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41 Cards in this Set

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Describe the urinary system's roles in excretion, elimination, and homeostatic regulation of blood.
Removes organic waste products from body fluids

Discharges waste products into environment

Regulates blood volume/pressure, regulates plasma ion concentrations, stabilizes blood pH, conserves nutrients
Describe the role of the kidney, ureter, urinary bladder and urethra.
Produces urine

Transports urine toward urinary bladder

Temporarily stores urine prior to elimination

Conducts urine to exterior
Label Diagram 1
1. Medulla
2. Cortex
3. Renal Pyramic
4. Connection to minor calyx
5. Renal sinus
6. Minor Calyx
7. Adipolse tissue in sinus
8. Major calyx
9. Renal pelvis
10. hilus
11. Renal lobe
12. Ureter
13. Renal columns
14. Renal papilla
15. Renal capsule
Label Diag 2
1. Segmental artery
2. Suprarenal artery
3. renal artery
4. renal vein
5. interlobar arteries
6. interlobular arteries
7. interlobar veints
8. Arcuate veins
9. Arcuate arteries
10. interlobular artery
11. arcuate artery
12. arcuate vein
13. afferent arterioles
14. nephron
15. interlobar vein
16. interlobular artery
Role of renal corpuscle
Production of filtrate
Role of prxoimal convoluted tubule
Reabsorption of water, ions, organic nutrients
Role of loop of Henle
Further reabsorption of water (descending limb) and Na/Cl ions (ascending limb)
Role of distal convoluted tubule
Secretion of ions, acids, drugs, toxins; variable reasbsorption of water, Na/Ca ions (under hormonal control)
Role of collecting duct
variable reasborption of water and or secretion of Na/K/H/Bicarbonate ions
Role of papillary duct
Delivery of urine to minor calyx
Which structures make up the collecting system of a nephron?
Collecting duct and papillary duct
Label Diag 3
1. proximal convoluted tubule
2. capsular space
3. glomerulus
4. efferent arteriole
5. afferent arteriole
6. bowman's capsule
7. renal corpuscle
8. descending limb of loop begins
9. renal capsule
10. thin descending limb
11. descending limb
12. loop of henle
13. ascending limb
14. thick ascending limb
15. ascending limb of loop ends
16. distal convoluted tubule
17. collecting duct
18. capillary duct
19. minor calynx
Difference between cortical and juxtamedullary nephrons?
Cortical make up ~85% of all nephrons; loops on henle of juxtamedullary extend deep into renal pyramids
Name 2 ways in which urine production maintains homeostasis
Regulated blood volume/composition

Excretes waste products (urea, creatinine, uric acid)
Compare plasma and urine contents of Na, K, Cl, HCO3, glucose, lipids, amino acids, proteins, urea, creatinine, ammonia, uric acid
More, much more, more, much less, much less, much less, much less, much much less (0), much more, much more, much more, much more
(in terms of urine)
Describe the 3 main steps of urine formation
Filtration: BP forces water and solutes across glomerular capillaries into capsular space, solute molecules small enough to pass thorugh filtration membrane are carried by surrounding water moleulces

Reabsorption: removal of water and solutes from filtrate

Secretion: transport of solutes from peritubular fluid into tubular fluid
Describe the four methods of carrier mediated transport employed by filtration.
Facilitated diffusion: carrier protein transports molecules along gradient

Active transport: ATP hydrolysis against membrane

Cotransport: two substrates cross membrane while bound to carrier protein. Substrate follow concentration gradient of one of substances. (reabsorption of organic/inorganic compounds from tubular fluids)

Countertransport: two transported ions (like in cotransport) move in opposite directions (PCT, DCT, collecting system)
What is transport maximum? What does it determine?
Concentration at saturation of a carrier protein; determines renal threshold: plasma concentration at which a specific compound/ion begins to appear in urine
What happens to concentrations higher than Tm?
No further transport, they are excreted
Compare the renal threshold of glucose, amino acids, and water soluble vitamines
HIGH, MEDIUM, LOW
Describe flow of nutrients in proximal convoluted tubule and their destination.
reabsorb and release into peritubular fluid
Describe flow of nutrients in distal convoluted tubule and their destination.
reabsorb sodium ions from tubular fluid
What process occurs in the renal corpuscle? How does this differ based on the size of the molecule?
Proteins/molecules smaller than 7nm pass into filtrate; larger cells/proteins stay in blood
What does the proximal convoluted tubule secrete
H+, NH4+, creatinine, toxins, drugs
What does the distal convoluted tubule secrete?
H+, NH4+, creatinine, toxins, drugs
What is the role of the loops of henle?
Regulate final volume/solute concentration
How would a drop in BP affect glomerular filtration rate? How could this decreased BP be achieved?
If drops to 40 mmHG, filtration ceases

Hemorrhaging, shock, dehydration
Describe the methods of autoregulation in controlling GFR
Diameter of blood vessels, decreased bp-->increased afferent arteriole diameter, dilation of capillaries, decreased efferent arteriole diameter
Increased BP causes decreased afferent arteriole diameter
Describe the methods of hormonal control in regulating GFR.
a drop in filtration pressure stimulated juxtaglomerular apparatus, releases rening + ertyhropoietn
What role does the sympathetic nervous system play in regulating GFR?
Vasoconstriction of afferent arterioles, decrases GFR+slows production of filtrate

Changes pattern of blood flow (to alter GFR)

Stimulates release of renin by JGA
What type of fluid (in terms of similarity) does glomerular filtration produce?
Plasma without proteins
What is countercurrent multiplication?
Exchange occurs between fluids moving in opposite directions: tubular fluid in descending limb flows toward renal pelvis, tubular fluid in ascending toward cortex
Multiplication: effect of exchange increases as movement of fluid continues
How is countercurrent multiplication achievedand what is its effect on urine concentration?
Descending limb is permeable to water, impermeable to solute, ascending limb is impermeable to water, but has active solute transport. So solutes pumped out of ascending (Cl-, Na+, and K+), thus forcing water out of descending (passively).
DCT and collecting duct have variable permeability to water and are impermeable to urea. So as water is reabsorped, urea concentration rises. Papillary duct permeability to urea accounts for 1/3 of solutes in deepest portion of medulla.

ION CONCENTRATION GRADIENT: high pressure towards medulla.
What is the role of DCT? Describe its mechanism of action.
Final adjustment of urine: active secretion or absorption

Tubular cells reabsorb (actively) Na and Cl from tubular fluid in exchange for potassium.

Reabsorption of HCO3- in exchange for H+ (secretes H+)
How is pH controlled for in the collecting system?
Secretion of H+ or bicabonate
Describe the mechanism of action of ADH and how things function in its absence.
Normally: H2O flows out of descending limb, and Na-Cl flows out of ascending, and the permeability of collecting duct is controlled and then you pee diluted urine.

WITH ADH, permeability of collecting duct increases for water, so water just flows out and gets reabsorbed (in DCT too), resulting in concentrated urine (smaller volume).
Describe the role and function of the vasa recta. What is this principle known as?
Solutes and water reabsorbed in medulla must be returned to general circulation without disrupting concentration gradient; this is mediated by vasa recta.

Blood entering vasa recta has an osmitc concentration ~300, as it descends it increases, involving solute gain and water loss (more solute gain though because of plasma proteins). Blood flow to cortex decreases in ostmotic concentration as solute concentration of preitubular fluid declines. In this case osmosis predominates (plasma proteins aint opposing osmotic flow of watr in blood).

NET RESULT: some solutes absorbed in descending portion of vasa do not diffuse out in ascending protion and more water moves into ascending protion of vasa than moved out.

THUS carries both water and solutes out of medulla. Precisely balances rate of reabsortpion and osmosis in medulla.

COUNTER CURRENT EXCHANGE
What do the ureters connect? Main role? How is this achieved?
From renal pelvis to bladder; transport; peristaltic contractions force urine toward urinary bladder
Main role of urinary bladder? How is its function achieved?
Storage reservoir of urine; contraction of detrusor muscle voids bladder
What does the urethra connect? Function? How is it achieved?
Extends from urinary bladder to exterior of body, passes through urogenital diaphragm (external urinary sphincter); differs in length and function in males and females
What is the function of the micturition reflex? How is it intiated? Describe its mechanism of action.
Corrdinates urination.
Intiiated by stretch receptors in bladder wall.
Urination requires coupling of micrution reflex with relaxation of external urethral sphincter.

Stretch receptor -->Afferent Sensory fiber in pelvic nerve-->SC-->IN to thala-->cerebral cortex

Also from afferent in SC-->Parasymp pregang MN in pelvic nerve-->efferent-->postgang in intramulral ganglion to stimulate detrusor muscle contraction