this is a discription of the excretory system...
|Scooped by Taylor Wiebe|
inside the excretory system
The excretory system is a combination of the kidneys (produces), ureters (transports), urinary bladder (stores), and urethra (excretes). The kidneys consist of millions of (really) tiny “filters” called nephrons. A nephron consists of a renal cortex and a renal medulla, which in turn consists of the glomerulus, Bowman’s capsule, proximal tubule, the descending and ascending loop of henle, distal tubule, and collecting duct. The renal arteries are intertwined with the nephrons to help hold everything together and so that nutrients can be reabsorbed.
Blood (unless something is horribly broken) usually flows from the renal artery and through the glomerulus where everything except red blood cells, starch, and proteins are squeezed through a membrane into the Bowman’s capsule. It is now referred to as “filtrate”. The filtrate flows into the proximal tubule where salt, water, organic solutes (primarily glucose and amino acids), potassium, phosphate, some water and negatively charged ions like chloride and are reabsorbed into the blood. Hydrogen ions are also secreted.
The semi filtered filtrate then flows into the descending loop of henle which is highly permeable to water, then to the ascending loop which is not permeable to water but to ions. The distal tubule (also the primary site for the kidneys' hormone based regulation of calcium) helps regulate potassium, sodium, calcium, and PH. hydrogen ions are secreted. Finally, is the collecting duct. It absorbs most water using osmosis and the filtrate that remains in the collecting duct is a suspension of water and various solutes and particles. It is now called urine and is ready to be excreted through the anus. And we all know how that’s done…but if you want details, the urine puts pressure on the Urethral sphincter, which then sends a signal to your brain telling you that you have to go to the bathroom.
now you have somthing to think about as you sit on the toliet, and my job is done!