Lecture 2
Physiology 435 with Lokuta at University of Wisconsin - Madison
About this deck
By: Brittany Schueller
Created: 2011-04-30
Size: 42 flashcards
Views: 12
Created: 2011-04-30
Size: 42 flashcards
Views: 12
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Filtered load equation
FL (mg/min) = GFR (ml/min) X [plasma]substance
- FL is of a specific solute
- GFR is everything being filtered
Excreted load equation
1. Excreted load (mg/min) = FL + secreted into tubule lumen - reabsorbed into tubule lumen
2. Excreted load = V (rate of urine flow : ml/min) X [urine]substance (mg/mL)
In relation to EL and FL, when does reabsorption occur?
FL > EL
In relation to EL and FL, when does secretion occur?
EL> FL
Water: amount filtered and excreted per day and percent reabsorbed
Filtered per day: 180 L
Excreted per day: 1.8 L
% reabsorbed: 99%
Na+: amount filtered and excreted per day and percent reabsorbed
Filtered per day: 630 g
Excreted per day: 3.2 g
% reabsorbed: 99.5%
Glucose:amount filtered and excreted per day and percent reabsorbed
Filtered per day: 180 g
Excreted per day:0 g
% reabsorbed: 100%
Urea: amount filtered and excreted per day and percent reabsorbed
Filtered per day: 54 g
Excreted per day: 30 g
% reabsorbed: 44%
What % reabsorption do nutrients have?
almost complete reabsorption
What % reabsorption do waste products have?
incomplete, they are excreted
-urea has 44% reabs because the kidneys need it to function properly
What percent of filtrate volume is reabs?
99%
Modes and routes of tubular reabsorption: Diffusion
- of lipid soluble substances that don't need carriers
Modes and routes of tubular reabsorption: mediated transport
- of large/charged substances
- i.e. glucose
Modes and routes of tubular reabsorption: transcellular
goes across cell
- Luminal membrane -> basolateral membrane -> renal interstitial fluid -> peritubular capillaries
Modes and routes of tubular reabsorption: paracellular
- goes through tight junctions
- Tight junctions -> renal interstitial fluid -> peritubular capillaries
- tight junctions are lose in the proximal tubule so a lot of ionic molecules can get through
Below TM
[solute] in plasma and therefore in filtrate < reabs capacity to tubule so it's fully reabs and none appears in urine
At TM
[solute] in plasma and therefore in filtrate is sufficient to saturate reabsorptive capacity of tubule
Above TM
[solute] in plasma and therefore in filtrate > reabs capacity of tubule and solute appears in the urine
- filtered = excreted
Renal threshold
when a substance is above TM and it appears in the urine
What important ion does not have a TM?
Na+
Tubular secretion: most secretion occurs into the....
proximal tubules (except K+ and H + ions are mainly secreted into the distal tubule
Tubular secretion: can secreted substances have a TM?
yes
What type of transportation does tubular secretion use?
active transport
- coupled to Na+ reabs
What types of substances undergo tubular secretion?
Foreign chemicals and toxins
Renal plasma clearance
- the volume of plasma per unit time from which all of a substance is completely removed ("cleared") by the kidneys and excreted in the urine
-
Clearance of plasma can be used to measure...
how well kidneys are functioning
Renal plasma clearance equation
RPCs = (Us X V) / Ps
RPCs = renal plasma clearance of a solute (ml/min)
Us = [urine] of solute (mg/ml)
V= urine volume per unit time (ml/min)
Ps = [plasma] of solute ( mg/ml)
Inulin
- freely filtered
- not reabsorbed and not secreted
- RPC of inulin = GRF
PAH
- freely filtered
- actively secreted (100%) but not reabs
- RPC of PAH = Renal Plasma Flow
Glucose
- freely filtered
- 100% reabs and not secreted
- RPC of glucose = 0
RPC of any new substance will show..
how that substance is handled
Substance is secreted if...(RPC and GFR relationship)
RPC > GFR
Substance is reabsorbed if...(RPC and GFR relationship)
RPC < GFR
-
Another reason RPC < GFR is that something is....
- partially (not freely) filtered at the level of the golmerular capillaries
- ex: hormones, Ca, and fatty acids bound to plasma proteins
- only partially because plasma proteins not filterable
Creatinine
- produced by muscles at a constant rate
- freely filtered
- not reabsorbed
- slightly secreted (~ 10%)
- RPC of creatinine = 110% of true GFR or
GFR = RPC / 1.1
Mictrurition : a.k.a....
urination
Mictrurition muscles
1. detrusor (smooth muscle)
2. internal urethral sphincter (smooth muscle)
3. external urethral sphincter ( skeletal muscle)
Detrusor: innervation
Type: parasympathetic (causes contraction)
During filling: inhibited
During micturition: stimulated
Internal urethral sphincter: innervation
Type: sympathetic (cause contraction)
During filling: stimulated
During micturition: inhibited
External urethral sphincter: innervation
Type: somatic motor ( causes contraction)
During filling: stimulated
During micturition: inhibited
Stimulation of sphincters causes...
contraction which causes opening to become smaller
About this deck
By: Brittany Schueller
Created: 2011-04-30
Size: 42 flashcards
Views: 12
Created: 2011-04-30
Size: 42 flashcards
Views: 12
About StudyBlue
STUDYBLUE makes things that make you better at school.
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Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
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“I have used this website for three exams, and I see a huge difference in my test results.”
Naj
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