Kidney Functions Flashcards
List the different functions of the kidney.
- Filtration
- Regulation of Acid Secretion
- Regulation of Electrolyte Excretion
- Renal Clearance
- Regulation of Water Excretion
- Erythropoetin Secretion
- Activation of Vitamin D
- Phosphate Regulation
Describe the nephron.
- The nephron is the functional unit
of the kidney.
~ Where filtration occurs
~ Where electrolyte resorption occurs
~ Where filtrate and urine are formed
Describe filtration in relation to the golmerulus.
- The glomerulus, composed of capillaries, are supplied with blood by an afferent arteriole and drained by an efferent arteriole.
- Blood pressure determines how fast and what pressure blood passes through the glomerulus.
- Filtering occurs as blood flow through the glomerulus
Describe filtration in relation to fluid.
- Water and small molecules pass through.
- Fluid is filtered through the walls of the glomerular capillaries and enters the tubules.
~ This fluid is called filtrate.
Describe filtration in relation to larger molecules.
- Larger molecules are not normally passed through the glomerulus.
- They have a high molecular weight
List some examples of molecules with a high molecular weight.
- Protein/albumin
- Red blood cells
- White blood cells
- Platelets
What substances are normally filtered by the glomerulus and excreted in urine?
- Na, Cl
- Bicarbonate, K, glucose
- Urea, creatinine, and uric acid.
What is Glomerular filtration rate (GFR)? What does it estimate?
- Glomerular filtration rate (GFR) is a diagnostic test used to assess kidney function.
- Specifically, it estimates how much blood/creatinine passes through the glomeruli each minute.
What are glomeruli?
Glomeruli are the filters within the nephrons of the kidneys that filter waste/excess from the blood.
What diagnostic tests can measure GFR?
- Creatinine Clearance(CrCl) via a 24-hour urine.
- eGFR via venipuncture
~ Which test is more accurate?
~ Which one is more convenient? - Note: Normal GFR is 90-120 ml/min
What do the kidneys do with hydrogen ions?
- The kidneys are supposed to get rid of excessive amount of hydrogen ions in the body.
- Hydrogen ions are acids within the body.
What happens if kidney function is compromised?
- If kidney function is compromised, there will be retention of hydrogen ions.
~ Increased acidity of the blood (serum)
~ Lowered serum pH level
~ Normal pH of the blood is 7.35 to 7.45. - Metabolic Acidosis
What do the kidneys do with potassium?
- The kidneys are supposed to get rid of excessive amount of potassium.
- If kidney function is compromised, there will be retention of potassium (hyperkalemia).
Why can potassium be a life-threatening electrolyte?
This can be a life-threatening electrolyte because hyperkalemia causes myocardial depression
What do kidneys do with metabolites?
- The kidneys are supposed to get rid of the components of cellular breakdown (metabolites), especially protein.
- Also known as waste products
- If kidney function is compromised, there will be retention of the metabolites.
What does the retention of metabolites lead to?
- This leads to an increase in BUN and creatinine levels and subsequent uremia.
- Uremia causes a a whole slew of problems to all systems in the body!
What is discoloration of the skin secondary to? What is dryness secondary to?
- Discoloration of the skin secondary to retained urochromes (uremia) which are normally excreted by the kidneys.
- Dryness secondary to decreased activity of sweat and sebaceous glands
What is excoriation related to? What are ecchymoses and purpura related to?
- Excoriation, bleeding and infection related to scratching to relieve itching.
- Ecchymoses and purpura related to abnormal blood clotting and capillary fragility in uremia.
What happens if kidney function is compromised?
- The kidneys are supposed to get rid of excessive amounts of water/fluid.
- If kidney function is compromised, there will be retention of fluid in different areas of the body.
What happens when GFR falls below 4-5 mL/min?
When GFR falls below 4-5 ml/min, significant amounts of water are retained in the blood–volume overload (hypervolemia)
What do kidneys do with erythropoietin? What happens if kidney function is compromised?
- The kidneys are supposed to secrete erythropoietin so red blood cells can be produced from the bone marrow. .
- If kidney function is compromised, there will a decrease in EPO (erythropoetin) release and subsequent decreased red blood cell production (anemia)
What is erythropoetin (EPO)? Where is EPO produced?
- Erythropoetin (EPO) is the principal factor that stimulates RBC production.
- In adults, about 80-90% of EPO is produced by epithelial cells of the renal peritubular capillaries.
- A small amount is produced by the liver but this amount is not adequate to maintain a normal number of RBCs in the circulating blood
Where can vitamin D be obtained?
- Dietary intake
- Exposure to ultraviolet light (natural or artificial).
What do kidneys do with vitamin D? Describe the active form of vitamin D. What happens if kidney function is compromised?
- The kidneys are supposed to convert Vitamin D (food and UV light) to an activated form.
- Vitamin D has to be in its active form to be utilized by the body.
- Active form of Vitamin D is needed for absorption of calcium in the GI tract.
- If kidney function is compromised, hypocalcemia will occur.
What do kidneys do with phosphorous? What happens if kidney function is compromised?
- The kidneys are supposed to get rid of excessive amount of phosphorus.
- If kidney function is compromised, there will be retention of phosphorus (hyperphosphatemia)
