anaphysio ch 12 urinary
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Urinary System
Edison D. Ramos, RMT, MPHAssistant Professor II
College of Medical Technology
Manila Central University
INTRODUCTION
- It helps keep the body in homeostasis by removing and restoring selected amounts of solutes and water from blood
Consists of:KIDNEY – main filtering organs of the system, paired organ that regulate the composition and volume of blood and remove wastes from the blood in the form of urine.
URETER – transport urine from the renal pelvis into the urinary bladder
BLADDER – hollow muscular organ located in the pelvic cavity posterior to the pubic Symphysis.
URETHRA – the tube that leads from the bladder to the outside
Urine Formation by Nephron
Blood pressure forces water, glucose, amino acids and urea from capillaries into nephron
Glucose and amino acids are reabsorbed into blood from nephron
Some water is reabsorbed into blood
Urine is urea and salt concentrated in water
Regulation of Water Balance
Brain monitors water content of blood
If low water content, pituitary releases ADH
ADH travels in blood to nephron
ADH causes more water to move from urine back into blood
Urinary SystemHas specific Performs specific
Structure Functionenables
Kidney
includes
Nephron
Collecting Ducts
Minor Calyces
Major Calyces
Renal Pelvis
Ureters
Urinary Bladder
Urethra
Lead to
Urine flows to
Urine flows to
Urine flows to
Urine flows to
Urine flows to
Urine flows to
Urine elimination
includes
Waste and foreign
substanceUrine storage
Urine formation
Tubular secretion
Tubular reabsorption
Glomerular filtration
by
FUNCTIONS OF THE URINARY SYSTEM
1. Excretion
- Kidney filter large amounts of fluid from the bloodstream. They are the major excretory organ because they eliminate nitrogenous wastes, drugs and toxin from the body. It also reabsorb needed substances and return them to blood.
2. Maintain blood volume and concentration
- Regulating the proper balance in the blood between salt and water, regulate concentration of ions in body fluids and blood so the proper balance of Na, K, Ca, and phosphate ions is maintained.
3. pH regulation
- Control the proper balance of hydrogen ions in the blood
4. Blood pressure
- Produce enzyme RENIN which helps maintain blood pressure
5. Erythrocyte concentration
- Produce the protein hormone ERYTHROPOIETIN which stimulates red blood cell production
6. Vitamin D production
- It converts vitamin D to calciferol which is its active form. Kidney participate along with liver and skin in vitamin D synthesis.
EXTERNAL ANATOMY OF THE KIDNEY
- Kidneys are paired organs that are reddish in color and resemble kidney beans in shape
- They are about the size of a closed fist
- The right kidney is slightly lower than the left because of the large area occupied by the liver.
HILUM – notch in the concave center of the kidney through which a ureters leaves the kidney and blood vessels, nerve, lymph vessels enter and exit the kidney
Three layers surrounding each kidney
1. Renal capsule – innermost layer, act as a barrier against infection and trauma.
2. Adipose capsule – second layer, mass of fatty tissue that protect the kidney from blows
3. Renal fascia – outermost layer, anchors the kidney to the abdominal wall.
CORTEX – outer area of kidney
MEDULLA – inner area of kidney
RENAL PYRAMID – striated, triangular structure within the medulla whose bases face the cortex and tips point to the center of kidney (renal papillae)
RENAL COLUMN – cortical material that extends between the pyramids
MINOR CALYX – funnel-shaped structures that surround the tip of renal pyramid
MAJOR CALYX – union of minor calyces
RENAL PELVIS – union of major calyces, large collecting funnel which narrows to form ureter
ANATOMY OF THE NEPHRONNEPHRON – functional unit of kidney
BOWMAN’S CAPSULE – double-walled globe where nephron begins.
GLOMERULUS – capillary network surrounded by bowman’s capsule
PROXIMAL CONVOLUTED TUBULE – first part of the renal tubule
DESCENDING LIMB OF HENLE – name given to PCT as it dips into the medulla
LOOP OF HENLE – U-shaped structure of the limb of Henle
ASCENDING LIMB OF HENLE – name given to loop of Henle as it ascends toward the cortex
DISTAL CONVOLUTED TUBULE – name given to the ascending limb of Henle as it enters the cortex and becomes convoluted
COLLECTING DUCT – connects with the distal tubules of the other nephron
Proximal Convoluted Tubule
Reabsorbs: water, glucose, Reabsorbs: water, glucose, amino acids, and sodium.amino acids, and sodium.
•65% of Na+ is reabsorbed•65% of H2O is reabsorbed
•90% of filtered bicarbonate (HCO3-)
•50% of Cl- and K+
Loop of Henle
Creates a gradient of increasing Creates a gradient of increasing sodium ion concentration towards sodium ion concentration towards the end of the loop within the the end of the loop within the interstitial fluid of the renal pyramid.interstitial fluid of the renal pyramid.
•25% Na+ is reabsorbed in the loop•15% water is reabsorbed in the loop•40% K is reabsorbed in the loop
Distal Convoluted Tubule
Under the influence of the hormone Under the influence of the hormone aldosterone, reabsorbs sodium and aldosterone, reabsorbs sodium and secretes potassium. Also regulates secretes potassium. Also regulates pH by secreting hydrogen ion when pH by secreting hydrogen ion when pH of the plasma is low.pH of the plasma is low.
• only 10% of the filtered NaCl and 20% of water remains
Collecting Duct
Allows for the osmotic Allows for the osmotic reabsorption of water.reabsorption of water.
ADH (antidiuretic hormone)- makes collecting ducts more permeable to water-- produce concentrated urine
BLOOD AND NERVE SUPPLY TO THE NEURON
- Nephrons are mainly responsible for removing wastes from the blood and regulating its electrolytes and fluid content, they are richly supplied with blood vessels.
RIGHT and LEFT ARTERIES – transport 1200ml of blood to the kidneys every minute
- The arteries that branch and pass between the renal pyramids in the renal column as the INTERLOBAR ARTERIES
AFFERENT ARTERIOLE – takes blood from the renal artery to bowman’s capsule, where the arteriole divides into tangled capillary network known as GLOMERULUS
EFFERENT ARTERIOLE – formed from union of glomerulus, carries blood away from the bowman’s capsule. Each efferent arteriole further divides to form a network of capillaries called PERITUBULAR CAPILLARIES
PERITUBULAR CAPILLARIES reunite to form INTERLOBULAR VEIN
PHYSIOLOGY OF THE NEPHRONS
Three major functions of Nephron
1. Control blood concentration and volume by removing selected amount of water and solutes
2. Help regulate blood pH
3. Remove toxic waste from the blood
Formation of Urine
1. GLOMERULAR FILTRATION
- removes water and dissolved substances from the plasma of blood (Na, K, Ca, Mg, Cl, Sulfate, Phosphate, glucose, urea, uric acid) 90% of the fluid gets reabsorb in the renal tubules and reenters the plasma. The remaining small portion leaves the kidney as urine
2. TUBULAR REABSORPTION
- transport substances out of the tubular fluid and back into the blood of the peritubular capillary. Majority of the reabsorption occurs in the PCT. Active transport reabsorbs glucose and osmosis reabsorbs water. Positively charged ions are reabsorbed by active transport and negatively charged ions are reabsorbed by electrochemical attraction
3. TUBULAR SECRETION
- moves the substances from plasma in the peritubular capillary into the fluid of the renal tubule
PCT: secretes penicillin, creatinine and histamine
RENAL TUBULE: secretes hydrogen ions
DCT, COLLECTING DUCT – secrete potassium ions
ANATOMY AND FUNCTIONS OF URETER
- Body has 2 ureters each one descending from a kidney
- Each ureter is an extension of the pelvis of the kidney and extends down to the urinary bladder
FUNCTION: transport urine from the renal pelvis into the urinary bladder
- The urine is carried through the ureters by peristaltic contraction of smooth muscle walls but gravity and hydrostatic pressure also contribute
URINARY BLADDER- Hollow muscular organ located in the pelvic cavity.
- It is a movable organ held in position by folds of peritoneum
- When empty, it resembles a deflated balloon. When full of urine, it is spherical shape. As urine volume increases, it becomes pear-shaped and ascends into abdominal cavity
- Urine is expelled from the bladder by an act known as MICTURITION commonly referred to as urination or voiding.
- The average capacity of bladder is 700 to 800ml
Ureter
Bladder
PROBLEMS OF THE URINARY TRACT
Incontinence (urine leakage)
Causes of Incontinence
Stress incontinence: leaking small amounts of urine when coughing, lifting, or exercising
Urge incontinence: the bladder suddenly and unexpectedly contracts and expels urine
Overflow incontinence: bladder cannot completely empty so urine dribbles
Treatments for Incontinence
Kegel exercises to strengthen the urinary sphincter Medicines that increase the sphincter’s ability to contract Surgery to strengthen the pelvic muscles or to lift the bladder Retrain the bladder to increase its storage capacity (allowing
3-4 hours between urinating) Drugs to prevent urge incontinence Surgery to remove part of prostate gland if responsible for
overflow incontinence
Kidney stones form in the kidney pelvis. There are 4 types of stones.
•Calcium stones (most common)•Uric acid stones•Bacteria caused stones•Cystein stones
Treatments for Kidney Stones Small stones may pass with no pain Larger stones may pass but cause extreme of pain,
requiring a lot pain medication Stones that are too large to pass may require
surgical treatment including: using a ureteroscope to go up and snare the
stone using a nephroscope to crush the stone and
retrieve it using shock wave lithotripsy where a person is
submerged in water containing shock waves to pulverize the stones
Urinary Tract Infection (UTI)
Second most common infection following respiratory infections
UTI occur when bacteria (E. coli) from the digestive tract get into the opening of the urinary tract and multiply
Bacteria first infect the urethra, then move to the bladder and finally to the kidneys
UTI tend to occur more in women than men
Women may have more UTIs than men because: 1) they have a shorter urethra, allowing quicker
access to the bladder2) the urethral opening is nearer the anus3) intercourse may result in UTIs in women
Symptoms of UTIs
Urge to urinate but only small amount of urine produced
Pain and burning sensation in bladder
Fever Blood in urine
Diagnosis and Treatment
Doctors check urine for white and red blood cells and bacteria
Bacteria grown in culture to determine which antibiotic will work the best
UTIs are treated with antibiotics and are often cured within 1 or 2 days
The End
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