The Renal System Flashcards
What are common symptoms of a UTI?
- Dysuria (painful urination) 2. Urinary frequency 3. Urinary urgency 4. Suprapubic pain or tenderness 5. Hematuria (blood in the urine) 6. Polyuria (excessive urine production) Urine may also be cloudy and have a strong smell. Also common are fevers, confusion, and nausea.
Risk factors for development of a UTI
- Institutionalization 2. Sexually active 3. Diabetes 4. Presence of a catheter
When is urine dipstick testing for a UTI unreliable?
- Pregnant women 2. Children under 3 3. Patients whose urinary tracts have structural abnormalities. 4. Patients with diabetes 5. Patients who are immunocompromised.
What is a common treatment for a UTI?
Trimethoprim
Hematuria
Blood in the urine
Nephrotic Syndrome
Nephrotic syndrome is a kidney condition characterised by: •very high levels of protein in the urine (proteinuria) •low levels of protein in the blood • swelling, especially around the eyes, feet, and hands. Other indicators include a high cholesterol level in the blood, and sticky blood which can cause blood clots in the legs (deep vein thrombosis) or lungs (pulmonary embolus). Some causes are serious.
What causes Nephrotic Syndrome?
It results from damage to the kidneys’ glomeruli – tiny blood vessels that filter wastes and excess water from the blood and send them to the bladder as urine. We eat about 80 g of protein per day. This goes into the blood and then to the kidneys. Healthy glomeruli allow less than 0.4 g (400 mg) of protein to escape into the urine per day. In nephrotic syndrome, more than 3 g of protein leaks through.
In the nephron, most salt and water are reabsorbed where?
In the proximal convoluted tubule.
Regulated reabsorption of sodium by the hormone aldosterone occurs in the….
Distal convoluted tubule.
eGFR
Estimated Glomular Filtration Rate A test used to measure kidney function. Measures the percentage of normal kidney function and is calculated by a laboratory based on the amount of creatinine in the blood.
Stages of Chronic Kidney Disease (CKD)
- eGFR greater than 90mls/min, some signs of damage other tests. 2. eGFR 60-90ml/min with some sign of kidney damage 3. eGFR 30-59ml/min, moderate reduction in kidney function 4. eGFR 15-29ml/min, severe reduction in kidney function 5. eGFR less than 15ml/min, established kidney failure, dialysis or kidney transplant may be needed.
What are the three stages of acute kidney injury?
- Pre-renal failure 2. Intra renal failure 3. Post renal failure
Acute kidney injury
The loss of kidney function which occurs over a number of hours or days causing a build-up of nitrogenous waste products which disturb volume, electrolyte and pH homeostasis.
The stages of renal disfunction defined by:
- Changes in serum creatinine levels in the urine 2. The glomerular filtration rate or urine output
Pre-renal failure
The physiological reaction to hypo-perfusion of the kidney. Blood flow to the kidney is maintained by stimulus of the renin-angiotensin-aldosterone system which helps regulate blood volume. When renal perfusion is re-established the renal function should recover. Continued decline in perfusion can result in Intra-renal failure.
Intra-Renal Failure
O
Acute Tubular Necrosis
Caused by ischemic or nephrotoxic changes in the kidney. Can occur as a result of prolonged pre-renal failure (reduced blood flow to the kidneys). Nephrotoxic changes can include use of nephrotoxic drugs, radio-contrast dye, antifreeze and anesthetics.
Post Renal Failure
Occurs anywhere between the rental tubules and the urethral outlet resulting in obstruction of urine flow.
Acute interstitial nephritis
??
Dysuria
Painful urination
Bacteriuria
The presence of bacteria in the urine
Prophylaxis
Any measure taken to prevent health problems.
Hyperkalemia
Abnormally high levels of potassium in the blood.
Functions of the Renal System
- Excretion of Nitrogenous Waste 2. Regulation of Blood pH 3. Regulation of Blood Electrolyte Balance 4. Regulation of Blood Pressure 5. Production of hormones
Hormones of the Urinary System
- Calcitrol - regulates calcium homeostasis 2. Erythropoietin - stimulates red blood cell production
Calictrol
A hormone which regulates calcium levels in the blood
Three main process in the production of urine
- Filtration 2. Selective Reabsorption 3. Tubular Secretion
Deamination
The breaking down of amino acids (from protein molecules) which produces nitrogenous waste (ammonia). Ammonia is then broken down into urea by the liver which is less toxic.
Encephalopathy
General disease that affects the brain. Patients with liver disease can not break down ammonia and die from encephalopathy due to the build up of ammonia.
Uremia
Excess urea in the blood. In patients with advanced kidney disease they can make urea but not excrete it and die of uraemia.
Function of the Bowman’s Capsule and Glomerulus
Blood is forced through the glomerular capillaries filtering out micro-moluecules like small ions, sodium, glucose, amino acids. This is called filtrate. Red blood cells and plasma proteins are too large to fit through the filter.
Glomerular capillary pressure
55mmHg
Average pressure in body capillaries
25mmHg
Name the process through which the blood is filtered and becomes urine.
- Blood the kidney through the afferent capillary. 2. Is pushed through the glomerulus. 3. Enters into the Bowman’s capsule as filtrate 4. Enters the proximal convoluted tubule 5. Enters the loop of henle 6. Enters the distal convoluted tubule 7. Enters the collecting duct
Function of the Proximal Convoluted Tubule
Active reabsorption sodium, glucose, etc get actively (ATP) pumped out of the tubule back into the blood capillaries. At the end of this process about 65% of filtered salt and water are reabsorbed. Most filtered nutrients (amino acids and glucose) are also reabsorbed here.
Loop of Henle
The descending loop water diffuses down the concentration gradient out of the loop and into the renal medulla. This side is ONLY water permeable. In the ascending loop sodium, potassium, and chlorine ions are pumped out into the renal medulla. This side is NOT permeable to water. 20% more salt and water are reabsorbed here.
Distal Convoluted Tubule
Final reabsorption of sodium. The levels are regulated by the hormone aldosterone according to the needs of the body. Tubular secretions are carried out here which is the active pumping of unwanted substances into the urine (like drugs and toxins). This rids the body of unwanted substances that would otherwise stay in the blood. Hydrogen ions are removed from the plasma by tubular secretion when the pH of the blood is too low. Bicarbonate can also be reabsorbed into the plasma to help neutralize acidity.
Collecting Duct
Begins at the end of the Distal Convoluted Tubule and passes through the renal medulla draining into the renal pelvis. Anti-diuretic hormone determines how porous the collecting duct is as it passes through the medulla and determines how much more water gets reabsorbed (diffused into the salty medulla) before leaving the kidney via the ureter.
Reabsorption of Glucose in Diabetes
In diabetic patients there is so much glucose that the proximal convoluted tubule cannot reabsorb all of it (it exceeds the renal threshold). Glucose is therefore passed out in the urine. This also means that not as much water can be reabsorbed and more water passes out in the urine (one of the symptoms of diabetes).
Aldosterone
A hormone secreted by the adrenal glands which controls the amount of sodium in the body. Promotes the reabsorption of NA+ by the distal convoluted tubule by active transport in exchange for secretion of K+ to balance the number of positively charged ions in the plasma. Secretion is regulated by the kidneys.
Renin
An enzyme secreted by the kidney when BP, blood volume or NA+ are low which activates Angiotensinogen to become Angiotensinogen 1. Angiotensinogen converting enzyme (ACE found in the lungs) converts Angiotensin 1 to Angiotensin 2.
Angiotensin 2
A powerful vasoconstrictor which raises blood pressure and stimulates Aldosterone secretion from the adrenal cortex.
Tubular Secretions
Occur in the distal convoluted tubule. Tubular secretions are the active pumping of unwanted substances into the urine (like drugs and toxins). This rids the body of unwanted substances that would otherwise stay in the blood.
Anti-diuretic hormone (ADH)
Produced by the posterior pituitary gland. Works by making gaps bigger between cells of the collecting ducts so water can diffuse out of the urine and into the peritubular capillaries.
Causes water retention.
Works on the DCT and the Collecting Duct
Erythropoietin
Hormone produced by the kidneys which when plasma oxygen levels are low stimulates bone marrow to produce more erythrocytes (red blood cells).
Calcium
Vitamin D is required for Calcium absorption. Mostly stored in bone but also important for: - contraction of process muscles - immune system - blood clotting - nerve and muscle function - function of cardiac muscle and conduction
Hypocalcemia
Too little calcium. Causes muscle spasm due to increased nerve excitability.
Hypercalcemia
Too much calcium. Reduces excitability of nerves and produces muscle weakness. Risk of kidney stones.
Parathyroid hormone
Produced in the parathyroid glands mainly responsible for regulation of calcium levels.
Blood Plasma
A solution of water with solutes dissolved in it including: - glucose - urea - amino acids - electrolytes - acid (H+ ions) - drugs and toxins - hormones - plasma proteins
Glomerular filtration rate (GFR)
120ml per minute of which 119ml are reabsorbed by the body.
Peritubular capillaries
Surround the nephron and return reabsorbed materials to the blood.
Substances actively transported out of the filtrate back to the plasma
- Glucose 2. Sodium
How does sodium affect blood pressure?
If too much sodium is retained by the body then extra water is also retained resulting in an increase in extracellular fluid increases thereby increasing blood pressure. If not enough sodium in the body, body fluids are lost to maintain the correct osmotic pressure, therefore extracellular fluid volume decreases and blood pressure drops.
Label the Parts of the Kidney
What are the functions of the kidney?
- Removal and excretion of waste products
- Regulation of Fluids
- Regulation of electrolytes
- Regulation of Acid-Base Balance (H+ and bicarbonate ions)
- Vitamin D activation
- Blood pressure regulation
- Erythropoietin production (regulation of red blood cell production)
Describe the Renin - Angiotensinogen Cycle
- Fall in blood pressure
- Kidney releases the hormone renin
- Renin is converts angiotensinogen (released by the liver) to angiotensin I
- Angiotensin Converting Enzyme (ACE) released by the lungs converst Angiotensin I to Angiotensin II
- Angiotensin II is a vasoconstrictor which increases BP. It also stiumulates the adrenal gland to produce aldosterone
- Aldosterone causes salt retention, therefore water retention and raises fluid in the blood to raise BP.
Hematemasis
Vomitting blood
Melena
Passing blood in the stool.
Hyperkalemia
Abnormally high levels of potassium in the blood.
Hypercalcemia
Abnormally high levels of Calcium in the blood.
Encephalopathy
Condition that affects the brain.
In liver disease the liver cannot convert toxic ammonia to urea causing this.
Uremia
In kidney disease urea can be made but cannot be excreted.
Excess uric acid in the blood causes gout.
Proteinuria
Caused by damage to the capsular epithelium causing wider holes allowing proteins to pass through the glomerulus into the Bowman’s Capsule.
