Urinary system also known as the renal system consist of the kidneys, ureters, bladder, and urethra. The purpose of the urinary system is to eliminate the excess water from the body, regulate blood volume and blood pressure, control and regulate the level of electrolytes and blood PH.
The kidneys are bean shaped bilateral urinary organs that lie in the upper abdominal area in close proximity to the stomach and liver. The two main layers of the kidney are the medulla and the renal cortex. The medulla is the inside portion of the kidney and the cortex is the outer layer of the kidney. The kidneys are made up of millions of nephrons, the primary functional unit of the kidney.
The bilateral ureters connect the pelvis of each kidney to the bladder. The ureters consist of smooth involuntary muscle which serves as the conduit of urine from the kidneys into the bladder.
The bladder is the muscular organ that serves as the collection and retention vessel which temporarily holds and retains urine prior to urination. A normal urinary bladder can hold up to 800 milliliters of urine.
Urethra transports urine from the bladder to the outside of the body. This image shows (a) a female urethra and (b) a male urethra.
The urethra is the opening through which the urine passes out.
The male gender has two urethral sphincters to control both the passage of urine and sperm and the female gender has only one urethral sphincter to control the flow of urine only.
The functional unit of the urinary system is the nephron. The actual filters are tiny structures called nephron and each kidney is made up of one million nephrons. A nephron is made up of two parts, a cluster of capillaries called glomerulus, and a long fine tube. The nephrons are doing the following functions.
Filtration occurs when the circulating blood passes through the kidney where the removal of proteins and other cellular particles. The ultra filtrate becomes urine after reabsorption and secretion.
Reabsorption occurs after filtration, entails the re-entry of some particles and molecules from the ultrafiltrate back into the blood for future use.
Secretion is the opposite of reabsorption which entails the movement of wastes and other molecules into the urine from the blood after it is processed by the kidney.
The entry of blood into the kidneys → filtration of blood → ultra filtration → Re absorption → Secretion → Excretion of urine
Kidney physiologically prompts the secretion of Antidiuretic hormone and Aldosterone and production of enzymes like Renin and Angiotensin II
· Eliminates wastes from the body
· Manages and controls the homeostasis of the body in terms of its pH or acid-base balance
· Manages and controls the homeostasis of the body in terms of its electrolytes and electrolyte balance
· Manages and controls the blood pressure
· Stores urine until voiding is prompted
· Enables the process of urination
· Remove wastes like urea and ammonia from the blood
· Manage and control the fluids and fluid balance in the body by holding or retaining water and releasing and removing water from the blood stream
· Serve with endocrine functions such as the production of erythropoietin and calcitriol which are needed for the production of red blood cells and the reabsorption of calcium, respectively.
· Urinary tract infection
· Renal failure
· Renal cysts
· Cancers of the urinary tract