Normal Kidney Function Part I Flashcards
How does the kinedy work to keep the total body content at a normal stable level?
Changing the Rate of Excretion
What determines the extracellular fluid volume (ECFV)?
• why is this so important?
Na+ , this is the KEY solute in renal physiology
Important in maintaining BLOOD PRESSURE - no blood pressure than no life
What ions maintain the intracellular and extracellular fluid volumes (ICFV/ECFV)?
• what ion is important in maintaining total body water?
ICFV - K+
ECFV - Na+
**Na+ is the important ion in maintaining total body H2O. - it does this by changing osmolality
What happens in the body when Na+ content is increased?
Na+ increased => Increased Osmolality => Thirst Stimulation => Increase H2O intake AND Vasopressin secretion => more H2O conservation
Approximately what percentage of the body is made of water in males and females?
60% - Males
50% - Females
***Differences in muscle mass accounts for the variation
What is the dominant extracellular cation, and anion?
• others that are predominant?
Cl- = anion Na+ = cation HCO3- = anion
What is the role of Bicarbonate (HCO3-) in the body?
- Works to buffer pH in the extracellular fluid
2. Keeps PLASMA pH at 7.40
What major Minerals does the kidney maintain the levels of?
- Calcium
- Phosphorus
- Magnesium
What are the waste materials excreted by the kidney?
• what are these materials the by-product of?
- Urea - Byproduct of PROTEIN Metabolism
- Creatinine - byproduct of MUSCLE metabolism
- Uric Acid - byproduct of NUCLEIC ACID breakdown
What are the 4 main endocrine functions of the kidney?
- EPO secretion
- Renin
- 1,25 (OH)2 D3 (vit. D production)
- Paracrine/Autocrine Functions
EPO
• What is it?
• Consequences of Kidney dysfunction on EPO?
EPO - Glycoprotein needed to stimulated differentiation of hematopoeitic stem cells into RBCs - ONLY SECRETED BY KIDNEY
**Less Functional Kidney Mass = Less EPO, these ppl. are ANEMIC!
What is the relationship of Vit. D and the kidney?
• lack of function in what part of the kidney could result in osteomalacia or ricketts?
1-ALPHA-HYDROXYLASE is only found in the kidney
- Produces CALCITRIOL (1-alpha-hydroxylase)
- Nephron dysfunction => less 1-alpha hydroxylase => less Vit. D
What paracrine and autocrine functions does the kidney have?
• molecules produced and their jobs
- Bradykinin - vasodilatory and natriuretic
- Prostaglandins - important in GFR maintenance
- Endothelial Factor production - NO (veno-/artero- dilatory), Endothelin (potent vasocontrictor used in endothelial injury)
What is the role of the kidney in Blood Pressure Regulation?
• substances responsible and their actions?
• Via RAAS it determines the Extracellular Fluid volume of the body
- Angiotensin II = vasocontrictor
- Aldosterone = Na+ reabsorption
• ALSO Many VASODILATORY substances are produced in the kidney
What role the the kidney play in diabetes and in regulation of blood sugar in normal people?
Diabetes
• Kidney Degrades Insulin
• [Insulin] stays higher for longer in people with compromised kidneys
Blood Sugar
• can do up to 25% of GLUCONEOGENESIS in fasting state
What is the risk of administering medications to people in renal failure?
• if the drug is renally excreted, then drug levels can build up to become toxic
What is meant by Neutral, Positive, and Negative Balance?
Neutral - intake = output
Positive - intake greater than output
Negative - output greater than intake
What is the main thing you can analyze to determine if the kidney is functioning properly?
URINE
**If someone looks like they have a high ECFV then look at urine to see if they are properly compensating via Na+ excretion
~180 L/day of blood is filtered by the glomerulus meaning plasma is filtered 60x per day. What is the driving force of this process?
• what is the end product?
• Where is this done?
- Blood is filtered by the glomerulus with the end product being ULTRAFILTRATE
- Starling Forces (osmolarity and hydrostatic pressure drive this)
T or F: the kidneys recieve 25% of cardiac output
False, they receive 10%, which is still a ton
T or F: ultrafiltrate is iso-osmolar to the plasma
TRUE, while it lacks proteins and cells, it is still isosmolar to the plasma overall
Of the 180 L/day of ultrafiltrate produced everyday, how much is reabsorbed?
• where is ultrafiltrate produced and where does reabsorption occur?
178 or 180 L is reabsorbed into the body meaning we only make 1-2 L of urine per day
• Utrafiltrate is produced in the GLOMERULUS while the TUBULES are responsible for SELECTIVE RE-ABSORPTION AND EXCRETION
What is the best measure of Kidney function and why?
GFR is the best measure because glomerulus and tubules must work IN CONCERT
• Low GFR is also indicative of dysfunction in the other HOMEOSTATIC mechanisms of the Kidney (endocrine function and BP control)
What 4 main processes occur in the kidney?
• describe what is happening in each of these processes?
- Glomerular FILTRATION - starling forces push fluid through fenestrations to make Ultrafiltrate
- Tubular REABSORPTION - H2O and solutes that the body NEEDS BACK are sucked into the PERITUBULAR CAPILLARIES
- Tubular SECRETION - Solutes (NOT water) are reabsorbed
- EXCRETION - urine is excreted
What percentage of the 10% of cardiac output goes to the Glomerulus?
90% goes to the Glomerulus (9% of body total)
10% goes to kidney tissue (1% of total)
What are the 3 sites of possible obstruction within the ureter?
- Pelvic - Urethral Junction
- Crossover the pelvic brim
- Urinary Trigone
What is the most common spot for urethral obstruction in males?
• Cause of the obstruction?
• advantages?
Prostatic Urethra often obstructed with Benign Prostatic Hypertrophy
• Longer Urethra gives less chance for a UTI
Advantages and disadvantages to the short female urethra?
Advantages:
• less obstruction here
Disadvantages:
• More UTIs from gram - organisms
Renal Circulation from Aorta to the Vena Cava.
- Aorta
- Renal Artery
- Segmental Artery
- Lobar Artery
- Interlobar Artery
- Arcuate Artery
- Interlobular Artery
- Afferent Arteriole
- Glomerulus
- Efferent Arteriole
- Peritubular Capillaries and Vasa recta
- Interlobular veins
- Arcuate Vein
- Interlobar Vein
- Renal Vein
- IVC
Compare the following for the two different types of nephron. • Abundance • Perfusion • Size • Location
Cortical Nephrons
• 85% of total Nephrons
• LOWER perfusion pressure than JM nephrons
• SMALLER than JM nephrons (short Loop of Henle)
• in CORTEX
Juxtamedullary Nephrons • 15% of total nephrons • HIGHER perfusion pressure • LARGER with Longer Loops of Henle • Next to medulla
Between cortical and juxtamedullary nephrons, which has a greater filtration rate and why?
Juxtamedullary Nephrons have higher GFR because they have a HIGHER PERFUSION pressure
When people donate a kidney do they cut their filtration capacity down to 50%?
• why or why not?
NO - they actually end up operating at about 75% capacity because the average kidney only works at a capacity of ~50%
What happens to GFR after eating a high protein meal?
• It goes up about 20%
T or F: some Juxamedullary Apparatuses will descend into the papilla.
True
