Week 6 – The Urinary System

Question 1

What are the mechanisms underlying water and solute reabsorption from the renal tubules into the peritubular capillaries?

Answer 1

• Filtered fluid flows through the renal tubules, through the collecting ducts where tubule cells reabsorb about 99% of filtered water and many solutes.
• The water and solutes return to the blood as it flows through the peritubular capillaries

Question 2

How is sodium and water reabsorption regulated in the distal tubule and collecting duct?

Answer 2

regulated by hormones (extrinsic) including
1. * Angiotensin II → reabsorption of Na+ and water ↑ BP
1. * Aldosterone → ↑ secretion of K+ and reabsorption of Na+ → ↑ water reabsorption
1. * Antidiuretic hormone → ↑ facultative reabsorption of water
1. * Atrial natriuretic peptide → ↑ urine ↓ BP
1. * parathyroid → ↑ reabsorption of Ca2+

Question 3

How is urine concentration and volume regulated?

Answer 3

If ADH present large amounts of water are reabsorbed from tubular fluid into interstitial fluid ↑ the concentration of urine and ↓ concentration

Question 4

What is urine made up of?

Answer 4

Urine - 95% water, 5% solutes including
* Urea
* Creatinine

Question 5

Name at least three homeostatic imbalances that can be detected through urinalysis.

Answer 5

• albumin - ↑ lvls indicate ↑ permeability of filtration membranes
• glucose - diabetes
• RBC - → pathological condition
  inflammation of urinary organs
  kidney disease
  tumours
  contamination via menstrual blood
• Ketones - diabetes, starvation, too little carbs
• Billirubin & Urobilinogen

Question 6

When does the urinary system start to develop in the embryo?

Answer 6

5 weeks

Question 7

Name the three sets of kidneys that develop from the intermediate mesoderm.

Answer 7

1. pronephros
2. mesonephros
3. metanephros

Question 8

Describe how the urinary tract structures develop in the embryo

Answer 8

Metanephros develops from the ureteric bud and metanephric mesoderm
The uretic bud forms the
* Collecting ducts
* Calcyes
* Renal pelvis
* and ureter
The metanephic mesoderm forms the nephrons