AN SC 310 - 22
Card Set Information
AN SC 310 - 22
AN SC 310
The Urinary System: Renal Function
What are the functions of the urinary system?
Regulate plasma: ionic composition, volume, pH
Remove metabolic waste products and foreign substances from plasma
Secrete erythopoietin & renin
Activate vit D3 to calcitriol
1. Inferior vena cava
2. Abdominal aorta
3. Adrenal gland
5. Renal hilus
6. Renal artery
7. Renal vein
10. Neck of bladder
What do kidneys do?
What do ureters do?
Transport urine from kidneys to bladder
What does the bladder do?
What does the urethra do?
Excrete urine from bladder to outside of body
What are anatomical characteristics of kidneys?
Approx size of fist
Where do renal arteries enter and renal veins exit the kidneys?
What percent of cardiac output does the urinary system receive at rest?
What percent of the bodies ATP does the urinary system use?
1. Renal cortex
2. Renal medulla
3. Renal papilla
4. Renal pelvis
5. Minor calyx
6. Major calyx
7. Renal pyramid
8. Renal artery
9. Renal vein
10. Bowman's capsule
11. Blood vessels
12. Collecting duct
What is the functional unit of the kidney?
What are the 4 renal tubules?
Loop of Henle
Distal convoluted tubule
What are the differences btwn cortical and juxtamedullary nephrons? What is the similarity btwn them?
: long loop of henle, medullary osmotic gradient
: short loop of henle, most numerous (80-85%)
Both produce urine
What are the 4 basic renal exchange processes?
Glomerular filtration (glomerulus to bowman's capsule)
Reabsorption (tubules to peritubular capillaries)
Secretion (peritubular capillaries to tubules)
Excretion (tubules to out of body)
What is glomerular filtration?
Movement of protein-free plasma from glomerulus to bowman's capsule
125mL/min or 180L/day
What are the starling forces that FAVOR filtration across glomerulus?
Glomerular capillary hydrostatic pressure
60 mm Hg
High due to resistance of efferent arteriole
Bowman's capsule oncotic pressure
0 mm Hg
Low due to lack of protein in filtrate
What are the starling forces that OPPOSE filtration across glomerulus?
Bowman's capsule hydrostatic pressure
15 mm Hg
High due to large volume of filtrate in closed space
Glomerular oncotic pressure
29 mm Hg
Higher than systemic caps due to plasma proteins in smaller volume of plasma
How is Glomerular Filtration Rate measured?
Filtration pressure = (P
) - (P
) = (60+0) - (15 + 29) = 16 mm Hg
What is the filtration fraction of the kidneys?
625 mL plasma into kidneys per min
125 mL filtered into Bowman's capsule
125/625 = 20%
What is filtered load?
Quantity filtered = Filtered Load = GFR x Plasma(...)
Filtered load of glucose
= GFR x Plasma(glucose)
= (125 mL/min) x (1 mg/mL)
= 125 mg/min
What are the 2 intrinsic mechanisms of regulation of GFR?
What happens during myogenic regulation?
Smooth muscle in wall of afferent arteriole contracts in reponse to stretch
What is the extrinsic mechanism of control of GFR?
Decrease in BP can decrease GFR
What is reabsorption?
Selective transport, movement from renal tubules into peritubular capillaries
Where does most of solute reabsorption occur?
Proximal convoluted tubule
Some in distal convoluted tubule
What is transport maximum?
Rate of transport when carriers are saturated
What is renal threshold?
Applies to solute which is 100% reabsorbed
Amt of solute in plasma that causes solut in filtrate to saturate carriers and spillover into urine
What is secretion?
Solute moves from peritubular capillaries into tubules
Same barriers as reabsorption
Transport mechs same but in opp direction
What substances are secreted?
What are the specializations of the renal tubule regions?
Proximal tubule - nonregulated reabsorption, leaky tight junctions
Distal Tubule and collecting duct - regulation reabsoption, tight junctions
Loop of Henle - water conservation, concentrated urine production
What is excretion rate?
Amt of substance excreted = amt filtered + amt secreted - amt reabsorbed
What does excretion amt depend on?
What is mucturition?
What are the steps of micturition?
Urine formed in renal tubules
Fluid drains into renal pelvis and ureter
Ureters lead to bladder
Blader stores urine until excreted through urethra
What muscle do we have voluntary control over when it comes to urination?
External urethral sphincter