L1c - Tissues & Systems (3) Flashcards
What are the functions of the renal system?
- Filtration of blood and removal of waste products (urine production)
- Calcitriol formation
- Erythropoietin production and release
- Ion level regulation & acid base balance
- Blood pressure regulation
- Gluconeogenesis
What are the primary anatomical structures of the renal system?
- Kidneys (2)
- Ureters (2)
- Urinary Bladder (1)
- Urethra (1)
Describe the shape of the kidney.
- Symmetrical
- Bean shaped
What is the approximate size and weight of the kidney?
- Same size as hand to second knuckle
- 100g
What is the hilum?
Point of connection for blood vessels, ureters and nerves.
Where are adrenal glands found?
On the superior pole
Describe the location of the kidneys.
- Found in the retroperitoneal space
- Posterior to the parietal peritoneum
- About the level of T12 to L3
What is unique about the location of the right kidney?
Right kidney is slightly lower due to size and position of liver
Describe the key anatomical features of the kidney.
- Outer renal cortex
- Inner renal medulla
Describe the flow of urine in the renal system.
Collecting ducts -> Minor calyx -> Major calyx -> Renal pelvis -> Ureter
What is the corticomedullary junction?
The boundary between the cortex and medulla
What is the purpose of the renal columns?
Separate structures of the renal medulla into renal pyramids
Describe calcitriol formation with reference to kidneys.
- Kidneys synthesise final enzyme pathway for calcitriol formation
- Calcitriol increases absorption of calcium from small intestine to increase blood Ca2+ concentration
Describe erythropoietin production and release with reference to kidneys.
- As blood passes through the kidneys, the kidney cells detect oxygen levels
- If low, EPO hormone is secreted
Describe ion level regulation & acid-base balance with reference to kidneys.
- Secretion and resorption of ions through walls of nephrons (kidney cells) help control inorganic ion balance (Na+, K+, Ca2+, PO43-)
- Same for acid-base (altering levels of H+, HCO3-)
Describe gluconeogenesis with reference to kidneys.
During periods of extreme fasting / starvation, kidneys may help to maintain blood sugar levels by producing glucose from non-carbohydrate sources
What is a nephron?
Functional filtration unit
What are the 2 main structures of kidneys?
- Renal Corpuscle (glomerulus and glomerular capsule)
- Renal Tubule (proximal convoluted tubule, nephron loop, distal convoluted tubule)
How is blood filtered in the kidneys?
- Blood is filtered through glomerular walls into capsule and drains into the renal tubule
- Specialised absorption and secretion mechanisms occur at specific points along the tubule to ensure that balance is maintained and essential products are not lost to the urine
Describe the 2 types of nephrons.
- Cortical (80-85%)
- Juxtamedullary (15-20%):
Longer loops, allow formation of a salt concentration gradient in interstitial space outside the nephron loop, collecting tubules and collecting ducts; responsible for concentrating urine (regulated by ADH)
How is urine formed?
- Filtration
- Tubular reabsorption
- Secretion
What happens when loop diuretics alter the slat gradient?
Less fluid is pulled back into the interstitial fluid, and more remains in the urine
Describe what happens to glucose in the renal system.
- Freely filtered
- Usually completely reabsorbed by the proximal convoluted tubule (specific transporters)
- Certain maximum that can be reabsorbed per unit time, so if levels in the filtrate exceed capacity for reabsorption, glucose will be detected in the urine
What do diuretic drugs do?
- Increase excretion of urine
- Mobilise fluids
- A common treatment for hypertension