Chapter 23: The Urinary System Study Guide

Comprehensive flashcards covering the anatomy, physiology, and pathology of the urinary system based on the provided study guide.

What are the six principal organs that make up the urinary system?

Two kidneys, two ureters, one urinary bladder, and one urethra.

How do male and female urinary tracts differ in terms of the urethra?

The male urethra is approximately $20\,cm$ long, serves both urinary and reproductive functions, and passes through the prostate. The female urethra is approximately $4\,cm$ long, serves only urinary functions, and does not pass through a prostate.

Beyond waste excretion, what are four other functions performed by the kidneys?

Regulating blood volume and blood pressure, regulating plasma ion concentrations ($Na^+$, $K^+$, $Ca^{2+}$), maintaining blood pH, and secreting erythropoietin.

What is the difference between waste and metabolic waste?

Waste is any substance needing elimination, while metabolic waste specifically refers to byproducts of cellular metabolism, such as urea, creatinine, and uric acid.

Which organs and processes are responsible for producing urea and uric acid?

The liver converts ammonia (from amino acid breakdown) into urea; uric acid arises from the catabolism of nucleic acids.

What is the scientific name for an elevated Blood Urea Nitrogen (BUN) level?

Azotemia.

What is uremia and how is it treated?

Uremia is the accumulation of urea and waste in the blood due to severe kidney dysfunction; it is treated with dialysis or kidney transplantation.

Describe the anatomical location of the kidneys using the term retroperitoneal.

The kidneys are located in the abdominal cavity between $T12-L3$ vertebrae and are retroperitoneal, meaning they are posterior to the peritoneum.

What are the three protective coverings of the kidney?

The renal capsule (fibrous capsule), adipose capsule (perirenal fat), and renal fascia (outer layer).

What is nephroptosis?

The downward displacement of the kidney, also known as "floating kidney," which is more common in thin individuals.

Which two regions of the frontal section of the kidney make up the renal parenchyma?

The renal cortex and the renal medulla.

What structures merge to form a major calyx?

Two or three minor calyces merge to form a major calyx.

Trace the pathway of blood from the renal artery to the glomerular capillaries.

Renal artery \rightarrow segmental arteries \rightarrow interlobar arteries \rightarrow arcuate arteries \rightarrow interlobular arteries \rightarrow afferent arterioles \rightarrow glomerular capillaries.

What blood vessels give rise to the peritubular capillaries and the vasa recta?

Efferent arterioles give rise to peritubular capillaries in cortical nephrons and vasa recta in juxtamedullary nephrons.

What are the two principal parts of a nephron?

The renal corpuscle (filters blood plasma) and the renal tubule (converts filtrate into urine).

What are the four regions of the renal tubule?

Proximal convoluted tubule (PCT), nephron loop (loop of Henle), distal convoluted tubule (DCT), and collecting duct.

Provide the complete flow of fluid from the glomerular capsule to the urethra.

Glomerular capsule \rightarrow PCT \rightarrow nephron loop \rightarrow DCT \rightarrow collecting duct \rightarrow papillary duct \rightarrow minor calyx \rightarrow major calyx \rightarrow renal pelvis \rightarrow ureter \rightarrow urinary bladder \rightarrow urethra.

What are the three barriers of the filtration membrane in the renal corpuscle?

1. Fenestrated endothelium of glomerular capillaries, 2. Basement membrane, 3. Podocytes with filtration slits.

How is Net Filtration Pressure (NFP) calculated?

$$NFP = BHP - (CHP + BCOP) = 55 - (15 + 30) = 10\,mmHg$$

What is the average amount of filtrate formed in 24 hours for males and females?

Males: approximately $180\,liters/day$; Females: approximately $150\,liters/day$.

How does the myogenic mechanism respond to increased arterial blood pressure?

The afferent arteriole constricts to reduce blood flow and maintain stable GFR.

What cell type releases renin and what is the stimulus?

Granular cells (juxtaglomerular cells) release renin in response to decreased blood pressure, decreased blood volume, or decreased sodium delivery.

What is the role of Angiotensin-Converting Enzyme (ACE) in the RAAS?

ACE, found in the lungs, converts angiotensin 1 into angiotensin 2.

What is solvent drag in the context of tubular reabsorption?

The process where solutes are carried along with water as it moves through the paracellular route.

What is transport maximum ($T_m$)?

The maximum rate of reabsorption; when exceeded, the substance (e.g., glucose) appears in the urine.

How does the permeability of the descending limb of the nephron loop differ from the ascending limb?

The descending limb is permeable to water but impermeable to salt; the ascending limb is permeable to salt but impermeable to water.

What pigment is responsible for the yellow color of urine and what is its origin?

Urochrome, which is produced from the breakdown of hemoglobin.

What are the ranges for urine specific gravity and pH?

Specific gravity: $1.001$ to $1.035$; pH range: $4.5$ to $8.0$ (average $6.0$).

Distinguish between diabetes mellitus and diabetes insipidus.

Diabetes mellitus is caused by insulin deficiency/resistance leading to glycosuria; diabetes insipidus is caused by ADH deficiency/resistance leading to dilute urine.

What are the three layers of the urinary bladder wall?

Outermost to innermost: 1. Adventitia/serosa, 2. Muscularis (detrusor muscle), 3. Mucosa (transitional epithelium).

What is the trigone?

A triangular region in the bladder formed by the openings of the two ureters and the internal urethral orifice.

How does the autonomic nervous system control the detrusor muscle and internal urethral sphincter during micturition?

Parasympathetic nerves contract the detrusor muscle and relax the internal urethral sphincter to promote urination.