Chapter 23: Urinary System Flashcards

This set of 200 flashcards covers the anatomy, physiology, and pathology of the urinary system based on Chapter 23 lecture notes.

What are the six principal organs of the urinary system?

Two kidneys, two ureters, the urinary bladder, and the urethra

How is 'waste' defined in the context of the urinary system?

Any substance that is useless to the body or present in excess of the body’s needs

What is metabolic waste?

A waste substance produced by the body

Which group of wastes are considered among the most toxic to the body?

Nitrogenous wastes

From what metabolic process is urea derived?

Amino acid (protein) catabolism

What is the product of nucleic acid catabolism?

Uric acid

What is creatinine a product of?

Creatine phosphate catabolism

What is the kidney's role regarding toxic metabolic wastes?

They filter blood and remove them

What aspects of blood do the kidneys regulate besides volume and pressure?

Osmolarity

What two balances do the kidneys regulate?

Electrolytes and acid–base balance

Which hormone do the kidneys secrete to stimulate red blood cell production?

Erythropoietin

How do kidneys handle hormones in the blood?

They clear them from the blood

The kidneys help detoxify which specific particles?

Free radicals

During starvation, how do kidneys synthesize glucose?

From amino acids

What is the granular-appearing outer region of the kidney?

Renal cortex

What region is deep to the renal cortex?

Renal medulla

What is the shape of medullary (renal) pyramids?

Cone-shaped

What is the name for the tip of a medullary pyramid?

Papilla

What structures separate the renal pyramids?

Renal columns

Of what are renal columns composed?

Inward extensions of cortical tissue

What components make up a kidney lobe?

A medullary pyramid and its surrounding cortical tissue

Approximately how many lobes are found in each kidney?

About eight lobes

What is the 'little cup' that surrounds the papilla and collects urine?

Minor calyx

What structure is formed by the convergence of 2 or 3 minor calyces?

Major calyx

What structure is formed by the convergence of 2 or 3 major calyces?

Renal pelvis

What is the tubular continuation of the renal pelvis?

Ureter

Trace the flow of urine from the pyramid to the bladder.

Renal pyramid $\rightarrow$ minor calyx $\rightarrow$ major calyx $\rightarrow$ renal pelvis $\rightarrow$ ureter

What percentage of cardiac output is received by the kidneys?

About $21\%$

What is the primary purpose of the rich blood supply to the kidneys?

Waste removal

In renal circulation, where does blood flow after the renal artery?

Segmental arteries

In renal circulation, where does blood flow after the segmental arteries?

Interlobar arteries

In renal circulation, where does blood flow after the interlobar arteries?

Arcuate arteries

What is another name for the cortical radiate arteries?

Interlobular arteries

In renal circulation, where does blood flow after the arcuate arteries?

Cortical radiate (interlobular) arteries

Which vessel leads blood into the glomerulus?

Afferent arterioles

Which vessel leads blood away from the glomerulus?

Efferent arterioles

What are the structural and functional units of the kidney?

Nephrons

Approximately how many nephrons are in each kidney?

About $1.2$ million

What are the two principal parts of a nephron?

Renal corpuscle and renal tubule

What is the primary function of the renal corpuscle?

Filters the blood plasma

What is the function of the renal tubule?

A long, coiled tube that converts the filtrate into urine

What identifies the glomerular capsule alias?

Bowman’s capsule

Which part of the renal corpuscle is a capillary network where blood is filtered?

Glomerulus

Which tube is closest to the renal corpuscle?

Proximal convoluted tubule

What are the two limbs of the nephron loop?

Descending limb and ascending limb

What is another name for the nephron loop?

Loop of Henle

Which part of the renal tubule is farthest from the renal corpuscle?

Distal convoluted tubule

Where does the distal convoluted tubule drain?

Collecting ducts

What gives renal pyramids their striped appearance?

Collecting ducts

What type of nephron has loops that dip only a short way into the medulla or none at all?

Cortical nephrons

Which type of nephron represents the majority in the kidney?

Cortical nephrons

What type of nephron is located close to the medulla and has very long loops?

Juxtamedullary nephrons

What percentage of nephrons are juxtamedullary?

Only $15\%$

What is the primary importance of juxtamedullary nephrons?

Production of concentrated urine

Which capillaries arise from efferent arterioles and wrap around renal tubules in the cortex?

Peritubular capillaries

Into which vessels do peritubular capillaries empty?

Venules

Which vessels arise from efferent arterioles serving juxtamedullary nephrons?

Vasa recta

What is the function of the vasa recta?

Formation of concentrated urine

What structure empties urine directly into the renal pelvis?

Major calyx

What are the two components of the renal corpuscle?

Glomerulus and glomerular capsule

Which type of nephron is essential for producing concentrated urine?

Juxtamedullary nephrons

What is the name of the fluid in the capsular space?

Glomerular filtrate

How does glomerular filtrate differ from blood plasma?

It has almost no protein

From which structure to which structure is the fluid called 'tubular fluid'?

From the proximal convoluted tubule through the distal convoluted tubule

Where is the fluid first officially called 'urine'?

Within the collecting duct and beyond

How many liters of blood are processed by the kidneys daily?

$$180\,L$$

How many liters of urine are typically formed daily?

$1$ to $2\,L$

What is the first stage of kidney conversion of plasma to urine?

Glomerular filtration

What is the second stage of kidney conversion of plasma to urine?

Tubular reabsorption

What is the third stage of kidney conversion of plasma to urine?

Tubular secretion

What is the fourth stage of kidney conversion of plasma to urine?

Water conservation

What process returns $99\%$ of substances from filtrate back to the blood?

Tubular reabsorption

What process moves substances from blood to filtrate in renal tubules?

Tubular secretion

What occurs during water conservation in the kidneys?

Removal of water from urine in collecting ducts and returning it to blood

Name seven solutes that pass from the blood into the capsular space.

Water, electrolytes, glucose, fatty acids, amino acids, nitrogenous wastes, and vitamins

In a healthy kidney, what two blood components do not pass through the filtration membrane?

Blood cells and proteins

What are the three components of the filtration membrane?

Fenestrated endothelium of the capillary, basement membrane, and filtration slits

What feature of the fenestrated endothelium allows small substances to pass?

Large filtration pores

What is the electrical charge of the basement membrane in the filtration membrane?

Negatively charged

Why does the basement membrane repel certain proteins?

Because it and the proteins are both negatively charged

What are podocytes?

Foot processes that wrap around the capillaries and form filtration slits

Where are filtration slits located?

Between the podocyte foot processes

What is the electrical charge of the filtration slits?

Negatively charged

Where is reabsorbed fluid ultimately taken up?

Peritubular capillaries

Which part of the renal tubule is the site of bulk reabsorption?

Proximal convoluted tubule

In the PCT, what percentage of water and electrolytes (NaCl) are reabsorbed?

$$65\%$$

What is obligatory water reabsorption?

Reabsorption where aquaporins are always present, specifically in the PCT

Which nutrient types are completely reabsorbed in the proximal convoluted tubule?

All nutrients, such as glucose and amino acids

How much urea is typically reabsorbed in the PCT before being later secreted back?

About half

In the nephron loop, what is the permeability rule for the descending limb?

$H_2O$ can leave, but solutes cannot

In the nephron loop, what is the permeability rule for the ascending limb?

$H_2O$ cannot leave, but solutes can

Which part of the nephron loop lacks aquaporin channels?

Ascending limb

Which three ions are reabsorbed in the ascending limb of the nephron loop?

$Na^+$, $K^+$, and $Cl^-$

Where in the nephron is reabsorption hormonally regulated?

Distal convoluted tubule and collecting duct

What gland releases Antidiuretic hormone (ADH)?

Posterior pituitary

What is the cellular effect of ADH on the collecting ducts?

It causes cells to insert aquaporins

How does ADH affect water reabsorption?

It increases water reabsorption

What is facultative water absorption?

Water reabsorption where aquaporins are inserted in the collecting duct only if ADH is present

What hormone fine-tunes reabsorption of remaining sodium ($Na^+$)?

Aldosterone

What parts of the nephron does aldosterone target?

Collecting ducts and distal DCT