Lecture 25- Chapter 25- Urinary System

Question 1

What is the function of the kidneys?

Answer 1

• Ensures long-term acid/base balance
• Excreting metabolic wastes, toxins, drugs
• Produces Erythropoietin (regulates RBC production)
• Activating vitamin D
• Carrying out gluconeogenesis

Question 2

What organs are part of the urinary system?

Answer 2

• KIdneys
• Uterers: transports urine from kidneys to urinary bladder
• Urinary bladder: temporary storage reservoir for urine
• Urethra: transports urine out of body

Question 3

Image of Urinary organs

Answer 3

Question 4

The inner kidney has three distinct regions. What are they?

Answer 4

1. Renal cortex: granular-appearing superficial region
2. Renal medulla: deep to cortex, composed of cone-shaped medullary (renal) pyramids
3. Renal pelvis

Question 5

Fill in the blank

**BLANK **are the structural and functional units that form urine.

Answer 5

Nephrons are the structural and functional units that form urine.

• There are more than one million per kidney
• Two main parts of the nephron are the Renal corpuscle and **Renal tubule **

Question 6

Image of the Renal corpuscle and Renal Tubule, that make up the nephron

Answer 6

Question 7

What are the two parts of the renal corpuscle?

Remember the renal corpuscle and renal tubule

Answer 7

1. Glomerulus : tuft of cappilaries composed of fenestrated endothelium.
   * Highly porous capillaries
   * Allows for effiecient filtrate (plasma-derived fluid that renal tubules process to form urine) formation
2. **Glomerular capsule **: also called Bowman’s capsule is a cup-shaped hollow structure surrounding glomerulus.

Question 8

The glomerular capsule consists of two layers. What are they?

Answer 8

1. Parietal layer: simple squamous epithelium
2. Visceral layer: clings to glomerular capillaries branching epithelial podocytes.

Question 9

BLANK is about 3 cm long and consists of single layer epithelial cells, but each region has its own unique histology and function

Answer 9

Renal tubule is about 3 cm long and consists of single layer of epithelial cells, but each region has its own unique histology and function.

If renal corpuscle consists of the glomerular capsule and glomerulus. Then the renal tubule consists of the Proximal convoluted tubule (PCT), Loop of henle, and DIstal convoluted tubule (DCT).

Question 10

Why does the proximal convoluted tubule (PCT) have cuboidal cells with dense microvilli that form the brush-border?

Answer 10

To increase the surface area of reabsorption and secretion.

Question 11

The nephron loop aka the loop of Henle is a U-shaped structure consisting of two limbs. What are the two limbs?

Answer 11

1. Descending limb (thinner)
2. Ascending limb (thicker)

Question 12

What is the function of the Distal convoluted tubule (DCT)?

Answer 12

Function in secretion and a little in reabsorption.

Question 13

What is the function of collecting ducts?

Answer 13

• To receive filtrate from many nephrons
• Runs through the medullary pyramids (Gives them their striped appearance)
• Ducts fuse together to deliver urine through papillae into minor calyces

Question 14

Two types of nephrons. What are they?

Answer 14

1. Cortical nephrons: make up 85% of nephrons.
   * Almost entirely in the cortex
2. Juxtamedullary nephrons: long nephron loops invade medulla.
   * Ascending limbs have thick AND thin sengments.
   * Important in production of concentrated urine

Question 15

Image of different types of nephrons

Answer 15

Question 16

Glomerulus has special capillaries that are fed and drained by arterioles. (No veins). Why does the glomerulus only have arterioles?

Answer 16

• The afferent arteriole is bigger than the efferent arteriole and this ensures that there is high hydrostatic pressure.
• High hydrostatic pressure results in more filtration

Afferent arterioles = blood entering; lower blood pressure than efferent arteriole because of bigger diameter
Efferent arterioles= blood exiting; higher blood pressure than afferent arteriole because of smaller diameter

Question 17

Three types of cells found in the juxtaglomerular complex. What are they?

Answer 17

1. Macula densa: has chemoreceptors that sense NaCl content of filtrate
2. Granular cells: has mechanoreceptors that sense blood pressure in afferent arteriole
3. Extraglomelular mesangial cells