Urinary System

Question 1

Ureters

Answer 1

Paired tubes that convey urine from the kidneys to the bladder (via peristalsis)

Question 2

Urinary Bladder

Answer 2

Muscular pouch that stores urine

Question 3

Urethra

Answer 3

Tube that conveys urine out the body

Question 4

Kidney: Gross Anatomy

Answer 4

• Location: High in the abdominal cavity, retroperitoneal
• Vascular Supply: Renal arteries (from aorta) and renal veins (to inferior vena cava)
• Renal Capsule: Protective layer, made of tough connective tissue

Question 5

Kidney: Gross Anatomy

Answer 5

• Renal Cortex: “Bark”, outer kidney layer
• Renal columns: Portions of renal cortex that invade the medulla, found between pyramids
• Renal Medulla: “Middle”, inner kidney layer

Question 6

Renal Pyramids

Answer 6

Pyramidal structures in the medulla that produce urine

Question 7

Renal Papilla

Answer 7

Tip of the renal pyramid, allow droplets of urine to enter the calyces

Question 8

Minor & Major Calyces

Answer 8

“Funnels” that capture urine from renal papillae

Question 9

Renal Pelvis

Answer 9

Collects urine to deliver to the ureters

Question 10

Renal Corpuscle

Answer 10

Glomerulus and Bowman’s Capsule

Question 11

Glomerulus

Answer 11

Tufts of fenestrated capillary beds (to filter blood)

Question 12

Bowmans Capsule

Answer 12

Capsules around glomeruli that capture filtrate

Question 13

Proximal Convoluted Tubule

Answer 13

• PCT takes filtrate from Bowman’s capsule and performs tubular reabsorption
• Reabsorbs essential nutrients and electrolytes back into the bloodstream via peritubular
  capillaries

Question 14

Nephron Loop/ Loop of Henle

Answer 14

• Important for concentrating urine (vasa recta blood vessels parallel it)
• Descending Limb: Thin segment, reabsorbs water ONLY
• Ascending Limb: Thick segment, reabsorbs salts ONLY

Question 15

Distal Convoluted Tubule

Answer 15

(DCT)performs tubular secretion in order to mix products in with urine

Question 16

Collecting Duct

Answer 16

Tube that conveys urine to the renal papilla, and if necessary, can further concentrate
urine

Question 17

Filtration

Answer 17

• Performed by: Renal Corpuscle
• Blood is filtered through a filtration membrane that excludes by size.
• Filtrate will contain anything small enough to fit through the filtration membrane.
• Filtrate is a combination of waste products, nutrients and electrolytes.
• Entire cells & large molecules stay in the bloodstream.

Question 18

Countercurrent Multiplier:

Answer 18

Loop of Henle (because osmotic pressure causes it to concentrate
urine)

Question 19

Countercurrent Exchanger:

Answer 19

Vasa recta (because substances enter and leave these blood
vessels)

Question 20

Maintaining GFR: Autoregulation

Answer 20

• When systemic BP is low, afferent arteriole dilates to increase GFR
• When systemic BP is high, afferent arterioles constrict to decrease GFR
• Result: GFR is maintained, and kidneys continually filter blood

Question 21

Blood Pressure Control: The JGA

Answer 21

• What is it? Juxtaglomerular Apparatus – Cluster of cells located near the
  glomerulus that are responsible for controlling BP
• Granular Cells: Sense pressure. When BP is low, granular cells secrete the enzyme renin.
• Macula Densa Cells: Sense [salt] When urine is dilute, macula densa cells trigger afferent arteriole dilation + granular cell renin secretion
• Mesangial Cells: Allow granular cells & macula densa cells to communicate

Question 22

The Urinary Bladder

Answer 22

• Bladder mucosa: Transitional epithelium (for distension)
• Bladder muscularis: Detrusor muscle (contracts to squeeze urine out)

Question 23

The Urethra

Answer 23

Urethral Sphincter Muscles:
* Internal: Smooth muscle (involuntary)

• External: Skeletal muscle (voluntary)

Question 24

Micturition

Answer 24

• Definition: To urinate/ To void the bladder
• Bladder distension will: Trigger stretch receptors that report to the brain’s micturition
  center
• The brain’s micturition center will then cause the: Contraction of the detrusor muscle and
  relaxation of the external urethral sphincter.