Flashcards in Normal Kidney Function Part I Deck (34)
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?
1. 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?
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
• 1,25 (OH)2 D3 (vit. D production)
• Paracrine/Autocrine Functions
• 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?
• Kidney Degrades Insulin
• [Insulin] stays higher for longer in people with compromised kidneys
• 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?
**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?
Prostatic Urethra often obstructed with Benign Prostatic Hypertrophy
• Longer Urethra gives less chance for a UTI
Advantages and disadvantages to the short female urethra?
• less obstruction here
• More UTIs from gram - organisms
Renal Circulation from Aorta to the Vena Cava.
- Renal Artery
- Segmental Artery
- Lobar Artery
- Interlobar Artery
- Arcuate Artery
- Interlobular Artery
- Afferent Arteriole
- Efferent Arteriole
- Peritubular Capillaries and Vasa recta
- Interlobular veins
- Arcuate Vein
- Interlobar Vein
- Renal Vein