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58 Cards in this Set
- Front
- Back
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What is the major excretory organ? |
Kidneys |
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What is the main function of the urinary system? |
waste removal |
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What organs are included in the urinary system? |
- kidneys (include nephrons): is the major excretory organ - ureters: muscular tube - urinary bladder: muscular sac - urethra: female and male |
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What does a urologist do? |
Treat both urinary and reproductive disorders |
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What are the functions of the kidneys? |
- filters blood plasma, separates waste from useful chemicals, returns useful substances to blood, eliminates waste. - regulates blood volume and pressure by eliminating or conserving water, by use of renin. - osmolarity - erythropoietin - calcitrol - gulconeogenesis - collaborate with the lungs to regulate the PCO2 and acid-base balance of body fluids |
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What are the functions of the other 3 urinary system organs? |
Ureters: transports urine from the kidneys to the urinary bladder Urinary bladder: temporary storage reservoir for urine Urethra: transports urine out of the body |
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What is renin? |
Enzyme which activates hormonal mechanisms that control BP and electrolyte balance. - this is how kidneys regulate blood volume and pressure by eliminating or conserving water |
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What is osmolarity? |
Regulation of body fluids by controlling the relative amounts of water and solutes eliminated. |
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What is erythropoietin? |
Hormone which stimulates the production of RBCs |
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What is calcitrol? |
Final step in synthesizing hormone, contributes to calcium homeostasis |
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What is gluconeogenesis? |
The metabolic process by which organisms produce sugars (namely glucose) for catabolic reactions from non-carbohydrate precursors. From amino acids in extreme starvation. |
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What is waste? What is metabolic waste? |
Waste= Any substance that is useless to the body or present in excess of the body's needs. Metabolic waste= waste substance produced by the body that contains nitrogen |
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What are the nitrogenous wastes? |
- blood urea nitrogen (BUN): expression of the level of nitrogenous waste in the blood. - ammonia: uric acid- product of nucleic acid catabolism - urea: formed by proteins to amino acids to NH2 removed to form ammonia, in which liver converts to urea. - creatine: product of creatine phosphate catabolism - ketones: water soluble molecules produced by the liver from fatty acids during starvation |
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Referring to the kidneys, what does retroperitoneal mean? |
They lie behind the peritoneum (membrane lining of the abdominal cavity) and they are cushioned by adipose tissue. |
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What are the 3 external layers of the kidneys? |
- renal fascia: anchoring outer layer of dense fibrous connective tissue - perirenal fat capsule: fatty cushion - fibrous capaule: prevents spread of infection to kidney |
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Internal anatomy parts of the kidney |
- cortex: granular-appearing superficial region. - medulla: composed of cone-shaped medullary (renal) pyramids which are separated by renal columns: inward extensions of cortical tissue which includes: - papilla: tip of pyramid that releases urine into minor calyx. - renal pelvis: funnel-shaped tube continuous with ureter. - minor calyces: drain pyramids at papillae. - major calyces: collect urine from minor calyces and empty urine into renal pelvis. |
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Trace urine flow |
Renal pyramid to Minor calyx to major calyx to Renal pelvis to Ureter |
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What percentage of cardiac output do the kidneys receive? |
20% |
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What supplies blood to and from the kidney? |
Renal artery and vein |
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What does the micro circulation of the kidneys consist of? |
- peritubular capillaries and vasa recta |
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Describe the micro circulation of the kidneys |
- in the cortex: PERITUBULAR CAPILLARIES branch off of the efferent arterioles supplying the tissue near the GLOMERULUS, the proximal and distal convoluted tubules. - in the medulla: the efferent arterioles give rise to the VASA RECTA, supplying the nephron loop portion of the nephron. |
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What is the basic functional unit of the kidney? |
Nephrons- responsible for forming urine. Each kidney has 1.2 million nephrons. |
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What are the 2 main parts of a nephron? |
Renal corpuscle: which has 2 parts: - THE GLOMERULUS: tuft of capillaries; fenestrated endothelium, highly porous, allows FILTRATE formation. - GLOMERULAR CAPSULE: (bowman's capsule) cup-shaped, hollow structure surrounding the glomerulus. Renal tubule: which has 3 parts: - PROXIMAL CONVOLUTED TUBULE: closest to renal corpuscle. - NEPHRON LOOP/LOOP OF HENLE: ascending and descending limbs. - DISTAL CONVOLUTED TUBULE: farthest from renal corpuscle. - COLLECTIN DUCT |
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What are the 2 types of nephrons? |
Cortical nephrons: 85% of all nephrons, short nephron loops, efferent arterioles branch into peritubular capillaries around PCT and DCT. Juxtamedullary nephrons: 15% of all nephrons, efferent arterioles branch into vasa recta around long nephron loop. |
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What are the 3 steps in urine formation? |
1. Glomerular filtration 2. Tubular reabsorption 3. Tubular secretion |
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Describe the 1st step in the process of urine production. |
1. Glomerular filtration: movement of water, nutrients and waste molecules from the glomerulus (blood) to the inside of bowman's capsule (filtrate). substances entering bowmans capsule are called glomerular filtrate.
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What are the 3 things that affect the rate of filtration? In 1st step (Glomerular filtration) |
* diameter of afferent/efferent arterioles * systemic BP * particle concentration of blood (concentration gradients) |
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What 2 pressures affect filtration? In 1st step (Glomerular filtration) |
* hydrostatic pressure: in capsular space (HPcs)- pressure of filtrate in capsule- 15mmhg. * colloid osmotic pressure: in capillaries (OPgc)- "pull" of proteins in blood- 30mmhg. |
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What is net filtration pressure? In 1st step (Glomerular filtration) |
NFP= the sum of forces. - 55mmhg forcing out - 45mmhg opposing= net outward force of 10mmhg |
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Describe the 2nd step in the process of urine formation |
2. Tubular reabsorption: particles move out of P convoluted tubules and loop (filtrate), back into bloodstream (peritubular blood capillaries). - 99% OF GLOMERULAR FILTRATE IS REABSORBED INTO THE BLOOD. - substances reabsorbed= glucose, amino acids, sodium, potassium, calcium, chloride, bicarbonate, phosphates, and water. You dont pee iron because it isn't flowing freely. |
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Describe the reabsorptive capabilities of renal tubules, in 2nd step (tubular reabsorption) |
PCT: proximal convoluted tubule - all nutrients, glucose and amino acids, 65% of NA+ and water, many ions. - all uric acid, 1/2 urea (later secreted back into filtrate). |
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Describe the reabsorptive capabilities of renal tubules and collecting ducts, in 2nd step (tubular reabsorption) |
Nephron loop: - DESCENDING LIMB: H2O can leave; solutes cannot. - ASCENDING LIMB: H2O cannot leave; solutes can. ... THIN SEGMENT: passive NA+ movement ... THICK SEGMENT: (NA+) - (K+) - (2CL-) symporter (NA+) - (H+) antiporter - Some passes by paracellular route (between cells of desmosomes junctions) - Includes ADH |
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Describe the countercurrent flow/mechanism, in the 2nd step (tubular reabsorption) |
Countercurrent flow/mechanism: occurs when fluid flows in opposite directions in 2 adjacent segments of same tube with hair pin turn. - LONG NEPHRON LOOPS OF JUXTAMEDULLARY NEPHRONS create an osmotic gradient within the medulla that allows the kidney to produce urine of varying concentration. Countercurrent multiplier: interaction of filtrate flow in ascending/descending limbs of nephron loops of juxtamedullary nephrons. Depends on the 3 properties of the nephron loop to establish the osmotic gradient. Countercurrent exchanger: blood flow in ascending/descending limbs of vasa recta. Fluid flows in the opposite direction (countercurrent) through 2 adjacent parallel sections of a nephron loop. - the descending limb is permeable to water but not to salt. - the ascending limb is impermeable to water, and pumps out salt. |
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Describe the 3rd step in the process of urine production |
3. Tubular secretion: particles move from bloodstream (peritubular blood capillaries) back into D convoluted tubules and collecting ducts. - WASTE REMOVAL: urea, uric acid, bile acids, ammonia, catecholamines, prostaglandins and a little creatine are secreted into the tubule. Clears blood of pollutants, morphine, penicillin, aspirin and other drugs. - ACID-BASE BALANCE: secretion of hydrogen and bicarbonate ions help regulate the ph of the body fluids. |
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What process allows body to retain nutrients and controls the volume of water in urine? |
Tubular reabsorption |
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What is the site of most reabsorption? |
PCT- proximal convoluted tubule |
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List the hormones responsible for the effects on nephrons (altering urine contents) |
- ADH (anti-diuretic hormone): aka vasopressin, released from pituitary gland, retains water (reabsorption), by causing principal cells of collecting ducts to insert aquaporins in apical membranes. When ADH levels increase, water reabsorption increases. - aldosterone: NA+, removes water. - ANP (atrial natriuretic peptide) NA+, reduces blood NA+ leading to decreased BV and BP (only hormone to decrease BP). Is released by cardiac atrial cells if BV or BP is elevated. - PTH (parathyroid hormone): acts on DCT to increase CA2+ reabsorption. Bone reabsorption= stimulating osteoclasts by increased blood CA2+. |
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Describe the renin-angiotensin-aldosterone system |
Renin-angiotensin: when BP is low, renin is secreted. Renin: travels to liver causing production of angiotensin I, which is quickly converted into angiotensin II. Angiotensin II: is a potent vasoconstrictor, BP rises. Aldosterone: is secreted, enhancing sodium and water reabsorption, therefore urine becomes more concentrated. |
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What moves where? |
- PCT reabsorbs: 65% of glomerular filtrate and returns it to peritubular capillaries. Much reabsorption by osmosis and transport mechanisms linked to active transport of sodium. - nephron loop reabsorbs: another 25% of filtrate. - DCT reabsorbs: NA+, CL-, and water under hormonal control, especially aldosterone and ANP. The tubules also extract drugs, wastes and some solutes from the blood and secrete them into the tubular fluid. DCT completes the process of secretion by determining the chemical composition of urine. - collecting duct: conserves water, and is influenced by ADH hormone. |
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Describe urine storage and elimination |
Urine is produced continually, does not drain continually from the body, urination is episodic: occurring when we allow it, made possible by storage apparatus and neural controls of this timely release. |
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Describe the ureters |
Retroperitoneal, muscular tube that extends from the kidney to the urinary bladder. |
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What are the 3 layers of the ureters? |
- mucosa: transitional epithelium, protects from acidic urine by secreting mucus. - muscularis: smooth muscle layer that carried on contractions to move urine. - fibrous coat: (serosa), connective tissue layer that connects ureter to surrounding structures. |
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Describe the urinary bladder |
Muscular sac located on floor of pelvic cavity (filled with urine). - Includes the trigone: smooth surfaced triangular area marked with openings of ureters and urethra. - collapses when empty; rugae appear - expands and rises superiorly during filling without significant rise in internal pressure- holds between 300-500ml before the urge to empty occurs, can hold much more (up to 2L)- pain starts at more than 1L (record is >4L but involves alot of pain) |
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What are the 3 layers of the urinary bladder? |
- mucosa: transitional epithelium, stretches and secretes mucus, has rugae. - muscularis: smooth muscle layer - serous coat: outermost layer |
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Describe the histology of the urinary bladder |
transitional epithelium (cuboidal to squamous) |
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What is the function of the bladder and what muscles are included? |
Main function= storage of urine. Micturition: urination, emptying of bladder. - detrusor muscle: located in the body of bladder that contracts when stretched making us aware we have to urinate. - external sphincter muscles: VOLUNTARY control, located at the base of the bladder, releasing urine at will. |
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What is the micturition reflex? |
The bladder contraction reflex for which the reflex center is located in the rostral pontine tegmentum (PMC: pontine micturition center). - 2 afferent pathways from bladder to brian: dorsal system and the spinothalmic tract. |
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Desveieb the characteristics of urine |
Can vary due to differences in diet and physical activity: - color: yellow (deeper if urine is concentrated), abnormal= red from blood, green from bile, milky from pus or infection. - ph: acidic~6. Low ph can be created from protein diet and starvation. High ph can be created from vegetarian diet and bacterial infection. - odor: ammonia - turbidity: clear when freshly voided, cloudy when infection exists. - specific gravity: ratio of urine to water. Higher values indicate particles in urine. - volume: 1-2L a day |
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Describe normal and abnormal urine chemical composition |
Normal: 95% water. sodium chloride. Metabolism end products= creatinine, urea, ammonia, uric acid. Abnormal: albumin, glucose, erythrocytes or leukocytes, ketone bodies, bilirubin. |
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List the 3 types of urinary tract infections |
- cystitis: inflammation/infection of the urinary bladder, especially common in females due to short urethra. Frequently triggered by unprotected sex. Can spread up to the ureter causing pyelitis. - pyelitis: infection of the renal pelvis. - pyelonephritis: infection that reaches the cortex and nephrons, can result from blood borne bacteria. |
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What is incontinence? What is retention? |
Incontinence: inability to control micturition voluntarily. Retention: inability of bladder to expel contents. |
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What is gout? What are kidney stones? |
Gout: high levels of uric acid accumulation which then deposits in joints and kidney tissue causing pain and arthritic symptoms. Kidney stones: formed when salts crystalize in urine causing intense pain. |
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What is the name of a visual examination of the urinary tract using a cystoscope? |
Cystoscopy |
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What is renal failure? |
Inability to carry on glomerular filtration resulting in toxic state, dialysis must be used to remove excess waste and fluid, may require transplantation. |
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What is hemodialysis? |
A dialysis machine and special filter called an artificial kidney or a dialyzer are used to clean your blood. Minor surgery in the arm required to access blood vessels. |
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What are the lengths of the female and male urethras? |
Female urethra= 3-4 cm Male urethra= 18 cm |
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Describe the female urethra |
- bound to the anterior wall of vagina - external urethral orifice: between vaginal orifice and clitoris. - internal urethral sphincter: detrusor muscle thickening, SMOOTH MUSCLE under INVOLUNTARY control. - external urethral sphincter: where the urethra passes through the pelvic floor, SKELETAL MUSCLE under VOLUNTARY control. |
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Describe the male urethra |
3 regions: - prostatic urethra: 2.5cm, passes through the prostate gland. - membranous urethra: 0.5cm, passes through the muscular floor of pelvic cavity. - spongy (penile) urethra: 15cm, passes through penis in corpus spongiosum. Also includes: - internal urethral sphincter: detrusor muscle thickening. - external urethral sphincter: part of skeletal muscle of pelvic floor. |
