Module 4/Chapter 21/Urinary System/Process of Urination
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- What are the 3 steps of urination?
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1)filtration
2)reabsorption
3)secretion - Explain the process of urination.
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1)BLOODSTREAM-blood enters each kidney from the aorta by way of the right and left renal arteries.
2)RENAL ARTERIOLE-after the renal artery enters the kidney at the hilum the artery branches into smaller arteries called arterioles ath the cortex of the kidney.
3)GLOMERULUS-each arteriole in the cortex of the kidney leads into a mass of very tiny coiled and intertwined smaller blood vessels called capillaries, each forming into millions of capillaries called glomeruli.
4)REABSORPTION, FILTRATION and SECRETION-as the blood passes through the glomeruli, the process of forming urine begins. The walls of the glomeruli permit water, salts, sugar and nitrogenous wastes to filter out of the blood.
5)BOWMAN'S CAPSULE-each glomerulus is surrounded by a cup-like structure called a Bowman's capsule. Large substances such as proteins and blood cells cannot pass through the walls of the glomerulus into Bowman's capsule and if the kidney is healthy, these particles remain in the blood.
6)RENAL TUBULE-if the process of forming urine ended here, the body would lose a good deal of needed water, sugar and salts that filtered out of the blood with the wastes. Each Bowman's capsule is connected to a long, twisted tube called the renal tuble. As the water, salts,sugar and wastes pass along the tubule, the materials that the body needs (water,salts and sugar)are able to re-enter the bloodstream through tiny capillaries that lie close to each renal tubule.
7)RENAL PELVIS-by the time the filtered material reaches the end of the renal tubule, the materials that must be kept have been reabsorbed into the bloodstream. Onlu the wastes pass from the renal tubule into the central collecting area of the kidney then to the renal pelvis.
8)URETER-from the renal pelvis, narrowing into the ureter, which carries the urinary bladder.
9)BLADDER-where the urine is temporarily stored.
10)URETHRA-the exit area of the bladder to the urethra is closed by sphincters that do not permit urine to leave the bladder.
11)URINARY MEATUS-as the bladder fills up, pressure is placed on the base of the urethra, which causes the desire to urinate. - renal arteries
- blood enters each kidney from the aorta by way of the right and left of these arteries.
- hilum
- On the medial side of a kidney is an indentation at which the renal artery enters and the renal vein and ureter emerge.
- arteriole
- any of the small terminal twigs of an artery that ends in capillaries
- capillaries
- any of the smallest blood vessels connecting arterioles with venules and forming networks throughout the body
- glomeruli
- a small convoluted or intertwined mass or capillaries
- Bowman's capsule
- a thin membranous (cup-like structure)double-walled capsule surrounding the glomerulus of a vertebrate nephron through which glomerular filtrate passes( It is a filter in the formation of urine).
- renal tubule
- each Bowman's capsule is connected to this long, twisted tube. As the water, salts, sugar and wastes pass along the tubule, the materials that the body needs (water,salts and sugar) are able to reenter the bloodstream through tiny capillaries that lie close to each renal tubule.
- sphincters
- The exit area of the bladder to the urethra is closed by this rings of muscle that contract and do not permit urine to leave the bladder. As the bladder fills up, pressure is placed on the base of the urethra, which causes the desire to urinate.