chapter 26: urinary system

Organs of the Urinary System

The system includes two kidneys, two ureters, the urinary bladder, and the urethra

Primary functions of the Urinary System (3)

Regulating blood volume and blood pressure (via water loss/hormone release), regulating blood pH, and eliminating organic waste products

Basic functional unit of the kidney

The Nephron is the basic structural and functional unit of the kidney

Point of entry/exit for vessels in kidney

The Hilum is the entry point for the renal artery and nerves, and the exit point for the renal vein and ureter

Blood flow path to the Glomerulus

Renal artery → Interlobar arteries → Arcuate arteries → Cortical radiate arteries → Afferent arterioles → Glomerulus

Components of the Renal Corpuscle

The renal corpuscle (where blood is filtered) consists of the Glomerulus (capillary network) and the Glomerular Capsule (Bowman’s Capsule)

Driving force for renal filtration

Blood pressure is the driving force for renal filtration in the renal corpuscle

"Mass absorber" segment of the renal tubule

The Proximal Convoluted Tubule (PCT) is the segment where 70% of reabsorption occurs

Difference between Cortical and Juxtamedullary Nephrons

Cortical nephrons (85%) have loops that barely reach the medulla; Juxtamedullary nephrons (15%) have long loops that descend deep into the medulla, aiding in osmotic gradient maintenance

Lining tissue of the ureters

The ureters are lined by transitional epithelia (uroepithelia)

Muscle layer responsible for bladder contraction

The Detrusor muscle consists of three layers of smooth muscle lining the bladder

Sphincters regulating urination (and control)

Internal urethral sphincter (smooth muscle/involuntary) and External urethral sphincter (skeletal muscle/voluntary/somatic control)

Where are the kidneys located?

They are paired, bean-shaped organs that lie in the Retroperitoneal area (at the rear wall of the abdominal cavity)

What are the layers of connective tissue and fat that protect and stabilize the kidney (from innermost to outermost)?

the Renal Capsule(fibrous, direct covering), the Adipose Capsule (perirenal fat for cushioning), and the outermost Renal Fascia

What are the two main internal regions of the kidney tissue?

The outer Renal cortex (deep to the capsule) and the inner Renal medulla (deep to the cortex)

What distinct structures are found in the renal medulla that help define this region?

The Renal pyramids, which are distinct triangular structures

What components make up a Kidney Lobe?

A kidney lobe consists of a renal pyramid, the overlying area of the renal cortex, and the adjacent tissues of the columns

What is the blunt tip of the renal pyramid called?

The Renal papilla

What is the name for the internal cavity within the kidney?

The Renal sinus

What structures receive urine from the collecting ducts at the renal papilla?

The Minor calyces

How is a Major Calyx formed?

Two or three minor calyces combine to form a major calyx

Where do the major calyces combine, and where does urine travel next?

They combine at the Renal pelvis (a urine collecting funnel). The renal pelvis is continuous with the ureter, which transports urine toward the urinary bladder

What structures separate the adjacent renal pyramids?

Renal columns, which are extensions of cortical tissue extending into the medulla

Does the pathway for Blood Flow through the kidney equal the pathway for Urine Flow?

No, blood flow does not equal urine flow

Trace the flow of blood into the kidney (arterial side) starting from the Renal artery

Renal artery → Segmental arteries → Interlobar arteries → Arcuate arteries → Cortical radiate arteries (or interlobular arteries)

Trace the flow of urine (tubular fluid) starting at the Renal Corpuscle

The fluid flows through the Proximal convoluted tubule → Loop of Henle → Distal convoluted tubule → Collecting Duct → empties into the Minor calyx

What two main structures make up the Renal Corpuscle?

The Glomerulus (a capillary network) and the Glomerular Capsule (or Bowman's Capsule)

What layers make up the Glomerular Capsule?

The capsule is a double-walled structure consisting of the visceral layer and the capsular outer layer (parietal layer)

What specialized cells cover the Glomerulus capillaries?

Podocytes

Which renal tubule segment is located closest to the Glomerulus

The Proximal convoluted tubule (PCT)

Where is the Distal Convoluted Tubule (DCT) located relative to the glomerulus?

It is the last part of the renal tubule, located farther away from the renal corpuscle (glomerulus) than the proximal tubule

How are the kidneys positioned relative to each other?

The Right kidney is lower than the left kidney due to the liver

Which layer of the Glomerular Capsule is the visceral layer, and what cells form it?

The Visceral layer is the inner layer of the double-walled capsule, consisting of specialized cells called podocytes

Which layer of the Glomerular Capsule is the parietal layer?

The Parietal layer is the outer layer of the double-walled capsule

Which segment of the Loop of Henle is located immediately following the Proximal Convoluted Tubule (closer to the glomerulus)?

The Descending limb of the Loop of Henle

Which segment of the Loop of Henle is characterized as having a thick segment and is farther away from the glomerulus?

The Ascending limb, which includes a thick segment, is located further from the glomerulus than the descending limb