The kidney 2 Flashcards
What occurs when isotonic fluid flows down the descending limb?
Becomes more concentrated
What happens when isotonic fluid flows up the ascending limb?
Becomes less concentrated
How can the collecting duct concentrate urine?
When an osmotic gradient has been established between each limb
When can water be reabsorbed?
Osmotic gradient and tubule is permeable to water
When are the tubules permeable to water?
In the presence of vasopressin
Where is vasopressin produced?
Hypothalamus
What is vasopressin?
Hormone that is stored in the posterior pituitary gland and secreted into the blood stream
How is osmolarity of fluid detected?
Osmoreceptors in the hypothalamus
When is vasopressin released, triggering thirst?
Increased osmolarity
When is vasopressin inhibited, suspending thirst?
Decreased osmolarity
Why are collecting tubules in hairpin shapes?
To prevent NaCl and water permeability of capillary walls and avoiding destruction of osmotic gradient
What are the 3 classes of urine?
Normal=isotonic
Over hydration=hypotonic
Dehydration=hypertonic
What controls the exit of urine from the bladder?
Internal and external urethral sphincters
What is Na+ reabsorption controlled by?
Proximal tubule, loop of Henle and distal tubule (hormonal control)
What occurs when sodium load is high?
Extra water is held in extra cellular fluid causes an increase in kidney volume