Urinary System

Question 1

Describe the position of the kidneys and how they are protected

Answer 1

• Retroperitoneal - behind the peritoneum

- Protected by layers of fascia and firm renal fat

Question 2

Describe the structure of the kidney

Answer 2

Renal cortex
Renal column
Renal Pyramid in Renal Medulla
Renal Papilla (opening)
Minor calyx (pl calyces)
Major calyx
Renal pelvis
Ureter

Question 3

Function of the renal pyramids

Answer 3

They house the nephrons, which filtrate and reabsorb

Question 4

What does the nephron consist of?

Answer 4

Renal corpuscle (glomerulus)
Proximal convulated tubule (PCT)
Loop of Henlé
Distal convulated tubule (DCT)
Collecting duct

Question 5

Differentiate between the two types of nephrons

Answer 5

Juxtamedullary

• Receives 10% of renal supply
• Concentrates urine
• Its glomeruli are found in the inner cortical regions, and it has a long nephron loop
• Associated with vesa recta

Superficial

• Receives 90% of renal supply
• Reabsorbs large % of fluid that filters from vasculature
• Its glomeruli are found in the outer cortical regions, and it has a short nephron loop

Question 6

Position of Ureter and Urethra in male and female bodies

Answer 6

In females:
- Ureter passes posterior to the ovary, lateral to the cervix and vagina

In males:
- Urethra passes through the prostate and into penis

Question 7

What’s the name of the muscular wall of the bladder?

Answer 7

Detrusor muscle

Question 8

What epithelium lines the bladder?

Answer 8

Transitional

Question 9

What is the muscle of the bladder like?

Answer 9

Smooth and involuntary

Question 10

What division of nervous system controls the bladder?

Answer 10

Autonomic, PSNS;

The external sphincter around the urethra however is striated and is under voluntary control

Question 11

What is the blood supply/drainage of the bladder?

Answer 11

Common iliac artery
Internal iliac artery
Superior vesical artery
Inferior vesical artery

Question 12

Describe the filtration process

Answer 12

The glomerulos is compromised of capillaries with densely fenestrated walls
Hydrostatic pressure forces plasma through the filtration barrier, separating it from cells and proteins - these leave through the vasa recta
The leftover filtrate is then sent along the proximal convulated tubule

Question 13

What is the blood supply/drainage of the kidneys?

Answer 13

Renal artery and Renal veins

Question 14

List the processes of urine production

Answer 14

Filtration
Reabsorption
Secretion

Question 15

Describe the function of the kidney

Answer 15

Cleanses blood of metabolic end products, toxins, water, and ions

It is also an endocrine and homeostatic organ controlling blood pressure, tissue osmolality and electrolyte levels

Question 16

Describe the reabsorption process

Answer 16

Na+ ions are transported through the cuboidal epithelial cells by Na-K-ATPase through active/co-transport in PCT
Water passively flows out after Na+ by osmosis and is reabsorped because of the salty nature of the intestitial space
The remaining filtrate is full of urea, and runs back through the medulla - some urea is reabsorped and makes the intertitial space even more salty, allowing even more water to be reabsorped - urea then returns to the collecting duct and is finally released into the urethra

Secretion - sneaking out extra waste like potassium and hydrogen - wastes that have already made their way into the blood in the capillaries, ready to leave the kidneys

Question 17

Describe the process of micturition

Answer 17

Bladder stores urine until micturition

Valves prevent urinary reflux into the ureters

Inner and outer sphincters control outflow via the urethra

Inner sphincter (and bladder contraction) is controlled by spinal reflexes and the CNS

Outer sphincter is under voluntary control

Bladder filling stretches its muscular wall and initiates a spinal micturition reflex - the reflex causes PS motor efferents to stimular bladder contraction

Emptying is prevented by the CNS until the outer sphincter is relaxed voluntarily