Chapter 25) Urinary System Flashcards

Question

Transport Maximum

Answer 1

* Transcellular transport systems for various solutes are specific and limited * Tramsport maximim (Tm) * reflects number of carriers in renal tubules avaible to carry a specific substance * Pleanty of trasnporters for susbtances that need to be retained (ex glucose) and few or none for substances of no use * When carriesrs saturated excess is secreted in the urine

Answer 2

* Entire renal tubule is involed but PCT cells are most active * PCT * Site of reabsorption * All nutrients, 65% of Na+ and Water and many ions. * Uric acid and 1/2 of urea are reabsorbed but later secreted back into filtrate * Nephron loop * descending loop) H2O can leave, solutes cannot * Ascending Limb) H2O cannot leace; Solutes can * vital to ability to concentrate or dilate urine. * DCT and collecting duct * Most water and solute have been reabsorbed by the time DCT is reached * small ammout of filtrared load is removed.

Answer 3

* Reabsorption Hormonally Regulated * Antidiuretic hormone (ADH) * released by posterior petuitary * Causes Principal cells (water and Na+) to insert aquaporians into collecting ducts. * ADH levels increase \> Increased water reabsorption * Aldesterone * Increases Na+ and therefore water via osmosis * Targets collecting ducts and Distal DCT. * Increases blood pressure. Decreases K+ levels. * Atrial Natriuetic Peptide (ANP) * reduces blood Na+to reduce blood volume/ pressure * Parathyroid hormone (PTH) acts on DCT to increase Ca2+ reabspprtion

Answer 4

* Reabsoprtion in reverse; one major exception is PCT is main site of secretion. * collecting ducts partially active * Selected substances (K+, H+, NH4+, creatine, organic acids/bases) move from Peritubular Capilaries throigh tubule cells to the filtrate * Substances created in tubule cells also secreted. * Important for 1. Disposal of Substances (like Drugs) that are tightly bound to plasma proteins 2. Eliminates Undesireable substances (urea and uric acid) 3. Rids body of excess K+ (aldesterone) 4. Controls blood pH (altering ammounts of H+ and HCO3- in urine) * ph drops \> more H+ in urine * pH rises \> more Cl- is absorbed than HCO3-; HCO3- leaves the body

Answer 5

* Osmolaity * number of sulute per kg of H2O * reflects ability to cause osmosis * Osmolality of Body Fluids * expresssed in milliosmole (mOsm) * kidneys mantain osmality of blood plasma at ~300 mOsm by regulating urine concentration and volume * Countercurrent mechanism * how kidneys regulate urine concentration and volume * term countercurrent means fluid flows in opposite directions through the same adjacent sements * makes it possible to echange material between segments. * Countercurrent multiplier) interacttion of filtrate flow in ascedning and descending limbs of long nephron loops * Countercurrent exhanger) Blood flow through the ascending and descending portions of the vasa recta.

Answer 6

* Depends on activly transporting solutes out of the ascending limb * start of positve feeback * Two limbs of nephron loop are close enough to influence exhancges with the interstital fluid they share. * More NaCl in ascending limb = More water diffuses out of descending limb = Saltier filtrate in descending limb * Salty Filtrate in descending limb icreases osmolity of medullary interstitial fluid further. * Descending Limb) * Freely permiable to H2O * H2O passes out of filtrate to hyperosmotic medullary interstitial fluid. * Filtrate osmolality increases to 1200~ mOsm * Ascending Limb * Impermiable to H2O * Selectively permeable to solutes (Na+ and Cl- actively reabsorbed in thick segment) * Filtrate osmoality decreased to 100 mOsm * 200 mOsm difference between the indide and outside of ascening limb

Answer 7

* Vasa Recta acts as countercurrent exchangers * Perserves gradeient by * Preventing rapid removel of salt from medullary interstitial space * Removing Reabsorbed water * Blood entering and leaving Vasa Recta have nearly same solute concentration * Water is picked up in ascending vesa recta from descending vasa recta and any lost from nephron loop and collecting duct. * Volume of blood at end of vasa recta grater than the begining

Answer 8

* Medullary Osmotic Gradient) created by the kidneyes to conserve water * Overhydration \> large volume dilutue urine (low ADH production)(~100 mOsm concentration) * Dehydration \> small volume concentrated urine (ADH releases) (~1200 mosm) * Urea helps form medullary gradient * urea enters filtrate in ascending limb * gets left behind during cortical reabsorption of water *

Answer 9

* Chemicals that enhance urinary output. * ADH Inhibitors (alchocol) * Na+ reabsorption inhibitors * Inhibits water reabsorption * Caffeine, Drugs for hypertension or edema * Osmotic Diuretics) substance not reabsorbed so water stays in urine * ex) glucose in diabetice

Answer 10

* Volume of Plasma from which the kidneys clear (completely remove) a particular substance in a given time * usually 1 minute * Used to determine Glomular filtration rate (GFR) * to detect dlomerular damage * to follow progress of renal disease. * C=UV/P * C) Renal clearence rate * U) concentration of substance in urine * V) flow rate of urine formation * P) concentration of the same substance in the plasma. * Inulin (plant polysacharide) * used to determine GFR because it is freely filtered (not absorbed) * Concentration of U=125 used to test (C=125) * C \< 125 ml/min = Substance reabsorbed * C= 0, Substance completely reabsorbed/not filtered * C=125, No Net reabsorption * C \> 125 no net reabsorption.

Answer 11

* Color and Transparency * pale to deep yellow * Urocrome; a pigment from hemoglobin gives yellow color * Abnormal color may indicate UTI * Odor * develops an ammonia odor * may be altered by some drugs and vegtables * pH * slightly acidic; about pH of 6 with a range of 4.5-8 * Acidic diet (protien, whole wheat) \> lower pH * Alkaline diet (vegitarien), vomiting, UTI \> higher pH * Specific Gravity * ratio of mass of substance to an equal volume of distilled water * 1.001 to 1.035

Answer 12

* 95% water and 5% solutes * Nitrogenous Wastes * Urea (from amino acid breakdown) largest component * Uric acid) from nucleic acid metabolism * Creatnine (metabolite of creatine phosphate) * Other normal solutes * Na+, K+, PO4^3-, SO₄^3-, Ca²⁺, Mg²⁺, HCO3₃- *

Answer 13

* Convey urine from the kidneys to the bladder * begin at level of L2, runs obliquley to bladder wall * Prevents backflow of urine * Three Layers of Ureter Wall * Mucosa) Transitional epitelium * Muscularis) smooth muscle sheets * contracts in response to streatch * propels urine into bladder * Adventitia) outer fibrous connective tissue.

Answer 14

* Kidney stones * Crytlized calcium, magnesium or uric acid salt * most are small and pass easy

Answer 15

* Muscular sac for temportary storage of urine * Males) prostate gland inferior to bladder * Females) bladder is anterior to vagina * Trigone (triangle) * Smooth triangular are outlined by opening for ureters and urethrea * Infections tend to presist in this region * Layers of the bladder wall * Mucosa) transitional epithelial mucosa * Thick detrusor muscle) three layers of smooth mucle * Fibrous adentitia (exept on its superior surface) * Rugae folds appear when

Answer 16

* Muscular tube draining urinary bladder * Mostly psuedostratified columnar epithelium * Transitional epithelium near bladder * Stratified squamous epithelium near external urethral orifice * Sphincters * Internal urethral sphincter) Involuntary * External uretheral sphincter) voluntery * Female Urethra * 3-4 cm * tightly bound to vaginal wall * External uretheral opening) anterior to vagina, posterior to the clit * Male Urethra carries semen and urine * Prostatic urethra) within prostate gland * Intermidite part of urehtra) urogenital diaphragm to begining of penis * Spongy urethra) passes throigh penis; opens via external urethral orifice

Answer 17

* Urination or voiding) act of emptuign the urinary bladder * Three simuletanous events * contraction of detrusor muscle by ANS * opening of internal uretheral sphincer by ANS * Opening of external sphincter by somatic nervous system * Refelxive urination (occurs in infants) * Micturition (when pontine control center matures between ages of 2 and 3) * Pontine storage center * inhibits urination * excited sympatiehtic and somatic pathways * Pontine micturition center promotes micturition * Excited parasympathetic pathways * Inhibits sympathetic and somatic efferent pathways.

Answer 18

* Weakened pelvic muscles are normal cause * Stress Incontience (laughing and coughung) * Increased intradominal pressure forces urine through the sphincter * Overflow incontinence * urine dribbles when bladder overfills.

Answer 19

* Bladder unable to expel urine * common after general anstesia * Hytrophy of the prostate * Treament) catheter