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31 Cards in this Set

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  • Back
General functions of the kidney
Regulate water and electrolyte balance
Removal of metabolic waste, drugs, and foreign chemicals
Activation of hormones
How does the kidney regulate water and electrolyte balance?
Regulate volume and osmolarity of the ECF
-Forming dilute or concentrated urine
-Regulate amount of Na+ in the urine
What hormones does the kidney activate?
Renin - Increases formation of Angiotensin II
Vitamin D3
Erythropoietin
Function of maculadensa cells
Detect increased Na+ in filtrate and releases something that constricts the afferent arteriole -->decreased filtration and decreased Na+ in filtration
Function of renin
Decrease in BP is detected and renin is released at juxtaglomerular apparatus.
Renin converts Angiotensinogen to Agtensin I. ACE concerts I to II in the lungs.
Agtensin II causes general vasoconstriction-->increased BP
Barriers to filtration
Capillary Endothelium stops RBCs from leaving
Basement membrane
-Negatively charged-->repels (-) ions
-Stops anything with a molecular weight >10,000 ie. plasma proteins
Filtration in glomerular capillaries
Capillary hydrostatic pressure doesn't decrease along arterioles-->filtration occurs all the way along capillary
Determination of GFR
Capillary Hydrostatic Pressure
Bowman's Capsule Pressure
Capillary Colloid Osmotic Pressure
Autoregulation
Renal blood flow remains relatively constant despite changes in mean arterial blood pressure
Theories of autoregulation
Myogenic hypothesis
Increased MAP-->increased stretch of renal artery-->vasoconstriction-->increased R
Tubuloglomerular Feedback
Increased MAP-->Increased GBR-->Increased GFR-->increased Na+-->detected by maculadensa cells-->Increased constriction of afferent arterioles -->decreased GBF & G. capillary hydrostatic pressure
External factors influencing Renal Blood Flow
Sympathetic NS-->Constriction of afferent arteriole-->decreased RBF-->decreased GFR-->decreased urine output
Inulin/Creatinine
Filtered, Not reabsorbed, not secreted
Used to monitor kidney function Cinulin=GFR
Para-aminohippurate (PAH)
Filtered, Not Reabsorbed, Completely Secreted
Cpah=RPF
Glucose
Filtered, Completely reabsorbed, not secreted
Cglucose=0
Glucose begins to appear in urine when plasma glucose reaches a certain point
Determined by transport max.
Diabetes Mellitus: presence of glucose in urine
Function of the proximal convoluted tubule
Reabsorbs 70% of Na+, K+, and H2O
Secretes ALL PAH
MOST H2O is reabsorbed here
Mechanism of reabsorption in Proximal Convoluted tubule
2* active transport of Na+ down its concentration gradient allows diffusion of glucose/amino acids
Mechanism of secretion in Proximal Convoluted tubule
3* Active transport allows PAH out of cell
Ion movement in Loop of Henle
Descending Limb-Water is reabsorbed
Ascending Limb-Reabsorb Na+ & Cl-
Ion movement in Distal Convoluted Tubule
Cl- is reabsorbed
Fluid becomes very hypotonic as it flows through the tubule
Ion movement in the collecting duct
Potassium is secreted here
Aldosterone
Increases the number of Na+/K+ pumps
Increased aldosterone-->increased # of pumps-->increased Na+ absorption-->increased K+ secretion
Anti-diuretic Hormone (ADH)
Increases permeability of cell to H2O-->Increases H2O reabsorption
*If no ADH-->increased volume of dilute urine
High ADH-->decreased volume of concentrated urine
How is H+ produced in the body?
Glucose metabolism-->lactic acid
Fatty acid metabolism-->Ketone Body Acids
Protein metabolism-->Strong acids
A mixed diet produces a net prodution of H+
Regulators of pH balance
Buffers
Respiratory System
Renal System
Buffers
React to changes in pH within seconds
Act to minimize pH change
-Phosphate
-Proteins (ie. Hb)
-HCO3/CO2-open system(remove or add these)
Respirartory System as a buffer
Reacts within minutes
Increased H+ -->Increased ventilation -->Decreased CO2-->Decreased H+
Renal System as a Buffer
Excrete H+
Reabsorb HCO3-
Create HCO3- (through excretion of ammonia)
Respiratory Acidosis
Low pH
Caused by decreased ventilation (asthma)
Compensated by kidneys by secreting more H+
Respiratory Alkalosis
High pH
Caused by increased respiration-->low CO2 (high altitude)
Compensated for by secreting less H+ and reabsorbing less HCO3-
Metabolic Acidosis
Always low HCO3-
Low pH
Caused by:
-kidney failure-->don't reabsorb HCO3-
-Diarrhea-->loss of HCO3-
-Exercise-->Lactic acid
*Compensated for by respiratory system reacts in minutes
*Increased respiration -->decreased CO2-->Decreased H+
Metabolic Alkalosis
Decreased H+ caused by increased levels of HCO3-
-Vomitting-->loss of H+
-Antacid Abuse-->Addition of HCO3-
Compensation:
Respiratory System-->decreased ventilation-->increased CO2-->increased H+