The Excretory System. By Duncan, Liana, Katie, Lauren. The Function of the Urinary System. Kidneys filter the blood! In general, the process excretes urine, eliminating excess water and solutes.
The Excretory System
By Duncan, Liana, Katie, Lauren
nephron: kidney's functional unit, millions in kidney4
next, renal tubule which has three sections:
filtrate enters proximal tubule where reabsorption of ions and molecules into blood (peritubular capillaries) occurs
continues to loop of Henle where water and salt leave
in distal tubule, water and other solutes are reabsorbed by blood and other solutes secreted into tubule (it's trying to regulate blood's pH, water, sodium, and other solutes levels)4
What remains in the tubule=urine
Urine made in nephrons by:
1)Filtration: pressure of the blood forces water and small solutes, not proteins, red blood cells or other large molecules, out of glomerular capillaries (in Bowman's Capsule)4
2)Tubular Reabsorption: in the nephron's tubular regions4
Process where solutes and water are removed from the tubular fluid and transported back into the blood
How it crosses the tubule's walls:
Water moves by osmosis.
Channel proteins move solutes across the wall.
Protein pumps actively transport things like glucose and amino acids back into the blood.
Solutes also move because with water gone--> higher concentration of solutes--> they diffuse out.
3)Tubular secretion:excess solutes from unfiltered blood are secreted into tubule including ions, mainly H+ and K+
substances produced from metabolism and drugs are also secreted2