Kidney 2 Flashcards
(17 cards)
What factors affect the composition, amount, and colour of urine?
Diet, exercise, volume of liquids drunk, health, etc.
How much urine is produced daily?
Approximately 1.0 - 1.5 litres.
What is the final composition of urine?
About 96% of urine is water, 1.5% salts (mainly sodium chloride), 2% urea, and small quantities of uric acid, creatinine, ammonium ions, drugs, colourants, and preservatives.
How does urine move out of the kidneys?
Urine passes from the collecting ducts into the renal calyx, then into the renal pelvis, and is propelled along the ureters to the bladder by peristaltic movements.
What is the process of expelling urine from the bladder called?
Urination (or micturition).
What is the capacity of a fairly full bladder?
A fairly full bladder holds 200ml of urine but can hold more than double this.
What triggers the reflex action of urination?
The filling of the bladder triggers impulses from the autonomic nervous system (ANS) to stimulate bladder muscle contraction and internal sphincter relaxation.
How do molecules or ions move passively?
They move from areas of high concentration to areas of low concentration down a concentration gradient.
What is osmosis?
The movement of water from a high water potential to a lower water potential through a differentially permeable membrane.
What is a hypertonic solution?
A solution with a high concentration of solutes that decreases the number of free water molecules, lowering the water potential.
What is a hypotonic solution?
A solution with a lower concentration of solutes that does not decrease the number of free water molecules, increasing the water potential.
What is an isotonic solution?
A solution where both sides of a membrane have the same number of free water molecules.
What is the water potential of pure water?
The water potential of pure water is 0.
What happens when solutes are added to water?
The water potential is decreased, becoming negative.
How do molecules move actively?
They combine with a carrier molecule and may move against the concentration gradient, requiring energy.
What does aldosterone do?
Controls the concentrations of sodium ions in the body
What is aldosterone?
A steroid hormone produced by the adrenal glands that are situated at the top of the kidney
