the urinary system anatomy & physiology. the urinary system removes salts and nitrogenous...
TRANSCRIPT
The Urinary System
ANATOMY & PHYSIOLOGY
The Urinary System removes salts and nitrogenous wastes, helps maintain water concentration, electrolyte balance, pH balance, fluid volume, control rbc production & blood pressure.
Kidneys:2 bean-shaped organs positioned retroperitoneally (in the
back)
Each kidney has:an inner region called the renal medullaan outer region called the renal cortexwithin the renal cortex are the nephrons , or the functioning
unit of the kidneys (more on them later).
FUNCTIONAL REVIEW:
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Pyramids: triangular tissue
Calyces: cup-shaped tips of pyramids
Renal Pelvis: basin of the kidney
KIDNEY ANATOMY:
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Help maintain homeostasis (regulate b.p., remove wastes for blood, control RBC formation, maintain volume of extracellular fluid)
Renal Blood Vessels:The renal arteries
bring blood to the kidneys.
The afferent arterioles from the renal arteries to the nephrons.
The renal vein takes blood from the kidneys to the abdominal cavity.
KIDNEY FUNCTIONS:
Each kidney contains about 1 million nephrons.
Within the nephron is a network of blood vessels (capillaries) called the glomerulus.
The glomerular capillaries filter fluid.
The glomerulus is surrounded by the glomerular capsule . This receives the filtered fluid.
NEPHRONS:
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1. Glomerular filtration (within glomerular capillaries)Glomerular capsule receives the glomerular filtrate
(the tissue fluid of the body) which is mostly water & large protein molecules.
2. Tubular reabsorption is the reabsorption of water, electrolytes & glucose .Returns substances into the internal environment
that the body needs. (glucose, water, & amino acids are reabsorbed as well as vitamin C and many ions) .
ADH and aldosterone (hormones) stimulate the reabsorption of Na+ and water.
URINE FORMATION:
ADH and aldosterone regulate the kidneys & diuresis (urination).
Aldosterone is secreted by the adrenal gland; it stimulates the reabsorption of more Na+ and, therefore water (decrease in urination).
ADH is secreted by the hypothalamus in response to a decrease in [water] in the blood; this signals the reabsorption of water (decrease in urination).
3. Tubular secretion is last.
Wastes such as toxins (nitrogenous wastes) and hydrogen ions are eliminated.
Final product is urine. Urine is composed of water (about 95%), urea, & uric acid.
URINE FORMATION:
1. Filtration
3. Secretion
2. Reabsorption
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If body fluids are in excess the filtration rate may increase.
If body fluids are low, the filtration rate may decrease (to conserve).
However, under normal circumstances filtration rate stays about the same.
REGULATION OF FILTRATION RATE:
Once urine is formed, it passes through collecting ducts through the kidney.
Urine then passes through the renal pelvis and a ureter, a tube connecting the renal pelvis to the bladder , and then to the urinary bladder .
The ureter has a flap-like mucous membrane that covers the opening which acts like a valve, preventing urine from backing up (urine goes only one way).
URINE ELIMINATION:
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The urinary bladder is a muscular organ that stores urine.
It may hold up to 600 milliliters of fluid before pain receptors are triggered but usually at about 200 milliliters, the urge to urinate is triggered.
Urine then passes through the urethra .
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Micturition is urination.
This requires the relaxation of the external urethral sphincter (skeletal muscle) which is controlled voluntarily .
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Thirst mechanism: drives water intake
Osmoreceptors: w/in hypothalamus, activate thirst center (makes you thristy)
Antidiuretic hormone (ADH): prevents excess water loss (decreases urination); tells kidney to absorb more water.
Aldosterone: tells kidney to reabsorb Na+; when sodium is reabsorbed, so is water (water follows salt). Therefore, urine output is decreased.
REGULATION OF WATER INTAKE & OUTPUT:
Look up in text or online!Know the following:
anuria, kidney stones, incontinence, Addison’s disease, polyuria, & adult polycystic kidney disease
THE END!
This slide show was developed by Dana Halloran, Cardinal Mooney High School, Sarasota, FL.
Used with her personal permission, adapted and amended by Rosa Whiting, Manatee School for the Arts, Palmetto, FL.