HSS 390 Ch. 24 Urinary System

What are the components of the urinary system?

• Kidneys (2)

• Ureters (2)

• Bladder (1)

• Urethra (1)

What are the functions of the kidneys?

• Regulates blood volume & pressure (eliminating/conserving Na+ and H₂O)

• Regulates composition of the blood plasma (filtration, secretion of wastes)

• Regulates blood pH (secretes H+, reabsorbs & produces HCO3-)

• Endocrine functions (secretes renin & EPO, activates vit. D [calcitriol])

Erythropoietin (EPO)

Hormone secreted when the kidneys detect hypoxemia (low blood oxygen)

• EPO is released into the blood and targets the red bone marrow

• Stimulates production of erythrocytes (RBCs)

• Increased RBC count → increased time RBCs are oxygenated → increased blood oxygen levels

A kidney is divided into an outer renal _____ and an inner renal _____.

cortex; medulla

Renal columns

Extensions of renal cortex that project into the medulla and subdivide it into renal/medullary pyramids

Lobe of kidney

Consists of a renal pyramid and cortical tissue immediately surrounding the pyramid

Renal papilla

Located at the tip of a renal pyramid; urine drains out of the papilla

Minor calyx

Funnel-shaped structure that “catches” urine drained out of the renal papilla called the minor calyx

Major calyx

Formed by the fusing of several minor calyces

Renal pelvis

Formed by the fusion of the major calyces; collects urine and transports it to the ureter

Nephron

The microscopic functional filtration unit of the kidney; consists of a renal corpuscle and a renal tubule

Renal corpuscle

Part of a nephron that filters the blood plasma and collects the filtrate; composed of…

• Glomerulus

• Glomerular (Bowman’s) capsule

Glomerulus

Part of the renal corpuscle — a thick tangle of fenestrated capillaries that filters the blood plasma for purposes of urine formation

Glomerular (Bowman’s) capsule

Part of the renal corpuscle — an epithelial capsule surrounding the glomerulus; made of two layers separated by capsular space…

• A permeable visceral layer (inner)

• An impermeable parietal layer that captures filtrate (outer)

Vascular pole of renal corpuscle

Where the afferent arteriole enters, and the efferent arteriole exits; location of blood flow into and out of corpuscle

Tubular pole of renal corpuscle

Where the proximal convoluted tubule (PCT) exits; location where filtrate moves into renal tubules

Renal tubule

Part of a nephron that is a long, coiled tube (duct) that converts the filtrate into urine; leads away from the glomerular capsule and ends at the renal papilla; consists of…

• Proximal convoluted tubule (PCT)

• Nephron loop (of Henle)

• Distal convoluted tubule (DCT)

• Collecting tubule → collecting duct (CD)

What are the parts of the cortical nephron?

The parts of the nephron in the renal cortex are…

• Renal corpuscle (glomerulus)

• Proximal convoluted tubule (PCT)

• Distal convoluted tubule (DCT)

What are the parts of the juxtamedullary neprhon?

The parts of the nephron in the renal medulla are…

• Nephron loop (of Henle)

• Collecting tubule → collecting duct

The kidneys receive about ___ L of blood/minute.

1.2

The kidneys receive about ___ percent of cardiac output every minute.

21

What is the path of blood through the kidneys?

• Entering: renal artery → segmental artery → interlobar artery → arcuate artery → interlobular artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries/vasa recta

• Exiting: interlobular vein → arcuate vein → interlobar vein → renal vein

Peritubular capillaries

Capillaries around the PCT and DCT in the cortex

• Exchange gases (O₂, CO₂), nutrients, and wastes with the kidney tissue

Vasa recta

Capillaries around the nephron loop in the medulla

• Exchange gases (O₂, CO₂), nutrients, and wastes with the kidney tissue