Download Anatomy and Function of the Urinary System: Kidneys, Nephrons, Filtration, and Excretion and more Quizzes Physiology in PDF only on Docsity!
Urinary System
consists of the KIDNEYS, URETERS, URINARY BLADDER, and URETHRA ~The left kidney sits higher than the right because the liver forces the right one lower. TERM 2
Location of Kidneys
DEFINITION 2 The kidneys, which are positioned RETROPERITONEALLY lie on either side of the vertebral column, high on the posterior wall of the abdominal cavity. TERM 3
Retroperitoneally
DEFINITION 3 Lie behind the parietal layer TERM 4
Functions of the Kidneys
DEFINITION 4
- Removal of metabolic wastes from the blood and excretion to the outside of the body. 2. Regulation of red blood cell production, blood pressure, calcium ion absorption, and the volume, composition, and pH of the blood. TERM 5
Renal Blood Vessels
DEFINITION 5 The left renal vein crosses over top of the Aorta.
Nephron
Is the functional unit of the kidney TERM 7
Glomerular Capsule
DEFINITION 7 Filtering starts in the glomerulus TERM 8
Cortical and Juxtamedullary Nephrons
DEFINITION 8
- Cortical Nephrons a. 80% of nephrons b. located close to the surface of the kidney 2. Juxtamedullary Nephrons a. regulate water balance b. located near the renal medulla TERM 9
Blood Supply of Nephron
DEFINITION 9
- The glomerular capillary receives blood from the afferent arteriole and passes it to the efferent arteriole. 2. The efferent arteriole gives rise to the peritubular system, which surrounds the tubule. 3. Capillary loops called VASA RECTA dip down into the medulla. TERM 10
Pathway of Blood Flow Through Kidney and
Nephron
DEFINITION 10 Renal artery -> Interlobar artery -> Arcuate artery -> Interlobar artery -> Afferent arteriole -> Glomerular capillary -> Efferent arteriole -> Vas recta and Peritubluar capillary -> Interlobular vein -> Arcuate vein -> Interlobar vein -> Renal vein
Control of Filtration Rate
- Primarily three mechanisms are responsible for keeping the GFR constant a. Increased sympathetic impulses decrease GFR by causing afferent arterioles to constrict b. RENIN-ANGIOTENSIN SYSTEM c. Autoregulation TERM 17
Sodium and Water Reabsorption
DEFINITION 17 Osmosis reabsorbs water in response to active transport reabsorbing sodium and other solutes in the proximal portion of the renal tubule. TERM 18
Regulation of Urine Concentration and
Volume
DEFINITION 18
- The distal convoluted tubule and collecting duct are impermeable to water, so water may be excreted as dilute urine 2. If ADH is present, these segments become permeable, and water is reabsorbed by osmosis into the hypertonic medullary interstitial fluid TERM 19
The Countercurrent Multiplier
DEFINITION 19 Helps maintain the NaCl concentration gradient in the medullary interstitial fluid TERM 20
Countercurrent Mechanism of Vasa Recta
DEFINITION 20
- Fluid in ascending limb becomes hypotonic as solute is reabsorbed 2. Fluid in descending limb becomes hypertonic as it loses water by osmosis
Role of ADH in Regulating Urine
Concentration and Volume
- Concentration of water in the blood decreases. 2. Increase in the osmotic pressure of body fluids stimulates osmoreceptors in the hypothalamus. 3. Hypothalamus signals the posterior pituitary gland to release ADH. 4. Blood carries ADH to the kidneys. 5. ADH causes the distal convoluted tubules and collecting ducts to increase water reabsorption by osmosis. 6. Urine becomes more concentrated, and urine volume decreases. TERM 22
Functions of Nephron Components
DEFINITION 22
- Renal Corpuscle a. Glomerulus - filtration of water and dissolved substances from the plasma. b. Glomerular capsule - receives the glomerular filtrate 2. Renal Tubule a. Proximal convoluted tubule - reabsorption of glucose; amino acids; creatine; lactic, citric, uric, and ascorbic acids; phosphate, sulfate, calcium, postassium, and sodium ions by active transport. Reabsorption of proteins by endocytosis. Reabsorption of water by osmosis. TERM 23
Urea and Uric Acid
Excretion
DEFINITION 23 Urea *By-product of amino acid catabolism *Plasma concentration reflects the amount or protein in diet *Enters renal tubules through glomerular filtration *Contributes to the reabsorption of water from the collecting duct Uric Acid *Product of nucleic acid metabolism *Enters renal tubules through glomerular filtration *Most reabsorption occurs by active transport *~10% secreted and excreted TERM 24
Urine Composition
DEFINITION 24
- About 95% water 2. Usually contains urea, uric acid, and creatinine 3. May contain trace amounts of amino acids and varying amounts of electrolytes 4. Volume varies with fluid intake and environmental factors TERM 25
Renal Clearance
DEFINITION 25
- The rate at which a chemical is removed from the plasma
- Tests of renal clearance a. inulin clearance test b. creatinine clearance test c. para-aminohippuric acid (PAH) test 3. Test of renal clearance used to calculate glomerular filtration rate
Life-Span Changes
- Kidneys appear scarred and grainy 2. Kidney cells die 3. By age 80, kidneys have lost a third of their mass 4. Kidney shrinkage due to loss of glomeruli 5. Proteinuria may develop
- Renal tubules thicken 7. Harder for kidneys to clear certain substances 8. Bladder, ureters, and urethra lose elasticity 9. Bladder holds less urine TERM 32
GLOMERULONEPHRITIS
DEFINITION 32
- Inflammation of glomeruli 2. May be acute or chronic 3. Acute glomerulonephritis usually occurs as an immune reaction to a Streptococcus infection 4. Antigen-antibody complexes deposited in glomeruli and cause inflammation 5. Most patients recover from acute glomerulonephritis 6. Chronic glomerulonephritis is a progressive disease and often involves diseases other than that cause by Streptococcus 7. Renal failure may result from chronic glomerulonephritis
