URINARY SYSTEM

-Filter waste products and excess water from the blood and excrete them from the body

- If kidneys didn’t remove them, these wastes would build up in the blood and damage the body

Inside each kidney we have millions of functional units that we call nephrons, which is the site where all these following steps happen

1. Filtration: separate substances that we want to eliminate from the ones that we want to keep in the body
2. Absorption: return to the blood stream the substances that we want to keep in the body (sodium, glucose, aminoacids)
3. Secretion: create the substance that we want to eliminate with all the waste particles and the excess water that we are going to release as urine

- urochrome is the compound that gives urine its color

- the kidneys also secrete hormones that help maintain homeostasis

- erythropoietin is a kidney hormone that stimulates bone marrow to produce red blood cells when more are needed.

- adrenal gland: controls the sleep/ waking cycle and stress

- Kidney: this pair of purplish brown organs are located below the ribs toward the middle of the back. Their function is to remove liquid waste from the blood in the form of urine keep a stable balance of cells and other substances in the blood.

- Ureters: these narrow tube scary your room from the kidneys to the bladder. Muscles in their was continually tighten and relax forcing urine downward, away from the kidneys. If urine backs up, or is allowed to stand still, a kidney infection can develop. About every 10 to 15 seconds, small amounts of urine are emptied into the bladder from the ureters.

- Renal vein

- Renal artery: supplies blood to the kidneys

- Urinary bladder: this triangle-shaped, hollow organ is located in the lower abdomen. It is hield in place by ligaments that ate attached to other organs and the pelvic bones. The bladder’s walls relax and expand to store urine, and contract and flatten to empty urine through the urethra.

The bladder is a hollow, sac-like organ that stores urine

- Pelvis

- Urethra: its a tube that allows urine to pass outside the body. The brain signals the bladder muscles to tighten, which squeezes urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra. When all the signals occur in the correct order, normal urination occurs.

The urethra is a muscular tube that carries urine out of the body. Urine leaves the body through another sphincter

Blood enters the kidney through the renal artery, which branches into capillaries

then, when the blood passes through the capillaries of the glomerulus of a nephron, blood pressure forces some of the water and dissolved substances in the blood to cross the capillary walls into Bowman´s capsule

then the fluid passes to a collecting duct, which reabsorbs some of the water and returns it to the blood stream

Then the filtered substances pass to the renal tubule of the nephron. In the renal tubule, some of the filtered substances are reabsorbed and returned to the bloodstream. Other substances are secreted into the fluid

Then , the fluid that remains in the collecting duct is urine

From the collecting ducts of the kidneys, urine enters the ureters, two muscular tubes that move the urine by peristalsis to the bladder

- Urinary tract infection: when microorgaisms, usually bacteria from the digestive tract, cling to the opening of the urethra, travel up into the bladder and/or kidney, and begin to multiply

- Incontinence: is accidental or intentional urination in people who are at an age where they should be able to have control of their bladders.

- kidney stones: are clumps of calcium oxalate that can be found anywhere in the urinary tract.  Kidney stones form when chemicals in the urine become concentrated enough to form a solid mass.

- kidney failure: also called renal failure and chronic kidney disease, can be temporary (often acute) condition or can become a chronic condition resulting in the inability of the kidneys to filter waste from the blood