renal artery (entering the kidney). Carbon dioxide concentration would be higher in the renal vein due to cellular respiration in kidney cells.

6. In a kidney machine what must be at the same concentration in the dialysis fluid and in the blood?

A) glucose and salts

B) protein

C) urea

D) water

Answer: A) glucose and salts

Explanation: In a kidney dialysis machine, the dialysis fluid (dialysate) must have the same concentration of essential substances like glucose and salts as the normal blood. This prevents the net loss or gain of these vital substances. The fluid has little or no urea, creating a concentration gradient that allows urea to diffuse out of the blood.

7. The four structures listed are part of the human excretory system.

1. bladder 2. kidney 3. ureter 4. urethra In order which does a molecule of urea pass through these structures? | | First | [source symbol unavailable] | Last | |---|---|---|---| | A) | 1 | 2 | 3 | 4 | | B) | 1 | 4 | 3 | 2 | | C) | 2 | 1 | 3 | 4 | | D) | 2 | 3 | 1 | 4 |

Answer: D) 2 [source symbol unavailable] 3 [source symbol unavailable] 1 [source symbol unavailable] 4

Explanation: The correct pathway is: Kidney (2) [source symbol unavailable] Ureter (3) [source symbol unavailable] Bladder (1) [source symbol unavailable] Urethra (4).

8. In a kidney machine, which of the following passes from the blood to the dialysis fluid?

A) glucose

B) plasma protein

C) red blood cells

D) urea

Answer: D) urea

Explanation: The dialysis membrane is permeable to small molecules like urea but impermeable to large molecules like plasma proteins and cells like red blood cells. Since the dialysis fluid contains no urea, urea diffuses from the blood into the fluid down its concentration gradient.

9. Which blood vessel carries blood with the lowest concentration of urea?

A) hepatic portal vein

B) pulmonary vein

C) renal vein

D) vena cava

Answer: C) renal vein

Explanation: The renal vein carries blood away from the kidney after it has been filtered. Since urea has been removed, the blood in the renal vein has the lowest concentration of urea compared to the renal artery and other veins in the body.

10. Lithotripsy is a procedure that breaks large kidney stones into smaller ones by using:

A) X-rays

B) microwaves

C) sound waves

D) ultraviolet rays

Answer: C) sound waves

Explanation: Lithotripsy is a medical procedure that uses high-energy shock waves (sound waves) to break kidney stones into tiny pieces that can be passed out of the body in urine.

11. Which row shows substances that are present in each of the structures of excretory system of a healthy human?

Answer: A (Renal artery: glucose, Renal vein: glucose, Ureter: salts, Urinary bladder: urea)

Explanation: Glucose is present in the renal artery and is normally completely reabsorbed, so it is also present in the renal vein. The ureter carries urine, which contains salts and urea. The urinary bladder stores urine, which contains urea. Protein should not be present in urine.

12. The filtration of waste takes place inside the kidneys in:

A) ureter

B) urethra

C) urinary bladder

D) nephron

Answer: D) nephron

Explanation: The nephron is the functional unit of the kidney where the entire process of urine formation, including filtration of waste from the blood, occurs. The renal corpuscle (glomerulus and Bowman's capsule) is the specific site of filtration.

13. The function of glomerulus and Bowman's capsule of the nephron is to

A) reabsorb water into the blood

B) eliminate ammonia from the body

C) reabsorb salts and amino acids

D) filter the blood and capture the filtrate

Answer: D) filter the blood and capture the filtrate

Explanation: The glomerulus and Bowman's capsule together form the renal corpuscle. Blood is filtered under pressure in the glomerulus, and the filtrate is collected in Bowman's capsule. Reabsorption of water, salts, and amino acids occurs in the tubules.

14. Evidence for glomerular filtration in the kidney could be obtained by comparing the sizes of the molecules present in Bowman's capsule with those in the

A) afferent blood vessel

B) collecting duct

C) loop of Henle

D) proximal tubule

Answer: A) afferent blood vessel

Explanation: By comparing the composition of blood in the afferent arteriole (which brings blood to the glomerulus) with the filtrate in Bowman's capsule, one can demonstrate that large molecules like proteins and cells are retained in the blood while small molecules pass into the capsule.

1. What is the role of urinary system in the body?

Answer: The urinary system plays a vital role in maintaining homeostasis. Its main functions are:

1. Excretion: Removal of metabolic waste products like urea, creatinine, and uric acid.

2. Regulation of Water Balance (Osmoregulation): Adjusting water excretion to maintain proper blood volume and pressure.

3. Regulation of Electrolyte Balance: Controlling levels of sodium, potassium, calcium, and phosphate.

4. Regulation of Blood pH: Excreting hydrogen ions and reabsorbing bicarbonate.

5. Regulation of Blood Pressure: Via the renin-angiotensin-aldosterone system.

6. Hormone Production: Secreting erythropoietin (RBC production) and calcitriol (vitamin D activation).

2. Name the structures of urinary system.

Answer: The structures of the urinary system are:

1. Kidneys (2): The primary organs that filter blood and form urine.

2. Ureters (2): Muscular tubes that carry urine from the kidneys to the bladder.

3. Urinary Bladder: A sac that stores urine temporarily.

4. Urethra: A tube that carries urine from the bladder to the outside of the body.

3. Write the functions of: kidney, ureter, urinary bladder, urethra, pelvis of kidney, capsule of kidney, dialysis.

Answer:

Kidney: Filters blood to remove waste, regulates water and electrolyte balance, and produces hormones. Ureter: Transports urine from the kidney to the urinary bladder via peristalsis. Urinary Bladder: Stores urine until it is expelled from the body. Urethra: Carries urine from the bladder to the exterior. Pelvis of Kidney: A funnel-shaped cavity that collects urine from the collecting ducts and channels it into the ureter. Capsule of Kidney: A tough, fibrous outer covering that protects the kidney. Dialysis: A medical procedure that artificially removes waste products and excess fluid from the blood when the kidneys fail.

4. What materials are returned to the blood?

Answer: During the process of urine formation, useful materials are reabsorbed from the filtrate back into the blood:

Water: Mostly reabsorbed in the proximal convoluted tubule and collecting duct. Glucose: Completely reabsorbed in the proximal convoluted tubule. Amino Acids: Completely reabsorbed in the proximal convoluted tubule. Salts (Ions): Sodium, potassium, chloride, calcium, etc., are reabsorbed. Vitamins: Reabsorbed.

5. What materials leave the body in urine?

Answer: The materials that leave the body in urine include:

Urea: The primary nitrogenous waste. Creatinine: A waste product from muscle metabolism. Uric Acid: A waste product from nucleic acid metabolism. Excess Water: To maintain water balance.

Excess Salts/Ions: Sodium, potassium, chloride, etc. Pigments: Urochrome (gives urine its yellow color). Toxins and Drugs: Metabolites of various substances.

6. Name the disorders of kidney.

Answer: Disorders of the kidney include:

Kidney Stones (Renal Calculi): Hard deposits of minerals and salts. Kidney Failure (Renal Failure): Loss of kidney function (acute or chronic). Glomerulonephritis: Inflammation of the glomeruli. Polycystic Kidney Disease: Genetic disorder with multiple cysts. Urinary Tract Infections (UTIs): Infections of the urinary system. Nephrotic Syndrome: Damage to the glomeruli causing protein leakage.

7. Write the causes of formation of kidney stone.

Answer: Kidney stones form due to:

Dehydration: Low water intake leads to concentrated urine. Diet: High intake of oxalate (spinach, nuts), calcium, or animal protein. Medical Conditions: Hyperparathyroidism, gout, UTIs. Medications: Some diuretics and calcium supplements. Genetics: Family history. Obesity: Increased risk.

8. Name the structures in the urinary system of man that is associated with each of these:

a. Urea formation

Answer: Liver (not part of the urinary system but produces urea).

b. Urine formation

Answer: Nephron (in the kidney).

c. Filtration

Answer: Glomerulus and Bowman's capsule.

d. Re-absorption

Answer: Proximal convoluted tubule, Loop of Henle, Distal convoluted tubule. e. Tubular secretion

Answer: Distal convoluted tubule and collecting duct. f. Temporary storage of urine

Answer: Urinary bladder. g. Conduction of urine out of the body

Answer: Urethra.

9. The given diagram shows the structure of a human nephron. Trace the pathway of blood with the help of arrows ([source symbol unavailable]) in the given diagram. (Note: Do NOT show pathway of the filtrate.)

(Diagram of a nephron)

Answer: (Diagram Description with Arrows)

Afferent Arteriole [source symbol unavailable] Glomerulus: Arrow from the afferent arteriole into the glomerulus. Glomerulus [source symbol unavailable] Efferent Arteriole: Arrow from the glomerulus out through the efferent arteriole. Efferent Arteriole [source symbol unavailable] Peritubular Capillaries: Arrows showing the efferent arteriole branching into the peritubular capillary network surrounding the tubules. Peritubular Capillaries [source symbol unavailable] Renal Vein: Arrow from the capillaries into the renal vein.

10. Describe the kidney transplant.

Answer: A kidney transplant is a surgical procedure to place a healthy kidney from a donor into a person with end-stage kidney failure. The donor kidney is usually placed in the recipient's lower abdomen. The renal artery and vein of the donor kidney are connected to the recipient's iliac artery and vein. The ureter is connected to the bladder. The recipient must take immunosuppressive drugs for life to prevent rejection.

11. What is kidney failure and dialysis?

Answer:

Kidney Failure: The loss of the kidneys' ability to filter waste and excess fluid from the blood. It can be acute (sudden) or chronic (gradual). It leads to the accumulation of toxins in the body. Dialysis: A medical procedure that replaces the filtering function of the kidneys. It removes waste products (like urea) and excess fluid from the blood using a dialysis machine (hemodialysis) or the peritoneal membrane (peritoneal dialysis).

1. Describe human urinary system.

Answer: The human urinary system consists of the kidneys, ureters, urinary bladder, and urethra.

1. Kidneys:

Paired, bean-shaped organs located in the posterior abdominal wall. The functional unit is the nephron, which filters blood and forms urine. Functions: Excretion, osmoregulation, regulation of blood pressure, and hormone production.

2. Ureters:

Two muscular tubes that carry urine from the renal pelvis of each kidney to the urinary bladder. Urine is moved by peristalsis.

3. Urinary Bladder:

A hollow, muscular sac that stores urine temporarily. It expands as it fills and contracts during urination.

4. Urethra:

A tube that carries urine from the bladder to the outside of the body. In males, it is longer and also carries semen. In females, it is shorter and only carries urine.

In summary, the urinary system is designed to remove waste, regulate water and electrolyte balance, and maintain homeostasis.

2. Relate the structure of the kidney with its function.

Answer: The structure of the kidney is highly adapted to its function of filtering blood and forming urine.

1. Renal Cortex:

Structure: Outer region containing renal corpuscles (glomerulus and Bowman's capsule) and convoluted tubules. Function: Site of filtration and initial reabsorption.

2. Renal Medulla:

Structure: Inner region containing loops of Henle and collecting ducts arranged in pyramids. Function: Concentration of urine through the countercurrent multiplier mechanism.

3. Renal Pelvis:

Structure: Funnel-shaped cavity. Function: Collects urine and channels it into the ureter.

4. Nephron:

Structure: Functional unit with a renal corpuscle and tubule. Function: Filtration, reabsorption, and secretion.

In summary, each part of the kidney is specialized for a specific step in urine formation.

3. Describe the structure of nephron.

Answer: The nephron is the functional unit of the kidney. Each kidney contains about 1 million nephrons.

Structure:

1. Renal Corpuscle:

Glomerulus: A network of capillaries. Bowman's Capsule: A cup-shaped structure surrounding the glomerulus.

2. Renal Tubule:

Proximal Convoluted Tubule (PCT): Coiled tube in the cortex. Loop of Henle: U-shaped tube extending into the medulla. Distal Convoluted Tubule (DCT): Coiled tube in the cortex. Collecting Duct: Carries urine to the renal pelvis.

Function: The nephron filters blood, reabsorbs useful substances, and secretes waste to form urine.

4. Explain the process of urine formation in human.

Answer: Urine formation involves three main processes:

1. Glomerular Filtration:

Blood enters the glomerulus under high pressure. Water, ions, glucose, amino acids, and waste products are filtered into Bowman's capsule. Blood cells and large proteins remain in the blood.

2. Tubular Reabsorption:

As the filtrate flows through the tubules, useful substances are reabsorbed into the blood.

PCT: Reabsorbs most water, glucose, amino acids, and ions. Loop of Henle: Reabsorbs water and salts. DCT: Reabsorbs ions and water (under hormonal control). Collecting Duct: Reabsorbs water (under ADH control).

3. Tubular Secretion:

Substances are secreted from the blood into the tubular fluid. H⁺ and K⁺ are secreted to regulate pH and electrolyte balance. Ammonia and drugs are secreted.

In summary, urine formation involves filtration, reabsorption, and secretion.

5. Describe the osmoregulatory function of kidney.

Answer: The kidney plays a crucial role in osmoregulation, maintaining the body's water and electrolyte balance.

1. Regulation of Water Balance:

Antidiuretic Hormone (ADH): When blood osmolarity increases (dehydration), the posterior pituitary releases ADH. ADH increases the permeability of the collecting duct to water, causing more water to be reabsorbed and producing concentrated urine. When blood osmolarity decreases (overhydration), ADH secretion is inhibited, less water is reabsorbed, and dilute urine is produced.

2. Regulation of Electrolyte Balance:

Aldosterone: Regulates sodium reabsorption and potassium secretion in the DCT and collecting duct.

Atrial Natriuretic Peptide (ANP): Promotes sodium excretion.

3. Maintenance of Blood pH:

Kidneys excrete H⁺ ions and reabsorb bicarbonate (HCO₃⁻) to maintain blood pH.

In summary, the kidney maintains osmotic balance by regulating water and electrolyte excretion.

6. Discuss the kidney stones and it's treatment.

Answer: Kidney Stones (Renal Calculi): Hard, crystalline deposits that form in the kidneys from minerals and salts in the urine.

Causes:

Dehydration, high oxalate/calcium diet, obesity, medical conditions (gout, hyperparathyroidism), genetics.

Symptoms:

Severe pain in the back and side, pain radiating to the groin, blood in urine, nausea, frequent urination.

Treatment:

Conservative: Drinking plenty of water, pain relievers, medications to help pass the stone. Extracorporeal Shock Wave Lithotripsy (ESWL): Uses shock waves to break stones into smaller pieces. Ureteroscopy: A scope is passed through the urethra to remove or break the stone. Percutaneous Nephrolithotomy (PCNL): Surgical removal of large stones through a small incision in the back.

In summary, kidney stones are a common and painful condition. Treatment depends on the size and type of stone.

7. Describe the following two types of Dialysis

a. Haemodialysis

Answer: Hemodialysis is a procedure where blood is pumped from the patient's body through a dialyzer (artificial kidney). The dialyzer contains a semipermeable membrane. Dialysate (a fluid with physiological concentrations of electrolytes) flows on the other side of the membrane. Waste products diffuse from the blood into the dialysate. The cleaned blood is returned to the body. It usually takes 3-4 hours, three times a week.

b. Peritoneal Dialysis

Answer: Peritoneal dialysis is a procedure where dialysate is introduced into the peritoneal cavity (abdomen) through a catheter. The peritoneum acts as a natural semipermeable membrane. Waste products diffuse from the blood into the dialysate. After a dwell time, the fluid is drained. It can be done at home, either continuously (CAPD) or automatically (APD).

8. Outline the causes of kidney failure and its treatment.

Answer: Causes of Kidney Failure:

Acute Kidney Injury (AKI): Dehydration, severe infection, blood loss, medication, obstruction. Chronic Kidney Disease (CKD): Diabetes, hypertension, glomerulonephritis, polycystic kidney disease.

Treatment:

Dialysis: Hemodialysis or peritoneal dialysis. Kidney Transplant: Surgical replacement of the failed kidney with a healthy donor kidney. Medications: To control blood pressure, blood sugar, and electrolyte imbalances. Dietary Changes: Low protein, low salt, and fluid restriction.

In summary, kidney failure is a serious condition requiring dialysis or transplantation for survival.