Practice Questions

Name the excretory structures found in most insects, such as cockroaches.

Define ammonotelism and name two types of animals that are ammonotelic.

Identify the two main components of the Malpighian body (renal corpuscle).

Define the condition known as uremia.

Describe the physical characteristics of normal human urine.

Recall the average amount of urea excreted per day by a healthy adult human.

List the three main processes involved in urine formation in the nephron.

Propose a reason why the glomerular capillaries have a much higher blood pressure than other capillary beds in the body.

Justify why Antidiuretic Hormone (ADH) is also called vasopressin.

An adult human excretes, on average, $25-30 \text{ gm}$ of urea per day. If a person excretes $1.25$ litres of urine in a day containing a total of $28 \text{ gm}$ of urea, calculate the concentration of urea in their urine in $\text{gm/L}$.

Examine how the lungs assist the kidneys in the process of excretion.

Justify the presence of podocytes with filtration slits in the Bowman's capsule, rather than a simple, flat epithelial layer.

Analyze the importance of the Columns of Bertini and the renal pelvis in the overall function of the human kidney.

Critique the classification of the liver as a secondary excretory organ. Is its role significant enough to warrant this title?

Describe the location and external features of the human kidneys.

Define Glomerular Filtration Rate (GFR) and state its approximate value in a healthy adult.

Analyze the functional differences between the nephridia found in earthworms and the Malpighian tubules found in insects, focusing on how they collect and process waste.

Propose how Atrial Natriuretic Factor (ANF) acts as a check on the renin-angiotensin-aldosterone system (RAAS).

A person has a GFR of $125 \text{ ml/minute}$ and a daily urine output of $1.5$ litres. Calculate the percentage of the filtrate that is reabsorbed and create an argument for why this high level of reabsorption is physiologically necessary.

Explain the structure of a nephron with its main parts.

Summarize the primary functions of the Proximal Convoluted Tubule (PCT).

Explain the process of micturition.

List and define three disorders of the excretory system mentioned in the text.

Compare and contrast the three major forms of nitrogenous wastes—ammonia, urea, and uric acid—based on their toxicity, water requirement for elimination, and the types of animals that excrete them.

Contrast the structure and primary functional roles of cortical nephrons and juxtamedullary nephrons in the human kidney.

Contrast the composition of the dialysing fluid used in hemodialysis with that of a uremic patient's blood plasma, and analyze how this difference facilitates the removal of waste.

Compare the permeability of the descending and ascending limbs of the Loop of Henle to water and electrolytes, and analyze how these differences contribute to the counter-current mechanism.

Demonstrate how the ADH (Antidiuretic Hormone) feedback mechanism helps a dehydrated person restore their body's fluid volume.

Compare the roles of the smooth muscles of the urinary bladder and the urethral sphincter during the micturition reflex.

A urine analysis for a patient reveals the presence of a significant amount of glucose, a condition known as glycosuria. Apply your knowledge of nephron function to explain the most likely physiological reason for this observation.

Propose a detailed physiological explanation for why terrestrial animals are generally ureotelic or uricotelic, but not ammonotelic.

Justify the statement: "The juxtaglomerular apparatus (JGA) functions as both a baroreceptor and a chemoreceptor."

Create a flowchart illustrating the complete sequence of events in the micturition reflex, starting from the filling of the urinary bladder.

A new drug is developed that selectively blocks the reabsorption of $Na^+$ ions in the distal convoluted tubule (DCT). Formulate a hypothesis on the drug's effect on blood pressure and urine volume, and justify your reasoning.

Evaluate the efficiency of Malpighian tubules in insects compared to nephrons in vertebrates for excretion and osmoregulation.

Calculate the total volume of filtrate reabsorbed by the renal tubules in a 24-hour period, assuming the glomerular filtration rate (GFR) is a constant $125 \text{ ml/minute}$ and the daily urine output is $1.5$ litres.

Explain the Renin-Angiotensin mechanism for the regulation of kidney function.

Analyze the immediate physiological consequences if a drug completely blocks the reabsorption of $\text{Na}^+$ ions in the Proximal Convoluted Tubule (PCT).

A patient has a condition where the osmolarity of their medullary interstitium cannot exceed $600 \text{ mOsmolL}^{-1}$ (normal is up to $1200 \text{ mOsmolL}^{-1}$). Analyze the effect this will have on their ability to regulate water balance.

A patient is diagnosed with kidney failure and exhibits symptoms of uremia. Formulate a dietary plan that would help manage their condition before transplantation, justifying your choices.

Analyze the complete sequence of events in the Renin-Angiotensin-Aldosterone System (RAAS) that is triggered by a fall in the glomerular filtration rate (GFR).

Evaluate the statement: "The counter-current mechanism is the single most important adaptation for producing hypertonic urine in mammals." Justify your evaluation by explaining its core components and their synergistic action.

Critique the design of an artificial kidney (dialysis machine) that uses pure, distilled water as the dialysing fluid. Identify potential life-threatening consequences for the patient.

Design a simple experiment to demonstrate that the ascending limb of the Henle's loop is impermeable to water but permeable to electrolytes.